Sunrise 5:31 AM   Sunset 7:57 PM Moonrise 12:45 AM   Moonset 8:00 AM

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FXUS66 KOTX 282255 AFDOTX

Area Forecast Discussion National Weather Service Spokane WA 355 PM PDT Sun Apr 28 2024

SYNOPSIS
Monday will be windy with gusts 30 to 40 mph. A cold front will bring snow to the Cascade mountain passes Sunday night and Monday morning and rain to much of the rest of the region. Temperatures will trend cooler with areas of frost returning Tuesday morning.
Unsettled conditions return for the remainder of the week, especially to the mountains.

DISCUSSION
Tonight through Tuesday Night: Breezy to windy conditions with gusts 20 to 30 mph this afternoon will decrease after sunset.
Speeds will remain elevated through the night, but gusts will generally be 20 mph or less. Showers have popped up again this afternoon across northeast WA and the ID Panhandle. Instability isn't as good as it was yesterday, and the potential for thunderstorms is decreasing quickly. Have removed mention of thunder for Washington and have it confined to the ID Panhandle through 7pm.

The trough will begin to move onshore late tonight. Rain will change to snow across the Cascade mountains after sunset and begin to accumulate towards midnight. Will continue with the winter weather advisory above 3500 ft. For Stevens Pass there is a 75% chance of 4 inches of snow and a 30% chance of 6 inches. Snow will continue through the morning hours at the pass, but by 10ish or after it will become increasingly difficult for snow to accumulate on the roads given the sun angle and temps warming above freezing.
Periods of snow will continue in the mountains through Tuesday, though accumulations will be minor.

As the trough moves inland Monday we will see an increase in westerly winds. Strongest winds will be across the Waterville Plateau with sustained winds to 25 mph with gusts up to 40 mph. As you head onto the Columbia Basin, Palouse and West Plains winds will be sustained winds 15 to 20 mph with gusts 25 to 35 mph. Have kept the patchy blowing dust in the forecast for portions of Grant, Lincoln and Adams counties from 3 to 7pm.

These strong westerly winds will shadow out portions of the Wenatchee/Waterville Plateau and Columbia Basin around Moses Lake.
Otherwise there is a 60% chance or greater of the rest of the region seeing rain showers Monday. During the morning, some higher bench locations like the West Plains could see snow briefly mixed in with the rain. No accumulation is expected on the roads.

As the low moves through in the late morning and afternoon hours there is a 15 to 25 percent chance of thunderstorms. Have the eastern third of Washington...mainly east of a line from Walla Walla to Ritzville to Republic and areas eastward into Montana highlighted for thunderstorm potential. Impacts from thunderstorms would be gusts to 40 mph, graupel and lightning.

Tuesday morning temperatures will dip to near freezing or below for a large portion of the lower elevations of the Cascade Valleys, northeast WA, the Spokane area, Palouse and ID Panhandle.
Have mention of frost for these areas.

Showers continue Tuesday as a secondary trough moves into the region. Tuesday there is a 15-20% chance of thunderstorms across southern WA and onto the Palouse and southern ID Panhandle.
/Nisbet

Wednesday through Saturday: Wednesday will be another day of unsettled conditions with showers and isolated thunderstorms mainly isolated over the Cascades and Shoshone County. Afternoon winds will still be a bit breezy with gusts of 15 to 20 mph.

Most of the region will see temperatures drop near freezing Tuesday night into early Wednesday morning, and a few locations in the mountain valleys and the northern Basin may drop below freezing.

Heading into the second half of the week starting Wednesday night, we start to see divergence in model solutions. Around 70 percent of models suggest a ridge will move in, taking the place of the trough that will be over us through the first half of the week, and warming our temperatures back into the 60s by next weekend. The other 30 percent of ensemble members want to keep us in a troughing pattern, which would result in temperatures staying in the 50s through the end of the week.
/Fewkes

AVIATION
00Z TAFS: Showers will decrease through the evening. Winds will continue region wide in a general south to southwest direction.
Gusts around 30-35 mph will be possible in the Okanogan Valley, Palouse and near the Blue Mountains. A potent cold front tonight into Monday will bring more widespread precipitation to the Idaho Panhandle and Eastern third of WA. Rain will transition to wet snow for elevations around 2500 feet and higher which includes Pullman, Spokane, and Coeur D Alene. Higher confidence for GEG and PUW to see snow mix in and have that in the TAF, but not for COE because of lower confidence. Confidence is moderate for little to no accumulations with steady winds keeping temperatures above freezing during this time. Winds will become gusty Monday from the west as well with potential for brief gusts around 30-40 mph. With the showers that pop up after the front moves through there is a chance of thunderstorms. Higher confidence exists to see them around COE than other TAF locations, and therefore have it in the tempo group. GEG/SFF/PUW/LWS have mention of -shra for the afternoon, but they also have a low chance of seeing thunderstorms as well.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is about a 10% chance of blowing dust across the Columbia Basin Monday afternoon, including MWH. Confidence is very low and do not have mentioned in the TAF.

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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 38 52 32 53 35 59 / 20 70 10 20 10 10 Coeur d'Alene 38 47 31 50 34 56 / 40 90 30 50 20 20 Pullman 36 46 31 49 32 53 / 20 90 30 50 30 20 Lewiston 43 55 37 56 37 61 / 10 70 10 40 20 20 Colville 33 50 26 54 29 61 / 30 80 10 30 10 10 Sandpoint 38 47 31 49 34 54 / 50 90 30 60 20 40 Kellogg 38 44 33 45 34 49 / 50 100 50 70 30 50 Moses Lake 38 58 34 59 35 66 / 10 20 0 10 0 0 Wenatchee 38 55 37 57 38 64 / 10 10 0 10 0 0 Omak 36 57 32 59 34 66 / 10 30 0 10 0 0

OTX WATCHES/WARNINGS/ADVISORIES
ID...None.
WA...Winter Weather Advisory from 11 PM this evening to 11 AM PDT Monday for Western Chelan County.

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