Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
549 FXUS66 KHNX 152055 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 155 PM PDT Sat Jun 15 2024 && .KEY MESSAGES... 1. A cooling trend will bring temperatures closer to seasonal averages for the weekend. Monday temperatures will be around 3 to 5 degrees below normal. 2. Snowmelt from the higher elevations of the Sierra Nevada, will continue to result in dangerously cold and fast flows along rivers and waterways. 3. Strong wind gusts will develop along the Mojave Desert Slopes each afternoon and overnight through Monday. Afternoon and evening breezes will develop across the San Joaquin Valley with locally gusty conditions near the passes of the West Side Mountains through Monday. 4. The gusty winds coupled with low relative humidity will bring elevated fire weather concerns to the Kern County mountains and desert and the San Joaquin Valley through Monday with a peak over the weekend. && .DISCUSSION... Seasonal temperatures will return to the San Joaquin Valley this afternoon, due in large part to an upper level trough progressing through the Pacific northwest region. A cold front moved through central California yesterday, bringing stronger winds and drier conditions to the region. Cyclonic flow around the upper level trough will continue to bring northwesterly winds over our CWA through the remainder of the weekend and into early next week as the system slowly moves eastward. An area of high pressure to the south over Baja California will enhance the winds across the valley and desert portions of the region each afternoon to overnight period through Monday. High resolution guidance from the HREF ensemble expresses a 60 to 90 percent probability for wind gusts to reach or exceed 25 miles per hour this evening in the San Joaquin Valley. Meanwhile, there is a 50 to 80 percent probability for wind gusts to exceed 60 miles per hour in the Mojave Desert Slopes, and as such, a High Wind Warning is in effect until 5 AM PDT Tuesday morning for this area. In addition to the increased winds over central California, the aforementioned trough will continue to bring dry conditions to the valley and desert areas of our CWA. HREF guidance suggests a 60 to 70 percent probability for relative humidity of 15% or less in the southern San Joaquin Valley this evening, though probabilities are above 90 percent for the foothills of the southern Coastal Range and the Kern County Desert. The combination of drier conditions and increased winds brings an elevated risk of fire danger, especially in areas where large swaths of dry grasses are present. The cooling trend over the region this weekend is expected to prolong through Monday, when afternoon highs will be 2 to 5 degrees below normal for this time of year. The National Blend of Models only gives a 20 to 40 percent probability to exceed 90 degrees in the San Joaquin Valley on Monday. As the aforementioned upper level trough exits the western United States midweek, temperatures will rise back to seasonal averages in the low to mid 90s. In the latter portions of the week, an upper level ridge is expected to propagate from the east, raising afternoon temperatures above 100 degrees in time for the weekend. The NBM gives a 40 to 60 percent probability to reach 100 degrees Friday afternoon, however probabilities rise to 60 to 80 percent for Saturday, with early indications suggesting a similar likelihood for these temperatures to last through Tuesday. && .AVIATION... VFR conditions will prevail across the Central CA interior for the next 24 hours. && .FIRE WEATHER... Very low minimum relative humidity values throughout the San Joaquin Valley and the Kern County Desert combined with the strong winds from the low pressure system will result in an enhanced fire risk through the weekend, with the peak occurring on Monday. Relative humidity will drop to the teens in the valley areas and into the single digits in the Kern County Desert. The Storm Prediction Center has indicated that there is a 40 to 69 percent chance of fire weather on Monday, June 17, in the western parts of Fresno, Madera, and Mariposa Counties, as well as nearly all of Merced County. && .AIR QUALITY ISSUES... ISSUED: 06/15/2024 12:56 EXPIRES: 06/16/2024 23:59 None. && .CERTAINTY... The level of certainty for days 1 and 2 is medium. 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... High Wind Warning from 5 PM this afternoon to 5 AM PDT Tuesday for CAZ338. && $$ public/aviation...SM IDSS..........Molina weather.gov/hanford