953 FXUS66 KSEW 111813 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 1113 AM PDT Mon May 11 2026 .SYNOPSIS... A ridge of high pressure will produce a warming trend through Tuesday. A transition to onshore flow and cooler temperatures will take place on Wednesday along with a chance of some precipitation. Cooler and unsettled conditions are expected into the upcoming weekend as a trough of low pressure over the Northeast Pacific sends a series of weak frontal systems across the area. && .SHORT TERM /TODAY THROUGH WEDNESDAY/... A ridge of high pressure aloft will rebuild into the area today with low level flow turning northerly. After areas of morning clouds, mostly sunny skies are expected today along with modestly warmer temperatures. The low level turns offshore tonight as thermally induced low pressure expands northward along the coast. Temperatures will warm further on Tuesday with most of the region getting into the 70s and lower/mid 80s. A few spots across the interior will briefly reach moderate heatrisk criteria. The low level flow turns onshore late in the day on Tuesday...with a cooling sea breeze for the coast. The forecast Tuesday night and Wednesday remains something of a a conundrum. A closed off and negatively tilted upper low will approach the coast somewhere between far northern California and Oregon. Model solutions remains split in their handling of this. Of note, the 00Z ECMWF deterministic run and many of it`s ensembles bring the low further north putting Western Washington squarely in the crosshairs of some elevated instability and diffluence aloft. Should this occur, we could be talking about some nocturnal convection popping up Tuesday night into early Wednesday morning. The GFS suite of ensembles are less enthused about this scenario, but about half of them do generate some precip on Wednesday. Needless to say, uncertainty in the Wednesday forecast remains high, but cooler temperatures and a chance of showers or isolated thunderstorms looks like a safe forecast. Stay tuned. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A mean upper trough position takes up residence over the Northeast Pacific for the second half of the week. This will lead to cooler conditions and some light precip at times Thursday into Saturday. There`s general agreement that weak upper ridging will attempt to make some inroads late in the weekend for perhaps drier conditions and temperatures recovering to around seasonal normals. 27 && .AVIATION... Westerly flow aloft will become southwesterly as the upper level ridge axis shifts east this afternoon and evening. The ridge overhead will result in clear skies. N winds 6-12 kt today, becoming NE again 5-7 kt tonight. Chance of low cigs/vis Tuesday morning remains confined to the coast. KSEA...Clear skies and VFR conditions through the period. N winds 8-12 kt, becoming NE 5-7 kt late this evening. HPR && .MARINE... A post-front push through the Strait of Juan de Fuca will weaken early this morning as high pressure builds again in the eastern pacific via a ridge. Coastal waters may have a couple pockets of fog underneath the stratus early this morning. There is also a thermal trough expected for Tuesday that may bring a brief period of offshore flow. Models have a trough/front passing through midweek, with a 40% chance of showers over the interior waters. While winds for most waters will remain light through the week, there will continue to be pushes of winds (likely greater than 20 kt) through the Strait of Juan de Fuca at times - particularly Wednesday and Friday. Seas will hold around 4-6 ft through the week, with a brief jump up to 6-8 ft midweek. HPR && .HYDROLOGY... The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated during this time as needed. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$

374 FXUS66 KPQR 111759 AFDPQR Area Forecast Discussion National Weather Service Portland OR 1059 AM PDT Mon May 11 2026 Updated aviation discussion. .SYNOPSIS...Temperatures rebound on Monday and Tuesday as high pressure re-builds, with the warmest temperatures on Tuesday. Precipitation chances return on Wednesday as a trough approaches the West Coast. Another low from the Gulf of Alaska will maintain precipitation chances and a trend towards cooler temperatures through the end of the week. && .DISCUSSION...Today through Sunday...Looking at the first part of the week, deterministic and ensemble guidance remain in agreement with upper-level ridging re-building over the Pacific Northwest. This will result in a return of sunny skies while dry weather prevails. There is high confidence that daytime high temperatures along the coast will be in the mid 60s to mid 70s, low 70s to low 80s for the Cascades and mid 70s to low 80s for the Willamette Valley. Tuesday is looking to be the hottest day of the week with daytime highs along the coast in the mid 60s to mid 70s, mid 70s to mid 80s for the Cascades and low 80s to upper 80s for the Willamette Valley. There is currently a 20-40% chance that high temperatures exceed 90 degrees on Tuesday across the Portland/Vancouver Metro Area. The rest of the Willamette Valley, southwest Washington lowlands, Columbia River Gorge, and Upper Hood River Valley have a 5-10% chance of exceeding 90 degrees. If KPDX (Portland Airport) ends up at or above 90 degrees, this would tie or break the daily record of 90 degrees which was set in 2023. Given the warmer forecast temperatures on Tuesday, there is now Moderate HeatRisk across the Portland/Vancouver Metro Area, Cowlitz Valley, and Columbia River Gorge. Those who are sensitive to heat will be affected, especially those without cooling and hydration. The next chances for precipitation return late Tuesday/Wednesday as the next trough approaches the West Coast. The majority (80%) of ensemble members show an upper level trough tracking over Oregon and as a result, chances for precipitation increases across our CWA towards 25-45%. However, current QPF forecasts remain around a few hundredths of an inch, if any. In addition, southerly/southeasterly flow from this pattern would bring increased mid-level moisture and instability, bringing a 15-25% chance for thunderstorms across the Linn and Lane County Cascades Tuesday and Wednesday afternoon. This pattern would also bring about cooler daytime highs through the latter part of the week. The other scenario depicted by the remaining (20%) ensemble members have a closed low aimed at Central California which would decrease precipitation chances as well as result in warmer daytime temperatures. There is greater uncertainty in the pattern Thursday-Saturday, however, most ensemble members are showing another trough dipping down from the Gulf of Alaska by the end of the week. This will maintain chances for precipitation across the area and bring lower 500 mb heights, resulting in temperatures cooling down to seasonal normals. However, the exact track of this system, timing, and precipitation amounts are still uncertain. About 30% of ensemble members have ridging re-building by the weekend. /42-10 && .AVIATION...Dry southwesterly flow aloft, with north/northwest flow at the surface continues as upper level ridging builds over the region today. Expect predominately VFR conditions for the majority of the airspace. The only exception is a 40-60% chance for the redevelopment of MVFR/IFR ceilings around and south of KONP after 10- 12z Tue. Elevated north/northwest surface winds around 10 kts. Gusts along the coast up to 25 kt from 19Z Mon through 03Z Tue. Winds decrease below 7 kts after 04-06z Tue. KPDX AND APPROACHES... VFR conditions expected through the period. North to northwesterly winds around 8-10 kts, decreasing below 6 kts by 04-06z Tue. -03 && .MARINE...Weak, upper level high pressure returns across all waters today which will maintain northerly winds. Daytime heating will increase the surface pressure gradient which will result in gusts up to 25 kt for all inner and outer marine zones starting at noon today through early Tuesday morning, granted zones will come on-line and go off-line at various times. Looking towards Tuesday through at least Thursday conditions return to a more benign pattern with north to west winds, with gusts below 20 kt and seas 5 to 7 ft. /42 && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 11 PM PDT this evening for PZZ251-271. Small Craft Advisory from noon today to 2 AM PDT Tuesday for PZZ252-253-272-273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

719 FXUS66 KMFR 111048 AFDMFR Area Forecast Discussion National Weather Service Medford OR 348 AM PDT Mon May 11 2026 .DISCUSSION... Warm and dry conditions will continue today as highs will push into the lower 90`s for highs in Medford. However, no records will be at risk on Monday based on the latest high temperature forecasts. The thermal trough at the coast will retreat farther inland on Tuesday and keep temperatures in the lower 90`s and upper 80`s in the west side valleys. Meanwhile, an upper level low will approach the Oregon coast increasing wind speeds aloft. With deep mixing up to 10000 and perhaps 12000 feet, we`ll mix down those higher winds and gusts to 30kts should be likely, especially east of the Cascades and in the Shasta Valley. Also, moisture will be increasing west of the Cascades as this low moves in. Models are not that ambitious initiating widespread convection, although there are hints some showers or thunderstorms could form in the evening hours. The NBM probability of thunderstorms is about 10% within 20km of most areas in Oregon on Tuesday evening, which seems a bit high based on the forecast soundings. In any case, there is a low fairly close to the shore, and that does fit the pattern for thunderstorms during these warm months. Eventually, this low to our west will move inland Tuesday night into Wednesday morning. Models are in good agreement that some precipitation will fall, although there are a few members(~5-10%) that are relatively dry and put most of the precipitation to our north in Portland`s CWA or south in Sacramento`s CWA. In any case, look for a cold front to move through Wednesday and push temperatures down 10 to 15 degrees. This progressive north west flow will continue through the remainder of the week and keep temperatures near normal for this time of year. No weather impacts anticipated, although the low chance of rain on Saturday could impact some outdoor events. Even if it does rain, it will likely be light. -Smith && .AVIATION...11/12Z TAFs... Patches of IFR and LIFR have developed along the coast under some marine stratus. It looks like slivers of the stratus are holding up against the north east winds, so this will likely stick around into the morning hours. ceilings will burn off by the afternoon hours and VFR will prevail through the remainder of the afternoon and evening hours. Look for gusty low level northerly winds at the coast into the evening. -Smith && .MARINE...Updated 330 AM PDT Monday, May 11, 2026...A thermal trough will bring gusty north winds and wind driven steep seas south of Cape Blanco through today. Gusty north winds and steep seas are expected to expand north of Cape Blanco this afternoon before subsiding again later tonight. Low pressure will move south of the waters Tuesday night into Wednesday with some showers developing over the region. Winds won`t be too strong and remain mostly from the north. A thermal trough pattern could redevelop Friday into next weekend with stronger north winds and steeper seas again, especially south of Cape Blanco. -Spilde/Smith && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this evening for PZZ350-356-370-376. && $$

780 FXUS66 KEKA 110721 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1221 AM PDT Mon May 11 2026 .SYNOPSIS...Temperatures will continue to warm and Monday is expected to be the hottest day. Clouds are expected to scatter out at the coast this afternoon. Slightly cooler temperatures and more marine clouds are expected Tuesday. There is the possibility of some rain, drizzle, and inland thunderstorms on Wednesday. Near or slightly above normal temperatures are expected late in the week and into the weekend. Breezy northwest winds with gusts of 25 to 30 mph are possible. && KEY MESSAGES: -High interior temperatures will peak today with moderate HeatRisk in Mendocino and Lake Counties. -Cooler temperatures, coastal drizzle and a slight chance for inland thunderstorms Wednesday. -Breezy winds possible this weekend. .DISCUSSION...A weak shortwave moved through the area Sunday afternoon. This increased the winds helped to clear out the coastal areas. This should help clear out the coastal clouds again on Monday. Most areas are expected to see 3 to 5 degrees of warming over Sunday. Even more warming is possible in the near coastal areas such as Gasquet, Garberville, and Legget, and Ukiah. These locations could see as much as 10 degrees of warming. These locations also have the potential for a forecast bust if the marine layer is more persistent than expected. Tuesday a weakening upper level low is approaching the area. This will start a cooling trend and will likely increase the marine layer. The near coastal areas will likely see the most cooling. Winds will continue to diminish as well. Tuesday night into Wednesday the models are coming into better agreement on a weak frontal boundary moving through the area ahead of the upper low, however there is still wide range of potential rainfall amounts. The current NBM and forecast is less than a tenth of an inch of rain. The individual models continue to show a wide range of solutions. Some of the models show upwards of a half inch in many areas, while some of the models show no rain at all. The future forecasts may need to increase the rainfall amounts. Wednesday afternoon there is the potential for a few thunderstorms. Probabilities for thunder have decreased slightly and this may be due to more model solutions with widespread cloud cover keeping it cooler and less unstable. Current inland highs Wednesday are expected to be in the 60s to low 70s. Inland areas may still see thunder, but it is now looking less likely. Late in the week the flow generally becomes more zonal keeping temperatures near seasonal normals with a marine layer in place. Thursday temperatures start to gradually rebound into the upper 70s to around 80. Friday and into the weekend there is increasing uncertainty on the timing of some weak systems moving by to the north. But it looks like temperatures will gradually warming into the low to mid 80s. Breezy northwest winds are expected each afternoon. The strongest winds look to be around 25 to 30 mph over the weekend. There is higher than normal uncertainty on this weather pattern. With the fairly fast zonal flow to the north of us, there will be some weak shortwaves moving through this flow. These may bring fluctuations in the temperatures and wind speeds. At this point very few solutions are showing rain. MKK && .AVIATION...The marine layer mixed out Sunday afternoon at the coast, but has come back this morning in Humboldt and Del Norte counties. The current forecast is for this marine stratus to clear out fairly quickly in the morning. There is still some uncertainty on this with quite a bit of stratus along the coast and up the river valleys of Humboldt county. This even stratus is expected to return fairly quickly to much of the coast bringing IFR conditions. MKK && .MARINE...The northerly winds are expected to start diminishing and pushing off the coast through the day Monday. The steep wind driven waves will gradually diminish as well. A northwest swell around 3 to 5 feet at 12 seconds is combining with these wind driven waves. These winds continue to diminish on Tuesday to be around 5 to 15 kt. The northwest swell continues to be around 5 feet Tuesday and is expected to continue Wednesday and Thursday. Wednesday and Wednesday night high pressure starts to build back into the area and northerly winds will slowly pick up again. The winds are expected to gradually increase into the weekend. Confidence remains lower than normal with increased uncertainty on the large scale pattern. MKK && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 3 AM PDT Monday for PZZ455. Small Craft Advisory until 9 PM PDT Monday for PZZ470-475. && $$ 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

212 FXUS66 KMTR 111754 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1054 AM PDT Mon May 11 2026 ...New AVIATION... .KEY MESSAGES... Updated at 1 AM PDT Mon May 11 2026 - Warming and drying trend will continue through Monday - Moderate risk for heat-related illnesses for sensitive populations across the interior East Bay on Monday - Gradual cooling trend and unsettled weather midweek through late week && .UPDATE... Issued at 926 AM PDT Mon May 11 2026 The marine layer compressed overnight and early this morning to around 1,000 feet in depth. This has resulted in earlier clearing where stratus did develop and low clouds are highly likely to clear to the coast by late morning or early afternoon. This will allow for interior areas to warm into the mid 80s to lower 90s while coastal locations stay in the upper 50s to mid 60s as high pressure over the Desert Southwest continues to strengthen. No updates anticipated for this morning as the forecast largely remains on track. RGass && .SHORT TERM... Issued at 1226 AM PDT Mon May 11 2026 (Today and tonight) Upper level ridge still remains locked over CA, but that will change after today. Let`s first take a look at the marine layer situation. Similar to yesterday we still have a marine layer. You can definitely tell there`s a ridge overhead due to compressed nature and discontinuous coverage of the stratus. Satellite fog product does show decent coverage along most of the coast, but inland coverage is lacking and less than 24 hours ago. Expect some additional expansion through sunrise. Will need to rely on the building May sun angle to help erode the stratus by this afternoon. Not much surface forcing to get rid of it. Regardless, today will be the peak of our little warm spell. 850 mb temps are still on track to be 20-22C, which under ideal conditions would yield max temps in the mid 90s. However, we still have some marine layer influence. The last three days NBM guidance was just too warm across the interior and think today will be the same. Did shave a few degrees from the NBM for today. Max Temps will be in the 60s to 70s coast and bays and 80s to mid 90s far interior. The slight downward trend on temps has now kept Moderate HeatRisk confined mainly to the East Bay interior valleys. By tonight the ridge shifts eastward and gets replaced by an approaching upstream trough. As such, 500 mb heights begin to fall and the airmass cools. The marine layer will develop again and with the exiting ridge coverage will be more and deeper. && .LONG TERM... Issued at 1226 AM PDT Mon May 11 2026 (Tuesday through Sunday) Tuesday will be a transition day as the ridge is to the east and a cut-off low develop off the NorCal coast. Deeper marine layer to start the day and cooling airmass will lead to cooler temperatures with no HeatRisk concerns. Temps will still be still above normal, but trending toward seasonal averages. There was more uncertainty regarding the longwave pattern midweek, but the latest cluster run and ensemble guidance has given a more clear picture. The cut-off low from Tuesday night deepens and then sweeps through NorCal - taking the more northern track. So wait does that mean? Will still have some light rain and/or drizzle in the forecast for the N Bay/ SF/ SF Peninsula late Tuesday night through early Wednesday. Not expecting much in the way of accum. Higher confidence this passing low will bring temps back to seasonal averages. Zonal flow then develops for the rest of the work week into next weekend with dry conditions and moderating temps. && .AVIATION... (18Z TAFS) Issued at 1054 AM PDT Mon May 11 2026 VFR everywhere except HAF which stratus continues to prevail. Winds pick up during the afternoon and evening, peaking between 10-15 knots. Moderate confidence in timing of stratus return tonight with a more compressed marine layer likely to lead to a smaller stratus footprint. A more compressed marine layer (1000 ft) would support a higher potential for IFR potentially LIFR CIGs tonight across the region. Highest confidence in lowered visibility and LIFR CIGs along the coast with IFR CIGs likely across the interior. There is a low chance for stratus to make it to LVK but confidence was too low to include in TAF. Vicinity of SFO...Breezy onshore winds around 15 knots expected this afternoon before winds ease overnight. Low to moderate confidence in timing of stratus arrival to SFO for tonight. Current thinking is that stratus will gradually fill in across the bay towards SFO with a later arrival around 10Z more likely. LAMP guidance suggests stratus could arrive as early as 04Z but confidence is low. It is also possible that another "donut hole" could form around SFO wherein the bay fills in with stratus and the actually airport stays VFR as was seen this morning. A few models do show this scenario occurring but fill the hole in by 12Z. SFO Bridge Approach....Similar to SFO. Monterey Bay Terminals...Moderate confidence that VFR will persist through this afternoon but there is a slight chance that stratus returns earlier given the substantial stratus deck just offshore. Breezy onshore winds continue through this evening before weakening overnight. Stratus returns around 00/01Z with CIGs to lower from IFR to LIFR overnight. Visibility is likely to be impacted with some potential for fog to develop early tomorrow morning. && .MARINE... (Today through Saturday) Issued at 926 AM PDT Mon May 11 2026 Winds have subsided everywhere except the far northern outer waters where occasional strong gusts continue. A moderate to fresh northwest breeze will continue over the waters through midweek. Seas subside but remain moderate with 4 to 6 foot seas through midweek. Winds increase and seas build starting mid-week with gale force winds likely starting Friday and continuing through the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM to 9 PM PDT Tuesday for Pt Arena to Pt Reyes 0-10 nm-SF Bay N of Bay Bridge. Small Craft Advisory until 3 PM PDT this afternoon for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...MM LONG TERM....MM 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

571 FXUS66 KOTX 111749 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1049 AM PDT Mon May 11 2026 .KEY MESSAGES... - Very warm temperatures Tuesday resulting in Minor to locally Moderate HeatRisk. This level of heat primarily affects those who are sensitive to heat. - Cold water temperatures pose a high risk for cold water shock and hypothermia. Wear a life jacket if recreating on or near the water. - Periodic shower and thunderstorm chances mid to late week. && .SYNOPSIS... Warming and drying Monday and Tuesday. High temperatures on Tuesday will be very warm, rising into the mid 80s to low 90s, then conditions will begin to cool late in the week. This late- week pattern shift will come with an increasing risk for showers and thunderstorms. && .DISCUSSION... Sunday night through Tuesday: Gusty northwest winds along the eastern slopes of the Cascades and across the western Columbia Basin will gradually decrease into Monday morning following Sunday`s dry cold frontal passage. Conditions will trend drier and warmer Monday and Tuesday as an upper-level ridge of high pressure builds over the Inland Northwest. Skies will be mostly sunny and winds will be light. Temperatures will be quite warm for mid May on Tuesday with high confidence for widespread mid to upper 80s. A few readings in low 90s will be possible across the warmer spots of the region including the deeper Columbia Basin (Ephrata, Moses Lake, Mattawa) and down the Okanogan Valley. Wednesday through Sunday: Details in the forecast become more uncertain heading into midweek. There is moderate to high confidence for the ridge axis to move inland into Central Montana as an upper level low spins toward the West Coast. The approaching low will place the Inland Northwest under southerly flow, ushering moisture into the region. What remains uncertain is the trajectory the low, which will determine how much precipitation we can expect. Around 45 percent of ensemble members depict the low moving inland over Northern California, while 20 percent show it tracking further north, taking a direct path across Washington. The other 35 percent of members are going for somewhere in the middle, suggesting the low will track across Oregon. If the low stays as far south as California, we`ll see little to no precipitation, but if it tracks directly over Washington, we could see widespread precip amounts ranging from 0.25 to over 0.5 inches. A more direct track over the region would also mean cooler temperatures in the mid to upper 60s Wednesday and Thursday as opposed to staying in the upper 70s to low 80s with the southernmost track. The NBM continues to show a 10-20% chance for showers and thunderstorms in the mountains Wednesday, which is likely a reflection of the 20 percent of ensemble members predicting a northward track of the low which would bring increased lift to trigger storms. A second low dropping down from the Gulf of Alaska begins to influence the region Thursday through Saturday, sending additional disturbances through. This late week period looks more favorable for showers and storms given increased odds for the necessary forcing. By next weekend there is stronger agreement on temperatures cooling to the low to mid 60s. Wednesday through Friday will be the transitional days with breezy to gusty winds and more uncertainty regarding temperatures. /Fewkes && .AVIATION... 18Z TAFS: Widespread VFR conditions expected with terrain driven winds generally less than 10 knots. Easterly pressure gradient strengthens overnight with east to northeast sustained winds increasing across eastern Washington 8-15 knots Tuesday morning. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions for all TAF sites. ----------------------- 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 73 44 83 53 68 45 / 0 0 0 0 60 40 Coeur d`Alene 71 45 84 53 66 45 / 0 0 0 0 70 60 Pullman 69 43 83 51 65 43 / 0 0 0 0 50 40 Lewiston 75 47 87 56 71 48 / 0 0 0 0 50 40 Colville 78 41 85 49 72 39 / 0 0 0 20 70 50 Sandpoint 73 45 83 51 68 43 / 0 0 0 0 70 70 Kellogg 72 44 88 52 69 44 / 0 0 0 0 70 80 Moses Lake 77 47 89 53 73 44 / 0 0 0 0 50 0 Wenatchee 77 52 85 57 69 49 / 0 0 0 10 60 0 Omak 78 48 87 55 74 43 / 0 0 0 10 70 10 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...None. ID...None. && $$

330 FXUS66 KPDT 111731 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1031 AM PDT Mon May 11 2026 .KEY MESSAGES... - Limited to Moderate HeatRisk on Tuesday Afternoon - Mountain rain shower and isolated thunderstorm chances return midweek && .DISCUSSION... Last overnights windy conditions will ramp down quickly this morning as an upper shortwave exits the region and high pressure develops as the primary sensible weather driver, resulting in light winds less than 10-12 knots across the entire forecast for Today. As compared to Sunday, the NBM is forecasting warmer temps across the Washington Cascades and central Oregon for This afternoon, and similar temperatures as compared to Sunday afternoon elsewhere. The ridging pattern will become messy by day 2 and 3 (Tuesday and Wednesday) as the models have to come to a solution on an eastern Pacific low resolving along the PAC NW. Varying solutions in the ensemble clustering groups vary between a more hot and isolated dry thunderstorms pattern with elevated heat risk, and other members that develop closer to normal temperatures with more of a pattern recognition favoring a few more scattered thunderstorms across central Oregon and the eastern mountains on Wednesday. That said with uncertainty with how the upper low will play out, at least Tuesday looks like the warmest day of the week, if the slightly wetter/more convective pattern develops Wednesday. NBM means on Tuesday bring highs to the upper 80s across the lower elevations and even low 90s across central Oregon and the Ochoco John Day basin. Uncertainty shows up strongly in the NBM`s high temps , for instance at Stampede Pass where the forecast highs range from 45 to 62 degrees on the 25th to 75th percentile, and likewise 73 to 89 degrees at Pasco. Tuesday the heat risk will be elevated to level 2 or 3 in central Oregon in the afternoon, affecting those who are sensitive to heat, especially those without cooling and hydration as well as some health systems industries. Lightning will be a possibility on Wednesday into Thursday, for which at this time, the NBM probability for thunder on a 6 hour basis Wednesday afternoon is about 18-25% across the central Oregon to and eastern mountains of Oregon. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... VFR conditions are forecast for all sites over the next 24 hours, with cloud cover ranging from SKC to SCT250. Winds will be diurnally and terrain-driven, predominantly 10 kts or less with periodic afternoon gusts. && .Preliminary Point Temps/PoPs... PDT 75 48 85 52 / 0 0 0 0 ALW 76 51 87 56 / 0 0 0 0 PSC 80 50 90 56 / 0 0 0 10 YKM 79 50 86 55 / 0 0 0 20 HRI 78 48 87 54 / 0 0 0 10 ELN 74 45 82 49 / 0 0 0 30 RDM 81 45 90 43 / 0 0 0 40 LGD 77 45 91 51 / 0 0 0 0 GCD 83 47 94 49 / 0 0 0 10 DLS 81 53 88 54 / 0 0 0 40 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...71 AVIATION...86

120 FXUS65 KREV 110947 AFDREV Area Forecast Discussion National Weather Service Reno NV 247 AM PDT Mon May 11 2026 .KEY MESSAGES... * Very warm days prevail through Tuesday with temperatures near record highs. * Dry conditions are expected through early this week with typical afternoon west breezes. A few stronger gusts may occur Tuesday afternoon in western Nevada with isolated thunderstorms. * Some cooling returns by mid-late week with isolated shower chances and periods of breezy winds. && .DISCUSSION... The latest RAP upper air analysis shows a high pressure ridge still over the W CONUS this morning. Model guidance projects this feature hanging around today and going into the tomorrow. By Tuesday afternoon, the ridge begins to move east as a closed low makes its way towards the west coast. With this pattern aloft, near record to record daytime high temperatures across the region will continue today and tomorrow with temperatures climbing to around 15-20 degrees above seasonal normals (please see the Climate section for a list of the current temperature records at our two climate sites: Reno, NV and South Lake Tahoe, CA). Generally, the temperature forecast for the next three days shows highs in the upper 80s to middle 90s range in NE CA and W NV valleys while the Sierra communities will range between the upper 70s and the lower 80s. The latest NWS HeatRisk forecast continues to display an areawide minor category of HeatRisk with the warmer valley portions of W NV being in the moderate category today and tomorrow. Please remember to stay hydrated and limit exposure to the sun during the warmest parts of the day, especially if you have outdoor plans and are sensitive to heat. Also, please use extra caution near rivers and resist the urge to enter them to cool off as area rivers still remain cold and could be flowing fast, presenting a risk of hypothermia. The ridge pattern will also allow for generally dry conditions to prevail today and tomorrow. However, increased daytime heating could allow for brief pop-up showers though chances look to be less than 10%. The latest runs of the CAMs do still show some isolated showers possible in Mineral and Southern Lyon Counties between 4-8 PM today. But in the late afternoon and evening on Tuesday, the latest runs of the RRFS and the HRRR both showing shower and thunderstorm potential in western Nevada as well as Mono County when the ridge has moved east. Model forecast soundings are showing an "Inverted-V" shape around that time along with DCAPE values over 1000 J/kg. This kind of environment signals that strong wind gusts (50+ mph) could be possible with this high based convection. There still is some low confidence on forecast details like exact locations that would see this threat, but please watch for forecast updates as they become available. Otherwise, winds look to gust up to around 25-35 mph on Tuesday afternoon with the Sierra ridges gusting up to around 45 mph. For Wednesday and Thursday, models show a potential cold front passage for the CWA as the Pacific low opens into a trough and passes over the region. This will cause the W NV valley high temperatures to cool down to the 70s and 80s on Wednesday and then drop a bit more to between the lower and upper 70s on Thursday. Sierra communities are forecast in the middle 60s and lower 70s on both days. Wednesday also looks to be the windiest day of the week for the region with westerly winds gusting up to around 40 mph in the after (up to 60 mph in the Sierra ridges). These winds may cause some potential hazardous maritime conditions on area lakes, so please be prepared for this. Precipitation chances (15-25%) are forecast on Wednesday and Thursday with portions of the CWA closer to the OR border seeing chances up to around 40% on Wednesday. On Friday and going into the weekend, forecast guidance shows a zonal flow over the region after the trough moves out. This pattern will allow for daytime high temperatures to rebound a bit with dry conditions returning to the region. -078 && .AVIATION... VFR conditions are expected at the main terminals through Tuesday, with potential density altitude concerns for western NV terminals due to very warm temperatures each afternoon. Southwest to west wind gusts of 20-25 kt are expected each afternoon today and Tuesday mainly between 20Z-03Z. There is a potential for isolated showers and thunderstorms in western NV on Tuesday afternoon that could produce strong wind gusts (45+ kts). MJD/078 && .CLIMATE... Both climate sites set new record high temperatures yesterday for the May 10th date. The Reno-Tahoe International Airport in Reno, NV recorded a high of 92F breaking the old record of 88F set in 1934. South Lake Tahoe, CA recorded a high of 79F breaking the old record of 75F set in 2025. Current record high temperatures for Reno, NV that have potential to be broken or tied (Today & Tuesday): May 11: 90F, set in 2001 and 2013. May 12: 89F, set in 1959 and 2013. Current record high temperatures for South Lake Tahoe, CA that have potential to be broken or tied (Today & Tuesday): May 11: 78F, set in 2013. May 12: 79F, set in 1988 and 1996. && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$

668 FXUS66 KSTO 101937 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1237 PM PDT Sun May 10 2026 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .KEY MESSAGES... - Hot and dry conditions throughout the week. - Hottest Days Monday and Tuesday with triple digit temperatures, possible daily record highs, and widespread Moderate HeatRisk. - Slightly cooler temperatures from Wednesday onward, though temperatures will still be well above normal. && .DISCUSSION... ...Today through Tuesday... Hot temperatures continue today and through early this week as ridging builds eastward. Widespread Minor HeatRisk with areas of Moderate Heat Risk is expected today in the Valley. Maximum Valley temperatures today will be primarily be in the low 90s, though closer to the Delta temperatures will remain a little cooler thanks to the influence of the Delta Breeze. On Monday and Tuesday, daytime temperatures will climb again, with widespread Moderate HeatRisk in the Valley both days. Valley highs have potential to both meet or exceed local records, as well as reach triple digits in some locations. The NBM has a 30 to 50% chance of 100 degrees or more in the northern San Joaquin Valley, as well as in the central Sacramento Valley (particularly around eastern Glenn and Colusa Counties, and Butte County). A Heat Advisory remains in place for these areas from 11am on Monday through 8pm on Tuesday. Areas closer to the Delta will see much better overnight relief on Monday and Tuesday, though daytime temperatures will still be quite hot. Be sure to practice heat safety! Drink plenty of fluids, stay in an air-conditioned room or in the shade during the heat of the day, and consider checking in on those more susceptible to heat. ...Wednesday through Saturday... Ensembles depict the ridge breaking down towards the middle of the week, which will result a decent amount of cooling on Wednesday; however temperatures will still be 5 to 15 degrees above normal through the end of the week. As lower pressure moves through the area on Wednesday, the change in pattern brings with it a slight chance (10-20%) for isolated thunderstorms in the northern Sacramento Valley, as well as the foothills and mountains north of HWY 50. Best chances are in northeastern Shasta County, though any thunderstorm chances are somewhat uncertain in the ensembles and will depend on the path of the troughing. && .AVIATION... General VFR conditions are expected over the next 24 hours. Surface winds generally 12 kts or less except near the Delta, where winds to 15 kts and gusts to 20-25 kts are possible through 12z on Monday. && .STO WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 11 AM Monday to 8 PM PDT Tuesday for Butte County Below 1000 ft-C. Stanislaus County including Modesto- Eastern Colusa County-Eastern Glenn County-W. Stanislaus County Above 1000 ft & I-5. && $$

242 FXUS65 KMSO 111728 AFDMSO Area Forecast Discussion National Weather Service Missoula MT 1128 AM MDT Mon May 11 2026 .DISCUSSION... KEY MESSAGES: - Above normal temperatures through Wednesday, reaching the mid 80s to low 90s by Tuesday and Wednesday. - Spring thunderstorms Wednesday and Thursday; main hazards will be lightning and erratic/gusty outflow winds. - This weekend could be a shock to the system after a warm start to the week. A cooldown is expected, and even a chance for some mountain snowfall! Near-record heat is expected Tuesday and Wednesday as high temperatures climb into the 80s and low 90s across the region. In western Montana, the northwest valleysincluding St. Regis, Libby, and Trout Creekhave the highest chance of reaching 90 degrees. In Idaho, lower valleys will reach the 90s. Salmon could reach 90 degrees on Tuesday, which would break the daily record of 89 set in 1993. While the air will feel like summer, recreationalists are reminded that mountain snowmelt has left rivers dangerously cold and fast-moving. Forecast confidence for Wednesday and beyond lowers, as weather models disagree on the path of the incoming storm system. Despite these differences, there is still a chance for showers and thunderstorms on Wednesday. While temperatures will certainly be much cooler across north-central Idaho, western Montana will see a sharp contrast in temperatures and winds. Currently, the forecast keeps temperatures in the 80s from Libby south and eastward. Breezy southwest winds are anticipated to develop, especially across southwest Montana Wednesday afternoon. The warm and dry conditions coupled with strong winds could elevate fire weather conditions into Wednesday evening. Thunderstorm trends for Wednesday have been leaning toward a more active day, especially in west-central Montana. There is a 15% chance that strong thunderstorms will develop along the Highway 12, Highway 200, and I-90 corridors. Strong wind gusts and lightning will be the two primary threats. Looking ahead to the weekend, a much cooler pattern will take hold as cold air from the Gulf of Alaska moves south into our region. High temperatures will likely drop into the 60s on Saturday and Sunday. This unsettled pattern will cause snow levels to fall. There is a 60% chance they will drop to around 4,500 feet, especially across northwest Montana. Those traveling into the backcountry should be prepared for winter-like conditions. This cool, unsettled pattern appears likely to continue into next week. && .AVIATION...Clear skies and good visibility will continue across the Northern Rockies through Tuesday as high pressure remains over the region. Expect breezy west winds today with gusts of 1525 knots, particularly near the Continental Divide. Unseasonable heat will continue with temperatures in the mid-80s to low 90s through mid-week. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...None. ID...None. && $$

864 FXUS65 KBOI 111801 AFDBOI Area Forecast Discussion National Weather Service Boise ID 1201 PM MDT Mon May 11 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Breezy and slightly cooler Today. - Very hot Tuesday. Record high temperatures in the mid to upper 90s in the lower valleys. - Low pressure system arriving Wednesday will bring a cooling trend and chances of showers/thunderstorms. && .SHORT TERM /Through Wednesday Night/... Issued 320 AM MDT MON MAY 11 2026 A dry cold front passing over our area early morning will bring slightly cooler temperatures and breezy northwest winds over the Snake Plain today. By early Tuesday, a strong ridge will build over the entire western CONUS. Considerably warm temperatures are expected Tuesday, with lower-elevation valleys expected to see peak temperatures in the lower to mid 90s; max temperatures were adjusted slightly downward from the previous discussions. A Pacific upper low will begin moving inland early Wednesday. There is slight guidance uncertainty over the exact arrival timing and behavior of this system as it approaches our area, but there is strong agreement on showers and thunderstorms expected Wednesday. Areas will generally see a 40-60% chance of showers and a 20-30% chance of thunderstorms Wednesday afternoon/evening. This system`s arrival will begin a cooling trend starting Wednesday. && .LONG TERM /Thursday through Monday/... Issued 320 AM MDT MON MAY 11 2026 An upper level trough will track across the Pacific NW on Thursday. Still some major differences in the positioning of this trough so forecast confidence is low. A couple of the models have the trough tracking across northern NV into southwest ID which would be much wetter and cooler than the current forecast. If this trough track comes to fruition, wetting rains possible for much of the area with 0.25 to 0.75 inch of precipitation for southeast OR and southwest ID. Eventually the models agree on cooler temperatures for Sunday and Monday of next week with temperatures 5 to 10 degrees below normal and snow levels of 5000 to 6500 feet MSL. Showers will mainly be confined north of a line from Baker City OR to McCall ID. && .AVIATION /18Z Monday through Tuesday/... Issued 1148 AM MDT MON MAY 11 2026 VFR. Surface winds: W-NW 5-15 kt, gusts up to 25 kt possible near KGNG KTWF KJER. Surface winds becoming variable 10 kt or less after 12/00Z. Winds aloft 10kft MSL: W 15-25 kt. KBOI...VFR. Surface winds NW 5-10 kt with gusts to 20 kt becoming variable around 5 kt after 12/00Z. && .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.....TL SHORT TERM...JY LONG TERM....KA

161 FXUS65 KLKN 110745 AFDLKN Area Forecast Discussion National Weather Service Elko NV 1245 AM PDT Mon May 11 2026 .KEY MESSAGES... * High pressure produces warm and dry weather through Wednesday. * Record high temperatures are likely, beginning Sunday and persisting through Wednesday * A low chance for rain showers and thunderstorms exists north of I-80 Wednesday evening * Increasing likelihood of Advisory level wind speeds on Wednesday && .UPDATE... Issued at 1232 AM PDT Mon May 11 2026 Model run trends continue to increase likelihood of Advisory level wind speeds on Wednesday especially along the US-50 corridor in central NV where probabilities have crept above 50% for wind speeds greater than 30mph and wind gusts greater than 44mph. Coverage of shower and thunder activity also continues to increase from north to south Wednesday night into Thursday AM. && .DISCUSSION... (Today through next Monday) WEATHER PATTERN OVERVIEW: Upper level ridge of high pressure will continue to dominate over much of the western US through Wednesday, as the result of a blocking pattern. As a result dry conditions with temperatures warming 15 to 20 degrees above normal will be likely through midweek. Daytime temperatures will likely be near to, or exceed record highs Sunday through Wednesday afternoon as highs reach the lower 90s, with a 75% to 100% chance of highs above 85 degrees Monday and Tuesday. Winds for this period will be generally Westerly at 10 mph to 20 mph with occasional gusts up to 35 mph possible. Wednesday afternoon models have been hinting at the passage of a upper trough that would kick the ridge east, and may bring a 10%-20% chance of showers across northern Nevada Wednesday evening. As well as, push a cool front through the area Thursday. EC and GFS solutions have continued to diverge as the EC favors a weaker trough that is farther north, and much faster, showing the trough over the northern plains by Thursday. The GFS solutions have continued to favor a much stronger system that is farther south with its track, with a closed low over central Nevada Thursday evening with showers and thunderstorms possible over much of the area. As a result confidence in the upper pattern has degraded after Wednesday evening. For now, have decided not to make any major changes in the longer term, but have went ahead and enhanced the cooling trend forecast Thursday through next weekend by a few degrees, as well as raised pops across northern Nevada to about 15% to 25%. Which may need to be raised and drawn further south if trends consolidate in a wetter solution. As for now temperatures look to cool back into the low to upper 70s, with a few 80s across N Nye county Thursday through Sunday. Winds will be a bit lighter too out of the west to NW at 5 to 15 MPH with gust up to 25 MPH possible FORECAST CONFIDENCE & DEVIATIONS: There is high confidence for warming temperatures and dry conditions through Wednesday of this week. There is high confidence for a period of near record to record heat through Tuesday afternoon. There is moderate confidence in cooler temperature Thursday through Sunday as ridge shifts eastward. There is low to moderate confidence in the possibility of isolated showers and thunderstorm north of the I-80 corridor Wednesday evening. There is very low confidence in the possibility of shower and thunderstorm south of the I-80 corridor Wednesday evening through Thursday. && .AVIATION... VFR conditions remain in place through Monday afternoon under mostly sunny and clear skies with a few high level clouds overhead at times. && .FIRE WEATHER... High pressure remains in control across much of the west through Wednesday afternoon leading to elevated fire weather concerns. Warming temperature are forecast to run 15 to 20 degrees above normal, reaching near to, or exceeding record highs, Monday and Tuesday afternoon. Breezy afternoon westerly winds of 10 to 20 mph with gusts up to 30 mph, will combine with the temperatures to drop Humidity levels to the teens and single digits through at least Tuesday. Winds will be even stronger Wednesday afternoon and evening as a upper trough passes to the north. West to SW winds will increase to 25 to 35 mph with gusts up to 45 mph will be possible, as well as a few isolated showers or thunderstorms across northern Nevada. Temperatures begin a cooling trend Thursday through Sunday as winds shift to the NW at 5 to 15 MPH. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...98 AVIATION...92 FIRE WEATHER...