Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
788 FXUS65 KBOI 091549 AFDBOI Area Forecast Discussion National Weather Service Boise ID 949 AM MDT Sun Jun 9 2024 .DISCUSSION...Forecast remains on track for scattered thunderstorms to develop early this afternoon. The morning 12 Z sounding from KBOI showed 0.86 inches of precipitable water and surface observations show dewpoint values in the mid to upper 50s across much of southwestern Idaho and southeastern Oregon. In addition to the moisture, forecast afternoon soundings depict the atmosphere becoming very unstable this afternoon with surface based CAPE expected to reach 800 to 1000 J/kg by 00z. This all supports a marginal risk of a few thunderstorms producing severe wind gusts and hail. Some of these thunderstorms will also produce brief heavy rain, but will be moving northeast at about 30 mph, which will limit total accumulations along their path. Morning WSR-88D radar and GOES satellite imagery at 15:45 Z already show a band of scattered showers extending from northern Harney County through Baker County. So far...this band of showers is not producing much lighting, but this will likely be the first area where thunderstorms develop and then move north and east across the area later this afternoon. && .AVIATION...Mainly VFR. Isolated showers/thunderstorms will become widespread across the E Oregon and SW Idaho this afternoon through tonight, impacting all TAF sites. Storms may be capable of strong winds 35-50 kt, hail, frequent lightning, and heavy rain producing MVFR conditions. Surface winds outside of storms: variable or NW 5- 15 kt, except NW 15-35 kt this evening with cold front. Winds aloft at 10kft: SE to SW 5-15 kt, then W-NW 10-20 kt this eve. KBOI...Mainly VFR. A series of showers and thunderstorms expected at, or in vicinity of, KBOI, with best chance Sun/22Z to Mon/04Z. Thunderstorms capable of strong gusty winds 35-50 kt, hail, frequent lightning, and heavy rain producing MVFR conditions. Surface winds outside of storms: NW 5-15 kt, except 15-35 kt with cold front passage at approximately Mon/00-03Z. && && .PREV DISCUSSION... SHORT TERM...Today through Tuesday night...A short wave trough will move toward and then over the state today into this evening. This will likely produce a greater coverage of thunderstorms than we have seen the past few days. SPC has placed roughly the southern half of the CWA in a marginal risk for severe weather, with winds being the main threat. Storms were ongoing mainly over the mountains of SW Idaho with isolated storms in SE OR as of 0745Z. New development is expected around 18Z today, with storms moving northeast around 25 mph. Storms should exit the area around midnight Sunday night. Weak ridging aloft will move in Monday behind the departing trough, followed by zonal flow Tue and Tue night. These features will keep us dry and warm (roughly 10 degrees above normal) both days. LONG TERM...Wednesday through Sunday...Zonal flow Wed will become SW Thursday and Friday, keeping us warm and dry. Models are consistent in depicting an upper level trough moving into the PacNW Friday night through Sunday, but differ in important ways on the details. At this time, the most likely solution is one with the low staying to our north, keeping us dry. We should be warm Friday, with temperatures cooling to near normal Sat and perhaps below normal Sunday. && .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...JB AVIATION.....SH SHORT TERM...SP LONG TERM....SP