Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
956 FXUS66 KHNX 312052 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 152 PM PDT Fri May 31 2024 .KEY MESSAGES... 1. A warming trend will continue today into Saturday which will result in afternoon highs of 7 to 10 degrees above normal. 2. Gusty west winds are possible Saturday night and Sunday morning for the Mojave Desert Slopes and Kern County Desert. 3. Following a cool down early next week, a more significant warming trend will take place next week with probabilities of exceeding 105 degrees at 35 to 55 percent for most of the San Joaquin Valley on Wednesday and Thursday. Excessive Heat Watch has been issued for the event. 4. The anticipated heat for later next week will lead to increased snowmelt from the Sierra Nevada with colder and higher flows along rivers and waterways. && .DISCUSSION... A very stable atmosphere over California is allowing for plenty of sunshine is allowing for a good warm-up today. So far today, temperatures have been (24 hour) trending up 4 to 6 degrees. That this rate, highs this afternoon have a very good chance (60-70 percent) of reaching the mid 90s. Currently, the Probability of Exceedance (PoE) of reaching 100 degrees is still less then 20 percent. On that same note, an afternoon breeze will occur with winds reaching 10 to 15 mph. PoE of reaching 40 mph (especially over the Mojave Desert) is less then 30 percent. Therefore, the chance of high winds are not likely today. With the introduction of a disturbance across the Pacific Northwest, another cool-down will be ushered in before a strong blocking ridge sets-up toward the middle of next week. A watch for excessive heat is in place a possible heat-wave hits Central California. Short-range High-Res Ensemble analysis showing yet another disturbance entering the Pacific Northwest. With the timing being this weekend, the warm-up will come to an end as cooling enters the region. In addition, satellite moisture analysis shows a good plume of high precip-water values targeting the Pac-Northwest. Ensemble analysis and Index values show the onset of precipitation remaining well north of Central California during the event. Yet, temperature analysis does indicate a surge of cooler air filtering into Central California this weekend. During that time, PoE of wind gust reaching 45 mph increases to between 50-70 percent. While high winds may not be reached, wind advisory criteria is more reasonable with the amount of cooling expected through early next week. Longer-range ensemble analysis show the disturbance continuing its trajectory eastward into the Northern Rockies between Monday and Tuesday. Longer-range ensemble upper-air analysis then switches gears and begins the rebuilding the West Coast Blocking High Pattern. While brief warming occurred with the present ridge pattern, the rebuilding will introduce a much stronger ridge pattern as a possible heat-wave is observed for the first time this year. Between Wednesday and Thursday, Ensemble Cluster Analysis only shows a strong ridge over the west. Therefore, with high confidence is the day 5 forecast, we issued an Excessive Heat Watch as high temperatures have more then a 70 percent PoE chance of reaching 100 degrees. In face, they have between a 30 to 50 percent PoE chance of reaching 105 degrees across the San Joaquin Valley. Looking toward Friday (day 7), uncertainty increases as an attempt is made in the ensemble solutions to push out the ridge. Confidence is not high enough to include Friday in the Watch product, but, adjustments can be made later if the ridge pattern is not pushed out. For now, the heat-wave will be for two days. && .AVIATION...VFR conditions will prevail across the central CA interior 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... Excessive Heat Watch from Wednesday morning through Thursday evening for CAZ301>307-309>317-319-321. && $$ Operations......Molina Support/IDSS....DS weather.gov/hanford