403 FXUS66 KOTX 072112 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 212 PM PDT Sat Apr 7 2018 .SYNOPSIS... This afternoon and evening look for isolated to scattered showers, with a chance for thunderstorms. Expect showers to increase in coverage again for some of the region overnight and Sunday. Breezy southwest winds are expected tonight and again Sunday across the Palouse, West Plains, and Columbia Basin. Mild and dry weather is expected Monday, then a series of weather disturbances will bring periods of showers and breezy winds back to the region Tuesday through Saturday. && .DISCUSSION... Tonight through Sunday: The weather will remain showery, breezy and cool, with some risk for thunderstorms. An upper trough near the Pacific NW coast will migrate inland over the next 24 hours. For this afternoon and evening a disturbance rounding it will interact with the moist and locally unstable atmosphere to bring a threat of scattered showers and the risk for thunderstorms. These will be possible just about anywhere. Yet looking at guidance the higher risk will be around the northern and eastern rim of the Columbia Basin into the mountain zones through sunset. These could contain some brief heavy downpours and gusty winds, as well as small hail. We will monitor the winds with any of t-storms as any may tap into some of the general wind field. In general, winds will be breezy to locally windy in wake of the passing cold front, especially across the Columbia Basin zones where speeds of 15-25 mph will be possible with gusts of 30-40 mph. After dark the threat of thunderstorms will abate and the winds will also abate a little, but in general those winds will remain breezy throughout the night. Overnight into Sunday the axis of that parent trough will be moving east of the Cascades and the lift along and ahead of it will revitalize showers throughout a good chunk of the area. The threat will start to develop between about 06-09Z and continue throughout the day Sunday. There will be a couple exceptions. First the lee of the Cascades/deeper Columbia Basin will see a limited risk. Second the threat will start to wane from the northern mountains later Sunday as the main trough starts to sag southeast. I did add a limited threat of thunderstorms around the northern mountains for the afternoon hours Sunday, but the risk is slight. Snow levels will be around 4-5kft, locally lower near the northern mountain zones and Cascades. Some of the sheltered areas north of Sandpoint have been locked into some cooler air, with temperatures in the mid to upper 30s. This has allowed some snow to mix in down to around 2.8-3kft here. However most guidance suggests temperatures will remain steady or slowly rise some, so while I kept snow levels here lower than guidance I don't have much accumulation here. Where there is some accumulation is in the mountains and near some of the passes, such as Stevens and Sherman and Lookout Pass. Widespread significant amounts are not expected so no highlights are expected, but we will monitor radar and computer model trends. Winds will remain breezy throughout the day Sunday with the good mixing with the incoming shortwave. Speeds are expected to be slightly lower than Saturday, but not by much at 10-20 mph with gusts of 30-35 mph possible. Once again the sheltered mountain valleys will see less wind. /J. Cote' Sunday night through Saturday: There will be a short lived warm and mainly dry period Monday and Tuesday. Then the weather through the remainder of the extended period will become mainly cool and unsettled as a parade of weather systems are expected to move through the region. Sunday night through Tuesday morning: High pressure will build into the region Sunday night behind the exiting storm system from the weekend. Southwest to westerly flow and lingering mid-level moisture will keep showers in the forecast for the Cascades and along the Idaho/Montana border through Monday morning. Snow levels will decrease to 3.5-4k feet, before rebounding again Monday afternoon. So precipitation will be as valley rain and mountain snow. 2-4 inches of new snow will be possible at the higher elevations by Monday morning. Otherwise we can expect the weather to be dry. Temperatures will increase 2-4 degrees over Sunday, making it feel a little like spring. Tuesday afternoon and Tuesday night: A fast moving weather system will move up the back side of the ridge and bring a quick shot of moisture Tuesday afternoon and Tuesday evening. A cold front will follow Tuesday evening to quickly cut off the precipitation from the west, but not before showers drop a quick tenth of an inch or so of rain and high mountains snow. The front, looks pretty dynamic and there will be a chance for thunderstorms and gusty wind with the frontal passage late n the day and mainly across the northeast mountains. Temperatures will be very dependent on the timing of the front. Across the western zones temperatures may just be a few degrees cooler than on Monday, with temperatures 2-4 degrees warmer across the eastern zones. Southwest winds will be on the increase late in the day as the front moves through. Winds gusts of 25-30 mph will be possible for the Basin, Palouse, the ridges of the Blue mountains and up towards the Spokane-Coeur D'Alene corridor. Wednesday through Saturday: Another storm system is expected Wednesday and Thursday, followed by another late in the day Saturday. We should get a brief respite Friday and early Saturday in between weather disturbances. But overall we are looking at continued cool and wet weather through the end of next week and into next weekend. Tobin && .AVIATION... ...VIGOROUS COLD FRONT PASSAGE WITH RAIN AND A RISK FOR THUNDERSTORMS AND WINDY CONDITIONS... 18Z TAFS: A cold front pushing across eastern WA this morning to early afternoon will bring areas of steady rain to the eastern TAF sites, turning to showers after 20-21Z. That will be accompanied by MVFR/IFR conditions and the potential for heavy downpours. This will be accompanied by some brief strong wind gusts as winds turn from northeast to southwest, with possible LLWS before 21Z. Thereafter the threat of isolated to scattered showers and maybe some thunderstorms will develop, including near GEG/PUW/LWS. These could bring more heavy downpours, small hail and strong winds. However coverage may be limited and will decrease after 01-03Z. Yet again more general precipitation will develop overnight into Sunday morning with the next upper wave moving inland. The precipitation is not expected to be as heavy but should bring some MVFR/isolated IFR cigs. Lastly, the general winds will be on the increase this afternoon and remain breezy tonight into Sunday. Aside from isolated gusts over 50kts with convection, most speeds will be in the 15-20 mph range with gusts of 30-40kts. These will abate slightly after dark. /J. Cote' && .PRELIMINARY POINT TEMPS/POPS... Spokane 40 52 36 56 38 59 / 70 60 20 0 0 50 Coeur d'Alene 39 49 36 53 37 57 / 80 80 20 10 0 60 Pullman 42 49 37 57 40 58 / 80 80 30 0 0 50 Lewiston 46 57 40 64 43 64 / 60 60 10 0 0 40 Colville 39 56 34 58 35 59 / 60 40 10 10 0 50 Sandpoint 36 47 36 51 34 53 / 90 80 30 20 0 60 Kellogg 35 43 35 50 33 54 / 90 90 60 20 0 70 Moses Lake 45 62 37 62 39 62 / 20 30 10 0 0 20 Wenatchee 41 58 40 61 41 59 / 30 20 10 0 0 30 Omak 41 62 37 61 40 60 / 50 30 10 0 0 40 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$