Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
525 FXUS66 KHNX 110714 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1214 AM PDT Tue Jun 11 2024 .KEY MESSAGES... 1. Isolated strong thunderstorms have a 10 to 25 percent chance of occurrence this afternoon and early evening along the Sierra Nevada crest from Yosemite NP to Sequoia NP. 2. Temperatures trend warmer to around 10 to 15 degrees above climatological averages today and Wednesday. 3. A Heat Advisory is in effect for later today into Wednesday, with probabilities of afternoon highs exceeding 100 degrees in the San Joaqin Valley around 65-90%. The probability of exceeding 105 degrees is less than 20% with the exception of Fresno and Visalia being about 30 to 45%. 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 seasonal averages. && .DISCUSSION... Latest satellite images show the upper-level low spinning off the coast of Southern CA. Guidance continues to show this low nearly stationary until Wednesday and finally moves inland over Southern CA by late Thursday. In the meantime, we remain under a strengthening ridge of high pressure which will allow temperatures to rise today into Wednesday. A chance of afternoon and evening thunderstorms returns to the Sierra Nevada crest later today. The chances for today are around 10 to 25 percent from Yosemite NP to Sequoia NP, with the highest values in the high country of Yosemite. While confidence lowers as we progress through this week, thunderstorms cannot be ruled out each afternoon and evening for at least the next couple of days in these areas, as snow continues to melt in the highest elevations. The Heat Advisory continues for most lower elevation locations, including the SJ Valley, adjacent foothills, and the Kern River Valley. Minor changes are shown in terms of latest probabilistic data provided in NBM (National Blend of Models) guidance. The probability of triple digit heat in these areas remains around 65 to 90 percent for both today and Wednesday. As for the Kern County desert, the chances for 100-degree plus readings are similar, while the probabilities for 105-degree plus temperatures are now up to around 40 percent, mainly towards Ridgecrest/China Lake. In addition, the best chance for a temperature of 105 degrees or hotter in the Central Valley remains below 20 percent for most locations, except 30-45 percent chance towards Fresno and Visalia, per NBM. High resolution ensemble guidance shows higher probabilities, especially in the San Joaquin Valley, for a maximum temperature of 105 degrees or hotter today and Wednesday. So, expect highs around 10-15 degrees above seasonal averages until Wednesday. A gradual lowering temperatures is projected for Thursday and Friday, as the track of the aforementioned upper-level low moves inland over the Desert Southwest along with the eastward progression of the ridge. Outside of the Kern County desert, triple digit heat is much less probable, but NBM shows chances of around 15 to 30 percent for the Central Valley until Friday. A trough arrives late Friday which will provide additional cooling and an increase in winds towards the higher terrain near the west side of the SJ Valley with stronger, gusty winds along the Mojave Desert slopes in eastern Kern County through at least the weekend. As temperatures heat up this week, we would like to remind everyone to take precautions if venturing into the water, as it remains dangerously cold and swift due to the ongoing snowmelt. && .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 from 11 AM Tuesday to 6 AM PDT Thursday for CAZ300>317-319-332. && $$ BSO weather.gov/hanford