Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
650 FXUS66 KHNX 130907 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 207 AM PDT Mon May 13 2024 && .KEY MESSAGES... 1. High temperatures will remain well above seasonal values through Saturday. 2. A cooling trend is expected to take place next weekend. 3. A few strong thunderstorms are possible in the Sierra Nevada each afternoon through Tuesday and again next weekend. && .DISCUSSION... The weak ridge over California early this morning is quickly replaced today by an upper low that is more of just a depression in the atmosphere with little to no impact for most the San Joaquin Valley. The primary impact will be an elevated risk of some Sierra thunderstorms. Convective energy begins to build around 18Z and peaks around 00Z. The threat ends around 03Z with the loss of afternoon heating for the higher elevations. The difference from Sunday is the speed shear with height is improved today with a 25-35 kt near the equilibrium level. The depth of the -20*c to -30*C layer is well within the cloud for lightning. Convective temperatures range in the mid 50s at higher elevations with max temperature expected in the upper 50s to lower 60s. Therefore the probability of a few thunderstorms is there. The risk of the thunderstorms rolling down into the valley is very low. The probability of thunderstorms this afternoon for higher elevations are as follows: Tioga Pass 33% Yosemite Valley 27% Wawona 23% Lake Thomas Edison 32% Oakhurst 17% Shaver Lake 17% Grant Grove 17% Three Rivers 12% Johnsondale 15% Kernville 10% Temperatures down in the SJV range from 50-77% probability of surpassing 90*F this afternoon seems very reasonable. The weak upper low hangs around central and southern California through Wednesday before kicking out into the Desert Southwest. The Eastern Pacific upper ridge remains in place and doesn`t fully invade the Golden State. The upcoming weekend features another upper low off the southern California coast moving into the region. The impacts remain above normal temperatures for the SJV through Saturday. Then Sunday as the upper low gets a little closer expect a slight cooling trend. Today through Wednesday afternoon there remains the slight risk of thunderstorms over the Sierra. Then a break until Sunday afternoon and the probability of Thunderstorms for the Sierra return. The 6 to 10 day CPC forecast is for near normal or slightly above temperatures for the SJV with normals now in the mid 80s for most locations. The precipitation forecast is for Above to Slightly Above precipitation. Note that "normal" precipitation ranges from near zero at Bakersfield to 0.01" at Fresno. Above normal precipitation is looking at probabilities that exceed only a trace. The 8 to 14 day CPC has the return to normal on both temperatures and precipitation for Central California with normal maximum temperatures in the upper 80s and normal lows around 60. && .AVIATION... VFR for the SJV terminals for the 24 hour cycle. The Sierra from 18Z-03Z has an ISOL potential MVFR due to thunderstorm development. && .AIR QUALITY ISSUES... ISSUED: 05/12/2024 13:57 EXPIRES: 05/13/2024 23:59 None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is high. 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/aviation/fire weather...Proton IDSS....AS weather.gov/hanford