Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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072 FXUS66 KOTX 232255 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 355 PM PDT Thu May 23 2024 .SYNOPSIS... Today will feature scattered afternoon showers and thunderstorms mainly across north Idaho as well as north central and northeast Washington. Friday, Saturday and Sunday will cool with highs in the 60s and low 70s with chances for afternoon and evening showers and thunderstorms. Memorial Day will be the warmest and driest day of the holiday weekend with afternoon temperatures well into the 70s. A return of cool, wet weather expected midweek. && .DISCUSSION... Today through Saturday: There is a 20-40% chance of showers/thunderstorms generally north of Highway 2 today. CAMs have underdone convection a bit in the waterville plateau this afternoon but otherwise they are tracking fairly well. Models continue to show this activity nearing the Spokane metro around the evening rush hour, but the highest chances for some beefy showers are north of the city. Storms have been capable of hail up to half an inch (north of the Canadian border so far) and isolated lightning A weak shortwave will bring the same chances for showers back tomorrow in much of the same areas plus the Blue Mountains/ID Panhandle south of I-90. Models diverge Saturday where the majority of the GEFS/GEPS ensemble bring a 500 mb low into central/southern WA while the EPS brings the 500 mb low in southern Canada bringing the chance for gusty winds. If the GEFS/GEPS solution comes to fruition, I would expect greater chances of showers for the Inland Northwest particularly around Spokane. If the EPS is closer, it would generally be drier. I am leaning towards the majority solution (wetter and less windy Saturday). /Butler Sunday and Memorial Day: There is good model agreement that our holiday weekend will trend drier and warmer Sunday and Monday. With the exception of a 20 percent chance of light showers in the mountains north of Sandpoint and Metaline on Sunday, the remainder of the Inland Northwest has a dry forecast Sunday and Monday. Medium range ensemble consensus is for a flat high pressure ridge Sunday to amplify Monday into Tuesday. After a chilly start to the day Sunday, look for highs to rebound close to average with afternoon temperatures ranging from the low to mid 60s in north Idaho to the low 70s in central Washington and the L-C Valley. Memorial Day will be a good day for outdoor activities. Partly to mostly sunny skies are expected with winds in the 5 to 15 mph range and high temperatures between 70 and 80. Tuesday: The National Blend of Models (NBM) advertises the arrival of a cold front Tuesday afternoon and evening. Ensemble consensus is Tuesday will be as warm or warmer than Monday. Many of the Canadian ensemble members suggest Tuesday could be significantly warmer with widespread 80s and a handful of hot spots like Moses Lake and Lewiston near 90. The timing of the cold front will be worth watching. The NBM generates a 20 to 30 percent chance of thunderstorms across southeast Washington, the Idaho Panhandle and northeast Washington Tuesday afternoon and evening. The chance of measurable precipitation in central Washington and across the Columbia Basin is 10 percent or less according to the current NBM to as high as 30 percent along the Canadian border of northeast WA and north ID. Needless to say, Tuesday`s front has a significantly lower potential for producing widespread rains than our system for Saturday. Wednesday and Thursday: Temperatures are expected to be near average Wed and Thu following the passage of Tuesday`s front. Highs in the upper 60s to mid 70s are advertised by the NBM. Precipitation chances are in question. There is a good deal of ensemble spread by mid to late week. The ensemble blend produces some 20 to 30 percent chances Thursday mainly over our mountainous terrain. /GKoch && .AVIATION... 00Z TAFS: There is a 30% chance of showers and thunderstorms mainly over the northern mountains and KGEG-KSFF-KCOE this evening. Models handled last night`s stratus deck very poorly and it looks to potentially underdo it again tonight. Rich boundary layer moisture (especially in the ID Panhandle and Northeast Washington would promote development of this. If KGEG-KSFF-KCOE get hit with some heavier showers this evening, MVFR conditions are not off the table into tomorrow morning. Isolated shower development is again on the table tomorrow around 22z near KPUW. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence on showers over the TAF sites in extreme eastern Washington and North Idaho this afternoon. Very low confidence on MVFR ceilings tonight for KGEG-KSFF-KCOE. /Butler ----------------------- 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 45 68 46 61 41 65 / 30 10 30 30 10 0 Coeur d`Alene 44 66 46 57 41 61 / 40 20 40 50 10 0 Pullman 39 64 43 56 39 63 / 0 20 40 40 10 0 Lewiston 46 72 51 65 46 72 / 0 30 40 40 10 0 Colville 38 67 40 61 36 63 / 60 30 30 70 10 10 Sandpoint 43 63 44 55 41 58 / 60 30 40 70 20 10 Kellogg 45 63 46 53 42 59 / 20 30 40 70 20 0 Moses Lake 43 71 46 67 40 72 / 0 10 10 10 0 0 Wenatchee 47 68 48 64 45 71 / 0 10 10 10 0 0 Omak 43 71 46 68 41 70 / 10 20 20 30 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$