Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
971 FXUS65 KBOI 191524 AFDBOI Area Forecast Discussion National Weather Service Boise ID 924 AM MDT Wed Jun 19 2024 .DISCUSSION...Continued warming and drying through Thursday even with an upper trough still over the area, but the main reason for the warming is deeper than normal thermal low pressure at the surface. The trend will slow down Friday as a weak upper trough passes north of us, but Saturday will be hotter again, and Sunday almost as hot. We now see a 40-60 percent chance of reaching 100F Saturday in the Treasure Valley. A Heat Advisory has been considered but nighttime low temps should be higher. After Sunday we see several more days of 90s in the valleys and 80s in the mountains before a stronger upper trough brings about ten degrees cooling. Models faintly hint at thunderstorms along the ID/NV border and Valley County/ID late Thursday, then slightly more in western Idaho Thursday night (not yet in our forecast). The hottest day, Saturday, looks mostly sunny until evening when instability for thunderstorms increases in northern areas. No updates for now. && .AVIATION...FR. Some mid-level cumulus cloud development over high terrain this afternoon. Surface winds: E-SE 5-10 kt, then variable less than 10 kt after Thurs./03Z. Winds aloft at 10kft MSL: SW-SE 10- 15 kt. KBOI...VFR with a few high clouds. Surface winds: SE 8-10 kt becoming variable less than 5 kt after Wed./22Z. && .PREV DISCUSSION... SHORT TERM...Today through Friday night...The warming trend will persist in the short term under a weakening upper-level trough. Clear skies will contribute to a temperature increase of about 10 degrees today, bringing temperatures just above the seasonal average. On Thursday, temperatures will rise by another 7-9 degrees ahead of a weak trough expected to pass through Thursday night into Friday. This weak system moving to the north will moderate Friday`s warming, resulting in valley temperatures in the low to mid-90s. Limited moisture will likely prevent showers or thunderstorms, but it could be sufficient for scattered cumulus cloud development on Friday afternoon. LONG TERM...Saturday through Wednesday...This weekend will be hot thanks to building heights and southwest flow aloft, with a few 100 degree highs in the forecast for Saturday and Sunday. Chances for 100 or higher max temps in the lower Snake Plain have risen to 25- 50% on Saturday and 35-70% on Sunday, with the highest chances being in Ontario, along the Snake River, and the Treasure Valley. An upper low moves slowly to the Washington coast after Sunday, causing upper level heights to fall slightly. This will cool us down, with highs in the low 90s Monday-Wednesday for the Snake Plain. Temps overall will still be about 5 degrees above normal, however. Even with the approaching low, the long term remains dry with some afternoon breeziness in SE Oregon and 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...LC AVIATION.....SA SHORT TERM...JDS LONG TERM....JM