Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
117 FXUS66 KHNX 120853 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 153 AM PDT Wed Jun 12 2024 .KEY MESSAGES... 1. Temperatures will remain around 10 to 15 degrees above climatological averages today. 2. A Heat Advisory remains in effect for today into Thursday morning, with probabilities of afternoon highs exceeding 100 degrees in the San Joaqin Valley around 70-90%. The probability of exceeding 105 degrees is generally less than 20% with the exception of Fresno and Visalia being about 20-30%. 3. Isolated strong thunderstorms have a 10 to 20 percent chance of occurrence Thursday afternoon and early evening along the Sierra Nevada crest from Yosemite NP to Sequoia NP. 4. The warm temperatures will allow increased snowmelt to continue over the Sierra Nevada, resulting in colder and higher flows along rivers and waterways. 5. A gradual lowering of temperatures is in store later this week, and a more noticeable cooling trend arrives by this weekend when highs fall closer to climatological averages. && .DISCUSSION... Easterly/offshore flow continue at this time, due to a strong ridge of high pressure over the Southwest and Great Basin with an upper-level low off the coast of Southern California, based on latest satellite imagery. Afternoon highs yesterday were mainly around 100 to 103 degrees throughout the San Joaquin Valley and hotter in the Kern County desert. Today`s highs remain on track to reach triple digits across much of the lower elevations, where the Heat Advisory remains in effect. Probabilities of highs at least 100 degrees in much of the Central Valley are still at about 70 percent and above. In the Kern County desert, similar probabilities for triple digits continue today, as well into Thursday and Friday, but decrease during the weekend. On Thursday, chances for readings at the century mark fall dramatically or down to 20 percent and lower in the SJ Valley. However, there is a slight uptick in the chances for a triple digit in the SJ Valley on Friday, or about 20-40 percent chance. The aforementioned upper-level low will move inland over Southern CA during Thursday and into the Desert Southwest, so this could allow temperatures to lower a bit. The ridge will also begin to shift further inland on Thursday, and this slightly increases the potential for Sierra Nevada crest thunderstorms. As for thunderstorm potential over the Sierra Nevada, the best chances are now on Thursday afternoon and early evening for mainly Yosemite to Fresno County north of Kings Canyon NP, and the probabilities are about 10-20 percent, or similar to recent days. However, the stronger zonal, or onshore, flow doesn`t quite make it this far south until around Friday evening. Nonetheless, a lowering trend in maximum temperatures occurs after today, with more noticeable cooling by the weekend. A mainly dry pattern occurs this weekend into next week. Daytime highs on Saturday lower closer to average with some additional cooling for Sunday due to the zonal flow. Mainly steady temperatures will continue into early next week. So, this translates to highs mainly in the 90`s, or lower 90`s for the Central Valley and mid to upper 90`s for the warmest portions of the Kern County desert. The potential for gusty winds in the prone areas along the Mojave Desert slopes in eastern Kern County continues to increase where gusts around 45 to 55 mph are projected. For now, the best opportunity for these gusty winds in this portion of Kern County will be during Friday until Sunday. Rivers and streams continue to flow dangerously fast and cold, and bodies of water, including the reservoirs, are also cold. Take precautions if venturing into the water. && .AVIATION... VFR conditions will prevail across the Central CA interior for 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... Heat Advisory until 6 AM PDT Thursday for CAZ300>317-319-332. && $$ BSO weather.gov/hanford