FXUS66 KOTX 282303 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 403 PM PDT Sat Sep 28 2024 .SYNOPSIS... Drier and warm 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... Today has been mild and dry ahead of a dry cold front passage expected overnight. On satellite, mid/high clouds from the baroclinic leaf are starting to spread into central Washington this afternoon and evening. High temperatures have topped out in the 70s and 80s today. The dry cold front will cross the Cascade crest late this evening and cross through much of central and eastern Washington before sunrise. In the wake of the cold front, an extremely dry airmass will be in place with PWATs as low as 0.15". This would be around 25% of the normal amount of moisture in the atmosphere. Surface dewpoint temperatures in the 30s to low 50s right now will quickly drop 20+ degrees behind the front passage leading to critical fire weather conditions. The PWAT values from the August 18th, 2023 fire event were 0.17" on the 00z sounding from the 19th. The surface dewpoint from that event was about the same (low 20s) during the peak of the event. The one piece that makes this event MUCH different from August 18th, 2023 is the surface temperatures. The 2023 event had surface temperatures in the 80s and 90s while this event tomorrow will feature 60s and 70s. There are some similarities in the upper air patterns but the overall thinking is the wind component will be about the same/slightly more windy than Aug 18th, 2023 but RHs will be 10-15% higher. This translates to wind speeds of 15 to 25 mph with gusts around 25 to 45 mph and relative humidity in the teens to low 20s. New and existing fires have potential to rapidly spread tomorrow. Blowing dust will be of concern tomorrow in the typical problem areas (Columbia Basin, Waterville Plateau, Palouse, Spokane area). After dark tomorrow, wind speeds will rapidly diminish and clear skies will promote strong radiational cooling. With the atmosphere being incredibly dry, the risk for frost/freeze will increase, particularly for northeast Washington and the north Idaho Panhandle. Have went ahead and issued freeze watches for those areas anticipating temperatures as low as 26 degrees in those cold sheltered valleys. /Butler Monday through Saturday: A weak wave passing by to our north for Tuesday into early Wednesday will result in winds becoming breezy, but likely not much else in terms of appreciable weather other than some chances for showers near the Cascades. Near-seasonable temps are anticipated to persist through the extended portion of the 7-day forecast, with daily highs generally within 5 degrees of average. Additional frost/freezing conditions are possible in our northern sheltered valleys as is fairly typical this time of year, but Monday morning currently looks the coldest. Most model ensembles bring another disturbance around Friday/Saturday. We have breezy winds and some chances for precip in the forecast during this period, but confidence remains low at this time. /KD && .AVIATION... 00Z TAFS: Winds and mid-to-upper level clouds will increase through the night, especially after 06Z. Wind gusts, locally around 30 to 40 mph, may lead to visibility reductions in blowing dust. Slight chances for showers in extreme northeast WA and north ID after 18Z Sunday. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate confidence in visibility reductions in blowing dust Sunday. && .PRELIMINARY POINT TEMPS/POPS... Spokane 52 67 36 63 38 70 / 0 0 0 0 0 0 Coeur d'Alene 51 66 35 62 38 69 / 10 10 0 0 0 0 Pullman 49 62 34 59 36 67 / 0 0 0 0 0 0 Lewiston 56 72 42 67 43 75 / 0 0 0 0 0 0 Colville 41 68 28 64 29 67 / 10 10 0 0 0 0 Sandpoint 49 64 33 60 35 65 / 10 10 10 0 0 0 Kellogg 52 61 38 58 41 66 / 0 10 0 0 0 0 Moses Lake 47 68 36 65 38 72 / 0 0 0 0 0 0 Wenatchee 51 63 41 64 46 74 / 0 0 0 0 0 0 Omak 47 69 37 67 41 74 / 0 0 0 0 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Red Flag Warning from 11 AM to 7 PM PDT Sunday for Northern and Central Idaho Panhandle (Zone 101). Freeze Watch from late Sunday night through Monday morning for Central Panhandle Mountains-Northern Panhandle. WA...Red Flag Warning from 11 AM to 7 PM PDT Sunday for Colville Reservation (Zone 702)-Eastern Columbia Basin -Palouse - Spokane Area (Zone 708)-Foothills of Northeast Washington (Zone 701)-Lower Palouse -Snake River (Zone 709)-Okanogan Valley (Zone 703)-Waterville Plateau (Zone 706)-Western Columbia Basin (Zone 707). Freeze Watch from late Sunday night through Monday morning for Northeast Mountains-Okanogan Highlands. && $$