Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
408 FXUS65 KBOI 080240 AFDBOI Area Forecast Discussion National Weather Service Boise ID 840 PM MDT Fri Jun 7 2024 .DISCUSSION...At 8 PM MDT thunderstorms were decreasing in southeastern Owyhee County but a new cluster was moving across southern Malheur County into western Owyhee County. Hi-res models were not tracking the new storms well but the eastward movement should keep them well south of the Snake Basin if they hold together. Otherwise, current forecast is in good shape with Saturday 1-3 degrees hotter than today, then 3-8 degrees cooler Sunday as a north Pacific trough comes inland, with the greater cooling in Oregon. A 10-15 percent chance of thunderstorms is indicated again along the ID/NV border late Saturday, but also in western Harney County. The trough will increase the chance of afternoon/evening showers and thunderstorms Sunday to 20-40 percent area-wide. Yesterday we noted that models were forecasting a drastic cooldown next weekend. Today`s models have backed away. Latest ECMWF still has a cooling trough from the Gulf of Alaska but not as deep or as far south as yesterday. The GFS has backed way off, now leaving the upper low out in the Pacific near 140W whereas yesterday it put the trough inland over our area. So it does look cooler late next week, but not nearly as cool as models showed yesterday. && .AVIATION...Isolated showers and thunderstorms in southeast Oregon near KBNO/KREO will end by Sat/06Z. Isolated to scattered showers and thunderstorms will develop Saturday afternoon and night across southeast Oregon and near the Idaho/Nevada border. Gusty and erratic outflow winds to 40 kt possible from storms as well as IFR/MVFR conditions due to heavy rain. VFR conditions outside of thunderstorms. Surface winds: variable 5-15 kt, except gusty near storms. Winds at 10k ft MSL: W-SW 10-20 kt. KBOI...VFR. Surface winds variable 6 kt or less overnight, becoming NW 6-12 kt Saturday afternoon. Sunday Outlook...Isolated to scattered showers and thunderstorms, with the most coverage across the higher terrain. Stronger showers and thunderstorms will produce brief IFR/MVFR conditions with heavy rain and gusty winds. Outside of thunderstorms, VFR conditions expected. Surface winds generally W-NW 5-15 kt. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday night...A weak wave in Nevada will bring unsettled conditions to far SE Oregon and the ID-NV border. Thunderstorms will develop around noon today and last until around sunset. Storms may produce heavy rain and gusty outflow winds, with the highest confidence for outflow winds along the ID-NV border and southern Twin Falls county. Outflow gusts will generally range from 40-50 mph, but there is a 5% chance for a gust up to 60 mph. After sunset, isolated showers will continue to impact SE Oregon, especially Harney county. High temps today of 10 degrees above normal warm to 15 degrees above normal on Saturday. Saturday night through Sunday night will be the most active precipitation day coming up as an upper trough moves through. Precipitation chances throughout the day range from 15-35%, with pockets of 40-50% chances in the Boise Mtns, West Central Mtns, and southern Twin falls. Thunderstorms will be possible throughout the area Sunday afternoon/evening. The strongest storms are expected south of Twin Falls, where the SPC has a Marginal Risk for severe weather. Temps will drop with the upper low on Sunday back to 10 degrees above normal and hold steady there for the long term. LONG TERM...Monday through Friday...The long term is mostly warm and dry as a low amplitude ridge develops. The flow is mostly westerly, with brief periods of west-southwesterly flow. This will keep temps around 10 degrees above normal each day. A southwesterly flow dominates Thursday through Friday as a deep upper low moves down from the Gulf of Alaska. As it moves into the area, a closed low south of California may interact with the Alaskan low to bring some moisture and favorable dynamics. However, the current forecast shows a much drier interaction, with chances of precip below 10%. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...LC AVIATION.....ST SHORT TERM...JM LONG TERM....JM