Area Forecast Discussion
Issued by NWS Reno, NV
Issued by NWS Reno, NV
022 FXUS65 KREV 081905 AFDREV Area Forecast Discussion National Weather Service Reno NV 1205 PM PDT Fri Aug 8 2025 .KEY MESSAGES... * Heat builds into early next week. Moderate HeatRisk for most lower valleys, with isolated Major pockets. * Low-end thunderstorm chances return Tuesday through Thursday. 5 to 10% eastern Sierra and 5% elsewhere. * Breezy to gusty winds mid-to-late week with a cooling trend. && .DISCUSSION... A trough moving into the northern Plains is clearing the way for a broad subtropical ridge to build inland from the eastern Pacific. 500 mb heights climb into the 592-596 dm range over California and Nevada through Monday, centered just offshore of southern California. The ridge axis then slides east into the Desert Southwest by midweek as a Pacific Northwest trough lowers heights over the Sierra and western Nevada. This shift knocks back the heat and tightens the onshore gradient, leading to stronger afternoon winds mid-to-late next week. * Temperatures and HeatRisk: Lower western Nevada valleys will warm into the mid-upper 90s this weekend, with a 70-80% shot at triple digits for Reno, Fallon, and Lovelock Monday-Tuesday. For Reno specifically, there is around a 50-60% probability of tying or exceeding the daily record high of 102 on Tuesday, set in 1970. Sierra towns like South Lake Tahoe and Truckee will be in the 80s to near 90, with higher valleys in the 70s. This isnt extreme for August, but it will be hot enough to cause issues for sensitive groupsolder adults, young children, outdoor workers, and those without cooling. Limit heat related health risks by planning outdoor work and recreation early or late in the day, hydrating regularly, taking shade/indoor breaks if working outside, and checking in on neighbors, friends, and family who may be at risk. * Moisture/Thunderstorms: PWAT values increase slightly Tuesday- Wednesday, peaking near 0.6-0.8" in Mono and Alpine counties and 0.3-0.5" elsewhere. Of note is the 400 hPa moisture signal, with ensemble guidance indicating pockets of 50-70% RH over the eastern Sierra. Elevated mid-to-upper level moisture can be a proxy for deeper convective potential by limiting entrainment and sustaining more robust updrafts. Even within a regime of modest surface-based instability, this environment could support isolated high-based convection along the crest with eastward drift into adjacent foothills. Current probabilities remain 5-10% for the eastern Sierra and 5% elsewhere, though stronger localized updrafts would enhance lightning potential despite low coverage. Any convection will likely be short-lived, producing occasional cloud-to-ground lightning, brief heavy rain, and gusty outflow winds. Confidence in coverage/timing is low given weak low-level convergence and limited cooling aloft to steepen lapse rates. * Winds/Cool-down: Lighter west-southwest winds of 10-15 mph, with occasional gusts greater than 20 mph, will persist through Monday. As heights fall midweek, tightening pressure gradients look to bring breezy to gusty west winds Tuesday-Thursday. Probabilities for gusts over 35 mph peak Wednesday, around 70% in far western Nevada, 45-50% for the eastern Sierra and the Basin and Range, and 25-30% for many other western Nevada and Sierra locations, before easing Thursday. Combined with ongoing dry conditions, this could lead to periods of elevated fire weather concerns. Highs cool to the low-mid 90s in lower western Nevada valleys and 70s-80s in Sierra towns by Thursday. -Johnston && .AVIATION... VFR with mostly clear skies. Afternoon W-SW gusts 18-25 kt each day, stronger Tuesday-Thursday with the potential for bumpy conditions along/east of the Sierra. Low chance (5-10%) of thunderstorms near KMMH/KTVL/KTRK Tuesday-Wednesday. Threats include outflow gusts, shifting winds, brief MVFR in heavier showers, and virga-driven downbursts. Density altitude concerns increase Monday-Tuesday areawide with highs near 100 in the lower valleys of western Nevada. && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$