Scattered severe thunderstorms are forecast across central and eastern North Dakota, as well as far northwest Minnesota Saturday (Slight Risk level 2 of 5). Damaging wind gusts are the primary threat. Elevated to critical fire weather conditions will persist through the weekend across the Western U.S. Isolated dry thunderstorms could lead to new fire starts over portions of the northern Rockies. Read More >
Seattle, WA
Center Weather Service Unit
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130 FXUS66 KSEW 270323 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 820 PM PDT Fri Jul 26 2024 .SYNOPSIS...A weak upper level trough remains over western Washington through the weekend. A passing front Monday will bring widespread rain chances to the area, with showers lingering into Tuesday as the upper trough moves through. Weak high pressure aloft begins to build again toward midweek. && .SHORT TERM /TONIGHT THROUGH MONDAY/...Fair skies over W WA this evening with some high clouds drifting over the area. Already seeing some 50s emerging along the coast, however the majority of the area seeing temps generally in the 60s...save for urban heat islands such as the Seattle metro area, which is still reporting temps in the lower 70s. Overall a fairly quiet evening. Inherited forecast looks on track and see no need for any evening updates. For additional forecast details, please refer to the Previous Discussion section below. 18 From Previous Discussion...Weak upper level troughing over the region this weekend for generally mild conditions. Temperatures will be close to late July normals. There is a slight chance of showers in the North Cascades (near the crest) Saturday afternoon, otherwise the remainder of western WA will be dry. A deeper trough taps into some moisture over the Pacific on Monday for wetter and cooler conditions. Much of western WA will see measurable rain with this system. Up in the mountains, there`s a 50-70% chance of seeing wetting rains (at least 0.25"). Temperatures will be cooler and in the 60s. 33 .LONG TERM /TUESDAY THROUGH FRIDAY/...From Previous Discussion...Showers linger on Tuesday as the upper level trough exits east toward Idaho/Montana. Heights will build and we`ll see a little warming (but still a few degrees shy of normal). Dry and warmer weather returns mid-week onwards with broad upper level ridging over the western CONUS. Temperatures on Thursday and Friday will reach the 80s again (across the interior lowlands) with pockets of Moderate HeatRisk. NW flow will keep the coast cooler and in the 60s and 70s. 33 && .AVIATION...Northwest flow aloft as subtle ridging resides offshore along with troughing nearby. VFR conditions in place and largely expected to remain that way for much of the TAF period. It is worth noting that latest runs are starting to suggest marine stratus pushing a little further inland when compared to previous runs. The usual coastal sites and those that tend to favor lower cigs will likely see MVFR to IFR conditions emerge late tonight into Saturday morning, however starting to see indications that SEA and PAE may see lower cigs as well. Have already included a hint to this in the 03Z SEA update but will re-evaluate for the 06Z TAF issuance. Otherwise, VFR conditions expected to resume by noon Saturday. KSEA...VFR expected for the remainder of the evening. May see cigs erode down to low-end VFR/high-end MVFR around or a little after 12Z Saturday morning. VFR conditions expected to return by 18Z. Surface winds northerly 6 to 10 kt this evening and tonight before easing overnight...then becoming more west-southwesterly late Saturday morning. McMillian/18 && .MARINE...Low-level onshore flow persists with high pressure over the coastal waters of the Pacific and lower pressure inland. Benign conditions over the marine zones expected tonight into Saturday. A westerly push through the strait this evening is seeing wind speeds largely remain below SCA criteria. Only Race Rocks is currently meeting criteria and, as such, conditions are not widespread enough to warrant any headlines or updates. The next best chance for SCA- level winds in the Strait appears to be Saturday night into Sunday morning. Marine stratus will persist in varying coverage for the next several days with visibility restrictions a possibility over the zones. A frontal system will move through the region early next week. At this time the threat for widespread breezy winds impacting small craft is low. Seas generally 4 to 6 ft tonight into Saturday...although some spots in the far outer waters may see seas reach 7 ft. Waves easing Saturday evening with resulting seas 3 to 5 ft. McMillian/18 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$ 677 FXUS66 KPQR 270322 AAA AFDPQR Area Forecast Discussion UPDATED National Weather Service Portland OR 820 PM PDT Fri Jul 26 2024 ...EVENING UPDATE, for aviation weather. .SYNOPSIS...Stable onshore flow will maintain fairly benign weather with seasonably warm days and cool nights through early next week. A passing system brings a chance for rain next Monday into Tuesday. Models then hint at a warming trend mid to late next week as high pressure builds back over the area. && .SHORT TERM...Tonight through Sunday Night...Typical summer weather today and through the weekend. Broad, weak troughing aloft with stable westerly flow across the region. Some light haze from nearby wildfire smoke, mainly east of I-5 will push t 5-10 kt with gusts up to 18 kt lasting until 05-06Z Saturday. back east of the Cascades tonight as another surge of onshore flow moves across the area. The main exception will be where near surface smoke is confined to the immediate vicinity of ongoing fires in the Linn and Lane County Cascades where LRAPA has issued an Air Quality Advisory through Saturday afternoon. Afternoon highs expected in the lower to mid 80s for the interior lowlands. Morning clouds from marine layer intrusions into the inland valleys each night will help moderate overnight temps a few degrees. Otherwise, mostly sunny skies continue through Sunday. Breezy conditions will continue through the central Columbia River Gorge Saturday and Sunday afternoon and evening, with a renewed onshore push perhaps allowing for slightly stronger winds gusting to around 25-35 mph in parts of Hood River County. /DH .LONG TERM...Monday through Friday...Still monitoring chances for rain early next week. Models continue to speed up the timing of the frontal system as a more well defined shortwave embedded within the large scale trough crosses the region. Rain is likely to begin as early as Monday morning for coastal areas, gradually spreading inland through Monday night. PWAT values peak Monday afternoon around 1.5 inches of precipitable water according to the ECMWF ensembles. Regardless, ensemble and probabilistic guidance continue to be rather bullish on the prospect of at least measurable rain across the area, depicting around a 70 percent chance for northern coastal areas and about a 50/50 shot for the Willamette Valley. Meanwhile, the chance for as much as a quarter inch of rain sits around 40-50 percent on the coast and 20-25 percent from Eugene to Portland. Also expect slightly cooler temps again Monday into Tuesday as this system crosses the region accompanied by increased cloud cover and highs closer tot he upper 70s in the inland valleys. WPC ensemble clusters continue depict a ridge of high pressure developing over the western CONUS and a subsequent warming trend mid to late next week. Guidance has backed off slightly for highs next Wednesday, keeping temps closer to the mid 80s for one more day before the chances to reach 90 degrees jump up to around 70-80 percent in the inland valleys by Thursday and remaining there through the end of next week. DH/CB && .AVIATION...Dry west to northwest flow aloft over the region. High pressure offshore will maintain low level onshore flow into Sat. As such, will see areas of MVFR CIGS reforming along the coast over rest of Fri evening, with that stratus pushing inland via the gaps in the coastal mtns/highlands. Should see areas of lower MVFR inland throughout the Cowlitz River Valley, and along the Columbia River upstream to the PDX/VUO/TTD area by 12Z to 13Z. But, inland stratus will gradually break up Sat am, with mostly clear skies afterwards. Stratus along the coast will persisting into the early afternoon, then gradually break apart, with scattered clouds in the afternoon. With westerly to northwest flow relaxing overnight, will maintain to see haze and smoke over and east of the Oregon Cascades. Expect some reductions to slantwise visibilities, along with smoke layers around the fires. PDX AND APPROACHES...VFR will continue, with dry air mass and mostly clear skies. But, with onshore flow, will see areas of MVFR marine stratus pushing up the Columbia River overnight, spreading across Clark County by 12Z, and into OPS area from 13Z to 17Z, mainly east of Interstate 5 to the Cascades foothills. /Rockey && .MARINE...A weak upper level trough will slowly meander eastward through the weekend. Currently, expect persistent north/northwest winds with low-end Small Craft gusts, primarily in our central and southern waters. Threat will subside late tonight (Friday) and seas will remain around 4 to 6 ft thereafter. Overall benign conditions through the weekend with a southerly wind shift expected late Sunday/early Monday. -JH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 2 AM PDT Saturday for PZZ252-253-272- 273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland 909 FXUS66 KMFR 270546 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1045 PM PDT Fri Jul 26 2024 Updated Aviation Discussion .DISCUSSION...Updates were made to the forecast for this evening into Saturday. The main updates were to adjust the weather to account for the areas impacted by the smoke, and the other was to make adjustments to pops for later tonight and Saturday afternoon and evening to add a slight chance of thunderstorms. A weak upper low is moving into northern Cal and it`sd starting to take on a negative tilt. This has raised concerns for isolated thunderstorms later tonight. Current data suggest instability is marginal and mid level moisture is lacking. So we`ll go with a low end chance (10%) chance of storms in eastern Modoc and southeast Lake and Klamath counties late tonight. The aforementioned upper low will move towards Modoc County Saturday morning and over Modoc County Saturday afternoon. Mid level moisture, instability and trigger should be sufficient enough for isolated storms to develop in eastern Modoc and portions of Klamath and Lake County mid to late Saturday afternoon and evening. The only thing that could keep a cap on storm development will be the extent of the smoke from the Park Fire southwest of our forecast area. This will be passed on to the night shift and we`ll let them evaluate this further. -Petrucelli && .AVIATION...27/06Z TAFS...IFR/LIFR marine stratus/fog at North Bend will return overnight, especially to areas north of Cape Blanco and from Brookings southward. These low clouds will clear to VFR in the late morning and early afternoon. Inland, expect VFR with areas of MVFR visibilities in smoke downwind of area fires. Areas of smoke with periods of MVFR and IFR visibilities are expected in the afternoons and evenings at Grants Pass, Medford and Lakeview. Periods of smoke with MVFR visibilities are possible at Klamath Falls as well. One area where persistent smoke may be a problem is in southeast Siskiyou and southern Modoc Counties, where smoke models indicate visibility could remain at or below 3 miles due to smoke from the Park Fire. -CC && .MARINE...Updated 800 PM Friday, July 26, 2024...A thermal trough will remain in place through Saturday evening with north winds and steep to very steep seas, highest from Gold Beach southward. Winds trend slightly lower tonight into Saturday, but steep seas linger, especially south of Cape Blanco. The thermal trough will weaken with winds and seas gradually diminishing Saturday night as a weak front brings south winds Monday into Tuesday. Calmer conditions are expected Sunday into early next week. -Miles/CC && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Red Flag Warning until 8 PM PDT this evening for ORZ624-625. CA...Red Flag Warning until 8 PM PDT this evening for CAZ285. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Saturday for PZZ350-370. Small Craft Advisory until 5 AM PDT Sunday for PZZ356-376. Hazardous Seas Warning until 11 PM PDT this evening for PZZ356- 376. && $$ 079 FXUS66 KEKA 262215 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 315 PM PDT Fri Jul 26 2024 .SYNOPSIS...Temperatures will diminish below average in the interior this weekend, followed by slow warming next week. Coastal areas will remain cool with occasional low overcast and patchy fog. && .DISCUSSION...Visible satellite imagery showed an area of stratus locked onto portions of the coast this afternoon. The depth of the marine layer appeared to be shallow based the rate of inland clearing and KACV profiler; no more than 1500 feet. Marine layer will most likely deepen tonight. Stratus clouds will probably cover much of the coast for the remainder of the weekend, though some afternoon clearing will certainly be possible a few miles away from the shoreline. Thicker stratus should also yield some patches of light misty drizzle, though confidence is not high there will any measurable amounts. Temperatures in the interior will begin to "cool" below normal on Saturday with highs mostly in the 80s for the warmest valleys. Most of Trinity county is forecast to remain in the 90`s. Trough aloft with below normal 850mb temperatures will remain over the area for the remainder of the weekend and early next week. Also, a 500mb vort max will move across the area this afternoon and evening, however showers and thunderstorms are not expected due to very limited moisture and low available buoyant energy. A deeper push of moist air associated with a decaying front and transient 500mb shortwave trough may bring some measurable precip (most likely drizzle) to the North Coast region early next week, specifically Monday night or Tue. RAW and uncalibrated ensemble probability for a tenth or more in 24 hours from the ECMWF ENS is 10-30% for Del Norte and far northern Humboldt. Some light measurable precip, most likely drizzle, appears possible (10-20% chance) even though NBM 6 hourly probabilities are silent (10% or less). Granted July is the driest month of the year on average and odds for 0.10 or more are not good with strong downstream ridging dominating. Ensemble means indicate a building 500mb ridge and above normal 850mb temperatures for the latter portion of next week. NBM probabilities for 100F or more increase to 50% or more for the typically hot interior valley locations in the interior late next week. Thus, after a break from the heat this weekend and early next week, it does appear likely that summer heat will return late next week. DB && .AVIATION...Stratus has clung to the immediate coast today, driving IFR to LIFR ceilings at KCEC and KACV. Brief clearing is possible at the terminals lat this afternoon, although confidence is low as to whether or not this will actually occur at the terminals, and if it does, should only be for a few hours at most. Stratus rebuilds this evening and overnight tonight. VFR is forecast to continue for the interior through the TAF period. TDJ && .MARINE...Northerlies are forecast to slowly weaken over the next few days as an upper low moves in from the SW. This will weaken the land-sea pressure gradient over the next couple of days causing winds and seas to calm down significantly. This wind shut down is currently forecasted to hold steady through the weekend into early next week, then the usual thermal trof pattern returns by mid week, generating northerlies of 10 to 15 kts. TDJ && .FIRE WEATHER...Elevated to locally critical fire weather conditions due to gusty diurnally driven winds and very low RH`s from 10-20% are expected through this afternoon and evening, primarily across Lake, Trinity and interior Mendocino counties. Overnight RH recoveries have been generally good to moderate, except for some exposed ridges of Mendocino and Lake Counties. A deeper marine is forecast to develop tonight and persist through this weekend as a trough aloft develops over the area. Humidities are expected to increase as temperatures decrease below average this weekend. Afternoon winds are also forecast to be lighter this weekend. Also, a mid level vort max will progress over the area this evening and generate slight instability into Saturday afternoon. Some cumulus will build, however deep layer moisture and buoyant energy appears insufficient to warrant thunderstorms. A slow and moderate warming trend is expected mid next week with 100F degree heat most likely returning late next week. Chance for wetting rain, based on the NBM, is near zero for the next 7 days. DB && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 4 AM PDT Saturday for PZZ450-455. Small Craft Advisory until 10 AM PDT Saturday for PZZ470- 475. && $$ 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 259 FXUS66 KMTR 270552 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1052 PM PDT Fri Jul 26 2024 ...New AVIATION... .SYNOPSIS... Issued at 305 AM PDT Fri Jul 26 2024 Temperatures cool down more significantly beginning today with below average temperatures to persist through mid next week. Some potential for light drizzle along the coast Friday into Saturday and Saturday into Sunday. && .UPDATE... Issued at 844 PM PDT Fri Jul 26 2024 Satellite imagery shows stratus building into the North Bay valleys, the northern San Francisco Bay, the Monterey Bay region, and into the Salinas Valley. Expect further stratus development through the night with the Fort Ord profiler now showing a marine layer over 2000 feet deep. Stratus will pare back to the coastal regions during the morning, but could persist all day in the western half of marin County, the northern San Francisco Bay (including the city of San Francisco and Oakland), and the southern Monterey Bay. The forecast remains on track with no updates necessary. DialH && .SHORT TERM... (This evening through tonight) Issued at 1254 PM PDT Fri Jul 26 2024 Temperatures look to peak in the mid-to-upper 90`s across the far interior, 70`s and 80`s around the South Bay and North Bay valleys, and upper 50`s to 60`s near the coast this afternoon. Tonight, expecting more widespread low clouds, fog, and coastal drizzle to impact the region as the marine layer deepens. This is in response to a mid/upper level trough moving across the region. Minimum temperatures are forecast to be in the upper 40`s across the colder interior spots with 50`s elsewhere. && .LONG TERM... (Saturday through Thursday) Issued at 305 AM PDT Fri Jul 26 2024 Temperatures continue to cool Saturday and Sunday with widespread 70s to 80s expected inland and 60s to 70s expected closer to the coast. Upper level troughing will continue to deepen over the weekend which will help to keep temperatures cooler and contribute to some slight potential for light drizzle. Overnight Friday into Saturday and Saturday into Sunday, decent low level moisture at 850mb and 700mb will support the development of light drizzle to light rain along the coast and in areas where upslope ascent is favored. Both the NBM and the HRRR pick up on light coastal drizzle overnight this weekend with some potential for light showers over the marine environment. The NBM is showing very light precipitation totals along the coast and bay shoreline with totals ranging from a trace to a few hundredths of an inch. The upper level pattern will become more zonal by early next week which will allow for temperatures to warm slightly. In general, temperatures are expected to gradually increase a few degrees each day beginning Monday but high temperatures will still remain below average through mid-week. By mid to late next week, a little more uncertainty enters the forecast in regards to how fast high temperatures will warm up again. Ensemble guidance indicates ridging will start to build over the Western US by mid to late next week but cluster analysis indicates that it is less certain where exactly the ridge will set up. Temperatures could be slightly warmer depending on if the ridge is centered more directly over the West Coast vs temperatures could be slightly cooler if the ridge is centered to the east of the coast. Regardless, it is looking likely that above average temperatures will return with the current forecast and the CPC 8-14 day outlook both in support of slightly above average temperatures returning by the first week of August. && .AVIATION... (06Z TAFS) Issued at 1048 PM PDT Fri Jul 26 2024 MVFR/IFR CIGs continue to move inland overnight, affecting the all TAF sites. Winds are expected to stay light to moderate overnight, with some pockets of mist and fog forming in areas with the lightest winds and along the coast. CIGs erode in the inland areas by mid morning, while the Monterey Bay sees clearing in the afternoon, however cloud cover looks to remain over the SF Bay for the remainder of the TAF period. Vicinity of SFO...Expect MVFR/IFR CIGs and moderate winds through the night and into Saturday morning. CIGs lift to MVFR into Saturday afternoon as breezy westerly winds arrive. CIGs are expected through the rest of the TAF period. SFO Bridge Approach...Similar to SFO, with some chances of spotty IFR-level cloud cover early Tuesday morning. Monterey Bay Terminals...LIFR/IFR CIGs and mist push inland this evening and last until the late morning before lifting, and eroding into the afternoon as breezy winds arrive. CIGs move inland again in the late afternoon on Saturday, Filling over MRY. && .MARINE... (Tonight through next Thursday) Issued at 844 PM PDT Fri Jul 26 2024 Moderate to breezy Northwest winds linger through the weekend before easing into the next work week. Expect some hazardous gusts in the northern outer waters as well as along the Big Sur Coast. Significant wave heights will continue to abate through the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 9 AM PDT Saturday for SF Bay N of Bay Bridge. Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Pt Pinos to Pt Piedras Blancas 0-10 nm. Small Craft Advisory until 3 AM PDT Sunday for Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...RGass LONG TERM....Kennedy AVIATION...Murdock MARINE...Murdock Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea 290 FXUS66 KOTX 270434 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 934 PM PDT Fri Jul 26 2024 .SYNOPSIS... Friday through the weekend will be mostly dry with near average temperatures. A weather system arriving Monday and Tuesday will bring a chance for some showers and thunderstorms in the Inland Northwest. Dry and hot weather returns later next week. && .DISCUSSION... Today: Northwest flow aloft and lower heights continue to bring more comfortable temperatures to the area. Winds across the area are light, which should help to reduce some smoke production. Nonetheless, the HRRR smoke shows a swath of smoke from the Swawilla fire migrating towards the Colville area this evening and overnight. The fires near Juliaetta are sending smoke to the southwest and the Lewiston has cleared out a bit. Saturday and Sunday: A closed low off California moving inland will help to maintain lower heights across the area, while an approaching shortwave will move across the area, bringing tighter pressure gradients and increased winds across central Washington on Saturday and central and eastern Washington Sunday. There is a 20-40% chance of meeting red flag conditions near Wenatchee and the L-C valley Saturday and Sunday. There is a 10-20% chance of thunderstorms in the north Cascades/northern mountains Saturday as model soundings show weak conditional instability building with the shortwave passage. Monday and Tuesday: Another stronger shortwave trough from the Gulf of Alaska will move onshore late Monday into Tuesday, bringing tighter pressure gradients and stronger associated winds, elevating fire concerns despite higher humidities. Associated with this is a chance for wetting rain approaching 50% northeast of Spokane and in the Cascades/Idaho Panhandle Monday through Tuesday night, as well as a 10-20% chance of lightning. Unfortunately, central Washington is unlikely to see a wetting rain during this time, and as wind increases, fire concerns will be elevated with the very dry fuels. Nonetheless, increased cloud cover and humidity will aid fire-fighting efforts. Temperatures will remain near-average during this period. Wednesday through Friday: Models are in good agreement that a ridge will start to build back in later next week, which will bring increasing heat to area, with high temperatures approaching the mid-90s to low-100s. Winds will abate to below critical levels during this period, but associated dry air and increased heat will still likely allow for fire risk levels to remain at or near levels seen earlier in the week. /Cooke && .AVIATION... 06Z TAFS: Dry northwest flow aloft will keep conditions VFR through the period with light and diurnally/terrain driven winds. Smoke from local and regional wildfires wildfires may result in intermittent visibility reductions to 6SM. The exception will be for KLWS where nearby fires (River and Gwen) to the east will result in reductions to 4SM or less, bouncing between MVFR and IFR conditions. Northwest winds in the afternoon may slightly improve conditions but confidence is low. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is low confidence on how smoke will impact visibility across the Inland Northwest. ----------------------- 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 53 87 56 86 59 84 / 0 0 0 0 0 10 Coeur d`Alene 51 85 54 84 57 81 / 0 0 0 0 0 10 Pullman 47 82 50 81 52 82 / 0 0 0 0 0 0 Lewiston 59 92 61 92 65 91 / 0 0 0 0 0 10 Colville 44 84 45 84 47 82 / 0 10 10 0 0 30 Sandpoint 47 82 50 82 52 78 / 0 0 0 0 0 20 Kellogg 55 80 57 80 59 79 / 0 0 0 0 0 10 Moses Lake 53 89 55 89 57 87 / 0 0 0 0 0 10 Wenatchee 61 88 61 88 64 84 / 0 0 0 0 10 20 Omak 58 91 58 91 60 86 / 0 10 10 0 0 30 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$ 276 FXUS66 KPDT 270523 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1023 PM PDT Fri Jul 26 2024 Updated aviation discussion .SHORT TERM...Tonight through Sunday night...Satellite imagery reveals widespread smoke and haze across most of eastern Oregon and eastern Washington, the result of regional wildfires which continue to burn. Have extended smoke and haze in the forecast through Sunday morning based primarily on HRRR smoke output. While smoke and haze will likely linger across the region, especially in the vicinity of ongoing wildfires, have opted to exclude mention in the gridded forecast due to uncertainty in the evolution of fires and smoke output. Weak troughing over the Pacific Northwest will keep near-normal temperatures and locally breezy westerly gap winds in place this weekend. Saturday, a weak disturbance tracking across southeast Oregon will bring non-zero, but low (<5%) chances of showers or thunderstorms across the southern Blue Mountains during the afternoon. A concurrent shortwave tracking across northern Washington appears mostly dry with the main consequence being the wind. .LONG TERM...Monday through Friday...Models continue to be in good agreement in having a trough over the Pacific Northwest with a ridge over the central CONUS Monday and Tuesday. Tuesday afternoon into Wednesday, a front moves through the area and carries the trough eastward while closed low develops out in the eastern Pacific. Models show general agreement in having a westerly zonal flow overhead Wednesday though about 40 percent of model ensemble cluster members begin having the ridge building into our area. Thursday and Friday, model ensemble members all have the ridge building and strengthening over our area with temperatures warming well above normal to around 100 degrees by Friday. The Extreme Forecast Index highlights Precipitation amounts along the Washington Cascades Monday and Tuesday with values of 0.72-0.82 and some shift of tails values indicating a possibility of heavier rain. It also highlights breezy winds Monday afternoon in central Oregon and portions of the Columbia Basin with a value 0.73. Cooler than normal temperatures are highlighted Monday and especially Tuesday due to cooler air with the front. Monday will see the trough coming ashore with a slight chance to chance of showers developing the Cascades in the late morning and afternoon then spreading into the rest of the area Monday night. The Cascade crest could get up to a half of rain but amounts will be fairly light away from the crest. Models are not showing enough instability for thunderstorms and the timing may be too late (evening) for convection in the eastern mountains, so just have showers. With the front, winds will increase to 10 to 20 mph over most of the area. Model probabilities show a 25-55 percent chance of 20 mph sustained winds, but chances of 25 mph sustained winds drop to below 15 percent and that is just in the Columbia Gorge and Kittitas Valley. Temperatures Monday will be similar to Sunday with highs in the mid 80s to around 90 in the lower elevations. Tuesday will see the trough overhead and then moving off to the east Tuesday night. This will be a more favorable day for showers and a slight chance of thunderstorms in the eastern mountains though amounts will be just a few hundredths of an inch for the most part. Showers and thunderstorms will end quickly in the early evening. The Columbia Basin will again have 10 to 20 mph winds but winds will be lighter in central Oregon. Temperatures will drop a few degrees to the lower to mid 80s with 70s in the mountains. With ridging beginning to develop Wednesday, foresee dry weather and light winds with temperatures warming to near normal in the upper 80s to lower 90s. The ridge will strengthen further Thursday with temperatures rising to the mid to upper 90s and in the mid 80s to lower 90s in the mountains. NBM probabilities show a 20-35 percent chance of reaching 100 degrees in the Columbia Basin, central Oregon and in the John Day valley. On Friday, the cutoff low that has been parked out in the eastern Pacific moves closer to the coast and our flow turns more southerly and unstable due to a possible ridge breakdown. There is some chance that this situation could pull some moisture into the area and PWATs are over an inch in the GFS, but at this time models are holding off on any showers or thunderstorms. It looks more favorable next Saturday but that is past the scope of the long term forecast. This will have to be watched during the course of next week. Temperatures will warm further with highs rising to 97-105 in the lower elevations and mainly in the 90s in the mountains. NBM probabilities give a 40-70 percent chance of reaching 100 degrees, but the chances of 110 degrees are less than 5 percent even in the warmest locations. Perry/83 && .AVIATION...06Z TAFs...VFR conditions with mainly clear skies will prevail through the night then expect some increasing high clouds on Saturday becoming SCT-BKN200. However, there will be considerable haze and smoke aloft and some reduced visibilities produced near many of the ongoing fires. Continue to expect YKM to have vsbys down to around 4SM overnight in HZ and FU with some possible improvement on Saturday. KBDN could also see a return of some SCT-BKN around 050 overnight through Saturday morning. Winds will be less than 10 kts overnight. KDLS will see winds increasing after 15Z tomorrow to 15- 20 kts and gusts around 30kts with other sites 5-15 kts. && .PRELIMINARY POINT TEMPS/POPS... PDT 51 86 56 87 / 0 0 0 0 ALW 54 89 60 90 / 0 0 0 0 PSC 56 91 61 91 / 0 0 0 0 YKM 53 89 55 89 / 0 0 0 0 HRI 54 91 60 90 / 0 0 0 0 ELN 56 87 57 86 / 0 0 0 0 RDM 47 86 48 85 / 0 0 0 0 LGD 51 86 51 87 / 0 0 0 0 GCD 51 88 51 88 / 0 0 0 0 DLS 58 86 61 85 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...86 LONG TERM....83 AVIATION...83 302 FXUS65 KREV 262103 AFDREV Area Forecast Discussion National Weather Service Reno NV 126 PM PDT Fri Jul 26 2024 .SYNOPSIS... * Isolated storms for portions of western NV this evening and overnight. Winds will remain gusty through Saturday across ridges. * Gusty southwest winds and lower humidity bring increased fire weather concerns to northeast CA and northwest NV this afternoon. * Dry conditions and more seasonal temperatures will prevail this weekend through the remainder of July although smoke may spread across portions of northeast CA and western NV. && .DISCUSSION... * THUNDERSTORMS: Confidence remains unchanged (medium) as HREF showed a decrease in the 40 dBZ echo potential overnight, but maintains a convective signature for elevated and quick moving clouds/showers starting along and south of US-50 late this afternoon or early evening and lifting northward into the late evening and early morning hours Saturday. Latest satellite imagery showed cumulus development beginning over southern Mono County which may lead to a few cells through 5 PM before best focus shifts eastward into NV this evening. Gusty outflow winds to 35+ kts will be a threat with any shower or storm that develops with a 10-20% chance for seeing lightning. We maintained a 5-10% chance as far west as Hwy 395. * WINDS: Gusty southwest winds will continue into this evening, especially along Hwy 395 and across NE CA/NW NV with most gusts 25-30 mph, but locally as high a 35 mph for a few hours. As a 70 kt 250 MB upper jet moves across the Sierra, winds will ramp up over the ridges and upper slopes with gusts 50+ mph (locally to 70 mph at the typical windiest spots). While winds will decrease at lower elevations, they may remain elevated on Lake Tahoe and across foothill locations overnight and Saturday AM behind the exiting shortwave. * SMOKE: Satellite and Alert cams indicate smoke across parts of northeast CA and northwest NV from wildfires (primarily the Park and Stockade Canyon wildfires) this afternoon. As winds turn back to more west-southwest behind tonight`s shortwave, HRRR indicates this smoke drifting farther south into western NV this weekend, possibly impacting areas as far south as Fallon and Reno by Sunday/Sunday night. * NEXT WEEK: After seasonal temperatures through the end of July, there are indications that the ridge will build near the Four Corners and expand westward into the Great Basin per latest ensemble clusters. This pattern would likely return temperatures to 10 degrees above average with 100+ degrees across western NV as we go into August. Also, the high`s position would bring a return southerly flow and increasing risk of thunderstorms. Hohmann && .AVIATION... * For late this afternoon/tonight, an upper level wave will bring a 10-20% chance of storms across W NV, focusing east and north of Reno. There is a 10-15% chance for storms at KMMH from 21Z to 00Z today with a 5% chance of storms at KRNO-KCXP-KMEV after 27/00Z. Storms may linger past midnight across NW NV as storms lift northward. * SW-W winds with gusts 20-25 kt across most of the main terminals with gusts to 40 kt across the ridges through sundown. As a 70 kt 250 MB jet traverses the Sierra tonight/early Saturday, 700 MB winds will increase to 30-35 kts with gusts up to 60 kts at ridge level. This will lead to increasing LLWS along the eastern Sierra from the Tahoe Basin southward to Mammoth Lakes. Leeside turbulence may increase to moderate at times along the eastern Sierra into far western NV. * Smoke and haze from local wildfires will produce areas of reduced slantwise visibilities from Susanville to Gerlach and points north, with high resolution models indicating this smoke slowly shifting south toward I-80 in W NV this weekend. Hohmann && .FIRE WEATHER... Afternoon west-southwest breezes to 25-30 mph and low daytime relative humidity will lead to elevated fire weather concerns areawide through this evening. Some areas across Lassen and northern Washoe counties may see a few hours of critical fire weather conditions, though this threat is too isolated spatially to warrant the issuance of a Red Flag Warning today. There is a slight chance for shallow nocturnal convection tonight, roughly along and east of a line extending from eastern Mineral County into far northern Washoe County. Isolated showers look to initiate along this line following sunset before tracking northeast and out of our region overnight. Thunderstorm chances are low, but non-zero, with main concerns for gusty outflow winds given steep low-level lapse rates. Fire weather concerns diminish this weekend as the cooling trend continues and overnight RH recoveries improve. For areas north of I- 80, dense smoke concentration from the Park Fire may further reduce daytime heating and thus limit fire activity for new or existing fires this weekend. Whitlam && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ 922 FXUS66 KSTO 262019 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 119 PM PDT Fri Jul 26 2024 .SYNOPSIS... Less hot with a cooling trend into the weekend. Critical fire weather conditions today in the central and northern Sacramento Valley and adjacent terrain with low humidity and gusty southerly winds. && .Key Points... - A Red Flag Warning is in effect for much of the central and northern Sacramento Valley and northern foothills thru 11 PM tonight. - Cooling trend into the weekend with gradual warming trend by the middle of next week. && .Discussion... The recent trend of widespread triple digit temperatures in the Valley and foothills begins to end today; currently, temperatures across the Valley and foothills are in the mid 80s to low 90s, with high temperatures in the Valley and foothills expected to range today from the low 90s to just over 100. Temperatures are expected to cool even more dramatically tomorrow, over 10 degrees in some locations, due to an upper low passing over the area. While the low has caused some of the recent gusty winds, the system itself is fairly dry and is not expected to bring any precipitation to the area. Winds themselves will continue to trend down as well, with conditions becoming lightly breezy over the weekend, as opposed to the gusty winds we`ve been experiencing. Fire weather conditions in general are expected to improve over the weekend, though a Red Flag Warning remains in effect until 11 PM tonight. Daytime and overnight relative humidities this weekend will be higher in the Valley, temperatures (as previously mentioned) will be cooler, and winds will trend down. However, higher elevations will see less relief in the form of elevated humidities, and fuels are still quite dry, so it will remain important to practice fire safety during this time. Finally, as quickly as the "cooler" weather arrived, it will be replaced by a gradual warming trend early next week. It is however, important to note that there is some ensemble and cluster disagreement over when exactly the low will move on, and how strong it will have remained by that point, meaning that temperatures will be slow on the road back to above normal for the time of year. Monday, high temperatures are expected to remain primarily in the 80s and 90s, only slightly warmer than over the weekend. //SP && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... As we move into the remainder of next week, temperatures will continue their Sisyphean climb back up to normal and above normal conditions. By Thursday, clusters and ensembles seem to be in good agreement that ridging will begin to encroach on the area once again, bringing back the near to above normal temperatures in earnest. Temperatures look to remain around the mid 90s to low 100s in the Valley through the end of next week, though there is some uncertainty as we head into the weekend. Otherwise, warm dry weather is expected through next week, with temperatures gradually increasing and daytime relative humidity gradually decreasing. //SP && .AVIATION... VFR conditions over interior NorCal next 24 hrs except local MVFR/IFR possible in haze/smoke vicinity of wildfires. In Central Valley, areas of southerly surface wind 10-15 kts, with gusts up to 25 kts until around 10z. In the vicinity of the Delta, southwesterly surface wind 15-25 kts with local gusts to 35 kts. && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 11 PM PDT this evening for Burney Basin and Northeast Plateau in Shasta County Including Northwest Lassen NF north of Lassen NP-Central Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below 1000 Ft- Northern Sacramento Valley to Southern Tehama County Line Below 1000 Ft-Northern Sierra Foothills from 1000 to 3000 Ft. Includes portions of Shasta-Trinity and Butte Units-Northern Sierra Including Lassen NP and Plumas and Lassen NF/S West of the Sierra Crest (West of Evans Peak-Grizzly Peak-Beckworth Peak). && $$ 266 FXUS65 KMSO 261915 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 115 PM MDT Fri Jul 26 2024 .DISCUSSION...Breezy afternoons, mainly dry conditions, and smoky skies will dominate the weather pattern through Monday. An exception will be tomorrow as a weak wave will provide the lift for a mix of wet and dry thunderstorms in the S. Bitterroot Valley, Lemhi County, ID, and southwest MT which will lead to concerns for a critical fire weather day in those locations. Any storms will be capable of gusty and erratic outflow winds. Tuesday a stronger wave associated with some Pacific moisture will transit the Canadian border bringing showers and thunderstorms mainly to northwest Montana and the Continental Divide. Slightly cooler temperatures will result from cloud cover. By Thursday, the model consensus is increasing temperatures with a reemergence of the 4-corners high pressure. A deepening Alaskan trough on the 2-3 Aug will force the axis of the ridge to the east. The question then becomes, will the ridge hold and the Northern Rockies experiences very warm temperatures with increasing instability or a complete ridge breakdown? Future forecasts will answer this question. && .AVIATION...Breezy winds out of the west will develop this afternoon and evening and will be the main weather feature at all terminals today. Smoke from local and regional wildfires will degrade visibility at times throughout the Northern Rockies today and tonight. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...&& $$ 040 FXUS65 KBOI 270257 AFDBOI Area Forecast Discussion National Weather Service Boise ID 857 PM MDT Fri Jul 26 2024 .DISCUSSION...Skies were smoky this evening, and there are even a few real clouds out there. Smoke is expected to continue tonight and tomorrow, with harmful levels in many areas. We have at least 8 detectable smoke plumes originating in our CWA. In addition, smoke from the Park Fire is moving over the region at a higher elevation, acting like a layer of cloud in some areas. All this smoke helped keep max temperatures down below what was forecast. Showers and isolated thunderstorms are in the forecast Saturday, with the highest chance in Twin Falls and Jerome counties. No changes will be made at this time. && .AVIATION...Widespread MVFR with local IFR in smoke from wildfires. Slight (<25 percent) chance of showers/thunderstorms south of a KBNO- KJER line and in central ID (east of KMYL) after Sat/18Z. Surface winds: light and variable less than 10 kt becoming northwest 5-15 kt after Sat/18Z. Gusts to 40 kt near thunderstorms. Winds aloft at 10kft MSL: W-SW 5-15 kt. KBOI...Periods of MVFR in smoke, with reductions to IFR possible. Northwest surface winds less than 10 kt. Sunday Outlook...Wildfire smoke with areas of MVFR and local IFR conditions. Winds generally W-NW 5-15 kt. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday night... An upper trough over the Pacific NW and northern Rockies will continue to bring near normal temperatures to the region through the weekend. A weak upper low off the California coast will get pulled northeast over Oregon and Idaho Saturday. Moisture is limited but there will be a chance (15-30%) of thunderstorms Saturday afternoon and evening near the Nevada border and over eastern portions of the Payette and Boise NF. Sunday looks dry across the forecast area. Breezy westerly winds Saturday and Sunday afternoon as a weak shortwave moves across northern Idaho. Smoke will continue to impact the region with southwest to west winds advecting smoke over the area from northern California fires in addition to our local fires over eastern Oregon and southwest Idaho. LONG TERM...Monday through Friday... Next chance of precipitation (15-20%) will be Monday night/Tuesday generally north of a line from around Burns to McCall as another weak Pacific trough sweeps across the region. This will kick westerly winds up again for breezy conditions Monday and Tuesday. The great basin high is expected to rebuild late next week for a return to above normal temperatures Thursday and Friday with triple digit heat in the lower valleys. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...SP AVIATION.....BW SHORT TERM...TL LONG TERM....TL 590 FXUS65 KLKN 262122 AFDLKN Area Forecast Discussion National Weather Service Elko NV 222 PM PDT Fri Jul 26 2024 .SYNOPSIS...Look for evening isolated to scattered showers and isolated thunderstorms to be focused mainly across the central and eastern portions of Nevada. Temperatures will be cooler on Saturday with isolated showers and thunderstorms possible across portions of White Pine and eastern Elko counties. Smoke from several California wildfires will impact much of the region over the coming days. && .SHORT TERM...Tonight through Saturday night. Radar is less active versus 24 hours ago with a few cells developing in far east- central Nevada. The air mass has dried out considerably since last night. Look for isolated to scattered showers and thunderstorms to continuing developing in the central part of the forecast area this afternoon and evening. Overnight lows will be in the 50s and 60s. Southwest flow aloft will keep the moisture at bay tomorrow as a weak upper trough tracks across northwestern Nevada. Afternoon highs will be much cooler than what we have experienced with readings in the 80s, with some low 90s possible in the central sections. Winds will be breezy with some gusts to 25 to 30 mph. An isolated shower or thunderstorm cannot be ruled out Saturday afternoon across northeastern Nevada. Highs will be in the 80s with low 90s possible in central Nevada. Clear and quiet conditions persist during the overnight with lows dipping into the 40s and 50s. .LONG TERM...Sunday through next Friday Confluent upper level flow over northern California and Nevada on Sunday lead in to a quiet weather pattern for the area in the long term. Zonal flow over the region separates the upper level trough to the north over the northern Rockies and the upper level ridge attempting to build back into the Four Corner region and southern Plains. Aided by an upper level low working its way up the Pacific coast from the Baja of California, the ridge will slowly amplify over the SW CONUS through Friday. Sunday afternoon there will be a low 10% to 15% chance for a stray storm over far NE Elko County, with any storms that do form most likely will be dry which will elevate fire weather concerns due to lightning strikes. Precipitation and convective chances are difficult to come by for the rest of this week over the area. Monsoonal moisture will steer clear of the region through Friday. Single digit RH values over Nye and White Pine counties Monday combined with potential 25-30 knot wind gusts prompt concerns for elevated fire weather in those areas. Temperatures will slowly increase through the week as the ridge builds into the region from the south. Highs in the 80s on Sunday will give way to low-to-mid 90 values Monday and Tuesday. By Thursday and Friday highs across the region will reach the upper 90s with a few locations even touching triple digits. What is unclear at this point will be the effects of potential wildfire smoke over the area. At the time of forecast the Park Fire in northeastern California was emitting appreciable smoke over northern Nevada. The impact of smoke on the forecast will need to be monitored and updated as the week progresses. && .AVIATION...VFR conditions exist this afternoon away from any thunderstorms that form over the southern portion of the CWA. Conditions could deteriorate over northern Nevada for the KWMC, KBAM, and KEKO terminals with the return of smoke from wildfires in California. MVFR and potentially IFR conditions (mainly KWMC- KBAM) may occur overnight as models indicate smoke drifting back over the area. Afternoon VCTS are expected to be present at KELY and KTPH, beginning later in the afternoon, between 22Z and 00Z. Winds will be somewhat breezy in the afternoon with gusts 18KT to 20KT expected at all terminals, though convective wind gusts to 45KT are possible with any storms that move on terminal at KELY and KTPH. Localized blowing dust, small hail, and brief heavy rain fall will be additional concerns under any thunderstorms and periods of MVFR or IFR may be possible. VCTS chances diminish after sunset and should remain away from the region through Saturday morning. && .FIRE WEATHER...Drier air has pushed across much of northern and central Nevada this afternoon. Enough moisture exists in east- central Nevada to allow for the development of isolated to scattered showers and isolated thunderstorms. These will continue into the evening hours tonight. By tomorrow, a weak upper trough will keep the southwest flow aloft with mainly dry conditions continuing. Isolated shower or thunderstorm is possible in northeast and east-central Nevada. Winds in the afternoon will become breezy with gusts to 30 mph in some locations. This will bring elevated fire weather conditions across portions of 437, 438, 469, 470, and 425 due to winds and minimum relative humidity values around 10 to 15 percent. Conditions will remain dry Sunday with lighter winds. However, Monday is looking like another elevated fire weather day as winds are expected to gust in the 25 to 30 mph with minimum relative humidity values around 10 to 15 percent. This will need to be watched for any fire weather headlines. Look for afternoon highs to warm back into the mid to upper 90s by mid-week, though smoke from wildfires in California may limit warming by a degree or two due to the smoke. && .LKN Watches/Warnings/Advisories... None. && $$ 86/99/99/86 |
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