Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
491 FXUS65 KBOI 230255 AFDBOI Area Forecast Discussion National Weather Service Boise ID 855 PM MDT Wed May 22 2024 .DISCUSSION...An upper level trough will move across central ID tonight and into SE Idaho by Thursday morning. This will keep breezy west to northwest winds through the night, keeping temperatures from realizing their lowest potential tonight. Tonight will be unseasonably cool with temperatures in the 20s in the mountains and 30s in the valleys, or around 10-15 degrees below normal. As the trough moves into SE Idaho, showers will mainly be focused on the Blue Mountains in OR, the central ID mountains, and the southern Twin Falls County highlands. Wrap around moisture will continue over the central ID mountains through midday Tuesday before tapering off as warmer air aloft moves into the area. Current forecast on track with no updates planned. && .AVIATION...Isolated showers persisting over SE OR and W Central Mtns through Thu/10z. Periods of MVFR/IFR in precip. Mountains obscured. Snow levels 4000-5000 ft MSL. Surface winds: Evening winds decreasing to W-NW 5-15 kt by Thu/05z. Strongest winds near KTWF/KJER. Winds aloft at 10k ft MSL: NW-N 15-25 kt. KBOI...VFR and mostly cloudy. Winds: W-NW 5-10 kt overnight, increasing to NW 10-20 kt around noon on Thursday. && .PREV DISCUSSION... SHORT TERM...Tonight through Friday night... A low pressure system will exit the area on Friday, with continuing low-end chances (20-40%) of light precipitation overnight. Snow levels will fall to around 5000 feet, with some mountain areas receiving up to a couple inches of snow, with locally higher totals at mountain peaks. Overall, coverage will decrease significantly into the late morning, with much drier air infiltrating into the region amidst a chilly air mass. Temperatures warm up at least a couple degrees on Thursday, but still remain about 10 degrees below normal for the date. Winds remain gusty through the Magic Valley on Thursday afternoon. Temperatures continue to warm up on Friday and will become closer to seasonal normals. LONG TERM...Saturday through Wednesday... The next in a series of shortwave troughs moves through the region Saturday. Model depictions of this feature still vary considerably given the short lead-time, varying between a closed low and a broad open wave. Regardless, precipitation chances will increase Saturday morning and afternoon across most of the area, but the potential for a significant rain event is low given the progressive nature of this system. Currently, the 90th percentile QPF amounts (or a 10% chance) range between 0.1" over eastern Oregon to 0.4" over the Boise and West-Central Mountains. The remainder of the period from Sunday into next week looks to generally be dry. A significant warming trend will be the primary weather impact as temperatures approach the first 90 degree reading of the year on Tuesday amidst an amplifying western CONUS ridge. There is also a weak signal for precipitation Tuesday as an offshore trough develops and imports moisture northward, but probabilities for precipitation are currently only 5-15%. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...Wind Advisory until 8 PM PDT this evening ORZ061. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...KA AVIATION.....JM SHORT TERM...JR LONG TERM....JR