Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
151 FXUS65 KBOI 281619 AFDBOI Area Forecast Discussion National Weather Service Boise ID 1019 AM MDT Tue May 28 2024 .DISCUSSION...A cold front will approach the region today, with warm southwest flow ahead of the front. Temperatures will be around 15 degrees above normal today. Morning sounding at BOI was pretty impressive, with 73F at 3500ft, indicative of a warm airmass, with a nice inverted V sounding. DCAPE values of 1200-1500 J/kg this afternoon will promote environment capable of producing gusty winds up to 60 mph with any showers or storms (downdrafts) that form, along with areas of blowing dust. CAMs models showing updraft helicities over NE Oregon this afternoon, favorable for hail up to 1 inch. Less of a threat for hail over the Idaho zones today. Cold front moves through this evening bringing northwest winds behind the front. Showers linger over the central ID mountains into Wednesday morning. Temperatures cool around 15-20 degrees on Wednesday with dry conditions. Breezy northwest winds continue Wednesday, especially during the afternoon. && .AVIATION...Scattered showers and thunderstorms this afternoon/evening will be capable of producing heavy rain, small hail, and gusty outflow winds up to 50 kt. Conditions mainly VFR with reductions to MVFR/IFR in heavier rain showers. A cold front passage tonight into Wednesday morning will support lingering showers over the W Central Mtns. The front will keep winds gusty overnight through Wednesday. Surface winds: SW-SE 5-15 kt becoming mainly SW-W after 20Z, except variable gusty/erratic winds near thunderstorms. Overnight W-NW 10-15 kt with gusts to 30 kt. 10k ft MSL winds: SW 15-25 kt. KBOI...20% chance of thunderstorms in the vicinity between Tue/22z and Wed/00z, increasing to 50% until Wed/04z. Development of storms will be mostly sporadic, but may become more organized if a strong outflow develops. While 50 kt outflow gusts are a possibility (5% chance), they are most likely to be between 30-40 kt. Winds SE around 12 kt becoming NW 12 kt after 20z, except variable gusty winds near thunderstorms. Overnight winds stay NW at 12-15 kt with gusts to 20-25 kt. && .PREV DISCUSSION... SHORT TERM...Today through Thursday night...Active weather is anticipated today as an upper level trough over the eastern Pacific moves inland today. Southwest flow aloft will strengthen as this feature approaches southeast Oregon and southwest Idaho, bringing even warmer temperatures and increasing moisture. Highs will reach the upper 80s in the lower valleys, with a 20-40% chance to hit 90 degrees. Instability will develop this afternoon ahead of the trough, and shower and scattered thunderstorm development will favor the higher terrain. However, the approaching trough will provide lift for storm formation and will aid storm organization and movement into lower valleys including the Treasure and Magic valleys. Storms may become strong to severe with wind gusts to 60 mph the primary hazard, but hail and heavy rain will also be possible. Showers and thunderstorms will decrease overnight as the trough and a cold front push through, with most activity limited to the central Idaho mountains after midnight MDT. The cold front will move across the area this evening, reaching the Magic Valley near or shortly after midnight MDT. Gusts to 45 mph are possible along the front, but could be stronger if thunderstorm outflows enhance the front. This may result in blowing dust reducing visibility. Much cooler and drier air will arrive behind the cold front on Wednesday. Dry conditions will return with temperatures nearly 20 degrees cooler than today. Winds will be breezy as the trough passes through, bringing gusts 20-30 mph, except up to 40 mph in the Magic Valley. Thursday will be very similar to Wednesday as dry northwest flow aloft sets up behind the trough, keeping temperatures around 5 degrees below normal. Additionally, winds will be lighter, but still breezy across the Magic Valley. LONG TERM...Friday through Tuesday...Models are in generally good agreement with regard to the large-scale pattern through early next week, but there are some differences with respect to short-wave troughs embedded in a westerly flow aloft. A weak upper trough could move through over the weekend, but precip chances remain slim (less than 20 percent) and confined to the far north. A more impressive trough could arrive early next week, but there are significant differences in its strength. There is a low (15-30 percent chance) of rain showers across the northern areas starting Sunday night and continuing into Tuesday. Near normal temperatures are favored on Friday, warming to slightly above normal temperatures for the remainder of the period. There is at least a 60 percent chance that high temperatures exceed 80F in portions of the Snake Plain from Saturday until Tuesday, including Boise. && .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...KA AVIATION.....JM SHORT TERM...ST LONG TERM....BW