


Area Forecast Discussion
Issued by NWS Boise, ID
Issued by NWS Boise, ID
687 FXUS65 KBOI 182101 AFDBOI Area Forecast Discussion National Weather Service Boise ID 301 PM MDT Fri Jul 18 2025 .SHORT TERM...Tonight through Sunday night...A disturbance in the zonal flow aloft is moving over the CWA this afternoon. Cumulus fields and convection are ongoing over much of our southern zones. This activity is expected to continue for the next few hours and weaken during the evening. Thunderstorm outflows from these scattered thunderstorms south of Twin Falls may produce wind gusts near 45 mph. After this evening, northwesterly flow aloft will keep conditions dry. The first push of cooler air, from the upper-level trough over British Colombia, will bring a "cold" front that will stall out across a SW-NE line from Burns, OR to McCall, ID. Late Sunday night, the upper-level trough that had been unmoving will finally drift south and begin to bring precipitation chances back in behind another "cold" front. Temperatures will be 5 degrees cooler than normal with these fronts on Saturday and Sunday. Winds will be breezy from the northwest over the area on Saturday, gusting to around 20 mph. .LONG TERM...Monday through Friday...The upper-level trough moving south from British Colombia is the main story over the long term period. To begin Monday morning, PoPs range from 15-20% currently over our northern zones. The ECMWF and GFS largely disagree on precipitation amounts at the moment, so that will be a forecast point to watch over the next few model runs. Afternoon to evening thunderstorms are possible (15-20%) on Monday. For Tuesday, more southwesterly flow will dominate, bringing drier air and lower PoPs. Temperatures through Monday and Tuesday will be 5 degrees below normal. Depending on the trough movement trend, PoPs may rise to mentionable amounts again Tuesday. Late Tuesday into Wednesday, the negatively tilted trough over the Pacific NW will cut off over the California coast, with the rest of the trough moving east. Wednesday and Thursday, the cut off low will stall, putting the CWA in southerly flow aloft. This will bring warmer air back into the area. Moisture and lift from the nearby upper-level low look to be increasing PoP chances again late Thursday in SE OR. On Friday, another upper-level trough looks to come from Canada again, although timing and amplitude is not well agreed upon at this time. && .AVIATION...VFR. Smoke aloft mainly from Cram Fire in north-central OR. Isolated/scattered thunderstorms along the ID/NV border until sunset. Thunderstorm outflow gusts to 40 kt but little rain. Surface winds: W/NW 5-15 kt. Gusts to 25 kt in SE OR and south of Snake River in ID until sunset. KBOI...VFR. Surface winds: NW 10-15 kt until sunset, then variable less than 7 kt. Weekend Outlook...VFR. Areas of smoke aloft. Surface winds: W-NW 5- 15 kt with afternoon gusts 15-25 kt. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...None. OR...None. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...CH LONG TERM....CH AVIATION.....LC