719 FXUS66 KSEW 041008 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 308 AM PDT Fri Sep 4 2026 .SYNOPSIS... Upper level low along the Central Oregon coast this morning will hardly move through Saturday morning. The low will drift north over Western Washington Saturday afternoon and remain in the vicinity until moving east Sunday night into Monday morning. Dry northwesterly flow aloft later Monday into Tuesday. A weak system will brush the area Thursday. && .SHORT TERM /TODAY THROUGH SUNDAY/... Satellite imagery shows upper level low along the Central Oregon coast early this morning. Showers spinning around the low moving off the Cascades into the lowlands of Skagit and Snohomish county. Doppler radar also indicating isolated showers over the south Puget Sound. Temperatures at 3 am/10Z under mostly cloudy skies were in the upper 40s to mid 50s. So far so good with the model predictions for where the low would go the last 24 hours. Low not moving much in the next 24 hours staying over Western Oregon. Once this current batch of showers rotates through early this morning a little break in the activity for the remainder of the morning. Air mass becoming somewhat unstable in the afternoon with showers developing over the higher terrain. Light east southeasterly flow aloft will try and push the showers into the lowlands late this afternoon into the evening hours. Winds at 700 mb and 500 mb 10 knots or less will make it hard for the showers to get all the way to the Puget Sound. With the light flow aloft any convection that does form has the potential to produce at least a brief heavy downpour with the cells moving slowly. Shower activity drying up in the evening hours with mostly cloudy skies overnight. A little bit of sun today pushing highs in the 60s and lower 70s. Lows tonight in the mid 40s to mid 50s. Low starts to drift north Saturday morning ending up over Western Washington Saturday afternoon. Like today, showers developing over the higher terrain by late morning will try and float down into the lowlands in the afternoon and early evening hours. Light flow aloft continuing with the low overhead making it most likely the convection over the Cascades only gets to the Cascade foothills with the activity over the Olympics not getting all the way to the ocean. Showers dissipating in the evening with partly cloudy skies into Sunday morning. Persistence a good forecast for the temperatures Saturday and Saturday night. Highs maybe a couple of degrees warmer than Friday. Low weakening but remaining in the vicinity Sunday. Could still see a shower over the Cascades especially the South Cascades in the afternoon otherwise just partly cloudy skies. Highs in the upper 60s to mid 70s. Felton && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Model solutions have been in good agreement for a few runs that the low kicks out to the east Sunday night and Monday. Dry northwesterly flow aloft developing over the area Monday will continue into Tuesday. Western Washington in a lull Wednesday with a weak upper level low developing well to the southwest and a weak system starting to slide down the British Columbia coast. System brushing the area Thursday for a slight chance of showers. Temperatures near normal through the period with mostly sunny days and partly cloudy nights. Highs upper 60s to mid 70s. Lows in the upper 40s to mid 50s. Felton && .AVIATION... Variable flow aloft this morning as upper level low moves very slowly over W WA. Surface winds at most terminals also light and variable with speeds less than 5 kts. This looks to persist for most terminals, although some could see a shift to southerly winds this morning with speeds remaining light. Direction will shift to west or northwesterly this afternoon. Terminals on the east side of the Sound will see winds turn again more northerly in the evening. Speeds for all terminals will increase some, generally ranging 4-8 kts to finish the TAF period. Widespread VFR conditions this early morning, although isolated patches of MVFR to IFR conditions are present along the coast, over the islands and in the SW interior. Cigs may lower a little more this early morning, however nothing indicating that bases will dip into lower flight categories. VFR conditions expected to persist throughout the TAF period as cigs lift further in the afternoon. KSEA...VFR conditions this early morning and are expected to persist as per above discussion. Models had suggested the prospect, albeit a minor one, of low clouds or fog in the 12-15Z time frame, but at this time, while there are FEW to SCT clouds around 2500, clouds at this level remain broken up enough to keep flight category persistent. Southerly winds this morning and early afternoon generally 4-8 kts becoming northwesterly mid-afternoon, then north to northeasterly tonight with similar speeds. 18 && .MARINE... Marine forecast remains uneventful as winds and seas remain below any sort of headline criteria. Broad low pressure remains in place, with showers and a few thunderstorms possible again today, which could bring isolated gusty outflow winds. Otherwise, northerly winds develop over the waters Saturday through the start of next week. A marginal westerly push through the Strait of Juan de Fuca around Monday looks to be the next potential period of advisory strength conditions. Seas currently 4 to 6 ft, expected to ease just a little more this afternoon, down to 3 to 5 kt...and will remain there through the first half of next week. 18 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$

899 FXUS66 KPQR 041137 AFDPQR Area Forecast Discussion National Weather Service Portland OR 437 AM PDT Fri Sep 4 2026 Updated aviation discussion. .SYNOPSIS...An unsettled airmass remains overhead into the weekend with lingering showers gradually diminishing day to day. Then conditions trend drier by the early to middle portion of next week as temperatures slowly claw their way back near normal for early September. However, uncertainty in the large scale pattern grows noticeably around the middle portion of next week. && .DISCUSSION...Friday through Thursday...Radar imagery around 12:30 AM PT on Friday shows rain showers have mostly cleared north of Salem with showers continuing south of Salem. The vertically stacked upper-level and surface closed low pressure system is spinning just off of the central OR coast with a shortwave producing the current showers. Ensemble guidance is in agreement that the core of the upper low has stopped pushing south and will slowly move east and inland into west-central OR today. With the core of the low beginning to move overhead, CAMs indicate showers will be less widespread today than yesterday, with better chances south of the Portland metro area and over the Coast Range and Cascades. As daytime heating increases today, convective potential increases, as well. Deterministic model sounds along with the HREF indicate just enough CAPE extending into the mix-phased region of the atmosphere for a lightning strike or two to be produced in stronger cells generally after 10 AM. However, a glaring lack of vertical shear means any storms which do develop will be short-lived and pulse-like. Infrequent lightning, heavy rain, and gusty outflow winds are the primary impacts. Any activity then quickly decreases after sunset into Friday night. Over the weekend, the majority of deterministic and ensemble members continue to show the broad upper-level closed low pressure system holding firm over the Pacific Northwest with multiple shortwaves within the flow. This will cause lingering shower chances over NW OR and SW WA, most likely during the daytime hours and over terrain features as diurnal heating likely plays a major role in shower generation. Also can`t rule out stronger cells and a thunderstorm or two forming in the afternoon and evening hours with similar impacts to Friday. Confidence is high that temperatures remain below normal for this time of year with upper 60s to mid 70s in the interior lowlands, 60s along the coast, and 40s to low 60s over the Cascades (coldest at higher elevations). It might be worth packing a jacket/coat if you plan on venturing into the mountains this weekend. The majority of ensemble members finally show the upper low beginning to accelerate eastward on Monday, favoring the return of dry conditions by Tuesday and a gradual warming trend. After Tuesday, ensembles begin to deviate from one another when trying to resolve the upper-level pattern, particularly in regards to a ridge of high pressure trying to develop over the Rockies into southeast Oregon while a trough amplifies over the eastern Pacific. Currently around 60% of ensembles favor a warmer/drier solution with highs above normal (mid 80s) by Wednesday/Thursday while the remaining 40% point to a somewhat cooler solution (low to mid 70s). Will have to see how guidance trends as we get closer to next week. -03/99 && .AVIATION...Through 12Z Saturday...A low pressure system remains over the area, maintaining moist, southwest flow aloft and southerly to variable light winds at the surface. Expect VFR conditions to prevail through the TAF period, with the exception of a 30-40% chance of MVFR conditions in showers at KONP through 18Z Fri. Showers continue Friday morning, mainly south of the Portland metro. Shower chances continue through the day Friday, though less widespread than previous days. Chances of thunderstorms around 15- 30% return Fri after 18z. Any thunderstorms that do develop will have the potential to produce lightning and gusty/erratic winds. Thunderstorm chances end by 02-03z Sat with showers becoming much more isolated. Expect light and variable winds inland and southeasterly winds around 4 to 8 kt along the coast to become light and northwesterly towards Fri afternoon. KPDX AND APPROACHES...VFR with scattered showers through the day Friday. There is a 15% chance of thunderstorms Fri afternoon. Light winds through the TAF period, ranging from southeasterly to variable. ~03/12 && .MARINE...A low pressure system will continue to weaken at the surface into Friday morning as it sits off of the central OR coast. Winds over the coastal waters have eased below 20 kts and are more easterly. Winds will continue to ease through Friday morning, becoming northerly Friday evening then more light and variable by Saturday morning. Seas have fallen below 10 ft and will continue to subside to 4 to 5 ft by Friday evening. Also, a 15% chance for thunderstorms exists across the inner waters south of Cape Foulweather Friday afternoon, which could produce lightning and gusty/erratic winds. Light offshore flow becomes northerly later Saturday into Sunday as weak high pressure rebuilds over the waters. Seas will remain around 3-5 ft through the weekend. Conditions look to remain rather benign into early next week. -03/DH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...None. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

158 FXUS66 KMFR 041414 AFDMFR Area Forecast Discussion National Weather Service Medford OR 714 AM PDT Fri Sep 4 2026 .KEY MESSAGES... * Scattered showers this morning. Showers will become numerous this afternoon and evening, with isolated to scattered thunderstorms. Activity will be focused on Coos, Douglas, and northern Klamath counties and northward. Amounts of a quarter of an inch or less will be common. * Temperatures remain 15 to 25 degrees below normal, with gradual warming through the weekend and into early next week. * A few stray showers are possible Saturday (especially in our northern section again), but activity will increase again Sunday and be accompanied by a slight chance of thunderstorms. The probability will be highest in and near the Cascades. * More seasonable September weather returns with a warming trend Monday into Wednesday. * Higher uncertainty late next week, but with another episode of wet weather possible. && .DISCUSSION...A broad, very slow moving upper level trough will continue to be the main driver of our weather through Sunday. This is the western lobe of a strong omega blocking pattern aloft over the contiguous United States, with a strong ridge centered over the Midwest. A shortwave rotating through the trough, and the aid of day-time heating will enhance shower activity today through this evening, with thunderstorms expected to be embedded. The highest probability will be in northern and eastern Douglas County, with activity possible across our area, but the probability of showers and storms tapering off to the south and east. The main uncertainty for Saturday is the extent to which the trough will shift/wobble north-northeastward. The NBM and GFS are on the progressive side of solutions, with activity expected to be focused upon Washingtion and northern Oregon. But, the ECMWF and its ensemble members do support a few light, stray showers making it into Coos and Douglas counties. A decrease in cloud cover is expected to help bring warmer temperatures. The trough is expected to wobble back southeastward on Sunday with a shortwave bringing an enhanced, increasing probability of showers and also isolated thunderstorms...with the highest probability near and in the Cascades. Another effect will be several degrees of cooling of high temperatures. The trough is expected to finally kick eastward Sunday night into Labor Day with a break between systems, before the next trough tracks southward, offshore from California. This is expected to bring a few days of dry and warmer weather to our area, at least into Wednesday and likely through Thursday. Late in the week, into next weekend, the interaction/track of the existing trough offshore of California, and another trough in the northern branch of the jet stream is highly uncertain. But, the probability is that a trough influenced or dominated pattern will bring at least modest cooling and at least sporadic shower chances. && .AVIATION...04/12Z TAFs...Conditions early this morning are mainly VFR with scattered showers from the coast to the Cascades. But, there are areas of LIFR/IFR, and patches of MVFR at the coast, and in the vicinity of Klamath Falls. These ceilings will lift and break later this morning, with patchy MVFR lingering at the coast. The probability of showers and thunderstorms will increase from late morning into the early evening, with the highest probability in Douglas County and northern Klamath County (10-30%). Shower activity will diminish later in the evening with ceilings lowering to LIFR/IFR again at the coast, and patchy valley LIFR developing (again likely near Klamath Falls after 12Z). && .MARINE...Updated 200 AM PDT Friday, September 4, 2026...Gusty south winds in the inner waters, and steep seas will continue through this morning while a surface low meanders just offshore of southern Oregon. Winds will diminish later Friday as the low shifts northeast and moves onshore. Winds will shift to the north Saturday morning, but remain light with relatively calm seas from the weekend into early next week. Steep seas are possible south of Gold Beach on Monday afternoon, where north winds will briefly increase. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until noon PDT today for PZZ350-356-370-376. && $$

658 FXUS66 KEKA 040749 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1249 AM PDT Fri Sep 4 2026 .KEY MESSAGES... * A general troughing pattern will bring additional light rain over the region today and periods of unsettled weather over the weekend. * Overnight temperatures for the interior will turn chilly, bringing chances for frost this morning and through the weekend. && .SYNOPSIS...Early this morning, temperatures for the interior will turn chilly, bringing chances for frost this morning and through the weekend. A general troughing pattern will bring additional light rain chances today and periods of unsettled weather over the weekend. && .DISCUSSION...A second colder and somewhat unstable area of low pressure will continue to move by the area. This will continue the chances for showers and perhaps a couple of coastal thunderstorms. As the environment attempts to clear out through this morning, much cooler overnight lows will develop for the interior. If clouds do clear out and fog does not develop, areas of frost will be likely for the interior. There is still some question on the amount of clearing or even additional light showers, especially with the numerous troughs forecast through the weekend. These will also bring a shot for some isolated thunderstorms. Despite the uncertainty, a Frost Advisory has been issued for southern Trinity, northeastern Mendocino, and northern Lake counties due to the forecast lows being in the mid 30s and the fact these cold temperatures are occurring so early in meteorological fall. The broad upper low to the north will stall ahead of blocked flow through the weekend, with weaker shortwave disturbances rotating in. More weak troughing may redevelop behind it. This gives mixed signals for the extended outlook. There looks to be some sort of warmup early to mid next week, but if it occurs, it should be short lived if the troughs continue moving through. There are also questions about whether tropical moisture may stream northeast toward the region from decaying tropical systems well off the coast. Model guidance has a large variance in possibilities ranging from completely dry after Sunday to several chances of showers and possibly thunderstorms mid to late week. && .AVIATION...(06Z TAFs)...Generally unsettled weather continues with isolated showers or drizzle moving through this morning, especially through Del Norte County and northern Humboldt. Ceilings are expected to lower to MVFR to IFR by this morning with some lifting into the afternoon for coastal terminals. Skies will continue to clear for interior regions of Northwest California through the next 24 hours. Ceilings will drop again for coastal terminals later this evening. && .MARINE...A trough from the north is bringing steep NW swell at 8 to 11 ft at 11 seconds to much of the waters. With buoys reporting over 10 feet a Small Craft Advisory has been issued for waters north of Cape Mendocino through this morning. Otherwise winds will be light for most of the waters through Saturday. Then, northerlies will strengthen some through the weekend, mainly over the southern waters south of Cape Mendocino. The northerlies do not look to fully strengthen again until early next week. Hurricane Marie will deliver a long period southerly swell Saturday. Though small, at around 4 ft at 16 seconds, is a larger than typical swell from this direction. && .BEACH HAZARDS...Hurricane Marie will usher in a long period southerly swell of 3-4 feet at 16 seconds for south facing beaches by Saturday into Sunday. Thus, there could be a risk of sneaker waves, especially if the swell comes in slightly larger. Sneaker waves are a unique hazard, with up to 30 minutes between waves. Large, unexpected waves can sweep across the beach without warning, sweeping people into the sea from rocks, jetties, and beaches. These sneaker waves can also move large objects such as logs, crushing anyone caught underneath. Even ankle to knee deep water can knock you down and drag you out when a sneaker wave hits. Pay attention and stay above the high water line and any wet sand to stay safe. If the ground is wet, waves have surged there recently. Stay safe and never turn your back on the ocean! && .EKA WATCHES/WARNINGS/ADVISORIES... CA... Beach Hazards Statement from late tonight through Monday evening for CAZ104-109. Frost Advisory until 9 AM PDT this morning for CAZ108-110- 111-114. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 9 AM PDT this morning for PZZ450- 470. && $$ NOTE: The full forecast discussion is now regularly issued between 10 am/pm and 1 pm/am. Additional updates will be issued as needed. Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png

455 FXUS66 KMTR 041139 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 439 AM PDT Fri Sep 4 2026 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 1151 PM PDT Thu Sep 3 2026 - Coastal Flood Advisory in effect around high tide bayside Marin County Friday afternoon and evening - Hazardous beach conditions at Pacific Coast beaches Friday through Monday - Below normal temperatures through the weekend, a gradual warming and drying trend Monday through Wednesday && .SHORT TERM... Issued at 103 AM PDT Fri Sep 4 2026 (Today and tonight) A 500 mb low pressure system (geopotential height 555 decameters, much below normal for early September) will move onshore over Oregon today. Over our forecast area 500 mb heights are in the 570 decameters range which is near the 10th percentile for early September. If it was any time in the cool season 570s would not be a big deal or impressive. However, for early September much below normal heights over our area are due to chilly temps in the air column above per inspection of the 925 mb, 850 mb, 700 mb temps on the Oakland air upper sounding. These readings are near or less than the 10th percentile as well, i.e. at the lower end (cool temps) but within Oakland upper air long term climatology for early September since 1948. The current weather pattern is a great example of water vapor rich air (precipitable water was 1.35", near the early Sep max moving average) and cool air within a trough of low pressure resulting in areas of measurable precipitation, in early September (normally the third driest month behind July and August) when it`s typically warmer/hot and dry when e.g. Sep-Oct favor offshore winds. The larger scale northern hemispheric pattern continues to be active with ~ 6 long wave troughs, a signature of rather strong jet stream winds, wind shear and unsteady flow. The August Pacific Decadal Oscillation remained negative. The North Pacific high and its clockwise wind flow remained rather robust. A strong equator to pole temperature gradient continues, and not to mention three hurricanes at the same time in the eastern Pacific, a powerful show of thermodynamics (flow of heat) from sea surface to the highest thunderstorm cloud tops. Just like a cup of hot coffee, an open system where heat and mass are free to flow, 100% whenever there is an imbalance heat and mass will flow. Back to our area, within the aforementioned long wave trough a much smaller scale cool frontal boundary with areas of light measurable rain will continue to move southeastward over the forecast area today. Early September rainfall has reached a few records, we plan to send a record event report on this overnight. Dry weather revisits the area today in the post frontal cooler than normal air mass for early September. Forecast daytime highs will vary from the 60s coastside/bayside to the 70s/80 inland. && .LONG TERM... Issued at 103 AM PDT Fri Sep 4 2026 (Saturday through next Thursday) Jet stream winds and additional shortwave energy will generally reach the base of the 500 mb low pressure system over the west. This will provide forward motion to the low, nudging the southern U.S. high forward through early to mid next week. The redevelopment of 500 mb troughing over the eastern Pacific during the middle of next week will provide a small chance of entraining tropical moisture. This is a long time from now, it`s a low confidence forecast, but bears monitoring. && .AVIATION... (12Z TAFS) Issued at 424 AM PDT Fri Sep 4 2026 A weak cold front is exiting the southern Bay Area and moving through the Central Coast this morning. Showers remain in the vicinity of SJC and LVK this morning but are expected to progress eastward over the next few hours. Patchy stratus has developed this morning after high clouds associated with the cold front cleared out. Stratus is more widespread across the North Bay where confidence is higher in MVFR to LIFR conditions prevailing. Comparatively, stratus is patchier over the Bay Area which is decreasing confidence as to how long stratus will linger this morning. Included a tempo for patchy stratus at most sites this morning where confidence was lower through 16Z. Breezy onshore winds return during the afternoon before winds ease overnight. Stratus is likely to return tonight but it will be later than normal. The forecast currently leans on later arrivals between 09-12Z with the marine layer remaining mixed out through Saturday. Initial guidance suggests the marine layer will try to redevelop around 2000 ft by late this weekend so we may see more traditional stratus patterns return by then. Vicinity of SFO...Stratus has cleared in the vicinity of SFO and the SF Bay with confidence low that stratus will successfully redevelop this morning. VFR conditions prevail this afternoon/evening with scattered clouds around 5000 feet moving in. Guidance is mixed as to if stratus will reach SFO tonight. For now, leaned on the side of VFR conditions continuing given the marine layer being mixed out/struggling to redevelop. If stratus does develop it will likely be later in the night (approx. after 08Z). SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...The cold front is making its way through the Central Coast with MVFR CIGs prevailing at both sites. As the front moves southwards, ceilings are expected to lower slightly and be more on the IFR-MVFR border. Stratus will clear by late morning with VFR persisting into the evening before stratus returns late tonight. Breezy onshore winds return during the afternoon and evening before winds decrease overnight. && .MARINE... (Today through Wednesday) Issued at 424 AM PDT Fri Sep 4 2026 A gentle to moderate west to northwesterly breeze will continue through the weekend with diurnal fresh to strong gusts across the Monterey Bay, the Big Sur Coast, and near Point Reyes. Occasional fresh to strong gusts are possible within the San Pablo and San Francisco Bays. More widespread fresh to strong gusts return early next week with hazardous conditions for small craft likely before winds diminish mid to late week. Long period southerly swell associated with tropical activity well to our south will arrive today and linger into next week. Unsettled weather is possible mid to late week as tropical moisture tracks northwards in the Eastern Pacific. && .BEACHES... Issued at 1010 PM PDT Wed Sep 2 2026 A Beach Hazards Statement is in effect Friday-Monday as the swell from both Hurricane Marie and Hurricane Karina reaches the coast. As these hurricane whip up the ocean, the waves travel over 1,000 miles in all directions, gradually flattening out to low amplitude, but long period swell. These waves aren`t very intimidating if you`re on a boat in the open ocean, but the long period allows them to push much farther up the beach. Long period swell always increases the chance for sneaker waves, but that`s particularly true this weekend since there are 2 different sets of southerly swell, and their energy will periodically combine. In addition to sneaker waves, expect strong rip currents and breaking waves up to 10 ft. As this is a holiday weekend and the weather is otherwise pretty nice, the exposure to the risk is high. Avoid the water if you`re not an expert swimmer. If caught in a rip current, swim parallel to shore until you stop feeling the pull. Even on the beach, be prepared for sneaker waves this weekend and never turn your back on the ocean. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement through Monday evening for CAZ006-505- 509-529-530. Coastal Flood Advisory from 4 PM this afternoon to 9 PM PDT this evening for CAZ506. PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Mry Bay. && $$ SHORT TERM...Canepa LONG TERM....Canepa AVIATION...Kennedy MARINE...Kennedy Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea

800 FXUS66 KOTX 041114 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 414 AM PDT Fri Sep 4 2026 .KEY MESSAGES... - Cool and showery weather expected through Labor Day Weekend with isolated thunderstorms. - A warming and drying trend returns around the middle of next week. && .SYNOPSIS... Active weather sticks around through Labor Day Weekend with scattered showers, isolated thunderstorms, and cooler than normal temperatures. A warming and drying trend commences around the middle of next week as higher pressure returns to the region. && .DISCUSSION... Friday through Monday: An upper level low pressure system will spin over the Inland Northwest keeping temperatures seasonably cool and the weather active. The center of the low is situated over northwest Oregon. A deformation band forming on the eastern flank will swing across the Idaho Panhandle through early Friday morning. Periods of light to moderate rain will soak the ground from the Lewiston- Clarkston Valley up across the Palouse region, and across the southern to central Idaho Panhandle. Total precipitation under this band will be up to between 0.50-1.0 inches across much of this area. Much needed rainfall after a warmer and drier than average June- August. Steady rain will transition to showers for Friday afternoon. Showers will favor the higher terrain, but even the Columbia Basin will see at least isolated showers. Weak surface based instability over the Cascades and the mountains of north-central Washington will bring an isolated threat for thunderstorms. Any storms that develop this afternoon will be capable of brief heavy rain, and infrequent lightning strikes. The center of the upper level low wobbles around over the Northwest Region through at least Sunday. This will keep the region conditionally unstable. Best chances for showers will come in the afternoon with diurnally forced showers. Perturbations that spin around the upper low will also help to force precipitation. The next one looks to be around Saturday afternoon with more organized development of showers across extreme eastern Washington into the Idaho Panhandle. Then another round with another shortwave spinning in across these same areas for Sunday night into Monday. It`s really tough to pin point how much precipitation will fall as there will be some convective elements in place with modestly steep lapse rates at mid levels of the atmosphere. There will be the potential for heavier showers that brings wetting rains (greater than a tenth of an inch), and this will all largely be beneficial for the ongoing drought across the region. Where rain may be of a nuisance is if it gets heavy over a recent burn scar, and that would bring a small chance for minor flooding impacts. The upper level low gets picked up by the Polar Jet stream around late Sunday into Monday. A 30-60% chance of precipitation will continue across the eastern half of the region while the Cascades begins to dry out. Temperatures will be below normal with highs generally in the upper 60s to mid 70s through Labor Day Weekend. Breaks in the cloud cover overnight may yield patchy fog as rain will moisten up the boundary layer. The next few days is a reminder that the fall season is right around the corner. Monday night through Friday: The Inland Northwest remains under a baggy longwave trough of low pressure into next week. A longwave high pressure area will be situated over the central portion of the U.S. The trough axis will be situated more offshore and it looks to dig around the Tuesday into Wednesday timeframe. The equatorial Pacific is also quite active with tropical systems, and there`s some indication that one of these systems could get entrained into the mid latitudes off of the coast of Baja California by Wednesday. This tends to muck up the models with reduced confidence in the extended forecast. The general consensus, however, is that the ridging in the central U.S. will build in toward the Inland Northwest with a warming and drying trend around mid week. We will need to keep an eye on that tropical moisture for later in the week though as there is a possibility for some of that to get entrained and advect northward into the region. Early indications is that if this happens, it will be a small fraction and won`t be more than a minor impact. /SVH && .AVIATION... 12Z TAFS: Light to moderate rain will fall across extreme eastern Washington into the Idaho Panhandle this morning under a deformation band for the next 4-6 hours. Ceilings will approach but most likely stay above MVFR for KGEG and KSFF as this band has been under performing in southeast Washington. Ceilings will lift to VFR for KCOE around 18z as showers depart to the north. Isolated afternoon thunderstorms expected over the Cascades and mountains of north-central Washington late this morning into the afternoon. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions after the band of rain in central Washington departs northward after 18z. ----------------------- Confidence descriptors: Low - Less than a 30 percent chance Moderate - 30 to 70 percent chance High - Greater than a 70 percent chance For additional probabilistic information for NWS Spokane airports, please refer to the Aviation Dashboard on our webpage: https:/www.weather.gov/otx/avndashboard && .Preliminary Point Temps/PoPs... Spokane 67 44 70 46 72 48 / 40 10 20 20 10 40 Coeur d`Alene 67 44 71 46 73 48 / 50 0 30 20 30 50 Pullman 65 41 68 41 70 42 / 50 0 20 10 20 50 Lewiston 70 51 73 52 74 54 / 30 10 30 10 20 60 Colville 67 39 71 39 74 42 / 30 0 30 30 10 30 Sandpoint 65 42 68 43 71 45 / 40 0 30 20 30 40 Kellogg 63 42 68 45 70 47 / 50 10 40 20 40 60 Moses Lake 71 45 72 46 76 48 / 10 0 20 20 10 30 Wenatchee 70 52 71 54 76 58 / 20 10 40 20 10 30 Omak 70 46 72 47 74 49 / 10 10 30 40 10 20 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

710 FXUS66 KPDT 041113 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 413 AM PDT Fri Sep 4 2026 .KEY MESSAGES... - Periodic shower chances (35-75%) across the mountain zones will continue through early next week, with lower chances elsewhere - Slight chance (15-25%) of isolated afternoon thunderstorms over the mountains through Monday - Below normal temperatures will continue through early next week, with near normal temperatures returning mid week && .DISCUSSION... Water vapor imagery tonight shows an upper level closed low over the PacNW, with the center of the low poised to move inland along the central OR coast. Meanwhile, nighttime satellite imagery shows cloudy conditions mainly across the Cascade east slopes, central OR, and the eastern mountains with clear to partly cloudy skies elsewhere. Though cloud cover is present, regional radar shows rain showers mainly outside of the forecast area, though a few light showers are moving over the Strawberry mountains and the southern Elkhorn crest. The PacNW will continue to be under the influence of the upper closed low through early next week, with persistent rain chances (rain/snow mix above 7.5kft) over the mountain zones. Afternoon temperatures across the region will be nearly 10-15 degrees below average each day, with afternoon high temperatures at their lowest in the mid 60s to mid 70s today (confidence 85-95%). While the upper closed low will remain parked over the PacNW through Sunday, the center of the low will remain west of the Cascade crest through Saturday before sliding east Sunday into Monday(confidence 80-90%). During this time, persistent rain shower chances (35-75%) will remain over the Cascades and eastern mountains each day, with shortwave impulses Friday/Saturday and the low passage Sunday/Monday producing light rain chances (15-40%) in the lower elevations. Isolated thunderstorms will be possible over the mountains today as weak instability develops with additional support from the cold core of the low aloft. As for precipitation amounts, the Cascades and Blues will see 0.1 to 0.25 inches of daily precip (confidence 70- 90%), with locally higher amounts where thunderstorms develop. Sunday into Monday, ensemble and deterministic members show the upper closed low beginning to push east, with the low over the forecast area during the day Sunday. While light to moderate rain showers are forecast across the area, the upper low being overhead and weak instability developing at the surface will also result in slight chances (15-25%) of isolated thunderstorms focused across the central OR Cascades and the eastern mountains Sunday afternoon and evening. By Monday evening, what is left of the upper level low will have pushed east of the region, with showers diminishing area wide. Tuesday, ensemble members are in good agreement of weak upper troughing developing from the PacNW into the eastern Pacific, though the forecast area within an area of split flow (confidence 55-65%). Winds will remain light under this pattern, with a warming trend bringing temperatures closer to normal. By Wednesday, ensemble members depict a weak cut-off low developing, however there is spread in the location of the low amongst ensemble solutions. Solutions (25% of cluster members) with the low offshore the OR/CA border favor light showers along the OR Cascade crest and Ochoco- John Day Highlands, while solutions (69% of cluster members) with the low further south favor dry conditions persisting. Spread in the evolution of the cut-off low only grows Thursday as members are split in timing, location, and strength of the low. Solutions (53% of members) that have the low become an open wave and approach the PacNW favor the return of widespread unsettled weather conditions, while remaining solutions (47% of members) favor a trough evolution that results in dry conditions across the forecast area. Confidence in forecast details is low (15-20%) for the mid- week period. Lawhorn/82 && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...VFR conditions to prevail through the period. Showers are expected to impact sites RDM/BDN between 22Z-03Z today, with dry conditions expected elsewhere. That said, there is a low chance (15-25%) of showers impacting sites ALW/PDT between 22Z-04Z as well. CIGS/vsby may drop to MVFR categories with heavy rain showers. Winds will be 12kts or less through the period. Lawhorn/82 && .Preliminary Point Temps/PoPs... PDT 71 42 69 45 / 10 10 40 0 ALW 72 48 71 49 / 30 10 30 10 PSC 74 45 73 45 / 10 10 30 0 YKM 73 47 71 47 / 10 10 30 10 HRI 74 45 72 45 / 10 10 40 0 ELN 69 41 68 42 / 20 10 40 10 RDM 64 34 67 37 / 50 60 10 40 LGD 68 40 71 41 / 40 20 50 10 GCD 68 40 70 41 / 20 30 40 0 DLS 75 51 74 52 / 20 20 50 30 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...82 AVIATION...82

436 FXUS65 KREV 040942 AFDREV Area Forecast Discussion National Weather Service Reno NV 242 AM PDT Fri Sep 4 2026 .KEY MESSAGES... * Light rain showers continue along and north of Interstate 80 into the afternoon with a low chance of thunderstorms. * Gusty winds will pose impacts to holiday travel and recreation today and Sunday. * Below normal temperatures, breezy afternoon winds, and low shower chances are favored next week. && .DISCUSSION... A swath of showers will continue to deliver light rain to areas along and north of the I-80 corridor through the morning before tapering in the afternoon. Weak instability from surface heating may allow isolated thunderstorms to develop in the afternoon near the Oregon border, but probabilities of this are only 10-20%. Another windy day is in store today with SW/W gusts increasing to 30-40 mph in the afternoon. Ridge gusts should vary from 45-65 mph throughout the day. Potential wind impacts include rough waters/more hazardous boating on area lakes -- including Lake Tahoe -- and bumpy flights into/out of regional airports. Drier and less windy weather prevails on Saturday before gusty winds and shower/thunderstorm chances return on Sunday. Highest rain probabilities (30-50%) on Sunday reside from Lassen County to the Oregon border, with a 10-20% chance of thunderstorms in the afternoon. Elsewhere, chances are 20% or less, but may increase (or decrease) depending on the depth/track of an upper compact cyclone and attendant shortwave. Winds become gusty once again Sunday afternoon, renewing wind impacts to holiday travel and recreation. Otherwise, this Labor Day holiday weekend is leaning on the cooler side with daytime highs in the 60s and 70s, which is 10-20 degrees below seasonal averages. Eastern Pacific troughing is favored to persist next week, extending cooler than normal temperatures, breezy afternoons, and low shower chances through the middle of next week. However, there remains high uncertainty in the prospect of remnant tropical moisture moving northward into the region. Should this happen to some extent, expect shower chances to increase around the middle of next week. -Salas && .AVIATION... Light rain showers may periodically lower CIGS/VIS to MVFR conditions at KTRK-KTVL through the morning, but shower activity should taper after 15Z. A few showers may pass over KRNO, but chances are lower (~20-30%). Low clouds may lead to mountain obscuration at all terminals today. 30-35 kt SW FL100 winds will maintain potential LLWS and mountain wave turbulence impacts into the evening before winds weaken. SW/W surface gusts are expected to increase to 20-25 kts at Tahoe Basin terminals and 25-30 kts at KRNO-KCXP-KMEV and KMMH in the afternoon. -Salas && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory until 9 PM PDT this evening NVZ001>004. CA...Lake Wind Advisory until 9 PM PDT this evening CAZ071>073. && $$

061 FXUS66 KSTO 032027 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 127 PM PDT Thu Sep 3 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Well below normal temperatures persist through this week - Wet weather continues this week, thunderstorms and scattered to widespread showers north of I-80 this afernoon and evening - Showers continue on Friday over the Sierra and southern Cascades and adjacent foothills - Mainly dry Saturday, with some mountain showers Sunday, mainly north of I-80 - There is the potential for some monsoonal moisture mid-next week, but confidence in details remains low at this point && .DISCUSSION... A cold front is traversing Northern California this afternoon, while the main upper-level trough located over the Northeast Pacific slowly dig southward. Scattered to widespread showers and isolated thunderstorms are expected mainly north of I-80 this afternoon and evening, including the N. Sacramento Valley. An additional half to an inch of rain is forecast over the west slopes of Shasta County, with the northern Sacramento Valley seeing a quarter to half of an inch. Some light showers or sprinkles are possible (10-15% chances) into the Sacramento Valley later this evening and into early Friday. In addition, there continues to be a 15-20% probability of thunderstorms this afternoon and evening in the mountains north of I-80, highest over the mountains of Shasta County and western Plumas County. Shower activity will gradually to taper off from west to east later this evening, with any lingering showers through Friday. Troughing will remains the dominant pattern through the weekend, maintaing cooler than normal temperatures. An upper low spinning centered over Oregon may have bring some weak disturbances in the mountains over the weekend, but Saturday has trended dry. On Sunday the center of the upper low passes along the California and Oregon border, with slight chance of mainly Shasta County showers, generally dry elsewhere. There is still some potential for monsoonal moisture moving into California next week, but confidence in precipitation potential from this extending into interior Northern California remains fairly low and now looks more likely mid next week. Currently the best potential for rain is over the mountains south of I-80 on Wednesday, especially in the mountains. Temperatures trend warmer, to near normal by Wednesday. && .AVIATION... MVFR ceilings with -SHRA moving along and north of I-80, while VFR conditions with mid to high level clouds southward. There is a 10% chance of a brief IFR with SHRA/VCTS for KRDD and KRBL through 00Z/02Z. Lingerings showers are expected to gradually taper off this evening into Friday. Valley south to west 10 to 15 kts through this afternoon with gusts up to 25 kts and Sierra gusts up to 30 to 40 kts until 06z Friday with lingering gusts over the Sierra through 18z Friday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

195 FXUS65 KMSO 040946 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 346 AM MDT Fri Sep 4 2026 .DISCUSSION... KEY MESSAGES: - Widespread showers and seasonably cool temperatures persist through the rest of the week and into early next week. - Scattered thunderstorms on Saturday. - 60-80% chance that Sunday into Monday rainfall could exceed one inch of additional rainfall from Missoula to northwest Montana! 50% chance that the Glacier Region experiences greater than 1.50" of rain! Very impressive rainfall amounts have been observed across north- central Idaho in the last 24 hours...generally around one inch of rain fell from northwest of McCall to Grangeville to Pierce! The heavier north to south oriented rainfall occurred as a spoke of energy will eventually move northwards into Canada later this morning. As this occurs, the steady rain will give way to partly cloudy skies with scattered showers/isolated thunderstorms this afternoon. Rinse and repeat tonight? A fairly strong 100 knot jet aloft will provide the lifting mechanism, interacting with a stalled frontal boundary to produce a mostly narrow southwest to northeast swath of steady moderate rain. Models shows this occurring from northern Lemhi County north and east to northern Powell County. So if you are traveling east of Missoula, be prepared for wet and cold conditions as lows will generally be in the 40s. On Saturday, with slightly warmer temperatures and possible breaks in the clouds, thunderstorms will be possible. Cloud cover will be a limiting factor in their strength. Heavy rain, lightning, gusty winds and small hail would be the main threats. The upper low will continue to bring rain chances on Sunday into Monday across the region as it begins to depart to the east and north towards Saskatchewan, Canada by early Tuesday. The range of rainfall amounts purely from this period could range from 0.25" to 1.00" over Idaho and southwest Montana, and 0.50" to 2.00" across northwest Montana! It finally looks like we may have a few days to dry out a bit next Tuesday through Thursday! The caveat could be that there could be lingering clouds from all the moisture. && .AVIATION...A south to north region of light to moderate rain will persist this morning across western Montana, then finally diminish by 04/1500Z or 0900 AM MDT. Sunny breaks are possible into the afternoon when showers and a few thunderstorms could be possible from near KSMN to KHRF to KMSO. An area of steady rainfall with lower ceilings will develop from Lemhi County north and east towards Powell County tonight. Scattered thunderstorms are possible on Saturday. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

123 FXUS65 KBOI 041142 AFDBOI Area Forecast Discussion National Weather Service Boise ID 542 AM MDT Fri Sep 4 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Showers and thunderstorms with local heavy rain today. - Areas of valley fog THIS MORNING AND early Saturday morning. - Temperatures 10 to 20 degrees below normal today, then around 10 degrees below normal Saturday and Sunday. - Cool Monday, then warming next week, with an increasing chance of thunderstorms Wednesday afternoon through Friday. && .SHORT TERM /Through Sunday Night/... Issued 218 AM MDT FRI SEP 4 2026 At 1 AM MDT radar showed a moderate to heavy rain band extending from Washington County/ID SSW-ward through Vale, OR, into central Malheur County/OR. Since then the band has shifted eastward into ID and has weakened since late evening when it had heavier rain in eastern OR. Radar showed the heaviest rain just west of Weiser/ID around midnight MDT, and a Flood Advisory was issued there for urban and small stream flooding until 3 AM MDT. Latest hi-res models show the rain band becoming stronger again in the eastern parts of Boise and Valley counties starting around 3 AM MDT, and especially the Wapiti Burn scar. A Flash Flood Watch is in effect on Burn scars through Friday in most of our CWA (except south of the Snake Basin), but greatest concern is on the Wapiti Burn Scar as the band should move right overhead 4-5 AM MDT. Meanwhile, a cold front reached Twin Falls and Jerome just before midnight with westerly gusts to 40 mph. The front will continue east today while colder air comes in from the west. Pre-dawn temps were in the 40s in the valleys and upper 30s in the mountains, with snow reported above 5500 feet in eastern OR. The cold air and pcpn were due to a deep upper low quasi- stationary on the Oregon coast. The low is forecast to gradually fill (i.e., weaken) through Saturday before moving inland Sunday and through our northern zones Sunday night. Back to today, instability will increase this afternoon leading to scattered thunderstorms in eastern Oregon late morning through afternoon, and southwest Idaho (mainly Owyhee County) by mid- afternoon and possibly the Treasure Valley late afternoon. Stronger storms will feature heavy rain and hail. Improving conditions will take place overnight through Saturday evening, but areas of fog will form overnight into Saturday morning after today`s rain. Becoming wetter again Saturday night through Sunday night, with a chance of thunderstorms Sunday afternoon/ evening, as the upper low moves through. Temps will stay below normal through the weekend, but Sunday should be a couple degrees warmer than Saturday. && .LONG TERM /Monday through Friday/... Issued 218 AM MDT FRI SEP 4 2026 High pressure aloft will rebuild starting Monday as the upper low exits through Montana into southern Canada. The higher pressure will bring warmer air back into our CWA the rest of the week, with temps rising back to normal or several degrees above Wednesday and beyond. The next upper low is forecast to stay off the Oregon coast, but latest models (GFS more than ECMWF) show southwesterly flow aloft tapping into moisture from the next westward-moving hurricane in the Pacific subtropics. We therefore have a slight chance of thunderstorms in the forecast as early as Wednesday afternoon, but more likely Thursday and Friday. && .AVIATION /12Z Friday through Saturday/... Issued 534 AM MDT FRI SEP 4 2026 Mostly VFR. Numerous rain showers in ID this morning, then scattered showers and isolated thunderstorms this afternoon. Areas of MVFR/IFR and mountain obscuration in heaviest pcpn. Snow level 6.5k-7.5k feet MSL in E Oregon, and 8k-9k feet in w-central ID. Surface winds: SW-NW 5-15 kt. Gusts to 25 kt in the afternoon. Winds aloft at 10kft MSL: SW 15-25 kt KBOI...IFR in stratus until 15Z, then becoming VFR. isolated showers until 15Z. A 20% chance of showers and thunderstorms this afternoon 21Z-24Z. 30% chance of showers and thunderstorms after 05/04Z. Surface winds: NW 5-15 kt. Gusts to 20 kt in the afternoon. Weekend Outlook...Mostly VFR. Scattered showers Saturday morning. Activity decreasing from SW to NE late morning. Then, showers increasing again Sunday, with highest chances (50-70%) over east Oregon and w-central Idaho. Localized MVFR/IFR and mountain obscuration in heaviest pcpn. Areas of valley/low stratus Saturday/ Sunday mornings. SW-NW surface winds 5-10 kt with PM gusts to 20 kt. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Flash Flood Watch through this evening for IDZ011-013. OR...Flash Flood Watch through this evening for ORZ061>063. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise AVIATION.....LC SHORT TERM...LC LONG TERM....LC

867 FXUS65 KLKN 040736 AFDLKN Area Forecast Discussion National Weather Service Elko NV 1236 AM PDT Fri Sep 4 2026 .KEY MESSAGES... * Breezy conditions across east-central Nevada this afternoon into this evening * Scattered rain showers and isolated thunderstorms across northern Humboldt County this afternoon * Below average temperatures will continue through the next several days * Periods of rain late this weekend into early next week && .DISCUSSION... (Today through next Friday) WEATHER PATTERN OVERVIEW: The forecast remains on track. An upper level low continues its journey around the PacNW, bringing cooler temperatures, strong winds and precipitation potential. A strong pressure gradient is developing across the area, resulting in strong winds across the area and temperatures ranging from the upper 60s in northern Nevada to the low 80s in central Nevada. Strong winds are expected to continue through Sunday, particularly in White Pine, northeast Nye and southeast Elko Counties. Moisture availability starting Sunday has been trending downward the last several forecasts and precipitation potential has noticeably decreased along with it. Isolated to scattered showers and thunderstorms continue to be forecast across much of the forecast area for Sunday but accumulation totals have dropped to 0.05 inches at best, with most of the area expecting a trace or less. Precipitation chances dry out by Monday morning, allowing a dry but cool day, with high temperatures in the 70s. Unsettled weather is expected to continue for mid week even as temperatures warm back into the 80s. FORECAST CONFIDENCE & DEVIATIONS: High confidence in cool temperatures and strong winds through the weekend. Weekend storm confidence continues to be moderate, with low confidence in storm potential next week. No changes from the NBM. && .AVIATION... Hazy skies continue to impact portions of northern and central NV due to recent strong gusty winds, including at KWMC and KBAM. Winds this afternoon will be lighter across northern NV, however east-central NV KELY and KENV will have breezy southerly winds with gusts to around 25 or 30kts this afternoon. Blowing dust is possible in these areas this afternoon with the potential for VIS to lower to a mile or less at time. Light rain showers approach KWMC from the NW today. && .FIRE WEATHER... Critical winds continue to be mitigated by non-critical humidity. Winds will be strongest today in zones 425, 426 and southern 470 with gusts around 40 mph expected, however RH will be 15 to 25 percent. Gusts decrease to 20 to 30 mph for Saturday and Sunday, with isolated to scattered showers and thunderstorms for Sunday. Scattered light rain showers and isolated thunderstorms are expected across mainly zone 437 today as an upper level low approaches Nevada from the Pacific NW. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...94 AVIATION...96 FIRE WEATHER...94/96