FXUS66 KOTX 281745 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 1045 AM PDT Sat Sep 28 2024 .SYNOPSIS... Drier and warmer weather continues across the region, with temperatures peaking today. On Sunday, another strong cold front will push through the area bringing gusty winds, blowing dust and cooler temperatures. Freezing overnight lows are expected again for much of next week, especially across the northern valleys. && .DISCUSSION... ...STRONG COLD FRONT PASSAGE SUNDAY WITH WINDY CONDITIONS...BLOWING DUST...AND ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS... Today through Sunday Night: One last very warm day for our region with temperatures in the upper 70s to upper 80s, which is 6 to 15 degrees above average for the end of September. Northerly winds will push down the Okanogan Valley this morning at about 10-15 mph. As winds try to go upslope in the afternoon the winds will decrease. Otherwise expect a quiet day with increasing high clouds. A trough will approach the region Saturday night. The pressure gradient across the Cascades will strengthen through the night and winds will pick up after midnight across the higher elevations and into the Wenatchee area and Waterville Plateau. This is a dry cold front, but ahead of the front there could be brief light sprinkles or very light precip across northeast WA and the north ID Panhandle overnight and Sunday. The winds will really increase late Sunday morning and through the afternoon hours as the cold front sweeps through. Models are showing very dry air move into the region through the afternoon. Elevated to critical fire weather conditions are expected with combined RH/wind values. Will be expanding our fire weather watch to include the Okanogan Valley, Colville Tribe, portions of northeast WA and the Idaho Panhandle. There is a 40-60% chance of seeing gusts to 30 mph extending from Omak to Wenatchee to Othello to Lewiston and up to Spokane. There is a 70% chance across the Waterville Plateau and into portions of the upper Columbia Basin. There is a 35-40% chance of gusts to 40 mph for a portion of the Waterville Plateau along Highway 2 and some of the higher terrain of Chelan county as well as Highway 12 across Garfield and Asotin counties. With these windy conditions forecast for Sunday, blowing dust will once again be a concern, especially across the Columbia Basin near any recently worked fields. The dust could be carried toward the Spokane area, given the speeds and direction. /Nisbet Monday through Friday: The Inland Northwest will remain in a progressive pattern through next week with a couple systems to pass through the area. Models are generally in good agreement through Thursday, but then begin to diverge in the specifics Friday into next weekend. Following the cold front passage on Sunday, dry, northwest flow will encompass the region with precipitable water values near 0.25 inches and below will result in a very chilly Monday morning. There is a high probability (70 to 90 percent chance) for temperatures below freezing Monday morning for locations within the northeast Washington and north Idaho Valleys such as Colville, Chewelah, Deer Park, Newport, Priest River. While we are nearing the end of the growing season for these areas, if you are still tending to a garden, this weekend will be a good time to finish up. Higher elevations across the Palouse such as Rosalia, Oakesdale, Tekoa have a 30 to 40 percent chance of temperatures below freezing. Elsewhere, lows in the mid 30s will pose a risk for frost. The flow aloft becomes more zonal by Tuesday as a low pressure system nears the northern British Columbia coast. Cold morning temperatures will continue into Tuesday morning across the northern valleys with the same probabilities for below freezing temperatures as Monday morning. The cold front associated with the low in British Columbia late Tuesday into Wednesday. Models have trended drier with this front with best chances for precipitation remaining west of the Cascades. Winds will be breezy Tuesday afternoon from the south- southwest ahead of the front and breezier on Wednesday behind the front from the west. The breeziest winds on Wednesday will be felt across the Waterville Plateau, the upper Columbia Basin, and the lee of the Blue Mountains where there is a 70 percent chance of sustained winds greater than 20 mph. These winds will be capable of producing patchy blowing dust around recently worked fields. Details in the forecast beyond Wednesday become unclear with distinct differences in the evolution of the upper level pattern. Examining the Weather Prediction Center’s Cluster Analysis tool for Friday and Saturday reveals about 30 percent of ensembles bringing through a fast moving upper level trough, 25 percent depicting a slower moving trough approaching the region, and the other 45 percent keeping some variation of ridging over the Pacific Northwest. The first two scenarios would bring better chances of precipitation across the region while the ridging scenario would keep the region mostly dry. /vmt && .AVIATION... 18Z TAFS: Mainly light winds with passing cirrus through 00Z. After 00Z Sunday, some midlevel clouds near 15kft AGL will be possible over Central WA. Winds begin to increase after 06Z, especially for KEAT. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in VFR conditions. && .PRELIMINARY POINT TEMPS/POPS... Spokane 84 51 68 36 64 37 / 0 0 0 0 0 0 Coeur d'Alene 81 51 66 34 63 34 / 0 10 10 0 0 0 Pullman 83 48 63 34 61 35 / 0 0 0 0 0 0 Lewiston 88 56 74 41 67 41 / 0 0 0 0 0 0 Colville 78 40 68 27 64 29 / 0 10 10 0 0 0 Sandpoint 78 47 65 32 61 33 / 0 10 10 10 0 0 Kellogg 83 51 62 37 59 35 / 0 0 10 0 0 0 Moses Lake 80 47 68 36 66 35 / 0 0 0 0 0 0 Wenatchee 77 51 64 41 65 45 / 0 0 0 0 0 0 Omak 79 46 70 36 68 39 / 0 10 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Fire Weather Watch from Sunday morning through Sunday evening for Northern and Central Idaho Panhandle (Zone 101). WA...Fire Weather Watch from Sunday morning through Sunday evening for Colville Reservation (Zone 702)-Foothills of Northeast Washington (Zone 701). Fire Weather Watch from Sunday morning through Sunday evening for Eastern Columbia Basin -Palouse -Spokane Area (Zone 708)-Foothills of Central Washington Cascades (Zone 705)- Lower Palouse -Snake River (Zone 709)-Okanogan Valley (Zone 703)-Waterville Plateau (Zone 706)-Western Columbia Basin (Zone 707). && $$