Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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283 FXUS66 KOTX 190442 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 942 PM PDT Tue Jun 18 2024 .SYNOPSIS... Scattered showers and thunderstorms will continue through the early evening. Shower activity will return Wednesday afternoon across the northern mountains. A warming trend is expected through the week, with high temperatures rebounding into the mid 80s to mid 90s on Saturday. A dry cold front on Sunday will elevated fire weather concerns with widespread breezy wind across the region. && .DISCUSSION... Tuesday night: Radar imagery this afternoon shows weak thunderstorms across much of northeast Washington, the far northern Idaho Panhandle and across the north Cascades. SPC mesoanalysis depicts 250-500 J/kg of MUCAPE across these areas. With virtually no wind shear, these storms are very short-lived with isolated lightning strikes and a handful of small hail reports. These storms will move to the east-southeast with some high resolution models showing activity to move into the Spokane metro area over the next couple hours. Showers will begin to diminish after sunset. Wednesday and Thursday: The Inland Northwest will remain under a broad Rex Block Pattern Wednesday and Thursday as a weak trough sits over the western US and a ridge builds over western Canada. 850mb temperatures will warm as the trough weakens and the flow aloft shifts back to the west-southwest. Diurnal showers will return on Wednesday but coverage will be limited mostly to the far northern mountains as the drier and warmer air moves in from the south. Temperatures will warm into the mid 70s to low 80s on Wednesday and into the upper 70s to upper 80s by Thursday. Models are showing a thermally induced surface trough to nose north across the Washington Cascades on Thursday, which will bring breezy north to northeast winds across central Washington and the Columbia Basin in the afternoon. /vmt Friday through Tuesday: Split flow pattern with upper level ridging to the north and trof to the south amplifies some and gets displaced to the east as a low pressure system drags a trof with not much in the way of moisture through Eastern Washington and North Idaho Sunday. The result is a continuation of the warming trend peaking on Saturday followed up with cooler and breezy conditions Sunday which may bring fire weather concerns. In addition the forecast is generally dry but not totally dry as minor pops remain in place for spotty short lived light showers in the afternoon/early evening. Monday is marked with general upper level trof thus marked with the coldest temps of the seven day forecast. The upper level trof may rebound somewhat into flat zonal flow Tuesday thus allowing for some warming. In addition this early portion of the next workweek has minor mention of shower and/or thunderstorm activity given the somewhat conditionally unstable atmosphere the presence of the upper level trof provides. /Pelatti && .AVIATION... 06Z TAFS: Weak impulses tracking NW to SE through the forecast areas are keeping showers ongoing this evening despite the loss of afternoon heating. Showers in the vcnty of Spokane- Cd`A-Sandpoint-Colville will be capable of brief IFR to MVFR cigs and breezy outflow winds near 25 mph. As the showers taper off, recent rainfall will bring a low threat for patchy fog or stratus through 17z. This comes with low confidence given the time of year but based on recent temperature-dewpoint trends, it will not take much for development. Greatest risk for fog will be in the sheltered northern valleys of NE WA and N ID around Colville, Ione, Deer Park, and Priest Lake. KSFF did receive heavy rainfall today increasing the risk there as well. Easterly winds could transport the moist boundary layer into Spokane International. Cumulus buildups will occur again on Wednesday afternoon with the highest chances for showers and weak thunderstorms across the northern mountains from Sandpoint to Colville to Omak and Winthrop. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence how the rich boundary layer moisture will play out overnight and coverage of fog. It is conceivable that some sites become IFR/LIFR if fog forms on the terminals. Fog will have a hard time persisting after 16-17z given the June sun angle. /sb ----------------------- 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 43 75 48 82 52 85 / 20 0 0 0 0 10 Coeur d`Alene 42 72 47 80 51 82 / 30 0 0 0 0 10 Pullman 42 74 46 80 50 82 / 0 0 0 0 0 10 Lewiston 48 84 54 90 58 90 / 0 0 0 0 0 10 Colville 37 72 41 79 44 84 / 40 20 0 0 0 10 Sandpoint 41 69 44 78 48 80 / 40 20 0 0 10 20 Kellogg 44 71 49 79 54 79 / 40 10 0 0 10 20 Moses Lake 46 82 53 87 54 90 / 0 0 0 0 0 0 Wenatchee 52 80 56 85 59 90 / 20 0 0 0 0 0 Omak 46 78 51 84 53 90 / 30 20 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$