Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
697 FXUS65 KBOI 190220 AFDBOI Area Forecast Discussion National Weather Service Boise ID 820 PM MDT Wed Jun 18 2025 .DISCUSSION...Skies are clear again this evening across the region, with active weather holding off until tomorrow. We expect any showers or storms to be able to produce strong outflow wind gusts, but storms are forecast to be relatively few in number, so most folks won`t experience the strong winds. The current forecast is on track and no update is planned at this time. && .AVIATION...VFR. Isolated showers and thunderstorms tomorrow afternoon/evening resulting in localized outflows of 45 kt and MVFR/IFR conditions. Mtns obscured in precipitation. Surface winds: W-NW 5-15 kt gusting to 30 kt overnight in the Snake River & Baker Valleys. Variable 5-15 elsewhere. Winds aloft at 10kft MSL: W-SW 10- 20 kt. KBOI...VFR. Slight chance (15%) of showers/thunder from Fri/00z to Fri/06z. Surface winds: W-NW 5-10 kt. && .PREV DISCUSSION... SHORT TERM...Tonight through Friday night...We`re heading toward a pattern change as the weekend approaches. For this evening gusty winds will develop across Baker County and push into southwest Idaho along the Snake River. Gusts to 30 mph will be common with windier spots in Baker County (Ontario to Huntington) seeing gusts to 45 mph through about midnight. The upper ridge axis over the area today shifts to the east on Thursday. This will take a few degrees off of temperatures and bring a shift to southwest winds aloft. A minor upper wave embedded in the flow will track through SE Oregon and w-central Idaho late Thursday. The dynamics, instability and accompanying mid-level moisture are enough to support a 15-20% chance of afternoon/evening showers and thunderstorms from southern Harney County, northeastward through the lower Snake Plain and into the w-central Idaho mountains. In the Snake Plain the Boise metro will be on the eastern edge of thunderstorm potential. The hot and dry near-surface conditions will be favorable for locally gusty outflow winds to 50 mph (DCAPE values generally 500-1000 J/kg, up to 1300 J/kg from the more excitable NAM guidance). The reach of these winds will be dependent on the size and organization of the showers/storms, but for now expect strongest outflow winds to be isolated. Thursday night sees a lingering 15-25% chance of showers across e-central Oregon and the w-central Idaho mtns with the probability of thunderstorms dropping to 15% or less. Friday will bring more widespread windy conditions as flow aloft increases ahead of a cold frontal passage. During the day, winds will be strongest across higher terrain near the NV border up into the Snake Plain. The chance for showers will increase Friday afternoon with the focus of development across SE Oregon and mtns of SW Idaho Friday afternoon into Friday night. The cold frontal passage will bring gusty winds Friday evening, especially across s-central Idaho where gusts to 45 mph are possible. Southeast Oregon will see temperatures will cool 15 to 20 degrees from Thursday to Friday with up to 15 degrees of cooling across southwest Idaho. LONG TERM...Saturday through Wednesday...An upper level low over the Pacific Northwest will bring unseasonably cool temperatures with mountain rain/snow showers and thunderstorms through the weekend. Saturday high temperatures will only reach 65F in Boise and barely scrape 70F for most valley locations, which is about 19 degrees below normal for the end of June. The best chance of precipitation will occur over high terrain through the weekend, although intermittent showers will bring up to a tenth of an inch of rain to valleys and up to a half of an inch of rain to mountains by Sunday. Higher elevation mountains above 6000 feet will see up to 2-4 inches of wet snow. The low center will move to the northeast, with an upper level trough lingering over us. Conditions look to remain dry over the region through midweek, but the trough will keep near normal temperatures over the region. Model agreement remains high with the long term forecast pattern, with precipitation totals steadily trending down as we progress towards the weekend. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise DISCUSSION...SP AVIATION.....NF SHORT TERM...DG LONG TERM....SA