


Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
017 FXUS65 KBOI 080233 AFDBOI Area Forecast Discussion National Weather Service Boise ID 832 PM MDT Mon Jul 7 2025 .DISCUSSION...No changes to forecast. Upper level high over the swrn US will build northward through the eastern Great Basin Tuesday as a Pacific upper low moves toward the California coast. This setup will increase southerly flow aloft and bring hot weather to our area Tuesday, supporting our Heat Advisory issued earlier today. On Wednesday the off-California low will come inland bringing slight cooling. A surface cold front will bring further cooling Thursday along with breezy winds. The upper low will also bring mid-level moisture and increased instability due to greater cooling aloft, leading to isolated thunderstorms in our northern and western zones Tuesday afternoon/evening, and then in our central and southern zones (except along the NV border) Wednesday afternoon/evening. A Fire Weather Watch has been posted for lightning Wednesday afternoon and evening in eastern Oregon. && .AVIATION...VFR under mostly clear skies. Isolated showers and thunderstorms developing Tuesday afternoon across SE Oregon and the west-central Idaho mountains. Gusts up to 40 kt near thunderstorms. High density altitude due to hot temperatures on Tuesday. Surface winds: variable less than 10 kt, becoming SE-SW 5-15 kt Tuesday afternoon. Winds aloft at 10kft MSL: W 5-15 kt, becoming SE-SW after Tue/12Z. KBOI...VFR. High density altitude due to hot temperatures on Tuesday. Surface winds: SE 5-10 kt, becoming variable less than 10 kt Tuesday afternoon. && .PREV DISCUSSION... SHORT TERM...Tonight through Wednesday night...High pressure will continue to build into the region today, bringing very hot temperatures and dry conditions Tuesday. Tuesday`s highs at 102-103F in the Boise metro area will be near record for this time of year (104F), with locations near Emmett, ID reaching nearly 106F. Despite relatively good overnight cooling, have opted to add a heat advisory for Tuesday afternoon and evening for the Treasure Valley zones. A weak shortwave trough stemming from a closed low moving into California will bring sufficient instability (400-700 J/kg of MUCAPE) to southeast Oregon tomorrow afternoon and evening. There`s a small risk of showers and thunderstorms with this trough passage Tuesday afternoon and again Wednesday evening. A weaker cold frontal passage will occur on Wednesday evening, so have opted to expand shower and thunderstorm chances across the region, with most locations seeing a 15-25% chance of thunderstorms. With both sets of showers and thunderstorms these days, dry surface air will limit precipitation and create optimal conditions for gusty and erratic outflow winds. Some hi-res models are showing gusts up to 40-50 mph with stronger showers. Because of the threat of lightning in drier thunderstorms and the higher confidence in coverage on Wednesday, we`ve added a fire weather watch over southeast Oregon zones for Wednesday afternoon and evening. Winds will continue to stay elevated on Wednesday evening, with slight improvement in humidity and much cooler temperatures thanks to the cold frontal passage. LONG TERM...Thursday through Monday...An upper trough moving through the northern Rockies will send a dry cold front across SE Oregon and SW Idaho on Thursday. The post-frontal winds are expected to be gusty in the afternoon, especially in s-central Idaho with gusts to 35 mph. Cooler temperatures arrive with the passage of the front with valley highs in the 80s, which is around 5 degrees below normal. A dry northwest flow aloft follows for the end of the week and into early next week. Temperatures begin to climb back up to slightly above normal by Saturday and remain at least a few degrees above normal through Monday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Heat Advisory from noon to 9 PM MDT Tuesday IDZ012-014. OR...Heat Advisory from noon MDT /11 AM PDT/ to 9 PM MDT /8 PM PDT/ Tuesday ORZ064. Fire Weather Watch from Wednesday afternoon through Wednesday evening ORZ670-672>674. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise DISCUSSION...LC AVIATION.....ST SHORT TERM...SA LONG TERM....BW