Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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002 FXUS66 KOTX 271032 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 332 AM PDT Mon May 27 2024 .SYNOPSIS... Dry and mild conditions on Monday with temperatures warming back into the 70s. Tuesday will see a return of showers and thunderstorms to Eastern Washington and Idaho Panhandle. A few storms could be strong with gusty outflow winds. Cool and showery conditions continue through the end of the week with drier and warmer conditions at the start of the upcoming weekend. && .DISCUSSION... Memorial Day: The short lived ridge will begin to breakdown as the next system begins to press into the coast. The Inland Northwest won`t experience too many impacts through the day. Starting in the afternoon, increasing mid to high level clouds will filter through the region. Winds will increase slightly in the afternoon with gusts into the low 20s MPH for the Basin and Okanogan Valley. Areas of the Blues Mountain and Northern Washington could have an isolated shower late evening to overnight. Highs for the day will be in the 70s and low 80s. Overnight lows will be in the 50s. ...STRONG THUNDERSTORMS POSSIBLE TUESDAY AFTERNOON AND EVENING... Tuesday: The morning will start with prefrontal shower activity over portions of Eastern Washington and Idaho Panhandle. It will bring a few hundredths of precip to the area. This and the cloudy sky conditions could inhibit some potential impacts for the cold front passage over the afternoon and early evening by limiting how high the max temperatures reach. The timing of thunderstorms will be around 1 PM to 8 PM. BAsin areas are expected to have gusty winds into the 30s with the frontal passage. Highs for the day are expected to be in the 70s to low 80s. Overnight lows will be in the upper 30s to 40s. Ensembles continue to show an unstable atmosphere with the frontal passage especially over the eastern third of Washington and the Idaho Panhandle. Probability of at least 300 J/kg of cape is at least 40%. The lower Idaho Panhandle has some areas reaching near 1000 J/kg. These areas have 0-6km shear (near 50 MPH), Lifted Index (-1 to -3), and lapse rates (-7 C/kg). These are favorable for thunderstorm development. Currently the Storm Prediction Center has these areas under a general to marginal thunderstorm outlook. For impacts, these areas can expect lightning, small hail, brief downpours, and gusty winds. The areas with the best potential for the strongest thunderstorms are Southeast Washington and the Idaho Panhandle south of I-90. These areas have the higher probability of strong thunderstorms. The main concern is the strong mid level winds (50+ MPH) reaching the surface from the thunderstorms. Precipitable water values have slightly increased from previous trends to near one inch. It has led to an increase in the large hail of 1" potential though still low. The period will continue to be monitored and fine tuned as it nears. /JDC Wednesday through Sunday: As an upper-level trough sweeps through the region from west to east, temperatures will cool into the 60s and low 70s for Wednesday and Thursday. Chances for showers and isolated thunderstorms will remain in the forecast Wednesday along the periphery of the Inland Northwest (over the Cascade Crest, along the Canadian border, and throughout the ID Panhandle down to Lewiston), though a lack of shear and decreased moisture in the atmosphere will keep any storms that develop weaker than those we`re expecting on Tuesday. Lightning, brief downpours, small hail, and wind gusts of 30 to 40 mph will be possible. Cold air aloft will allow for snowfall down to 4000 feet Wednesday morning, so anyone planning on hiking or recreating in the mountains should dress accordingly. The upper-level trough will continue moving eastward through the day on Thursday, making room for a ridge of high pressure to slide onshore and take its place. Northeastern WA and the ID Panhandle will see one last afternoon of showers and weak thunderstorms before the ridge brings dry conditions regionwide. By Friday evening the ridge will be centered over us keeping us dry and warm heading into the first weekend of June. Just how strong the ridge will be and how long it will stick around remains uncertain at this point. /Fewkes && .AVIATION... 06Z TAFS: High pressure will build in overnight into Monday with passing mid and high clouds. VFR conditions will occur through 06z Tuesday. Weather changes arrive late Monday night into Tuesday for an increasing chance of showers and thunderstorms over eastern Washington and north Idaho along with breezy winds. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: There is high confidence for VFR conditions to continue across the TAF sites. JW ----------------------- 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 73 51 76 45 63 39 / 0 10 20 20 20 20 Coeur d`Alene 72 51 74 46 61 39 / 0 10 30 40 30 30 Pullman 72 52 72 44 59 38 / 0 10 10 50 10 20 Lewiston 81 57 80 52 68 46 / 0 10 20 60 10 20 Colville 73 45 73 39 62 33 / 0 10 60 40 60 30 Sandpoint 70 49 72 45 57 38 / 0 10 50 70 60 50 Kellogg 70 54 75 48 56 41 / 0 10 30 70 40 40 Moses Lake 78 53 78 44 68 40 / 0 10 0 0 0 0 Wenatchee 76 56 74 46 64 44 / 0 0 10 0 10 0 Omak 76 51 76 42 68 39 / 0 10 20 10 20 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$