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Forecast Discussion for Boise, ID
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000 FXUS65 KBOI 300239 AFDBOI Area Forecast Discussion National Weather Service Boise ID 838 PM MDT Wed Mar 29 2023 .DISCUSSION...Evening radar imagery shows rain and snow showers persisting in Idaho north of the Snake Basin under upper trough over the area. The trough extends to a weakening upper low near San Francisco. The portion over our CWA is forecast to develop a weak low center of its own tonight and Thursday, maintaining rain and snow showers through midday Thursday. Northwest surface winds will increase Thursday afternoon as the low center shifts to eastern Idaho. Our CWA will dry out from the west Thursday night into Friday as the low exits east. After that the next trough from the Gulf of Alaska will renew pcpn in our CWA Friday night. By Sunday the whole trough will come inland bringing another surge of cold, moist air to our CWA that will last through next Thursday. Current forecast is on track with all this. No updates for now. && .AVIATION...MVFR and IFR conditions with mountain obscuration will continue with widespread snow across the mountains north of the Snake River Plain into Thursday. Isolated MVFR/IFR rain showers this evening in the Western Snake River Plain becoming widespread snow early Thursday morning. Snow levels around 3500-4500 ft MSL lowering to 2500-3500 ft MSL after midnight. Surface winds: westerly 10 kt or less through tonight then increasing to 15 to 25 kt Thursday. Winds aloft at 10k ft MSL: NW-N 10-20 kt increasing to 20-35 kt Thursday. && .PREV DISCUSSION... SHORT TERM...Tonight through Friday night...Tonight will see drier conditions across SE Oregon and portions of SW Idaho from the Snake Plain to the ID/NV border. Periods of snow will continue to the north as an upper low forms over central Idaho. The moisture will wrap around the upper low late tonight, spreading into the lower Snake Plain Thursday morning around sunrise as rain and snow. Snow levels will be 2500-3000 feet MSL with a rough transition around the Ada/Canyon county line in the lower Snake Plain. While accumulation will be limited to colder surfaces in the Boise metro, the higher elevations between Boise and Mountain Home could see a brief accumulation on roadways. This area of rain/snow will shift south and eastward, reaching the Western Magic Valley by late morning. By that time expect temperatures and late March sun to limit accumulation in those areas. SE Oregon will remain on the western fringe of the wrap-around with the focus of precipitation in the mountains. Snow will taper off in the valleys during the afternoon, while continuing in the mountains through the evening. Accumulating snow will lift above 5000 feet MSL Thursday afternoon. Expect additional snow amounts of 1 to 4 inches in mountain valleys and 4 to 8 inches above valley floors through Thursday. Northwest winds will increase on Thursday as the low wraps up over eastern Idaho. Wind gusts of 25 to 40 mph will be realized across open terrain Thursday afternoon and evening. It will remain gusty across the middle Snake Plain through the day Friday. The upper low will shift east on Friday with the region remaining in a cool northwest flow. A weakness in the flow will support continued light showers over the e-central Oregon and w-central Idaho mountains while lower elevations stay dry. The break will be shortlived as another cold and wet storm system moves into the Pac NW late Friday bringing more valley rain and mountain snow Friday night. Temperatures will remain 5-10 degrees below normal through the period which will close out a well below normal month of March at all climate sites across SE Oregon and SW Idaho. For most sites this will go down as a top 10 coldest March on record. LONG TERM...Saturday through Wednesday...An upper trough will move over the Pacific Northwest Saturday and Sunday bringing another round of widespread precipitation and breezy to windy conditions to the region. Snow levels are forecast to remain above valley floors, but lower from around 4000-5000 feet MSL on Saturday to 3000-4000 feet on Sunday. Significant snow accumulations in the mountains are likely, especially for much of the west-central and Boise Mountains where total amounts through the weekend of a foot or more are likely along with gusty westerly winds causing blowing/drifting snow. The precipitation will transition to more of a showery regime on Monday as the core of the trough moves over the area and snow levels lower to valleys floors. Potential for minor snow accumulations in the lower valleys. Models continue to diverge beyond Monday so forecast confidence is low the middle of next week, with a continued chance of precipitation and below normal temperatures. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise www.facebook.com/NWSBoise www.twitter.com/NWSBoise DISCUSSION...LC AVIATION.....JDS PREV SHORT TERM...DG PREV LONG TERM....TL |
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NWS Boise, ID (BOI) Office Forecast Discussions.
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