Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
033 FXUS65 KBOI 020237 AFDBOI Area Forecast Discussion National Weather Service Boise ID 837 PM MDT Wed May 1 2024 .DISCUSSION...Isolated showers continue to move southeast through the West Central and Boise Mountain zones this evening. Radar indicates rapid weakening of the remaining cells, and there should be very little activity overnight. It will be quite cool, with lows expected to be 5-10 degrees below normal. Showers are in the forecast again tomorrow, as another upper level system will move in from the northwest and pass over the area in from morning through early evening. All this is handled well in the current forecast and no changes will be made at this time. && .AVIATION...Mainly VFR. Rain/snow will arrive in SE Oregon after Thu/08Z, then spread into SW Idaho beginning Thu/14Z. Showers will bring brief MVFR/IFR conditions and mountain obscuration. Isolated lightning strikes possible in the afternoon. Snow levels 3500-4500 ft MSL. Surface winds: variable 5-15 kt, then generally northwest by late afternoon Thursday. Winds aloft at 10kft MSL: westerly or variable 5-20 kt. KBOI...VFR with scattered/broken clouds 6000-9000 ft AGL. Showers will develop Thursday near KBOI, with a 20% chance of rain showers hitting terminal between Thu/16Z-Thu/23Z, and again Fri/04Z-09Z. Maintaining VCSH in TAF for now until forecast confidence increases. Surface winds: SE 5-15 kt overnight, shifting to NW 5-15 kt around Thu/22Z. && .PREV DISCUSSION... SHORT TERM...Tonight through Friday night...A weak shortwave is continuing to move southeastward across central Idaho, sustaining scattered showers primarily over the West Central and Boise Mountains. Additionally, weak showers have cropped up in Baker County and the Lower Treasure Valley. Snow levels are hovering around 3500 feet, leading to predominantly snowy conditions in mountainous regions, while lower valleys may experience a mix of rain and snow. However, snow accumulation is expected to be minimal, with most areas receiving between 0.1 to 0.3. In the Treasure Valley, showers will likely yield little to no rainfall until early evening. There`s a slight possibility of lightning strikes, particularly in the central Idaho mountains. Shower activity will wane as the evening progresses and the low pressure system shifts over Utah. In the Western Magic Valley, gusts of up to 40 MPH have been observed, anticipated to persist through the evening before tapering off post-sunset. Overnight, there will be a brief respite before another low- pressure system traverses the forecast area on Thursday. The brunt of precipitation is forecasted to remain south and west of the Western Snake River Plain, initially affecting Southeast Oregon and later moving into the Southwest Highlands on Thursday afternoon. This region has a 30% chance of receiving over 0.10 of rainfall. Furthermore, scattered showers and isolated thunderstorms are expected to develop over the central Idaho Mountains Thursday afternoon due to increased instability and dynamics associated with the approaching low center. Friday will bring warm and dry conditions as a weak ridge builds over the area ahead of the next upper-level low. Temperatures are forecasted to rise above normal with heightened southerly flow aloft. LONG TERM...Saturday through Wednesday...A deep upper low will move into the Pacific Northwest on Saturday. Ahead of the low, southwest flow will bring mild temperatures to much of the area, with lower valley highs in the upper 60s to mid 70s. However, southeast Oregon will be closer to the low center and significantly cooler. Warm temperatures will be aided by gusty southeasterly winds, with gusts up to 40 mph in the Snake Basin. Precipitation will move into southeast Oregon by Saturday morning, then push into southwest Idaho Saturday afternoon and evening. A band of moderate to heavy precipitation may develop along a cold front as the low moves east. Snow levels will be high initially, then fall to 3500-6000 feet as the low center moves overhead. The lowest snow levels will develop where the low center and core of cold air aloft moves across. The coldest air looks to arrive mainly behind the cold front on Sunday, with significant snow accumulations limited to the mountains. However, light snow accumulations are possible above 3500 feet. Sunday will be cool and showery as the low tracks across our area. Highs will be 10-15 degrees below normal, and gusty northwest winds will make it feel even colder. The pattern will remain active into early next week as a large upper level trough develops across the northern US, with shortwave troughs rotating through our area under northwesterly flow aloft. This will bring periodic chances of rain and snow with fluctuating snow levels, but at times dropping as low as 3000-3500 feet. Each day will bring a 20-60% chance of precipitation, with the highest chances Monday and Wednesday. Precipitation amounts with each system look to be light. Temperatures will remain 5-10 degrees below normal. Each passing system will bring periods of gusty winds, particularly in the Magic Valley. && .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...SP AVIATION.....SH SHORT TERM...JDS LONG TERM....ST