Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
046 FXUS65 KBOI 220250 AFDBOI Area Forecast Discussion National Weather Service Boise ID 850 PM MDT Sat Sep 21 2024 .DISCUSSION...A few clouds will continue to move across the area this evening associated with a weak frontal passage. The clouds will have no impact on temperatures tonight, which are expected to drop to the mid-40s in the Western Snake River Plain and the mid-30s in the mountains. Late Sunday, high clouds will increase in the northern zones, with southern zones seeing more cloud cover by Sunday night as another weak dry cold front moves in. The clouds and post-frontal northwest winds will prevent the typical nighttime inversion, resulting in slightly warmer low temperatures Monday morning. Monday night, lighter winds and fewer clouds will allow for the inversion, but low temperatures will only be marginally cooler due to a warming Pacific upper ridge moving inland. High temperatures for both Sunday and Monday are expected to remain close to normal, similar to today. Additionally, the autumnal equinox will occur at 6:44 AM MDT on Sunday. No updates are needed at this time. && .AVIATION...VFR. A few clouds this evening becoming clear after midnight. Increasing high clouds north in the afternoon. Surface winds: Variable less than 10kt. Winds at 10kft: Variable around 10 kt. KBOI...VFR. Light and variable wind. && .PREV DISCUSSION... SHORT TERM...Tonight through Monday night...Little change through Sunday under dry northwest flow aloft. A band of high clouds passing through tonight will have little effect on low temperatures. High clouds will increase again in northern areas late Sunday and southern zones Sunday night as a weak, dry cold front passes through. The clouds and post-frontal northwest winds will inhibit the usual nighttime inversion and low temps Monday morning will be several degrees warmer. Lighter winds and fewer clouds Monday night will allow the inversion but low temps will be only slightly cooler as a warming Pacific upper ridge will also be coming inland. High temps Sunday and Monday will be close to normal, much like today. The autumnal equinox occurs at 644 AM MDT Sunday. LONG TERM...An upper level ridge will be centered over the area Tuesday, and will bring dry and warmer weather. As it rapidly moves to the southeast Tue night and Wed, we will become even warmer as southwest to southeast winds increase. A weak shortwave trough is forecast to move by to our north Wed into early Wed night, with excellent ensemble agreement on the timing and strength. Dry west to southwest flow aloft should then remain over the PacNW through Saturday, and precipitation chances are low (a small part of northeast Valley County gets up to 15% Fri-Sat, but otherwise the chance of precipitation is too small to mention in the forecast). Temperatures will cool after a very warm Wed (around 10 degrees above normal), with readings falling back down to near normal by Saturday. && .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...JDS AVIATION.....JDS SHORT TERM...LC LONG TERM....SP