511 FXUS66 KSEW 181609 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 909 AM PDT Mon May 18 2026 .SYNOPSIS... High pressure will remain situated offshore through much of next week, maintaining near-normal temperatures across western Washington with cloudy mornings and sunshine in the afternoons. A few weak systems will move over the top of the ridge towards the middle of next week, bringing little more than a few periods of sprinkles. && .SHORT TERM /TODAY THROUGH WEDNESDAY/... Upper-troughing currently over the Great Basin while an upper- level ridge is just offshore the PNW. High clouds are currently streaming in under northwest flow aloft. Stratus has been confined to west central Washington between the Kitsap Peninsula and into the South Sound with the edges beginning to erode away. This will give way to mainly just high clouds and some fair weather cumulus across the area this afternoon. High temperatures are forecast in the 60s across the interior with 50s along the coast. Increasing onshore flow will lead to breezy winds through the Strait of Juan de Fuca this evening with gusts up to 30 mph on Whidbey Island before gradually decreasing later tonight. HREF suggests a 35% chance of gusts exceeding 35 mph. Overnight lows will fall into the 40s. Upper-ridging is likely to maintain through midweek as conditions remain rather benign. Weak disturbances will attempt to traverse along the periphery of the ridge - maintaining slight (15% or less) PoPs but mostly for the mountains. Temperatures are to remain near-seasonal throughout this period with highs in the 60s to near lower 70s and lows in the 40s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The upper level ridge offshore will begin to flatten on Thursday as a low pressure system slowly strengthens and lowers from the Gulf of Alaska. Conditions are favored to remain dry into the first half of the weekend as zonal flow sets up aloft, with continued mild temperatures. Ensembles are honing in on a potential pattern change by the end of next weekend, with increasing chances for widespread rainfall arriving Sunday evening. However, the details remain uncertain at this time. 41 && .AVIATION... North/northwesterly winds will persist aloft as an upper level ridge remains nudged over the region. Onshore flow will continue in the low levels, which allowed for some localized stratus to push inland this morning, mainly for areas along the coast, the Southwest Interior, and the south Sound where these terminals are seeing MVFR/IFR conditions likely through 18z (most likely for KHQM, KPWT, and KOLM). Expect cigs at the remainder of the terminals to remain VFR through the day. Winds remain light southerly at 6 kt or less across the majority of the interior terminals this morning, outside of KPAE, where winds continue out of the north. Winds along the coast are light northwesterly and KCLM remains westerly between 8-12 kt under increased onshore flow. Winds will increase to 7-10 kt this afternoon and look to switch to the north across the interior between 00-03Z tonight. A weak, splitting frontal system will move into the area tonight into Tuesday, with the main impact being more widespread stratus by Tuesday morning. KSEA...MVFR ceilings this morning with broken clouds at the terminal around 1500 to 2000 ft. Ceilings will rebound to VFR likely after 17z and will remain VFR throughout the day. A much greater probability (40-45 percent) exists of ceilings dropping to MVFR by Tuesday morning. Winds are southerly and will increase to 7-10 kt this afternoon, before switching to the north between 00-03Z. 14/Mazurkiewicz && .MARINE... High pressure will remain situated over the northeastern Pacific through much week, bringing a prolonged period of north/northwesterly winds to the coastal waters. A weak, splitting frontal system will move into the waters tonight into Tuesday and will bring an increase of onshore flow along the central and eastern Strait of Juan de Fuca, with another round of small craft westerlies expected this afternoon and evening. High pressure will build back into the coastal waters in the wake of the front. Onshore flow will persist throughout much of the week and will result in daily pushes of westerly winds along the Strait. The next weak frontal system looks to move into the area waters Thursday into Friday, followed by another late next weekend. Seas will generally hover between 6-8 ft through the first half of the week, before increasing towards 8-10 ft mid to late week. The latest GEFS probabilistic guidance is highlighting roughly a 20-40 percent chance of seas exceeding 9 ft by next weekend. 14 && .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...Small Craft Advisory from 2 PM this afternoon to 5 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca. && $$

602 FXUS66 KPQR 181823 AAA AFDPQR Area Forecast Discussion...UPDATED National Weather Service Portland OR 1123 AM PDT Mon May 18 2026 Updated aviation discussion. && .SYNOPSIS...Dry and benign weather is expected across the region through much of the next week as high pressure builds over the Northeast Pacific, bringing a warming trend. Weak systems aloft may bring enhanced cloud cover on some days, but rain chances are minimal. && .DISCUSSION...Now through Sunday...A weak upper level disturbance passing over the region this morning will maintain high level clouds through late morning, before skies become mostly sunny this afternoon. Concerns for hazardous weather remain minimal through the next week. There is high confidence that upper-level ridging and surface high pressure will build over the Northeast Pacific, with increasing uncertainty in the amplitude and position of the upper ridge later in the forecast. Early in the period, while the ridge is centered well offshore, upper shortwaves within northwesterly flow aloft may produce increased cloud cover, but chances for rainfall remain 5% or less through the middle of the week. On clearer nights, areas of fog are most likely to develop within sheltered valleys. As the ridge axis shifts east, temperatures will trend upward through at least Thursday, reaching the 60s along the coast and upper 70s to around 80 degrees along the I-5 corridor. Later in the forecast period, uncertainty in the evolution and possible break-down of upper-level ridging introduces a similar uncertainty in forecast temperatures. Highs are most likely to continue in the 60s to mid 70s, but the spread of possible outcomes becomes wider: chances of reaching 80 degrees along the I-5 corridor are generally 15-45% Friday and Saturday, but there are also 10-25% chances of remaining below 70 degrees. The next opportunity for widespread rain holds off until late next weekend when there is greater consensus that the ridge breaks down. 36/DH && .AVIATION...High pressure will maintain fair conditions with high level clouds moving overhead through the day. Northwest flow of 5-10 kt through the day with wind gusts along the coast up to 20 kt possible. Winds relax this evening and overnight. Marine stratus pushed back toward the coast this evening, mainly along the northern Oregon and southern Washington coast. Probabilities increase to 60-90% for development between 02-06z Wednesday for KAST and much lower at 20-30% for KONP. Guidance suggests stratus developing along the Columbia River toward the Portland/Vancouver Metro between 10-1z Wednesday. KPDX AND APPROACHES...VFR conditions expected through at least 06z Tuesday. High clouds expected to clear out this afternoon. Light northwest winds expected to increase to 8-10 kt by 22z this afternoon. Stratus pushing inland along the Columbia River could reach the metro between 10-16z Tuesday with a 30-60% chance for sub-VFR CIGs, mainly for KTTD and KPDX. -19 && .MARINE...Northerlies are expected to persist through much of the week as the summer-like pattern settles in. Strongest winds are expected during the afternoon and evening periods as a surface thermal trough strengthens over the southern Oregon coast. A Small Craft Advisory has been issued for the inner coastal waters south of Cape Foulweather later this afternoon into this evening for gusts up to 25 kt. Similar conditions are expected on Tuesday. Seas around 6 to 8 feet are expected through the week as well. Small Craft Advisories are in place for the Columbia River Bar early this morning, and again early Tuesday morning, for strong ebb currents which will produce hazardous conditions to small craft. Strong ebb currents are possible during the morning hours each day this week. /DH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 5 AM to 9 AM PDT Tuesday for PZZ210. Small Craft Advisory until 11 PM PDT this evening for PZZ253. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland

594 FXUS66 KMFR 181814 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1114 AM PDT Mon May 18 2026 ...New Aviation Section... .AVIATION (18Z TAFs)... VFR conditions are expected at all terminals throughout the valid TAF cycle. Northwesterly flow aloft is anticipated through this cycle as high pressure maintains over the Pacific. Main thing this cycle will be the breezy wind speeds this afternoon, but not expecting these speeds to continue after sunset with speeds decreasing overnight in a typical diurnal fashion. && .PREV DISCUSSION... /Issued 1212 AM PDT Mon May 18 2026/ DISCUSSION...The weather will be quiet with little impact as dry and stable conditions persist this week. With near unanimous agreement across the model suites, forecast confidence is high through Friday with upper level ridging gradually building into our area from the west. High pressure will remain anchored offshore through Wednesday, then build slightly eastward for additional warming on Thursday and Friday, when daytime highs expected to be around 10 or 15 degrees above normal for mid to late May. Slight cooling is possible next weekend or early next week, with a trough expected to move into western Canada. The majority of ensemble members keep the moisture associated with a couple of cold fronts well north of our area, but the second front around Memorial Day could be strong enough and near enough for a marine push and chance of showers for Coos and Douglas counties northward. AVIATION...18/12Z TAFs...Some marine stratus is forming near Cape Blanco this evening and the models have some of that spreading into Roseburg overnight. The boundary layer in some of the models do hint at stratus forming in the Umpqua Basin overnight with IFR ceilings developing for a few hours. Otherwise, those should clear out as we mix out into the day. VFR will prevail in all other areas for the next 24 hours. MARINE...Updated 1200 AM PDT Monday, May 18, 2026...A thermal trough will bring a typical pattern of gusty north winds and steep to very steep seas over the coastal waters much of this week. Winds will be strongest and seas will be highest during the afternoons/evenings. Through this stretch, very steep seas of 10- 12 ft are most likely south of Cape Blanco with steep seas (6-9 ft) north of Cape Blanco. Ensembles indicate winds will strengthen Wednesday into Thursday with a potential (50-70% chance) for gales across portions of the southern waters (especially from around Gold Beach south). && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...None. PACIFIC COASTAL WATERS...Hazardous Seas Warning until 11 PM PDT Tuesday for PZZ356-376. Small Craft Advisory until 11 PM PDT Tuesday for PZZ350-370. && $$

903 FXUS66 KEKA 180741 AFDEKA AREA FORECAST DISCUSSION National Weather Service Eureka CA 1241 AM PDT Mon May 18 2026 .SYNOPSIS...Gusty north winds continue to ease today. Clear and dry conditions will remain through the week with a warming trend through Thursday. && .KEY MESSAGES... -Strong north winds will weaken today and through the week with only moderate north winds close to shore. -Generally clear skies and dry conditions, even along shore, through the week. -Conditions will warm through Thursday with highs in the interior peaking near 90. .DISCUSSION...Strong north winds continue to subside for Northwest California, especially near shore when compared to yesterday, but will persist through early today around the rim of the Sacramento Valley, especially Lake County. Strong mixing will continue to keep skies clear as temperatures begin to warm, especially across the interior. Wind overnight will continue to preclude any frost formation. High pressure will already begin to weaken but move more onshore today and through the week. This will lead to much weaker north winds with some moderate gusts to 20 mph still pushing in right along shore in the afternoon. Interior winds will transition to a more terrain controlled regime. Conditions will remain very dry with warming temperatures through the week. Highs will most likely top out around 90 for the interior on Thursday. This will constitute only a minor HeatRisk for this time of year. Hotter temperatures will help reform a marine inversion. Any stratus and fog; however, will most likely be very shallow and mix out quickly during the day. Compared to previous runs, most ensemble members continue to show a weak trough in the far extended forecast, but have it delayed until after next week. Rather most models show high pressure slowly weakening, allow temperature to drop, through next weekend. A trough early next week could bring some light showers or thunderstorms, but the vast majority of models currently remain dry. /JHW && .AVIATION...VFR conditions are expected for terminals in Northwest California as gusty north winds remain elevated, but quickly diminish early this morning. Winds will remain elevated for higher elevation areas of the Yolla Bollys and Lake County. Winds have diminished for more protected areas; however, winds remain elevated aloft, bringing LLWS concerns mostly for Mendocino County. && .MARINE...The pressure gradient relaxes slightly and the strongest winds move farther off the coast as the high pressure builds in. However, a large area of gale force gusts around 34-45 kts expected across all zones, with the strongest winds downwind of Cape Mendocino. Steep to very steep, hazardous seas will continue with the elevated winds. Conditions will remain hazardous across the waters for much of the workweek with strong to gale force gusts north winds and steep to very steep seas. Gale force winds and very steep seas are forecast to persists across the outer waters through Friday. /ZVS && .FIRE WEATHER...Strong north winds will continue, but diminish into the early morning. Winds will especially remain elevated around the rim of the Sacramento Valley and in Lake County today. Winds will weaken by this evening and transition to more gentle terrain wind through the week. Conditions will remain very dry with high temperatures increasing to near 90 for the interior by Thursday. && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Gale Warning until 3 AM PDT early this morning for PZZ450- 455. Gale Warning until 3 AM PDT Wednesday 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

917 FXUS66 KMTR 181721 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1021 AM PDT Mon May 18 2026 ...New AVIATION, MARINE... .KEY MESSAGES... Updated at 1147 PM PDT Sun May 17 2026 - Breezy to windy conditions, especially across the North, East, and South Bay Mountains and the Santa Cruz Mountains through today - Hazardous beach conditions through this morning - Hazardous marine conditions expected through today - Elevated fire weather concerns continue through today across the interior with low humidities and strong gusts && .UPDATE... Issued at 842 AM PDT Mon May 18 2026 Gusty offshore winds continue through this morning with winds gradually easing this afternoon/evening. The Wind Advisory remains on track to expire at 11AM PDT across the higher elevations. Notably, the current hourly temperatures are running 6-7 degrees above what the current forecast has. This is likely due to the stronger offshore (NE) winds bringing in warmer and drier air, with some additional warming from downsloping occurring at the base of the mountains. Bumped temperatures up using the NBM90th percentile to better account for the already warmer temperatures observed this morning. This puts the interior into the 80s to low 90s today with the coast staying in the 70s. Winds don`t look to switch onshore again until after peak heating (3/4PM) so would not expect much marine influence on today`s high temperatures outside of the direct coastline. && .SHORT TERM... Issued at 1147 PM PDT Sun May 17 2026 (Tonight through Monday) An upper level low pressure system digs into the tri-state area of CO, UT, and WY by late Monday morning. We remain under the influence of the broader trough associated with it, leading to breezy offshore flow. North to northeast winds pick up tonight across the Santa Cruz Mountains, the interior North Bay Mountains, and the Eastern Santa Clara and East Bay Hills. Sustained wind speeds of 15 to 30 mph along with gusts up to 50 mph, though localized gusts up to 60 mph are expected for favored ridges, gaps, and passes. These winds will usher in drier air to the region as well, keeping the fire weather threat elevated for interior Bay Area and Central Coast locations. In terms of more every day hazards from the winds, impacts include, but are not limited to difficult driving, especially for high profile vehicles, downed tree limbs, the potential for power outages, and the possibility of loose or unsecured items being blown around. Winds begin to ease late Monday morning into the afternoon and will continue to decrease into the evening and overnight hours. Offshore winds should bring some warmer temperatures to the region, the 90s for the interior Bay Area valleys, the 60s to low 70s along the coast, and the mid 70s to low 80s for the Central Coast Valleys. && .LONG TERM... Issued at 1147 PM PDT Sun May 17 2026 (Tuesday through next Sunday) Upper level troughing looks to hold just west of the Desert Southwest and into southern CA Tuesday into Wednesday, leaving us with teetering between quasi-zonal and barely trough-y. Weak offshore lingers at least over the interior mountain ranges through Tuesday into Wednesday, with onshore flow trying to make a diurnally driven push each afternoon/evening. During this time high pressure just to the west of us (over the eastern Pacific) builds, pushing towards the coast mid week. The upper level trough begins to meander south to southwest of southern California late week. This should bring a return of onshore flow to the region and perhaps the marine layer. Current guidance suggests we could see a 500ft marine layer return by Wednesday, with a 1000-1200ft marine layer by Thursday and Friday. Will need to keep an eye on this as it will affect how temperatures pan out. && .AVIATION... (18Z TAFS) Issued at 1021 AM PDT Mon May 18 2026 VFR conditions prevail through the TAF period. Breezy and gusty northeast winds will gradually diminish through the next couple of hours as an onshore push returns to the coastal regions this afternoon, with the coastal breeze continuing through the evening. Breezy winds will continue across the interior mountains of the Bay Area through the night, with northeast winds spreading across the interior valleys Tuesday morning towards the end of the 24-hour TAF period. Beyond that, Tuesday`s coastal breezes look to be stronger than today`s. Vicinity of SFO... VFR conditions through the TAF period. Breezy and gusty northeast winds will turn more northwesterly through the afternoon, before diminishing through the evening and remaining light overnight through Tuesday morning. West-northwest winds will resume on Tuesday afternoon. SFO Bridge Approach... Similar to SFO. Monterey Bay Terminals... VFR conditions through the TAF period. Breezy northwest winds will develop imminently and continue into the evening. Winds remain light overnight before resuming Tuesday afternoon after the end of the TAF period. && .MARINE... (Today through Saturday) Issued at 1021 AM PDT Mon May 18 2026 Winds continue to diminish throughout the marine environment, but moderate to rough seas and moderate to fresh northwest breezes will still offer hazardous conditions for small craft into the mid weak before easing for most zones. Fresh to strong northwest breezes will remain hazardous for small craft into the late week for the northern outer zone. && .FIRE WEATHER... Issued at 449 AM PDT Mon May 18 2026 Strong and gusty north to northeast winds continue to affect the region. Expect peak gusts greater than 30 mph for most areas, with around 45 to 55 mph along through gaps and passes, and across higher terrain. These winds will begin to reduce in the late morning but remain breezy until the late night. Daytime humidity retentions loos to stay around 10- 25% across the interior regions and higher peaks, with limited overnight humidity recoveries. Humidities will be slow to recover into the work week as a light offshore flow will continue to affect the district. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory until 11 AM PDT this morning for CAZ504-512-514- 515. Coastal Flood Advisory until 3 AM PDT Tuesday for CAZ506. PZ...Small Craft Advisory until 3 PM PDT this afternoon for SF Bay N of Bay Bridge. Small Craft Advisory until 9 PM PDT this evening for Mry Bay- Pigeon Pt to Pt Pinos 0-10 nm. Small Craft Advisory until 3 AM PDT Tuesday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm. Small Craft Advisory until 3 AM PDT Wednesday for Pt Arena to Pt Reyes 10-60 NM. Small Craft Advisory until 9 AM PDT Tuesday for Pigeon Pt to Pt Pinos 10-60 NM. && $$ SHORT TERM...KR LONG TERM....KR AVIATION...DialH MARINE...DialH 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

818 FXUS66 KOTX 181730 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1030 AM PDT Mon May 18 2026 .KEY MESSAGES... - Pop up showers and isolated thunderstorms primarily over the higher terrain Monday afternoon. - Chilly overnight temperatures will bring an isolated threat of morning frost Tuesday. This could impact sensitive plants or crops. - Conditions trend drier and warmer through the workweek regionwide, with periodic breezy winds for the Cascades and central WA. && .SYNOPSIS... Diurnally forced showers with isolated afternoon thunderstorms will continue today Monday. Precipitation chances decrease and afternoon highs trend warmer through the workweek, climbing back into the 70s and 80s by Thursday and continuing through next weekend. Breezy winds are expected at times through the Cascade gaps and across the western Columbia Basin. && .DISCUSSION... Today through Friday night: A deep longwave trough of lower pressure will remain over the CONUS for this weekend through the workweek. The axis of this longwave trough will slowly migrate over the Rockies by through Wednesday and then over the Plains by Thursday into Friday. The Inland Northwest will remain under the backside of this trough today with a conditionally unstable air mass. Lingering showers over extreme eastern Washington into the Idaho Panhandle early this morning will wane with decreasing instability at mid levels. However, diurnal heating will destabilize the lower levels of the atmosphere for the afternoon. There will be a lack of instability over the Columbia Basin today, which should result in much of the showers and thunderstorm activity confined to mainly the higher terrain today. Instability parameters will be much less compared to Sunday with upper levels trending warmer. Much less likely to see as much small hail like we`ve seen with this storms, but some is expected with slightly stronger thunderstorms over the mountains. Convection will also be capable of wind gusts up to around 20-25 mph and infrequent cloud to ground lightning strikes. Best potential for thunderstorms today will be over northeast Washington into the Northern Panhandle with 20-25% chance of occurring. Convection is expected to wane more quickly into the evening hours compared to Sunday. We then see a drying trend into mid week as a ridge of higher pressure in the eastern Pacific nudes east into the Northwest. There is a shortwave disturbance that pushes across BC on Tuesday and does bring a 20-30 percent chance for showers across the far northern mountains closer to the Canadian border, and this potential could linger into Wednesday for North Idaho as the shortwave pushes across fairly slowly. There is a 15% chance that places like Lauier, Northport, Metalline Falls, Porthill, and Eastport may also see a passing thunderstorm. Temperatures warm up above normal by Wednesday with our highs back into the 70s. The risk for morning frost will decrease as well as temperatures see a slow warm into the weekend. Saturday through Sunday: Model ensembles remain in pretty good agreement with a shortwave trough of lower pressure to flatten the ridge. There is uncertainty with how deep this shortwave will be. About 80 percent of the ensemble members show this disturbance to be fairly weak with minimal cooling of just a few degrees Saturday into Sunday. Westerly winds will see an increase. Stronger wind gusts of up to around 30 mph will be across the Cascades and into the western basin and up to around 20-25 mph potentially into places like Spokane and the Palouse. Winds would pick up Saturday afternoon, but could also remain fairly breezy into Sunday as well. Models continue to diverge as we head into the beginning of next week. Outliers such as the 00Z operational ECMWF and Canadian indicate a deep trough to dig in into BC and potentially as far south as the Pacific Northwest. This scenario would represent more cooling and a better potential for showers than what is in the forecast. The NBM suggests a more zonal flow pattern with the potential for progressive weaker waves that could bring light shower activity but nothing looking all that substantial. After our warm up late in the week, temperatures look to cool near normal for Sunday into the beginning of next week. /SVH && .AVIATION... 18Z TAFs: Antecedent boundary layer moisture and surface heating will result in developing cumulus fields 18-20Z. There is 40% chance for cells to develop showers and 10-25% for convection to grow deep enough for lightning. Greatest risk will be over the mountains of northern WA and the Idaho Panhandle though cells drifting south will pose a small risk into the upper Columbia Basin and Spokane-Cd`A area. Given the latest output from the cam models, did introduce prob30 for KGEG-KSFF-KCOE for -shra with a 10-15% chance for -tsra. Any thunderstorms will bring a threat for brief downpours of rain/small hail, lightning, and erratic outflow winds to 30 mph. Pending where rain falls, areas of valley fog will be possible overnight. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is a small risk for MVFR cigs mainly around KGEG-KSFF- KCOE-KPUW this morning as cumulus clouds are developing and cloud bases are slowly lifting. Main uncertainty this afternoon will be if thunderstorms survive off the higher terrain into KGEG-KSFF-KCOE as we have seen the last two afternoons. /sb ----------------------- 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 66 41 69 44 72 45 / 10 10 0 0 0 0 Coeur d`Alene 64 41 67 44 70 45 / 20 20 10 0 0 0 Pullman 62 39 65 42 68 43 / 10 0 0 0 0 0 Lewiston 67 43 71 46 73 48 / 10 0 0 0 0 0 Colville 69 36 71 40 75 41 / 20 30 10 10 0 0 Sandpoint 62 40 66 43 68 43 / 30 30 10 10 0 0 Kellogg 61 39 66 43 68 43 / 20 20 10 0 10 10 Moses Lake 73 42 75 46 78 49 / 0 0 0 0 0 0 Wenatchee 72 48 74 51 77 54 / 10 0 0 0 0 0 Omak 73 43 75 48 78 51 / 10 10 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... WA...Frost Advisory until 7 AM PDT this morning for Northeast Mountains-Okanogan Highlands-Spokane Area-Washington Palouse. ID...Frost Advisory until 7 AM PDT this morning for Central Panhandle Mountains-Coeur d`Alene Area-Idaho Palouse- Northern Panhandle. && $$

683 FXUS66 KPDT 181728 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1028 AM PDT Mon May 18 2026 .KEY MESSAGES... - Breezy Gap winds Today and Tuesday - Pleasant weather for most of the week with a warming trend - Mountain showers in the Wallowas This afternoon && .DISCUSSION... GOES satellite showed cirrus overspreading east of the Cascades but mainly clear conditions across the much of eastern Oregon with the caveat of lingering mid level clouds from earlier rain showers over the Wallowas and northern Blue Mountains of Washington. Roughly 20 to 50 % chances remain for shower across the Wallowas This afternoon, where snow could mix in but is unlikely to accumulate even above 6500 ft AGL. Models going forward show a gradually building ridge across the PAC NW as 500 mb heights rise from about 564dm to 570 by Tuesday. This sunny high pressure setup will bring some modification to surface temperatures especially in the second half of the week where highs in the 80s should be returnable by Thursday and Friday. Westerly gap and valley winds will also be a diurnally driven sensible weather beginning with the Kittitas valley and the Eastern Columbia Gorge, and adjacent Blue Mountain foothills. Here, areas around Ellensburg has about 75% chances for wind gusts above 30 mph but little if any appreciable chances for gusts above 40 mph. Strongest winds in the region look to be along ridge tops. As the transition form the cooler airmass to the a warmer on on Wednesdays with the upper ridge becoming more centered across Washington and Oregon, the winds will become lighter over a broader area. && .AVIATION /18Z TAFS THROUGH 18Z TUESDAY/... VFR conditions are forecast for the next 24 hours at all sites. Winds will be diurnally and terrain-driven, breezy from late morning through evening. There is a very low (10 percent) chance of rain showers this afternoon at YKM with even lower chances (5 percent or less) elsewhere. && .Preliminary Point Temps/PoPs... PDT 69 42 72 46 / 0 0 0 0 ALW 69 46 72 49 / 0 0 0 0 PSC 75 44 77 48 / 0 0 0 0 YKM 74 44 76 47 / 0 0 0 0 HRI 73 44 75 48 / 0 0 0 0 ELN 68 41 68 43 / 0 0 0 0 RDM 68 30 72 37 / 0 0 0 0 LGD 64 36 68 40 / 0 0 0 0 GCD 65 34 71 38 / 0 0 0 0 DLS 73 45 74 49 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...None. && $$ DISCUSSION...71 AVIATION...86

305 FXUS65 KREV 180705 AFDREV Area Forecast Discussion National Weather Service Reno NV 1205 AM PDT Mon May 18 2026 .KEY MESSAGES... * Expect widespread freezing to near freezing temperatures this morning and again Tuesday. * A ridge builds back into the region by mid-week, allowing for warmer and drier conditions into the weekend. && .DISCUSSION... We tied a snowfall record at the Reno Int`l Airport today with officially a trace of snow, thanks to the cold frontal passage today. Expect a very cold morning today with lows near to below freezing for much of the area. Overnight lows rebound a bit Tuesday morning, but will remain on the chilly side. As for today, expect breezy afternoon winds with highs back to the mid 60s (valleys) and upper 50s (Sierra). We remain in a troughing upper-level pattern, with a low sitting off the coast of Baja California and high pressure building off the coast of the PacNW. This will allow for weak pressure gradients aloft, letting us slowly warm up through the week (as the ridge progresses eastward) with light and typical diurnal winds. Dry conditions will also accompany the warming trend. Looking towards the holiday weekend, there`s a ~40% chance to see highs above 90 degrees in Reno and ~40% chance to see over 80 degrees in Tahoe. Shower chances look slim to none for the weekend as well. -Giralte && .AVIATION... VFR conditions expected for all terminals today with breezy east/northeasterly afternoon winds (gusts up to 20 kts), albeit not nearly as strong as the winds yesterday. -Giralte && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory until 5 AM PDT early this morning NVZ002. CA...Lake Wind Advisory until 5 AM PDT early this morning CAZ072. && $$

632 FXUS66 KSTO 181830 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1130 AM PDT Mon May 18 2026 .KEY MESSAGES... - Red Flag warning expires this evening. - Less wind rest of the week but above normal temperatures returning with widespread moderate heat risk Thursday. && .DISCUSSION... ...Tonight and Tuesday... The upper trough/inside slider that brought us widespread gusty winds is quickly moving off to the east and causing severe weather in the central U.S. This will shift upper winds from the north to a more zonal westerly directions. In other words, less wind for the rest of the week. Relative humidities will remain low this week but not as dry as today. Once the pattern settles in on Tuesday/Wednesday it looks to stay pretty consistent. Warmest day looks to be on Thursday with very little spread in maximum temperature in the NBM percentiles. Currently looks like widespread moderate heat risk with temperatures in the 90s to approaching 100 in the north. Confidence pretty high that temperature forecast shouldn`t change too much. HeatRisk probabilities very low to reach above moderate risk but will keep an eye on this. Things look to cool down enough Friday into the weekend but still very warm. No rain in site right now in the 7 day forecast. && .AVIATION... VFR conditions are expected over the next 24 hours. Northerly winds 15-20 kts with gusts 20-30 kts for the Valley and Delta until around 00z-03z Tuesday. Northeast to east wind gusts up to 20-35 kts through mid-day today. && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM PDT this evening for Butte County Below 1000 ft-C. San Joaquin County including Stockton-C. Solano County including Fairfield-C. Stanislaus County including Modesto-C. Yolo/NE Solano including Woodland-Central Colusa County Incl. I-5-Central Glenn Co & Interstate 5-Eastern Colusa County-Eastern Glenn County-N. Sac Valley in Tehama County-NE San Joaquin Valley Below 1000 ft-SW Solano County including Vallejo-Sac Metro/W. El Dorado/Amador County-Sacramento County Delta-San Joaquin County Delta-Shasta Metro-Sutter/Yuba counties below 1000 ft-Tracy Triangle Below 1000 ft-W. Stanislaus County Above 1000 ft & I-5-W. Yolo County including Capay/I-505. && $$

145 FXUS65 KMSO 181359 CCA AFDMSO Area Forecast Discussion National Weather Service Missoula MT 142 AM MDT Mon May 18 2026 .DISCUSSION... KEY MESSAGES: - Frost/freeze concerns remains Tuesday morning. - Northwest flow becomes established for the rest of the week with unsettled but mild conditions. Clear skies are allowing temperatures to drop overnight. Expect widespread temperatures in the 20s and low 30s this morning and while there will be moderation Tuesday, expect another cold start. For the kids, a jacket in the morning will be carried home during the afternoon. Vulnerable vegetation will need to be taken care of over the next two mornings. Afternoon heating today and potentially again tomorrow will allow for isolated showers, production of graupel, and potentially a lightning strike or two. We will remain in northwest flow with a high pressure ridge just off the west coast. In the simplest terms, this week will see a warming trend and by Friday temperatures will be a few degrees above normal. A few disturbances will slide south along the eastern part of ridge producing periods of showers. Currently, the models are not overly excited, however, Wednesday evening into Thursday could be a period of more organized shower activity, especially along the continental Divide. && .AVIATION...Cold mornings may allow for fog in the vicinity of terminals, especially KBTM and KGPI. Otherwise, the atmosphere will remain unstable but dry, showers may develop in the vicinity of KGPI between 18/2100 and 19/0000z. Thunderstorms are very low probability, 20% or less, however a lightning strike is possible in the Flathead Valley and surrounding mountains. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...Frost Advisory until 8 AM MDT this morning for Kootenai/Cabinet Region...Lower Clark Fork Region. Frost Advisory until 9 AM MDT this morning for Flathead/Mission Valleys...Missoula/Bitterroot Valleys. ID...None. && $$

444 FXUS65 KBOI 181755 AFDBOI Area Forecast Discussion National Weather Service Boise ID 1155 AM MDT Mon May 18 2026 .UPDATE...Updated aviation discussion. && .KEY MESSAGES... - Mountain showers on Monday, otherwise dry, breezy and slightly warmer. - Dry with temperatures warming back above normal starting on Wednesday. && .SHORT TERM /Through Wednesday Night/... Issued 257 AM MDT MON MAY 18 2026 The tight surface pressure gradient behind an eastward exiting low pressure system will continue to generate breezy northwest winds today across much of the area. Wind gusts between 25 and 35 mph can be expected this afternoon, though they will not be quite as strong as what was observed on Sunday. While a stable air mass dominates the lower elevations, lingering afternoon instability will support a slight chance of light showers over the mountains today, with minimal accumulation expected. Northwest flow aloft will carry into Tuesday as high pressure builds over the Pacific. A more stable and dry air mass will keep conditions clear across the region, allowing temperatures to warm back to near normal values for this time of year. By Wednesday, an embedded shortwave trough will move through the intermountain west, tracking across our area into Wednesday night. This system will bring an increase in cloud cover along with light, isolated showers primarily focused across the West Central Mountains of Idaho. The arrival of this shortwave and its associated cloud cover will also work to slow down the overall warming trend as we transition into the long term period. && .LONG TERM /Thursday through Monday/... Issued 257 AM MDT MON MAY 18 2026 A trough over Montana will dig into southern Idaho on Thursday, bringing cooler temperatures and a slight chance of high terrain showers (10-20% chance). This trough will quickly move east on Friday, bringing a return to dry northwest flow through Saturday with temperatures 5-10 degrees above normal. A weak shortwave passage will bring another low chance of showers over high terrain late Saturday into Sunday, but forecast confidence is very low. By Sunday, a ridge of high pressure will build into the region, bringing warm and dry conditions ahead of a strong upper level low diving down off the British Columbia coast. Models diverge substantially on the path of this upper level low early next week, with some members (ECMWF) bringing this low directly over the region by Monday evening. Current forecast does not favor this outcome, with a strong bias towards the warm and dry scenario on Monday. && .AVIATION /18Z Monday through Tuesday/... Issued 1155 AM MDT MON MAY 18 2026 VFR. Scattered showers this afternoon, mainly across higher terrain. Brief MVFR/IFR conditions and mtn obscuration in showers. Snow levels: 5.5-6.5 kft MSL. Surface winds: W-N 5-15 kt with gusts to 20-25 kt this afternoon. Becoming variable 5-10 kt overnight. Winds aloft at 10kft MSL: N 10-20 kt. KBOI...VFR. Showers over the foothills this afternoon. Surface winds: NW 10-20 kt with gusts up 28 kt this afternoon, becoming SW-NW up to 8 kt overnight. && .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.....NF SHORT TERM...JDS LONG TERM....SA

593 FXUS65 KLKN 180822 AFDLKN Area Forecast Discussion National Weather Service Elko NV 122 AM PDT Mon May 18 2026 .KEY MESSAGES... * Temperatures will be cold with below normal readings at all locations today * Overnight lows are expected to drop to below freezing this morning * A slow warmup will start today and persist through the rest of the week && .UPDATE... Issued at 112 AM PDT Mon May 18 2026 Added patchy freezing fog to the valleys in northern Nevada due to the precipitation received over the area yesterday. Skies are expected to scatter out later this morning. The freezing fog is expected to burn off quickly due to the early sunrise. No other changes have been made. && .DISCUSSION... (This evening through next Saturday) WEATHER PATTERN OVERVIEW: Strong late season upper trough currently pushing into northern Nevada has over-performed so far with respect to prior forecasts across Humboldt and Elko counties as snowfall with the front has kept temperatures cooler than expected and with precipitation amounts higher than forecast. Elko so far had seen about 0.21 of water which fell as 1.6 inches of snow so far this morning. Winnemucca has seen 0.17 of water including 0.2 of snow so far. Models suggest that this performance should continue as the front moves into central Nevada this afternoon and evening. Still think the snow rain transition will be at 4500 feet, but could drop to valley floors if clouds can keep the sun at bay. Winds are still expected to be the main story with this system though as model trends outside of the NBM support current wind headlines across northern and central Nevada. The NBM is the low outlier with respect to winds so went ahead and upped the winds to better capture current trends with this system. This afternoon the precipitation will become more isolated to scattered, and become more convective in nature as the upper low moves overhead bringing stronger dynamical lift. So it would not be a surprise to see a few rumbles of thunder this afternoon especially across central NV as better instability develops. Overall amounts look to be better with up to an additional 0.10 of water for the valleys and 1 to 3 of snow for the mountains of northern NV. Amounts for central NV have risen too, with precipitation approaching Eureka and snow starting in Ely. Current trends favor 0.05 to 0.5 of water for the valleys, and up to 2 to 7 for the mountains, with the higher amounts favoring eastern White Pine County. Upper trough look to make its exit across Utah and into CO Monday afternoon. Temperatures this afternoon and Monday will be cool, with highs in the 30s and 40s today, recovering into the 40s and 50s Monday afternoon. After Monday weak WNW flow will develop across NV along with weak and subtle ridging aloft. This will be in place through next weekend allowing for quiet conditions to return, along with a warming trend that will see temperatures warm back into the upper 70 to low 80s by next Sunday. Overnight lows will bottom out Monday morning in the upper teens to upper 20s, however as the warming trend gets under way lows to will warm back above freezing, reaching the upper 30s to upper 40s by Sunday night. Winds after Monday will shift back to the west to northwest, with speeds of 10 MPH to 20 MPH with gust up to 30 MPH in the afternoons. FORECAST CONFIDENCE & DEVIATIONS: Departure: Went ahead and had to bump up the winds/wind gusts for the High Wind Warning and wind advisory areas across Humboldt, N Elko, S Lander, S Eureka, N Nye, and White Pine Counties as the NBM winds were not representative of current trends. There is high confidence for strong northerly winds Sunday through Monday morning as upper trough digs through eastern Nevada. There is high confidence for scattered to numerous light rain and snow showers for Elko and White Pine counties as upper trough pushes strong cold front through the region through Monday morning. There is high confidence for isolated to scattered light valley rain and mountain snow showers for western NV through Monday morning. There is high confidence for a return to quiet weather conditions through the following weekend as WNW flow aloft with subtle ridging allows temperatures to warm back into the upper 60s to low 80s by next Sunday. && .AVIATION... Patchy FZFG is possible this morning across the northern valley locations with VCFG near KEKO. Winds will be breezy in the afternoon NW10-20G30KT. && .LKN Watches/Warnings/Advisories... None. && $$ DISCUSSION...86/98 AVIATION...98