Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
689 FXUS65 KBOI 190254 AFDBOI Area Forecast Discussion National Weather Service Boise ID 854 PM MDT Sat May 18 2024 .DISCUSSION...Another dry cold front will move across the area late this evening, bringing brief gusts 30-40 mph with winds remaining breezy overnight. Cooler air behind the front will result in highs on Sunday 10-15 degrees cooler than today. The winds will remain breezy into Sunday, strongest in the Magic Valley where gusts to 40 mph may occur. Any significant chance (20-50%) of showers will be limited to the northern mountains of central Idaho and northeast Oregon, closer to the core of the upper level trough. Weak instability will develop Sunday afternoon in these areas, so a few strikes of lightning will also be possible in stronger showers. Forecast remains on track and no updates planned this evening. && .AVIATION...VFR with some high clouds over the region. There is a 20 to 50 percent chance of showers in far northern Baker County and the West Central Idaho mountains on Sunday. Snow levels 5000-6000 ft MSL. Surface winds: NW 5-15 kt increasing to 10-20 kt with gusts 25- 40 kt tonight with a cold front. Winds aloft at 10k ft MSL: W 20-35 kt. KBOI...VFR with high clouds tonight, becoming clear on Sunday. Winds NW 5-10 kt increasing to 10-15 kt with gusts 20-30 kt around Sun/05Z due to cold front. Winds diminishing early Sunday morning, but gusts to 20 kt return Sunday afternoon. && .PREV DISCUSSION... SHORT TERM...Tonight through Monday night... The successive upper level lows to our north will continue to bring near normal temperatures and breezy westerly winds to most of the forecast area. A low chance of showers (30% chance or less) exists for the West Central and Baker County, OR mountains late this evening into Sunday morning from the passing front. Snow levels will be right around 5000 feet overnight, jumping to 6000 feet during the day, so some late showers this evening could bring some snow flurries to mountain valleys north of a Cascade, ID-Baker City, OR line. Cooler temperatures are anticipated for the region late Sunday into Monday as a trough digs into the region, bringing a cooler air mass over the Intermountain West. This air mass will most likely be dry, but some models are showing weak showers over the Central ID mountains on Monday morning. This low will then slowly move east on Monday evening, but wraparound showers are likely (40-50% chance) over higher terrain that evening. Current hi-res model blends show weak thunderstorms forming near the OR-NV order and over the Snake River Valley in ID, although confidence is low with exact locations of convective development. LONG TERM...Tuesday through Saturday...An upper level trough will move to the east on Tuesday, bringing dry and cool northerly flow to the region as a weak ridge builds in by Tuesday afternoon. This will bring a slight warming trend ahead of a deep cut off low on Wednesday. There is substantial model agreement in cooler temperatures and widespread precipitation at some point on Wednesday-Thursday, but there`s still significant variability in precipitation timing. Current forecasts show around a tenth of an inch of QPF in the valleys, with up to three quarters of an inch in the mountains by Thursday evening. Snow accumulation is mostly isolated to above 6000 feet, with around 1-3 inches expected by Thursday evening to those elevations. A similar pattern to earlier in the week will return on Friday, with dry upper level northwest flow ahead of another potential system incoming on Saturday. Models currently disagree much more on timing and positioning of that upper level low. && .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...ST AVIATION.....BW SHORT TERM...SA LONG TERM....SA