Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
994 FXUS66 KHNX 220940 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 240 AM PDT Sat Jun 22 2024 .KEY MESSAGES... 1. Temperatures will rise to around 10 to 15 degrees above average this weekend with widespread triple digit afternoon highs across the lower elevations. A Heat Advisory is in effect from today through Monday morning. 2. There is a 50 to 80 percent probability for a high temperature of 105 degrees or above across most of the San Joaquin Valley on this afternoon and Sunday afternoon. 3. Above average temperatures continue until the middle of next week, with triple digit heat persisting for many locations. && .DISCUSSION... With the upper-level ridge of high pressure now shifting over California, the heat-wave is set to start as Central California will see widespread triple digits. High-Res Short Range Ensemble temperature analysis is giving the San Joaquin Valley a 60 to 90 percent Probability of Exceedance (PoE) of reaching and exceeding 105 degrees this afternoon. With many valley locations near the 80 percent PoE, confidence is high on obtaining heat- wave criteria. Along with the heat, the ridge of high pressure will keep winds light as only afternoon diurnal breezes occur. The surface pressure gradient from KSFO to KLAS is now down to 4-mb and trending downward. Therefore, light winds expected. While moisture will alter the heat-wave later this weekend, the ridge will maintain itself over the West as temperatures remain above normal. High-Res Short Range Ensemble, along with Heat Risk analysis, is showing high confidence in that start of the Heat Wave today. With PoE values averaging near 80 percent this afternoon, will keep the Heat Advisory in place as we get ready for a hot weekend. At the same time, mean ensemble Precip-water values show a steady rise over the next 24 hours. At the moment, will maintain the Heat Advisory going to Sunday as only mid to high level clouds push into the Desert Southwest and portions of Kern and Tulare Counties. With mean ensemble moisture analysis keeping the bulk values southeast of Central California, minor temperatures changes will occur as PoE of reaching 105 degrees remain at 50 to 70 percent on Sunday. Still Hot. By Monday, mean daytime relative humidity values show an up-tick in percentages which will translate into additional clouds over the area. PoE on Monday of reaching 105 degrees falls to values of 20 to also 50 percent. With this trend, will see temperatures remain hot with less of a heat risk threat. This will end the heat wave. Longer range ensemble upper air analysis shows the ridge pattern maintaining itself over the West Coast for much of the week. The blocking high pattern will translate into the continuation of near and above 100 degrees over the Central California Interior. While heat risk falls out of the major category on Monday, moderate values continue through Thursday. By the end of the week, Ensemble Cluster Upper-Air Analysis shows less uncertainty in the development and passage of a disturbance near Friday. Therefore, confidence grows toward allowing temperatures to fall below the century mark and place heat risk in the minor category by next weekend. Yet, higher wind speeds may become a factor as temperatures cool down. && .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 this morning to 11 AM PDT Monday for CAZ300>317-319-321-332. && $$ Operations.....Molina Support/IDSS...JPK weather.gov/hanford