Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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212 FXUS66 KOTX 112223 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 323 PM PDT Sun Aug 11 2024 .SYNOPSIS... There will be a couple more days of showers and thunderstorms for some of the region, followed by a brief lull around mid-week, before additional shower and thunderstorm chances arrive heading into the end of the week. In the near term, the focus for thunderstorms will be over the Cascade and northern mountains, as well as over southeastern Washington into the southern Panhandle tonight through Monday night. Lightning from thunderstorms will be capable of starting new fires. Daytime temperatures will begin the week slightly warmer than normal but should drop to average or slightly below by midweek. && .DISCUSSION... This afternoon through Tuesday: The threat of showers and thunderstorms will continue across some the Inland NW this period. There are a lot of moving parts to this potential over the next couple days or so. The main players will be a long-wave trough near the west coast and the shortwaves embedded within it and the instability these will interact with. This afternoon there is a smattering of showers and isolated thunderstorms around the periphery of the CWA. These have been mostly north of the Canadian border, aside from a few stray cells over near the ID Panhandle and near the northern mountain. However this activity is expected to increase. Toward the west and northern CWA: satellite showed a well-defined circulation near northwest Washington around the 3 PM hour. As this afternoon moves into tonight that circulation will gradually move east. Instability and this feature is expected to lead to a continued increased in showers and embedded thunderstorms around the Cascades and northern mountains through this evening, potentially spreading as far east of the Waterville Plateau or northwest Columbia Basin. As the sun sets, the activity further removed from the circulation center will wane. Closer to the center around Okanogan county the threat of showers and t-storms will continue through the night, though some models dissipate that threat more than others. Activity dissipates here heading into Monday morning, but will be revitalized here and the northern mountains through the Monday afternoon. All of these are expected to move a bit quicker and lessen the potential for wetting rains. A Red Flag Warning remains in place for the Cascades to north-central WA through Monday evening for lightning. Any lightning that starts fires could could also be impacted by gusty outflow winds from t-storms. The threat wanes through Monday night only to return in more isolated fashion in the daytime heating Tuesday afternoon. Toward the southeast CWA, the upper trough pivoting in and the aforementioned disturbances coming along it will also bring some showers/t-storms chances in this area. Isolated activity is possible this evening near the Blues and around the central Panhandle mountains. A few could form around the Spokane/CdA area and Palouse too, but there is very low confidence in that. As the evening progresses into tonight the threat of showers will persist over the Blues and also a higher confidence threat will expand over the L-C Valley/Camas Prairie and Palouse to central Panhandle as a shortwave pivots along the near jet axis. With all that said, this activity is expected to be isolated in nature. The chances will continue through Monday and then will be invigorated late Monday into Tuesday morning in this same area as another wave moves in along the jet. This will be slightly further north than the first, meaning some potential may also slip a bit further north into the Spokane/C`dA area late Monday night into Tuesday morning. Heading into Tuesday afternoon the threat here starts to shifts further east. In a broader sense all of this will be accompanied by some marginally breezy conditions, near the Cascades gaps and also on Monday and Tuesday around the Columbia Basin and Palouse and lower Panhandle, with gusts near 15-20 mph. Sustained winds and afternoon RHs are not expected to reach critical values for fire weather concerns. High temperatures are forecast to reach the upper 80s to low 90s Monday and then the mid-70s to mid-80s on Tuesday. Overnight lows will be in the upper 50s and 60s Monday morning and then the upper 40s and 50s Tuesday morning and Wednesday morning, with Wednesday morning the cooler of the two. Wednesday to Sunday: The middle of the week starts cooler and dry with weak high pressure, while a deeper trough starts to develop around the coast heading into the end of the week. A leading wave starts to move into the region Thursday night, expanding shower and embedded t-storm chances across the region. There are still model disagreements over the details heading into Friday through Sunday, but they are coming together in developing a deeper trough near the coast with waves moving inland. This bring continued and broader shower/t-storm chances throughout the region in that time frame. Overall the best chance for wetting rain will be around the mountain zones at around 30-60%, with areas outside of the mountains will have around 10-30%. Temperature warm closer to normal on Thursday, then drop slightly below normal again Friday into Sunday. Saturday looks like the coolest day with highs in the mid-70s to low 80s, with some mid-80s in the L-C Valley. /Solveig && .AVIATION... 00Z TAFS: Low pressure dropping in from northwest will bring the threat of showers/isolated t-storms around the Cascades and northern mountains and northern and central ID Panhandle. The threat over this region will wane after dark over all but north-central WA, especially central and eastern Okanogan County where the risk will continue through the night before waning into early Monday AM. Elsewhere, later tonight into early Monday the threat will develop around southeast WA and lower ID, potentially moving into the areas such as PUW/LWS after 09-12Z. Wildfire smoke will continue to bring hazy/smoky conditions, particularly near the wildfires, but impacts at TAF sites are not expected at this time. Otherwise look for VFR conditions. Winds will be generally light, but if a t-storms passes near a TAF sites brief gusty winds are possible. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence is high for VFR conditions. General haziness from regional fires may result in brief MVFR conditions with reduced visibility, particularly in the Methow Valley and possibly at KPUW. Confidence is high for thunderstorms near the Cascades this afternoon into this evening, but confidence is low around TAF sites but the threat is not zero. ----------------------- 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 62 87 56 81 53 83 / 10 10 10 10 0 0 Coeur d`Alene 60 85 54 80 52 80 / 20 10 10 20 0 0 Pullman 57 83 51 75 48 78 / 20 20 20 20 0 0 Lewiston 67 93 64 84 59 88 / 20 20 30 20 0 0 Colville 50 87 47 83 45 83 / 20 20 20 20 10 0 Sandpoint 57 84 52 79 50 79 / 20 10 10 10 0 0 Kellogg 64 83 57 77 55 78 / 30 20 20 20 10 0 Moses Lake 60 89 56 84 53 85 / 0 10 0 0 0 0 Wenatchee 66 89 62 84 61 85 / 20 10 10 10 0 0 Omak 63 92 61 88 58 90 / 30 30 20 20 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Red Flag Warning until 11 PM PDT Monday for East Portion of North Cascades National Park/Lake Chelan National Recreation Area (Zone 697)-East Washington Central Cascades (Zone 696)-East Washington North Cascades (Zone 698)-Methow Valley (Zone 704)-Okanogan Highlands and Kettle Mountains (Zone 699)-Okanogan Valley (Zone 703). && $$