Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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692 FXUS66 KOTX 212307 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 407 PM PDT Sat Sep 21 2024 .SYNOPSIS... Temperatures will be chilly Sunday morning, promoting frost formation for many areas and freezing temperatures in the mountain valleys of northeast Washington. There is a small chance of light mountain showers in the north Sunday afternoon and evening. A ridge of high pressure will deliver above normal temperatures early next week. A more active pattern is expected for the latter half of next week, with the potential for breezy conditions, showers, and temperatures returning to near normal. && .DISCUSSION... Tonight through Monday night: Another chilly night is expected. Temperatures will overall be a little warmer, but much of the deeper and sheltered mountain valleys in northeast Washington and the Idaho Panhandle will see the potential for near freezing temperatures and frost. Best potential for sub-freezing temperatures will be in the valleys of the Northeast Mountains that include Colville, Chewelah, Metalline Falls, Deer Park, Ione, Cusick, and Newport where a freeze warning remains in effect. These colder, sub-freezing temperatures will also extend into the northern Panhandle around Priest Lake and along the west of Lake Pend Oreille that includes the communities of Athol, Spirit Lake, Blanchard, and Priest River. Most communities along US-95 in the Northern Panhandle from Porthill to Sandpoint are expected to remain above freezing, but will see the potential for frost. Frost is also expect tonight in the valleys of the Central Panhandle Mountains extending into the Palouse region, including the communities of Pinehurst, Kellogg, St. Maries, Plummer, Moscow, Pullman, Rockford, Oakesdale, Garfield, and Colfax. A weak disturbance moving in on Sunday will result in increasing cloud cover. This will be followed up be a warm front Sunday night. The warm front will bring a healthy sub-tropical moisture plume into the Northwest; however, lack of forcing and dynamical support along with a very dry near surface layer, will result in little to no precipitation. There`s only a 10-30 percent chance for measurable rainfall through Monday at the Cascade crest and over the mountains right near the Canadian border. Winds aloft won`t be particularly strong with the upper level jet well north into northern BC resulting in continued weak winds. The exception will be in the lee of the Cascades where typical westerly drainage winds into the Wenatchee- Chelan areas and Waterville Plateau is expected Sunday evening. Winds will generally be sustained 8-15 with gusts up to around 25 mph though and not of a particular concern. Temperatures will begin to see a warming trend on Monday with the western half of the forecast area seeing more of a bump with highs expected to be in the upper 70s to low 80s. Clouds will be clearing in the wake of the warm front passage with sunny to mostly sunny skies. Further west, the temperatures are expected to be in the low to mid 70s in the Idaho Panhandle. /SVH Tuesday through Saturday: Tuesday and Wednesday will be the last days of warm, dry conditions as the ridge begins to breakdown. Increasing clouds are expected through the day as a trough begins to press into the Pacific Northwest. While the trough will increase the moisture, much of the lowlands will not benefit from any precip. The precip will mainly rain showers over the mountains starting Wednesday afternoon. Some of the very high peaks of the Cascades could receive light snow. There is also a weak chance of an isolated thunderstorm along the Canadian Border and Cascade Crest. Another concern is the winds and RHs across the Basin as the ridge breaks down. Ensembles are showing an increase probability of low RH/breezy winds Wednesday afternoon. It is increasing concern for fire starts and spread. Highs for these days will be in the upper 70s and 80s. Overnight lows will be in the upper 40s and 50s. Thursday through Saturday: The region will be under a zonal flow pattern for for the rest of the period. While models indicate shortwaves passing through the region, the rain shadow effect will continue to keep the Basin mainly dry with continue showers over the higher terrains. Highs will dip into the 50s and low 60s for highs. Overnight lows will be in the upper 30s and 40s for most. A few cold pockets in the northern valleys could hit freezing overnight. /JDC && .AVIATION... 00Z TAFS: VFR conditions will prevail. Bands of mid and high clouds will move over the region into early Sunday with light winds. Mid to high level clouds will thicken up in the afternoon on Sunday. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions. /SVH. && .PRELIMINARY POINT TEMPS/POPS... Spokane 42 75 46 76 50 83 / 0 0 0 0 0 0 Coeur d`Alene 36 73 47 74 50 81 / 0 0 0 0 0 0 Pullman 39 71 45 71 48 80 / 0 0 0 0 0 0 Lewiston 47 78 55 79 55 87 / 0 0 0 0 0 0 Colville 30 72 38 77 41 82 / 0 10 0 0 0 0 Sandpoint 36 71 43 71 47 77 / 0 10 10 0 0 0 Kellogg 39 68 49 70 52 79 / 0 0 10 0 0 0 Moses Lake 44 78 48 79 50 84 / 0 0 0 0 0 0 Wenatchee 53 78 56 80 58 82 / 0 10 0 0 0 0 Omak 47 77 51 83 55 85 / 0 10 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Frost Advisory until 8 AM PDT Sunday for Central Panhandle Mountains-Idaho Palouse-Northern Panhandle. WA...Frost Advisory until 8 AM PDT Sunday for Washington Palouse. Freeze Warning until 8 AM PDT Sunday for Northeast Mountains. && $$