124 FXUS66 KSEW 040904 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 204 AM PDT Mon May 4 2026 .SYNOPSIS... Upper level ridge over Western Washington through Thursday shifting east Thursday night. Dissipating front trying to move into the area later Friday into Saturday morning. Another upper level ridge builds Saturday afternoon into Sunday. Low level flow turning onshore today with varying degrees of onshore flow through most of the week. && .SHORT TERM /TODAY THROUGH WEDNESDAY/... Satellite imagery shows stratus surging up the coastline has reached the Grays Harbor/Pacific county border at 2 am/09z. A few high clouds over the remainder of the area. Temperatures were in the 50s and lower 60s. Stratus will continue moving up the coastline reaching the North Coast this afternoon. Outside of the Grays Harbor area the stratus will remain near the beaches. Light flow in the lower levels this morning becoming onshore later this morning into the afternoon. The marine layer will be too shallow to get east of Puget Sound with highs similar to Sunday`s readings, in the 70s and lower 80s. The marine air will filter into the Lower Chehalis Valley, Southern Hood Canal and portions of the Southwest Interior cooling highs about 5 degrees from yesterday. Highs in these locations in the 70s to lower 80s as well. Significant cooling along the coast with highs in the mid to upper 60s. Warmer temperatures along the North Coast. Low level onshore flow peaking tonight with the marine layer getting into the Puget Sound area by early Tuesday morning. Lows in the mid 40s to mid 50s. Onshore gradients going light during the day Tuesday with the marine layer retreating to the coastline by afternoon. The weak marine push will lower highs by about 5 degrees over the interior, into the upper 60s to mid 70s. Marine layer remaining intact along the coast keeping highs in the lower 60s. Little change in the pattern Tuesday night into Wednesday with an upper level ridge over the area and light low level onshore flow. Lows in the mid 40s to mid 50s. Highs Wednesday a little cooler again over the interior, mid 60s to lower 70s while along the coast highs near 60. Felton && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Extended models still showing good consistency. Upper level ridge over the area Wednesday night and Thursday shifting east Thursday night. Dissipating negatively tilted front falling apart over Western Washington later Friday into Saturday morning. Slight chance of showers in this window. Another upper level ridge building over the area Saturday afternoon into Sunday. Highs in the 60s and lower 70s Thursday cooling into the upper 50s to mid 60s Friday. Warming trend for the weekend with 60s and lower 70s Saturday and mid 60s to mid 70s Sunday. && .AVIATION... North to northeast flow aloft continues with an upper ridge located offshore. Low level onshore flow will increase today with IFR/LIFR stratus reaching most of the coast this morning. VFR conditions will prevail across the interior today. Stratus will spread into the interior late tonight with IFR conditions expected across much of the interior lowlands on Tuesday morning. KSEA...VFR today. IFR stratus expected to return around 12Z-14Z Tuesday. Surface wind light and variable becoming W/SW 7 to 10 knots this afternoon then light southerly tonight. 27 && .MARINE... A thermal trough will shift inland today for a return to onshore flow. Varying degrees of onshore flow will then persist through the week as a surface ridge remains anchored offshore with lower pressure inland. Small craft advisory westerlies are likely in the central/east strait each of the next several afternoons and evenings. 27 && .HYDROLOGY... No river flooding in the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca. && $$

631 FXUS66 KPQR 041135 AFDPQR Area Forecast Discussion National Weather Service Portland OR 435 AM PDT Mon May 4 2026 Updated aviation discussion. && .SYNOPSIS...Cooler but still above-normal temperatures with largely dry weather expected through much of the workweek beneath broad and persistent upper-level ridging. Chances for rain increase Friday into Saturday as the ridge deamplifies, but uncertainty in timing and coverage of precipitation continues. && .DISCUSSION...Now through Sunday...Broad upper-level ridging spanning the Northeastern Pacific and western CONUS is favored to remain in place with a slight eastward tendency through the next week. An upper cutoff low over California which supported offshore flow resulting in record high temperatures on Sunday will exit eastward more quickly, favoring a return to more seasonable northerly to northwesterly flow aloft. Despite upper heights rising in the wake of the departing low, temperatures will actually trend cooler while also remaining seasonably warm thanks to this pattern change. Through midweek, renewed onshore and southerly flow will maintain fairly steady daytime high temperatures in the 60s along the coast and in high terrain and in the 70s to near 80 degrees within inland valleys, some 10 or so degrees above normal. This southerly surge will see marine overcast and periods of mist and drizzle along the coast and clouds reaching inland through coastal gaps each night, before retreating back toward the coast during the day. As such, largely dry and tranquil weather is expected for most. By the end of the workweek, long-range ensembles depict a shortwave trough transiting the apex of the ridge, bringing cooler temperatures closer to seasonal norms as well as the most widespread chances for rainfall to the region. There is still uncertainty in the timing and distribution of precipitation, but the ensemble consensus favors rain occurring some time between Friday morning and Saturday afternoon, with the highest chances to the north and in areas of higher terrain and lower chances to the south and for valley locales. At this time, potential rainfall amounts look to be light, generally 0.1 inch or less. Beyond this late-week system, ridging aloft will most likely rebuild, favoring a return to dry and warmer-than-normal conditions. There remains uncertainty, however, in the position, orientation, and amplitude of ridging, which could affect the sensible weather on the ground. -36 && .AVIATION...A southerly marine surge is ongoing with the latest satellite imagery depicting low stratus along the Oregon and southwest Washington coast, as well as reaching inland through gaps in the coastal terrain, particularly toward the southern Willamette Valley. This will result in persistent IFR/LIFR cigs for coastal terminals through much of the period. As diurnal mixing increases, cigs may lift slightly, with increasing chances of reaching MVFR levels to the north along the coast toward KAST, while to the south near KONP, the improvement will more likely be from LIFR to IFR. High-end IFR to MVFR vis of 2-5 SM is also currently being observed at coastal terminals south of KTMK, these restricted vis will tend to improve after 15-16z Mon. Meanwhile, gusty south-southwesterly winds of 8-12 kt with gusts to 20 kt are expected to continue through at least 21-24z Mon. Reinvigorated marine stratus late in the period, after 00-03z Tue, will yield a downward trend in vis/cigs to IFR/LIFR late in the period while winds ease to around 5 kt. Inland, coverage of low stratus remains relatively low, with MVFR cigs limited to the southern Willamette Valley as of 12z Mon, however some additional inland expansion is expected through 15z Mon. While VFR conditions are most likely, chances for MVFR cigs peak around 15z Mon, reaching 20-40% at terminals along the Willamette and Lower Columbia Valleys. Low clouds will tend to mix out through the morning, largely clearing by 20-22z Mon. Winds out of the south to southeast at around 5 kt at Portland-area terminals and 5-10 kt along the Willamette Valley will veer out of the south to southwest at 5-10 kt through this afternoon, before easing below 5 kt out of the south to southeast after 00-06z Tue. Renewed marine stratus will again be most likely to yield MVFR cigs in the southern Willamette Valley including at KEUG after 06z Tue. KPDX AND APPROACHES...VFR flying conditions favored to continue through the period. Marine stratus will continue to expand inland through 14-15z Mon, resulting in 20-40% chances for MVFR cigs this morning before tending to decrease in coverage as mixing increases. Largely clear skies expected by 20-22z Mon as light southeast flow veers out of the south at 5-10 kt this afternoon. Marine stratus may return late, after 06-09z Tue, as winds ease back out of the southeast tonight. -36 && .MARINE...A southerly surge is underway this morning, bringing gusty south winds up to 20 kt, marine overcast, and patchy mist and drizzle to the coastal waters, especially within 20-30 NM of shore. A diurnal tendency will persist through Wednesday, with increasing clouds, wind, and chances for drizzle or light rain at night before clouds recede and winds ease during the day. A lessening northwest swell will see seas fall from 6-8 ft today to 4-5 ft by Wednesday. Winds look to turn northerly Wednesday through Thursday night with persistent seas of 5-7 ft. A system moving onshore Friday into Saturday will favor a return of southerly flow and increased chances for rain showers, before high pressure rebuilds later this weekend and northerly flow strengthens. Chances increase late Saturday into Sunday for northerly gusts of 20 kt, conditions which may be hazardous to small craft. -36 && .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

174 FXUS66 KMFR 041221 AFDMFR Area Forecast Discussion National Weather Service Medford OR 521 AM PDT Mon May 4 2026 .DISCUSSION (Today through Sunday)... Key Points: * Only minor impacts expected the next several days * Warm, above normal temperatures continue this week * Low pressure remains to our south through midweek - Isolated showers and thunderstorm chances continue today - Similar setup for Tuesday with isolated thunderstorms * Drying trend starts Wednesday Further Details: A closed low remains to our south and will maintain an east to northeast flow aloft. As we reach peak heating and convective temperatures, we should see showers and isolated thunderstorms this afternoon and early evening. This would be mainly for areas along and near the Cascades, westside areas south of the Umpqua divide, and northern California. We are not expected severe weather, but deep mixing and very dry low levels (inverted-v profiles) could lead to occasional gusts around 45 mph. This would be very isolated to the strongest storms today through peak heating. Lightning will be the other hazard. This closed low doesn`t move much Tuesday, and we may see a very similar outcome with isolated thunderstorms over these same areas through peaking heating. Similar threats would be expected Tuesday with occasional strong gusts and lightning as the main threats. High pressure aloft starts to nudge in Wednesday and will maintain dry conditions through the end of the week. Temperatures near 90 degrees will come to fruition Wed/Thurs. Slightly cooler temperatures expected on Fri/Sat, but temperature near 90 will be possible again on Sunday. -Guerrero && .AVIATION... Areas of fog and low clouds are expected through today along the coast which the possibility of these low clouds spilling into the Umpqua basin. These areas could see IFR/MVFR conditions this morning and early afternoon with some improvement today for KRBG. However, KOTH will likely see these low clouds stick around throughout this cycle. Otherwise, isolated showers and thunderstorms are possible through peak heating, which could impact both KMFR and KLMT. At this time only went with vicinity as confidence is low given the isolated nature of showers today. -Guerrero && .MARINE...Updated 300 AM PDT Monday, May 4, 2026...An extended period of relatively calm conditions has begun, with west-northwest swell dominated seas likely remaining below 10 ft through Friday. Light south winds and fog are expected through today, with gradually diminishing seas. Moderate north winds likely develop on Friday with the return of the thermal trough. Stronger north winds are possible Saturday into next week. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...None. CA...None. PACIFIC COASTAL WATERS...None. && $$

480 FXUS66 KEKA 040702 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1202 AM PDT Mon May 4 2026 .SYNOPSIS...Showers move south and taper off today into Tuesday. A few thunderstorms are possible in Trinity County this afternoon and evening. Warmer and drier conditions build midweek. && .DISCUSSION...Thunderstorm activity has waned into the early morning hours. Lingering showers will generally shift southward today with rain likely only in Mendocino & Lake Counties by the afternoon. Cloud cover and lingering moisture will keep interior temperatures cooler, with most valleys in the 60s. There is around a 15-20% chance for thunderstorms this afternoon and evening in the Trinity Horn, and low chances (10-15%) to the south in interior Mendocino and northern Lake Counties. Confidence is low as cloud cover and cooler temperatures may keep thunderstorms from forming. Drier conditions will quickly return by Tuesday. That said, there is a very slight (10%) chance of some weak lingering thunderstorms over the interior on Tuesday. Benign and weak high pressure will build late in the week, bringing slightly warmer than average temperatures but otherwise dry, seasonable, and calm weather. There is chance for the marine layer to finally clear out around Wednesday before rebounding later in the week as a marine inversion reforms under the interior heat. /JHW/JB && .AVIATION...IFR to MVFR ceilings are likely across the terminals through sunrise as the deep marine layer remains steady. Thunderstorm activity will also ease, but lingering showers will continue through the day and move southward. By the afternoon, showers will only be likely Mendocino & Lake. MVFR ceilings are likely to remain through the day as coastal stratus persists and showers continue at UKI. A brief rise into VFR is possible late afternoon. JB && .MARINE...A long period northwest swell has filled in on Sunday, peaking at around 8 ft at 15 seconds. Winds have generally turned light and southerly across the area. A few areas of brief gusty winds, up to 20 kts, are possible north of Cape Mendocino early this morning as stronger showers move over the waters. These will subside by sunrise. Seas will generally ease over the coming days as winds remain light. Winds turn northerly Tuesday and Wednesday, but remain fairly light at around 5 to 15 kts, with the highest winds south of Cape Mendocino. Combined seas remain mild at around 4 to 7 ft, with a mix of short period waves of around 3 ft and mid and long period NW swells of up to 5 ft. JB && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... None. && $$ 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

775 FXUS66 KMTR 041139 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 439 AM PDT Mon May 4 2026 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 1210 AM PDT Mon May 4 2026 - Cooler temperatures through Tuesday with a chance for drizzle and light rain, mainly along the coastline and the Bay Area - Warmer and drier conditions return mid to late week && .SHORT TERM... Issued at 151 AM PDT Mon May 4 2026 (Today and tonight) The 500 mb low center we`ve been monitoring is currently drifting and wobbling around approx 100 miles southwest of Monterey. It`s temporarily quasi-stationary with the polar jet stream winds on the back side of the low while supported by subtropical jet stream winds at the base of the low. The geopotential height of the low center is ~ 559 decameters, for reference that`s near the 10th percentile compared to Oakland upper air long term climatology for early May. Higher surface pressures extend underneath the upper low corresponding to chilly to cold lower level temperatures (925 mb and 850 mb temps). The cold air intrusion lifted the temperature inversion and ultimately did cause deeper vertical mixing to partially clear the sky for sunny breaks Sunday thanks to the May sun angle (heat energy into the system i.e. the Earth-atmosphere system). And it`s chilly across the area with temperatures in the 50s, 40s and a few upper 30s at higher elevations. Partial cloudiness continues through this morning. With the low moving slowly today and tonight, warm air advection to the north of the low center will have a chance to interact with the colder air aloft resulting in light to moderate stratiform rain beginning later today over the North Bay then spreading across much of the Bay Area tonight. Rainfall forecasts have increased. Several hundredths to two to three tenths of an inch of rain (possibly slightly higher amounts may occur) are forecast across much of the Bay Area. On first glance, one may think the counter-clockwise wind flow to the north of low center (east to northeast winds) from the Sierra Nevada would produce downsloping, a drier atmosphere and near zero or zero rain chances. And it is true it most certainly can do this. However, this low is in a different synoptic pattern. The low is in a temporary quasi-balance long enough for the warm air advection to arrive while most likely in near balance because of near surface higher pressures (surface pressures are lower over the Great Basin, meaning no offshore winds) and the net forces due to the upper level winds around the low. This is a great example as to how complex the atmosphere is, with numerous modes of circulation, etc. && .LONG TERM... Issued at 151 AM PDT Mon May 4 2026 (Tuesday through Sunday) The subtropical jet stream at the base of the 500 mb low will move the low eastward away from California by mid-week. After this, high pressure will move in from the west and northwest bringing with it dry conditions and a warming trend. In general because of the strengthening long wave troughing on each side of the high pressure ridge, meridional (north-south) displacements will also amplify/strengthen the ridge, with greater compressional warming and surface warming resulting in above to well above normal high temperatures in our forecast area by late week and weekend. Far inland locations especially by next weekend will likely reach the 80s and 90s. && .AVIATION... (12Z TAFS) Issued at 438 AM PDT Mon May 4 2026 Scattered showers are expected to move into the Bay Area today with the highest confidence in showers impacting the North Bay. Given the more mixed out marine layer ceilings are higher with VFR conditions across the board. There have been temporary dips into MVFR territory overnight but these have been short lived with CIGs quickly rising. Moderate confidence that VFR conditions will last for much of the TAF period with MVFR conditions returning first to the North Bay this evening and spreading into the rest of the Bay Area overnight. Rain chances increase around 00Z for STS and APC with chances increasing closer to 09-12Z for the rest of the Bay Area. Not currently expecting showers to reach the Central Coast. Vicinity of SFO...VFR with MVFR conditions becoming more likely overnight as showers reach SFO. Periods of MVFR CIGs are possible this morning but they are expected to be short lived with ceilings predominantly >3000 ft. Breezy onshore winds are expected this afternoon with gusts to around 18 knots. Showers are likely to reach SFO around 09Z but could arrive as early as 06Z. CIGs are expected to lower as showers return with MVFR CIGs returning tonight into tomorrow morning. SFO Bridge Approach....Similar to SFO. Monterey Bay Terminals...VFR with increasing chances for MVFR to return towards the end of the TAF period. Periods of MVFR CIGs are possible this morning but they are expected to be temporary. Breezy onshore winds return during the afternoon/evening before winds ease overnight. Isolated showers may impact MRY/SNS today into tonight but confidence is low that widespread showers will reach the Central Coast. && .MARINE... (Today through Saturday) Issued at 438 AM PDT Mon May 4 2026 A light to gentle breeze continues over the waters with winds to become more moderate by Tuesday. A weak upper level disturbance lingers over the region through midweek. This disturbance will bring light, scattered showers and a non-zero chance of thunderstorms Monday into Tuesday. Northerly winds and seas strengthen Thursday into next weekend as high pressure rebuilds. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ 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

969 FXUS66 KOTX 041052 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 352 AM PDT Mon May 4 2026 .KEY MESSAGES... - Breezy winds developing down the Okanogan Valley, Washington Central Basin and north Idaho Panhandle Purcell Trench on Monday. - Minor to locally moderate HeatRisk through the week. This level of heat primarily affects those who are sensitive to heat. - Dangerously cold water temperatures poses a high risk for cold water shock and hypothermia for anyone who unexpectedly falls in. Wear a life jacket if recreating on or near the water. && .SYNOPSIS... A prolonged period of above normal temperatures will continue this week. Expect some breezes Monday and Tuesday as cooler air moves in from Canada. Longer range predictions favor elevated chances of warmer than normal temperatures for the middle of May as well. Conditions will be dry outside small chances for mountain showers in the north Idaho Panhandle near Canada Wednesday and again Saturday. && .DISCUSSION... Today through Tuesday: A dry northerly flow with a ridge edging in from the west will dominate the pattern. Variable middle to high clouds slip over the region over the next couple days, but the weather remains dry. Winds will be gusty from the north to northeast. Speeds of 10-20 mph, with gusts of 20-30 mph will be possible. The stronger of these are expected down the Okanogan Valley southward into the Basin. Winds abate tonight and start to shift to the east to southeast heading into Tuesday, becoming breezy again in the afternoon across the basin with gusts near 20-30 mph again. Temperatures push into the 70s and 80s, with the warmest temperatures today and a slight cool-down Tuesday. Wednesday to Sunday: The period starts with a warm temperatures and shortwave flattening the ridge over the region by later Wednesday, then a more progressive pattern comes for Thursday to Sunday. The area remains largely dry with a few exceptions, but a bit of increased cloud cover is in the forecast. The wave passing Wednesday will bring slight shower and t-storm chances over north Idaho and along the ID/MT border late Wednesday. Some shower chances linger near this area on Thursday afternoon too. The more notable feature of the passing wave looks to be another surge in winds by later Wednesday afternoon and evening, especially near the Cascades and western basin. Speeds of 10-20 mph are possible there, with gusts of 20-40 mph. Ensembles show a 60-80% chance of wind gusts of 30 mph or greater and 2540% chance of gusts of 40 mph or greater. It will also be warm and dry, with afternoon highs in the mid 70s to 80s, with some areas near 90 in the deeper basin; RH values will fall into the teens to mid-20s in this stronger wind area. So we will be watching for any fire weather concerns again. Other minor mountain shower chances are forecast for Friday and Saturday afternoon with the next passing wave, but for the most part it remains dry. Yet winds also increase again Friday with that wave, with the forecast showing speeds of 15-30 mph and gusts of 20-40 mph and locally up to 50 mph possible. The strongest winds are forecast over the lee of Cascades into the western basin and near the Blue Mountains. There is currently a 50-90% chance of wind gusts of 30 mph or greater, a 30-70% of 40 mph or greater, and 20-50% chance of 50 mph or greater for Friday. It remains breezy through the weekend too, but not as strong. Highs will be in the mid-70s to upper 80s Thursday, cool to the 70s to low 80s Friday and Saturday, then warm up again toward Sunday. /Solveig && .AVIATION... 12Z TAFS: VFR conditions will continue for all TAF sites through the week. For today into Tuesday north to northeast winds are expected to increase with 15-20 kt gusts across the Columbia Basin into the Spokane, Coeur d`Alene area as a weak dry cold front drops down from the north. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions and increasing north to northeast winds across the region. Yet some of the recent models show gusts a little lower (10-15 kts), so confidence in precise gusts speeds and timing carries lower confidence. JW ----------------------- 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 76 49 72 46 79 52 / 0 0 0 0 0 0 Coeur d`Alene 74 46 69 44 75 49 / 0 0 0 0 0 10 Pullman 75 47 70 46 75 52 / 0 0 0 0 0 0 Lewiston 80 50 76 49 81 55 / 0 0 0 0 0 0 Colville 80 45 77 44 82 46 / 10 10 0 0 0 10 Sandpoint 70 45 67 44 73 48 / 0 0 0 0 0 20 Kellogg 72 45 67 44 73 49 / 0 0 0 0 10 10 Moses Lake 85 53 82 51 86 52 / 0 0 0 0 0 0 Wenatchee 85 58 82 57 85 56 / 0 10 0 0 0 0 Omak 84 53 82 52 85 52 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

098 FXUS66 KPDT 040956 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 256 AM PDT Mon May 4 2026 .KEY MESSAGES... - Warm and above normal temperatures persist through the week. - Dry conditions through the workweek. - Slight chance for mountain showers Friday. && .DISCUSSION... Current radar and infrared satellite imagery shows dry conditions under mostly clear skies. This is in response to an upper level ridge encroaching in from the coast that will keep skies sunny and temperatures well above normal. High temperatures across the Lower Columbia Basin, Blue Mountain foothills, Central Oregon, and the Yakima/Kittitas Valleys should be slightly warmer (+1-2 degrees) from Sunday. Temperatures will cool 2 to 5 degrees on Tuesday due to northerly flow aloft becoming more enhanced and extending into the Yukon and Northwest Territory provinces. High temperatures rebound back into the upper 80s to low 90s across the Lower Columbia Basin, Gorge, Blue Mountain foothills, Central Oregon, and the Yakima/Kittitas Valleys on Wednesday. This is a result of a weak shortwave that suppresses the upper level ridge to bring more upper level flow from the west, as advertised by both the ECMWF and GFS AI ensembles. The best chance for any high temperature records being broken will be in Yakima today, with the current forecast being two degrees shy (88/90) set back in 1966. The NBM suggests there to be a 28% chance of tying the record and a 7% chance of breaking it. The continued presence of the upper level ridge across the Pacific Northwest will keep conditions dry and humidities rather low. This is clearly visible across our Oregon zones when viewing the Hot-Dry-Windy Index (HDWI), which shows 75-95 median percentiles exceeded from climatology over the last 30 years. Afternoon humidities have dropped into the low teens across Central Oregon and the John Day Basin over the last 3 days, with areas of the Lower Columbia Basin, Blue Mountain foothills, Union county, and the Yakima Valley experiencing minimum humidities in the teens on Sunday. These conditions are expected to improve through Tuesday associated with northerly flow aloft, however the downward trend returns beginning Wednesday. Afternoon humidities are expected to bottom-out Thursday and drop into the low to mid-teens across Central Oregon, John Day Basin, Lower Columbia Basin, Gorge, Blue Mountain foothills, and the Yakima Valley. Humidities look to moderate on Friday as ensemble members suggest an incoming upper level trough clipping the region, but guidance hints at the ridge rebuilding and dropping humidities through the weekend. Ensemble members are in fairly good agreement related to an incoming upper level shortwave Friday, that spins off its parent low pressure that is located off the Gulf of Alaska. The shortwave is expected to suppress the upper level ridge that set up earlier in the week, which effectively shears the shortwave north and into British Columbia. 86% of ensemble members keep precipitation confined to our Cascade and Blue Mountain zones, with 35% of members suggesting only precipitation over the Cascade crest. Guidance has trended toward a drier solution over the last 24 hours, which may continue. The more dry cluster ensembles (1 and 3) consist of 76% and 75% of ECMWF and CMC members, with 40% of GFS members advertising showers extending into lower elevations of the Basin and along the Blue Mountain foothills. Even with this wetter cluster scenario (14% chance), rain amounts are expected to stay below a wetting rain (0.10"). Depending on the strength of the incoming shortwave and how effective it is in breaking the ridge down, there is a slight chance (10%) of isolated afternoon/evening thunderstorms across Grant, Union, and Wallowa Counties on Friday. Not only will this potential be related to shortwave strength, but also the timing of the shortwave coinciding with peak afternoon heating. The ECWMF has slowed the shortwave passing to later in the evening over the past two model runs (18z and 0Z), which is also suggested via the LREF showing a passing over the Cascades in the early afternoon and between 7PM-9PM across Grant, Union, and Wallowa counties using a 567mb threshold in relation to the 500mb height timing product. Thus, showers outside the Cascades and isolated thunderstorms across our eastern zones on Friday is currently an unlikely scenario (10%). 75 && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... VFR conditions currently across all sites, which will stay the course through the period. Breezy winds of 15-25kts are expected for KDLS/KRDM/KBDN/KYKM through the afternoon and evening, with winds of 10kts or less for all other sites. 25kft ceilings are also likely across KPSC/KRDM/KBDN toward the end of the period. 75 && .Preliminary Point Temps/PoPs... PDT 82 52 79 52 / 0 0 0 0 ALW 82 55 78 55 / 0 0 0 0 PSC 88 54 84 52 / 0 0 0 0 YKM 88 56 84 54 / 0 10 0 0 HRI 87 53 83 52 / 0 0 0 0 ELN 83 51 79 51 / 0 10 0 0 RDM 80 44 79 43 / 0 0 0 0 LGD 78 50 74 48 / 0 0 0 0 GCD 78 46 76 46 / 0 0 0 0 DLS 85 57 83 56 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...75 AVIATION...75

835 FXUS65 KREV 040803 AFDREV Area Forecast Discussion National Weather Service Reno NV 103 AM PDT Mon May 4 2026 .KEY MESSAGES... * A weather system continues to bring showers, thunderstorms, and cooler temperatures today. Be prepared for recreation and travel impacts due to gusty winds, rain, hail, and mountain snow. * Warmer, showery weather with additional thunderstorm chances expected Tuesday. * Warm and dry weather returns mid-week through this weekend. && .DISCUSSION... Another round of storms is expected this afternoon. Overall strength of these storms appears to be limited and weaker than yesterday`s storms due to lack of instability and much cooler afternoon temperatures. Some showers across western NV will continue into the early morning and linger until the next round of storms fire off 10 AM. Snow levels do come down quite a bit to 7500-8500 feet over Mono County this afternoon. That being said, there is a 40-50% chance of 6 or more inches of snow above 8500 feet in Mono County. The most likely range is between 4-8", with 8" falling on the highest peaks. Graupel will likely get mixed in with the snow in the more convective, stronger cells as well. Chances for precip are around 50-80% area-wide, with a 25-35% chance for lightning. CAMs have MUCAPE anywhere between 400-1100 J/kg across the CWA, with DCAPE between generally 300-800 J/kg. Storms over Pershing County and northern Washoe County will have higher LCLs with more DCAPE(>900 J/kg), so the potential for stronger gusts up to 50-55 mph is more likely further north. Could see more blowing dust out in the Basin and Range today too as those storms extend north. Storms will be moving from east to west today at 25kt, so they`ll be moving fairly fast. In general, with this kind of environment we`re expecting any hail to remain around pea size and outflow gusts up to 45 mph. However, I do want to call out a narrow corridor from Fallon to Reno where a stronger thunderstorm could develop this afternoon (hail 0.5", gusts 45+ mph). This many hours out I don`t want to put too much confidence in it, but the CAMs are consistently hinting at it to where it`s worth mentioning. Timing and placement of a brief clearing in the clouds to allow additional instability will be key with this, so that`s why the uncertainty is so high. These showers and thunderstorms will taper off tonight around 8-10 PM. The low off the coast will continue to track south and east, then by Tuesday afternoon we`ll be set up for another round of showers and thunderstorms focused more over S. Lyon, Mineral, and Mono counties. Current probabilities for those storms are 50-60%, with a 15-20% chance of lightning. Wednesday through this weekend, high pressure will set in where we`ll finally dry out and warm up to the mid 80s in western NV valleys and mid 70s in Sierra valleys. Expect really nice spring weather heading into this weekend with light winds and sunny skies. -Justin && .AVIATION... Showers and thunderstorms are once again expected this afternoon for all terminals. Probabilities are higher in the Sierra (80-90%) and lower into western NV (50-70%). Chances for lightning will be 25-35% this afternoon as well. With these storms expect frequent lightning, brief heavy rainfall (IFR), gusty outflow winds (30-40 kt), and small hail (less than 1"). Lower cloud heights are expected today, which may cause mountaintop obscurations. More storms are in the forecast Tuesday, with KMMH having the highest probability to see a storm. -Justin && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

283 FXUS66 KSTO 031902 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1202 PM PDT Sun May 3 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Showers and thunderstorms this afternoon and evening for the mountains, foothills, and northern Sacramento Valley. A few isolated strong to severe storms are possible. - Continued chances for showers and thunderstorms Monday afternoon/evening and again on Tuesday for the mountains, Valley, and foothills. - Hot and dry conditions are expected to develop end of the week and into next weekend, with Minor and Moderate HeatRisk. && .DISCUSSION... ...Sunday through Tuesday... Upper level system is tracking across the Southwestern United States bringing moisture, instability, and sufficient shear to the region. Breaks in the cloud coverage at times has helped increase instability across the area. Current satellite and radar have a few cells developing in the mountains around Hwy 50 and tracking NW. HIRES guidance has picked up on this and started to initialize further development around 20-21z and continuing through the evening hours. Shear profiles show sufficient speed and directional shear to support thunderstorm growth. A few of the thunderstorms could be strong to severe, with hail up to 1 inch, gusty winds, frequent lightning, and brief heavy rain rates. Make sure you have a way to receive alerts this afternoon and evening. Precipitation chances shift down into the Valley overnight and into tomorrow morning with scattered rain showers Monday morning. Chances for thunderstorms arise once again during the afternoon and evening, with a few stronger storms possible. We will continue to see rain and thunderstorm potential into Tuesday, but chances are on the lower end as the main upper level system shifts further away from the area. At the highest peaks south of Highway 50 there will be chances for snow tonight through Tuesday, with minor accumulations possible. Temperatures through Tuesday will be on the cooler side across the area, with highs in the 60s to lower 70s Monday and the 70s on Tuesday. ...Wednesday and beyond... Conditions dry out as we move into Wednesday and continue into next weekend. An upper level ridge builds and amplifies over the western United States end of the week into next weekend. This increases our temperatures and drys out conditions across the area. Minor HeatRisk is expected across the Valley Wednesday, but becomes more widespread into the foothills and mountains by the end of the week. Minimum RH values start to drop into the 20s across the area, with a few isolated values in the teens. By next weekend, we are seeing increasing confidence temperatures will reach into the 90s, with the probabilities of seeing over 95 degrees 50-60 percent Saturday and Sunday. Potential for Moderate HeatRisk Saturday. && .AVIATION... BKN to OVC skies through the TAF period, with thunderstorm chances near RDD and RBL this afternoon and evening. Winds will begin to increase out of the southwest at 10-15kts for the Sacramento sites this afternoon and go light and variable overnight. Near 08z-13z chances for rain develop through the Valley affecting each site through the end of the TAF period. Ceilings go MVFR during this time. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$

804 FXUS65 KMSO 040806 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 206 AM MDT Mon May 4 2026 .DISCUSSION... KEY MESSAGES: - A cold front arriving this morning will bring cooler temperatures and gusty northeast winds of 20 to 30 mph across western Montana. - High pressure builds by midweek, bringing a dry warming trend with valley temperatures returning to the 70s and 80s. The Northern Rockies are sitting under northerly flow aloft as high pressure amplifies to the west and a broad trough of low pressure sites to the east. The low to the east will send a backdoor cold front over the Continental Divide early this morning. The front will bring cooler temperatures and strong northeast winds. Expect windy conditions across western Montana throughout Monday, with northeast wind gusts reaching 20 to 30 mph at times. Wind direction becomes more northerly on Tuesday as the upper level jet becomes oriented almost straight out of the north and a tight pressure gradient sets up over the Northern Rockies between the high to the west and the low to the east. Strong winds will eventually spill into the valleys of north-central Idaho on Tuesday afternoon. That gradient will relax on Wednesday as the ridge of high pressure expands eastward and encompasses the Northern Rockies. Daytime high temperatures will bounce back up to about 10 degrees above normal. Along with the increase in temperatures, a weak shortwave will bring chances for precipitation on Wednesday into Thursday morning. By Thursday and Friday, most valley locations will see afternoon high temperatures climbing back into the 70s, with the lower valleys of north-central Idaho reaching the low 80s. && .AVIATION...A backdoor cold front will bring increasing northeast winds to KGPI early this morning. Expect gusts of 20-30 knots lasting until about 04/1200Z this morning, then picking up again later this afternoon, around 04/2200Z. All other terminals will also see increasing easterly winds (northerly at KHRF) this afternoon and evening to about 20 knots. Aviators flying over the Continental Divide in northwest Montana today will experience chances for precipitation resulting in obscured terrain along with gusty north or northeasterly winds. Gusty winds continue through Tuesday, though wind direction become more northerly. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

107 FXUS65 KBOI 041122 AFDBOI Area Forecast Discussion National Weather Service Boise ID 522 AM MDT Mon May 4 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Above normal temperatures into next weekend. - Isolated PM showers and thunderstorms through Tuesday, mostly along the NV border and across south-central Idaho. - Windy Monday and Tuesday afternoon, especially in southeast Oregon and the Snake Basin in Idaho. && .SHORT TERM /Through Wednesday Night/... Issued 346 AM MDT MON MAY 4 2026 Interesting pattern over the region, with a high-over-low along the West Coast and deepening trough east of the Continental Divide. Our region will remain on the edge of/in-between these features. Moisture aloft will continue to converge along the northern NV border as southerly flow around the low meets a strengthening northerly flow associated with the northern high and deepening trough. Forecasts have been trending toward the drier northerly flow winning this battle, which is supported by overnight water vapor satellite imagery. The result is a lower chance of precipitation (15-25%) from the ID/NV border through the western Magic Valley and Boise Mtns for today. While cumulus buildups and an isolated shower/storm could be seen further north and west, the dry air and mid-level warming from the northern high will likely be too much, especially west of the ID/OR line. Gusty winds and brief heavy rain are possible from storms that develop. Outside of showers/storms northerly winds will ramp up this afternoon, then more so on Tuesday as widespread gusts of 30-40 mph set in. The prolonged period of gusty winds could bring blowing dust to SE Oregon and portions of the Snake Plain. Wednesday is dry and less windy as the northern high expands across the West. Tuesday and Wednesday are the coolest days of the week, with high temperatures dropping to within 5-10 degrees of normal. && .LONG TERM /Thursday through Monday/... Issued 346 AM MDT MON MAY 4 2026 The upper-level ridge building into the Western U.S. will continue to move overhead Thursday into midday Friday, providing mostly dry conditions and above normal temperatures. An upper-level shortwave will disrupt this briefly Friday PM into Saturday, moving east/southeast through the Southern Canadian provinces / Pacific NW into the Intermountain West and lee side of the Rockies. This will cause cloudier skies, precipitation chances (10-20% chance of showers over high terrain in southwest Idaho and southeast Oregon), and still above normal (but slightly cooler compared to Thursday) temperatures. Once this feature moves further east/southeast late Saturday, another upper-level ridge builds in over the Western U.S., with this lasting into at least early the next week. Some clusters / ensembles have this upper-level ridge as particularly intense, enabling the potential for the lower Snake River Plain temperatures to reach the upper 80s and possibly even 90F (10-20% chance in the Boise area of 90+F). && .AVIATION /12Z Monday through Tuesday/... Issued 520 AM MDT MON MAY 4 2026 VFR with with mostly clear skies through morning. Patchy valley smoke in the Boise Mountains. Isolated showers/thunderstorms will return mainly over NV border and high terrain of SW ID in the afternoon/evening. Surface winds: variable up to 10 kt through morning, becoming W-NW 10-20 kt with gusts to 25 kt in the afternoon. Winds aloft at 10k ft MSL: NW-NE 10-20 kt. KBOI...VFR with clear skies. Surface winds: variable less than 7 kt through morning, becoming NW 8-13 kt with gusts up to 20 kt in the afternoon. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise AVIATION.....CH SHORT TERM...DG LONG TERM....CH

925 FXUS65 KLKN 040858 AFDLKN Area Forecast Discussion National Weather Service Elko NV 158 AM PDT Mon May 4 2026 .KEY MESSAGES... * Periods of valley rain and high mountain snow continue thru Tuesday * Thunderstorms expected this afternoon and Tuesday afternoon * Daytime high temperatures climb to the low and mid 80s by Friday && .UPDATE... Issued at 1228 AM PDT Mon May 4 2026 The current forecast remains on track and no significant updates are required. && .DISCUSSION... (This evening through next Saturday) WEATHER PATTERN OVERVIEW: Upper level low situated along the California coast continues to slowly move inland today and tomorrow resulting in periods of precipitation lasting thru Tuesday night. Snow levels will be high and are expected to remain around 8-9000 feet thru the duration of the event. Therefore expecting most precipitation will fall as rain save for the highest mountain ranges across the forecast area. Isolated to scattered thunderstorms will also be present each afternoon today and tomorrow as daytime heating increases convective potential. Cloud to ground lightning and strong and erratic wind gusts around 45 mph will be the main hazards. The highest precipitation accumulations will be found along a southwest to northeast line from northwest Nye County to central Elko County. 0.25 to 0.50 inches of rainfall is forecast thru Tuesday night. An upper level ridge will move in from the west as the low exits to the east and weather clears thru Tuesday night. This will lead to dry conditions and warming temperatures beginning Wednesday. As a result, high temperatures are expected to reach the low to mid 80s for many locales by Friday, roughly 15 degrees warmer than normal for this time of year. Overnight lows will also be warmer than normal, residing in the 40s as compared to normal lows that would otherwise be in the 30s. Low confidence and low probability (10%) for light rain showers across northern Elko County Saturday as a progressive shortwave trof ejects across the PacNW from a robust upper level low poised over the Gulf of Alaska. However, the shortwave will effectively flatten the ridge and render daytime high temperatures around 5 degrees cooler than observed Friday. Dry weather and warming temperatures Sunday and Monday as the ridge reamplifys. FORECAST CONFIDENCE & DEVIATIONS: High confidence in precipitation thru Tuesday. Moderate confidence in afternoon thunderstorm potential. Low to moderate confidence this weekend. Opted for a blend of various model outputs and WPC guidance for PoP and weather fields as NBM continues to come in much too bullish. Otherwise little deviation from NBM elsewhere. && .AVIATION...Period of active weather will impact all terminals thru Tuesday night. Some combination of -SHRA, VCSH, -TSRA, and VCTS is forecast at times with the greatest TS threat present during the afternoon today and tomorrow. Main threats associated with any TS that move on terminal will be cloud to ground lightning and strong and erratic wind gusts around 40KT or 45KT. The prevailing flight category will be VFR though any SH or TS that move on terminal may produce temporary MVFR conditions. Afternoon breezes will also be present with gusts 20KT to 25KT. && .FIRE WEATHER...Active weather will be present thru Tuesday night including rain showers and afternoon thunderstorms. The greatest rainfall accumulation will be focused in and near zone 427 where between 0.25 and 0.50 inches is expected. Thunderstorms will be isolated to scattered with areal coverage effectively including the entire forecast area this afternoon. Isolated to scattered storms again expected Tuesday afternoon though areal coverage will be focused along a southwest to northeast swath that will more or less exclude zones 437, 426, and the southern half of 425. Cloud to ground lightning will be present along with the typical gusty and erratic outflow winds of around 45 mph. Afternoon breezes will also be in place across the forecast area, gusts 20 to 30 mph. Fairer weather Wednesday and thru the end of the week though afternoon breezes will persist, primarily across northern Nevada. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...92 AVIATION...92 FIRE WEATHER...92