Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
758 FXUS66 KHNX 200546 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1046 PM PDT Sat Jul 19 2025 .UPDATE... Aviation Section Updated && && .KEY MESSAGES... 1. Showers and thunderstorms developing across the Sierra Nevada Crest with a 10 to 30 percent chance through tonight, especially for Tulare county. 2. Gusty outflow winds across the eastern Kern County deserts may lead to low visibilities because of dust, associated with thunderstorms in western San Bernardino county. 3. Probability of greater than 0.10" of rain is 30%-50% in the high Sierra of Fresno and Tulare counties through tonight, thus some dry lightning strikes will occur. 4. Nocturnal thunderstorms can occur in this weather pattern, not just reserved to afternoon and evening. 5. Long string of cooler temperatures and breezy conditions for the middle of next week, with some fire weather concerns. && .DISCUSSION... Moisture will reach a maximum over the next 48 hours across the high Sierra and eastern Kern, from the disturbance near Baja California. Upslope flow along the high Sierra in combination with the elevated instability will also contribute to showers and thunderstorms through tonight. For several runs, hi res near term models have focused thunderstorms in the high Sierra of Tulare County, but the overall atmospheric profile suggests that showers and thunderstorms, in the most extreme case, will stretch from south to north along the Sierra Crest and through the Kern County Mountains and Deserts with a 10%-30% probability. This monsoonal setup suggests that showers and thunderstorms are possible well after midnight and into the morning hours, with instability remaining aloft due to the incoming moisture, late Friday night through late Saturday night. Although the chance of 30 mph wind gusts is only 30% in the eastern Kern Deserts, still need to keep am eye on the complex of showers and storms currently in San Bernardino county. Best case, nothing arrives across the Kern county border. Worst case, outflow from this complex speeds west and leads to low visibilities because of dust being kicked up by the wind. In addition, some thunderstorms may sneak into Kern County, which may be close to the sensitive Borel Burn Scar and the currently burning Kay Fire, which would lead to erratic changes in wind direction and speed which are very dangerous for the firefighter on scene. Again although some of these outcomes are worst case/low probability, they still deserve our attention. Any thunderstorms producing less than a tenth of an inch of rain, or lightning strikes far from the center of any storm, can contribute to fire starts also. As the Baja Low disappears, our moisture flow is cut off, leading to a dry Sunday with hotter temperatures. After a respite of 100F, the probability of high temepratures reaching that mark climbs to 40% for Fresno to Bakersfield and points just east of I-5 on Sunday. However, any chances of a heat wave quickly diminish as another trough builds along the entire west coast into midweek. This scenario has happened many times this summer, but becomes more and more unusual into mid July. 100F Probabilities disappear, and cities like Merced in the north valley may not even reach 90F (60%-80% Probability) next Tuesday and Wednesday. But, with the arrival of cooler air comes gusty winds for this time of year, with 50%-70% Probabilities of Wind Gusts of 25 mph or more for the valley floor, even Fresno, Tuesday and Wednesday. Best outcomes would be temperatures near 90F with an unusually persistent July breeze, worst case scenario would be that drier air along with gusty winds contributes to increased fire danger and spread potential. Cluster and ensemble guidance largely agree in the depiction of west coast troughing, but disagree with regards to its strength. The most extreme solutions close off an area of Low pressure aloft which would be the breeziest and cooler solution, although that is not expected. Into next weekend, cluster and ensemble guidance lifts the trough away to varying amounts, with ridging over the four corners region oozing west, leading to increasing temperatures and slightly increased probabilities for mountain thunderstorms. && AVIATION... 06Z Update There remains a low (5-10%) chance of thunderstorms in the mountains and desert. Otherwise, expect VFR conditions and mainly light winds over the next 24 hours. && AIR QUALITY ISSUES... None. .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ public...EW aviation....JPK weather.gov/hanford