Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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792 FXUS66 KOTX 171209 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 509 AM PDT Fri May 17 2024 .SYNOPSIS... It will be another windy day with gusts of 45 mph or more around Wenatchee, Pullman, and Lewiston. Cooler weather has arrived. High temperatures in the 60s will be common through the weekend and into next week. Tonight will be quite chilly with the potential for frost in our sheltered valleys of north Idaho and northeast and north central Washington. The weekend will feature the chance for showers. A more widespread rain event will be possible Tuesday night into Wednesday. && .DISCUSSION... Today: It will be another windy day, but our areas of strongest gusts will likely shift compared to yesterday. An upper level disturbance will descend out of British Columbia this morning bringing a reinforcing shot of cool air and establish a more northwesterly pressure gradient. Yesterday`s southwest gradient directed the strongest winds from Moses Lake into Spokane with gusts between 45 and 55 mph. High resolution models for today highlight the Waterville Plateau and Wenatchee area as well Pomeroy, Pullman, Lewiston, and elevations above 3000 ft in Lewis county in the southern Idaho Panhandle. Guidance from the ECMWF ensembles and the High Resolution Ensemble Forecast (HREF) advertise wind gusts of 40 to 45 mph with localized gust potential to 50 mph for these locations. A patchwork of Wind Advisories are in effect through early evening. There was a considerable plume of dust that originated around Moses Lake on Thursday. High resolution models don`t produce as much wind there today, but patchy dust will be possible near recently worked fields on the Waterville Plateau. Early morning rains over the Palouse and Camas Prairie may limit dust across southeast Washington and the open wheat country around Grangeville. As of 2 AM, Pullman got 0.15 of rain. The Camas Prairie probably won`t get as much rain in the lee of the Blue Mountain rain shadow, but the dryland wheat fields of Lewis county should get a few hundredths by mid morning before the winds fire up. The chilly upper level disturbance from B.C. will also generate rain showers today across northeast Washington and the Idaho Panhandle. A few of the showers will be capable of lightning, brief downpours, and pea hail this afternoon before quickly exiting north Idaho early this evening. Tonight: It will be our coolest night in over a week. Clearing skies and decreasing winds will allow temperatures to tumble into the 30s and low 40s by early Saturday morning. Some of our sheltered valleys in northeast/north central Washington and north Idaho will flirt with freezing. Gardeners may want to protect tender vegetation in our typical cold spots like Republic, Mazama, Springdale, Deer Park, and spots around Colville. Saturday: Tired of the wind? Well, Saturday will be a typical showery and breezy spring day. Our typical breezy areas like the Columbia Basin, Palouse, and West Plains will experience 15 to 25 mph winds...still annoying for fishermen and golfers, but relatively low impact compared Thu/Fri. There will be a 30 to 60 percent chance of showers over the mountainous terrain of northeast/north central Washington and north Idaho as another shortwave during the afternoon and evening. The highest concentration should be near the Canadian borer. Again some of the strongest cells will be capable of lightning and small hail. /GKoch Sunday to Thursday: The Inland NW will remain in a somewhat active and largely cooler than normal pattern. As Sunday starts one trough continues to exit, then Monday a weak ridge briefly builds in. A chance of showers will be found over much of the region on Sunday, with the best chance for wetting rains around the northern WA and ID Panhandle mountains. A chance for t-storms will also be found around the region, especially those northern mountains. Chances wanes through the night into Monday, with some risk re-developing in the afternoon around the eastern mountains in west-northwest flow and a subtle shortwave passing through the ridge. Expect continued breezy conditions, especially Sunday compared to Monday with gusts of 15-25 mph. Then Tuesday into Thursday a deeper low moves into the region. This looks like a wetter system, with a modest chance of wetting rains over all but the deeper Columbia Basin and lee-side zones. Chances are somewhat low Tuesday morning then starts to increase over the region Tuesday afternoon and especially Tuesday night into Wednesday. The 24-hour probability of wetting rains per ensembles is about 50-90%, with the higher end of that range around the Cascade crest and the Idaho Panhandle and northeast Washington mountains. However as we head into later Wednesday into Thursday models start to diverge over how the low evolves. However there is enough confidence to say there will still be a modest chance of rain, but there is less confidence there will be wetting rains by this time. There will be some opportunities for embedded t-storms with the instability associated with the low. Some breezy conditions linger each afternoon, with models showing gusts in the 10-20 mph range. As for temperatures, there could be some pockets of frost in some the sheltered northern valleys in morning hours Sunday and, to a lesser extent, Monday. Otherwise lows will be in the upper 30s and 40s. Highs will largely be in the upper 50s and 60s, with some lower 70s in the deeper basin and L-C Valley. The exception will be Monday as the warmest day, with highs in the mid-60s to mid-70s, approaching near 80 in the deeper basin. /Solveig && .AVIATION... 12Z TAFS: West winds will fire up again today. By 15-17z the arrival of a shortwave descending from B.C. will increase winds into the 15 to 20kt range with gusts up to 30kts or more at Wenatchee, Pullman, and Lewiston from mid-day into the afternoon. Scattered showers will also accompany the passage of the shortwave across northeast/north central WA and the ID Panhandle. PROB30 and TEMPO groups have been included in the Spokane and Coeur d`Alene TAFs. Chances for lightning are limited to north Idaho and northeast Washington between 19-01z. Short term TAF amendments will handle any thunderstorms. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Blowing dust limited visibilities to 3 miles for a few hours at Moses Lake and Spokane on Thursday with winds gusting in the 45 to 55 mph range. There should be less dust today since winds won`t reach that magnitude over the source region of the dust around Moses Lake. However, the last 10 days has been quite dry so recently worked fields that happen to be near an airport could produce visibility reductions. /GKoch ----------------------- 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 63 39 63 40 60 40 / 20 10 10 30 40 10 Coeur d`Alene 59 38 61 39 56 40 / 40 20 20 30 50 10 Pullman 58 37 60 38 56 40 / 10 0 0 20 20 10 Lewiston 67 43 70 44 65 45 / 20 0 0 10 20 10 Colville 63 32 62 35 62 36 / 40 10 60 50 70 10 Sandpoint 57 37 58 38 54 39 / 80 20 50 50 80 20 Kellogg 54 39 58 40 52 41 / 80 20 30 30 60 20 Moses Lake 68 39 68 40 69 42 / 0 0 0 10 10 0 Wenatchee 64 44 64 43 66 45 / 0 0 0 0 0 0 Omak 69 39 66 40 68 42 / 10 0 20 20 20 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Wind Advisory until 5 PM PDT this afternoon for Idaho Palouse- Lewis and Southern Nez Perce Counties-Lewiston Area. WA...Wind Advisory until 5 PM PDT this afternoon for Lower Garfield and Asotin Counties-Washington Palouse. Wind Advisory until 7 PM PDT this evening for Waterville Plateau- Wenatchee Area. && $$