Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
902 FXUS65 KBOI 150243 AFDBOI Area Forecast Discussion National Weather Service Boise ID 843 PM MDT Fri Jun 14 2024 .DISCUSSION...Today was 5-10 degrees cooler than yesterday behind last night`s weak cold front. A stronger cold front over eastern Oregon late today will move across Idaho zones later tonight with increasing west/northwest winds and a 15 to 30 percent chance of showers and thunderstorms. Saturday will be about 15 degrees cooler than today along with significantly stronger west winds than today, especially in the Snake Basin and Camas Prairie. These changes are due to a deep upper low approaching from the Gulf of Alaska. Further cooling will occur Sunday and especially Monday when the upper low center passes right over our CWA. Showers will increase in northern and central areas with snow as low as 5500 feet MSL. Southern areas will have less chance of showers (15-30 percent chance) but will also be breezy and about 20 degrees cooler than normal for mid-June. Current forecast is on track with all this and supported by most models. && .AVIATION...VFR with mid and high level clouds. A chance of showers and thunderstorms through Sat/08Z. Surface winds: W-NW 5-15 kt with gusts to 30 kt. Winds aloft at 10kft MSL: W 10-20 kt, becoming SW 15-25 kt by 15/12Z. KBOI...VFR. Low confidence (around 10 percent chance) of showers/thunderstorms between Sat/00Z and Sat/06Z. Surface winds: W to NW 8-12 kt overnight, then NW 14-22 with gusts to 28 kt after 15/14Z. Sunday Outlook...VFR. Mid and high clouds with a 15-30 percent chance of rain/snow showers in SE Oregon and w-central Idaho mountains Sunday night. Snow levels falling to 5500-6500 ft MSL when precipitation chances increase. Surface winds on W-NW 5-15 kt with afternoon gusts to 15-25 kt. && .PREV DISCUSSION... SHORT TERM...Tonight through Sunday night...A deep upper level low will move into the Pacific Northwest today, with a weak cold front moving through the region this evening and another stronger front moving through tomorrow morning. A low chance (20-30% chance) of showers and thunderstorms with this initial frontal passage will develop through the region in a line from Rome, OR to McCall, ID late this afternoon into the evening. Current soundings show dry lower level conditions, with high based thunderstorms/virga showers as this front moves through. Localized strong outflow winds anywhere from 40-50 mph are possible with these showers. As successive fronts move through the region, breezy westerly winds 10-20 mph with gusts to 30 mph will accompany each frontal passage. High ridgetops will see gusts to 40 mph. In addition to these frontal winds, a strong gradient wind will develop today and tomorrow as the upper low center moves into the Pacific northwest, tightening the pressure gradient aloft. Temperatures will plummet from about 5 degrees above normal today to 10-15 degrees below normal tomorrow with the incoming cold air mass. The anomalously low pressure system will continue to bring below normal temperatures through the rest of the short term period, but Sunday looks relatively dry except for some high terrain showers in Baker/Valley County. LONG TERM...Monday through Friday...The unsettled pattern will continue into the long term period, with another upper level low pressure system developing over the Pacific Northwest on Monday. There is current model disagreement on where the low center will go, therefore, there is quite a bit of uncertainty in the amount and extent of precipitation for our region. The best chance of precipitation with the highest model agreement is in high terrain in southwest Idaho. Temperatures will remain below normal, with a chance of snow above about 6000 feet Monday night into Tuesday morning. There is about a 10% chance of snow accumulation in McCall, ID on Tuesday morning. After Tuesday, the unsettled conditions look to move east, as a ridge starts to build into the region. There is still model discrepancy on the development of this ridge, but the cluster and ensemble solutions favor the development of a ridge. This outcome will bring dry conditions and above normal temperatures for most of the region starting Wednesday through the end of the long term period. && .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...LC AVIATION.....SP SHORT TERM...SA LONG TERM....SA