Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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357 FXUS66 KOTX 221855 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1155 AM PDT Wed May 22 2024 .SYNOPSIS... Today will be cool with steady rain across far north Idaho and northeast Washington. Scattered showers will occur across parts of southeast Washington this afternoon. Thursday will feature scattered afternoon showers and thunderstorms mainly north of Spokane. Memorial Day weekend will be cool and showery Saturday and Sunday followed by dry weather Monday with highs in the 70s. && .DISCUSSION... Rest of Today: Satellite imagery as of 11 AM showed the center of our upper low near the Tri Cities. Bands of rain were wrapping around the low continue to be focused across north Idaho and northeast Washington. Rainfall amounts with this system have been the highest along an axis from Republic to Kettle Falls to Cusick where sensors report between a half inch and an inch of rain since last night. For the remainder of the afternoon into the early evening an additional quarter to third of an inch is generated by the HREF along the Canadian border from north central Washington into northwest Montana with localized amounts up to a half inch in Bonner and Boundary counties. A 10 to 20 percent chance of lightning has been added to the Moses Lake, Ritzville, Washtucna, and Pomeroy areas this afternoon under the heart of the upper low. Breaks in the cloud cover in the Columbia Basin should generate the best low level instability across the region, and this is where the GFS and HREF generate up to 200 J/Kg of surface based CAPE. Any thunderstorms should be short-lived due to marginal instability and shear. Winds have been increased early in the afternoon to 15 to 25 mph from Wenatchee to Moses Lake to Pullman in response to surface pressure falls in eastern Washington under the upper low. As the upper low dives southeast into Oregon and southern Idaho this evening, winds will relax and remnants of the deformation band near the Canadian border sink south producing additional light rain through the night over the Idaho Panhandle, Palouse, and Camas Prairie. /GKoch && .AVIATION... 18Z TAFS: The most persistent band of rain with ceilings of 2500-3500ft will pivot north of Coeur d`Alene and Deer Park this afternoon and stall around Sandpoint, Bonners Ferry, and Colville. Overnight, remnants of this band of rain will sink southward as the upper low sinks into Oregon and southern Idaho bringing another shot of light rain to Coeur d`Alene, Spokane, Pullman, and Lewiston. Boundary layer moisture from today`s rain will likely result in 1500-2500ft ceilings across southeast Washington and the southern/central Idaho Panhandle where the HREF gives Pullman an 80 percent chance 2000ft ceilings between 12-18z. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: HREF probabilities for 2000-3000ft ceilings at Coeur d`Alene and Spokane are than 20 percent Thursday morning. There will be a good deal of dry northerly winds in the mid and upper levels suggesting clearing in the morning. Since GFS MOS produces a stratocumulus deck at Coeur d`Alene, and NAM/GFS soundings support that idea a BKN025 deck has been included. It wouldn`t be surprising to see similar conditions at SFF and GEG, and may need to be added later TAFs. /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 54 40 64 45 68 46 / 20 20 30 10 20 20 Coeur d`Alene 49 40 60 45 67 45 / 50 40 40 20 30 30 Pullman 50 39 59 40 65 44 / 10 30 10 0 20 40 Lewiston 59 47 66 46 73 51 / 10 40 10 0 20 40 Colville 50 35 64 39 67 41 / 90 40 70 60 50 40 Sandpoint 49 38 58 44 64 44 / 90 70 60 50 50 40 Kellogg 46 42 57 45 64 47 / 70 70 40 20 40 50 Moses Lake 58 42 72 44 73 47 / 50 20 0 0 10 10 Wenatchee 58 47 71 47 71 49 / 50 20 0 0 10 10 Omak 58 43 72 45 72 46 / 80 50 30 10 20 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$