Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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190 FXUS66 KOTX 300452 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 952 PM PDT Mon Apr 29 2024 .SYNOPSIS... Scattered showers will continue into Tuesday. Winds will decrease tonight with the potential for frost expanding across the mountain valleys through Wednesday morning. A warming trend through the rest of the week into the weekend. Weather conditions will remain unsettled for the rest of the week with a weather system moving in off of the eastern Pacific on Thursday and another one over the weekend. && .DISCUSSION... Evening update: The mid level disturbance responsible for today`s convection is beginning to shift out of the area with a couple remaining bands of showers stretching from the Palouse and Camas Prairie up towards Lookout Pass as of 830 PM. Radar was also showing some showers up near Lauier and Northport. As this system continues to push east shower activity will continue to be on the decrease. The evening POP`s were adjusted based on radar trends. The showers helped cool the lower level considerably this evening with many areas across northeast Washington and the Idaho Panhandle already down into the upper 30s to low 40s as of 8 PM. Expect frost in many areas of Eastern Washington and north Idaho Tuesday morning. Another low pressure system near Vancouver Island will drop southeast towards the south WA coast tonight. Bands of snow showers will continue to rotate north into Stevens Pass tonight where a Winter Weather Advisory remains in place through 2 AM PDT. The focus of more persistent snow showers for the Cascades will shift south of Stevens Pass Tuesday morning as the main energy from the low slides into southern Washington and northern Oregon. JW && .AVIATION... 06Z TAFS: Following the showers that went through the Idaho Panhandle this evening is a moist boundary layer. Expect increasing areas of MVFR stratus between 9-15z Tuesday over the Idaho Panhandle and southeast Washington as light upslope winds continue which includes KCOE/KPUW. Drier air in Central Washington has spilled into the Spokane area which leads to a better chance for conditions remaining VFR at KGEG/KSFF. On Tuesday another round of showers will develop as the atmosphere destabilizes but less in coverage compared to today. Isolated thunderstorms may also develop, but the main threat will be over the higher terrain of SE Washington (Blue Mountains), and up over NE Washington around Republic and Colville. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: The HREF is showing near a 60% chance of MVFR stratus expanding over the Palouse into the Idaho Panhandle overnight, but keeping probability closer to 20% for KGEG/KSFF. There is high confidence in continued VFR conditions in Central Washington due to a much drier boundary layer. There is a 20% chance of thunderstorms on Tuesday mainly across southern Washington into the Lewiston area, and up over the mountains of NE Washington. Confidence is any of the TAF sites being impacted is too low to include in the TAF forecast. JW ----------------------- 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 31 53 34 58 36 60 / 0 20 10 10 10 20 Coeur d`Alene 30 50 33 55 36 59 / 10 30 20 30 10 20 Pullman 31 48 32 53 34 57 / 20 40 20 30 20 30 Lewiston 36 56 37 61 39 62 / 20 40 30 20 10 30 Colville 25 54 30 61 33 61 / 10 40 10 20 10 30 Sandpoint 29 50 34 53 36 58 / 20 40 20 50 20 40 Kellogg 32 45 34 48 36 56 / 20 50 30 70 20 40 Moses Lake 34 59 34 66 38 62 / 0 10 0 0 10 20 Wenatchee 38 57 38 63 41 59 / 10 20 0 0 10 20 Omak 32 58 35 66 41 64 / 0 20 0 0 10 20 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...Winter Weather Advisory until 2 AM PDT Tuesday for Western Chelan County. && $$