Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
067 FXUS66 KHNX 130919 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 219 AM PDT Thu Jun 13 2024 .KEY MESSAGES... 1. Temperatures will hover between 95 and 100 degrees through Friday in the Central Valley before a cooling trend brings temperatures closer to seasonal averages for the weekend. Monday temperatures will be around 2 to 5 degrees below normal. 2. Isolated strong thunderstorms have a 10 to 20 percent chance of occurrence this afternoon and early evening along the Sierra Nevada crest from Yosemite NP to Sequoia NP. 3. Snowmelt from the higher elevations of the Sierra Nevada, will continue to result in dangerously cold and fast flows along rivers and waterways. 4. Afternoon and evening breezes with locally gusty winds will prevail at times until at least this weekend near the passes of the West Side Mountains. Stronger, gusty winds will occur along the Mojave Desert slopes each afternoon and evening from Friday through the weekend. 5. The winds coupled with low relative humidity will bring elevated fire weather concerns to some of the mountain areas. && .DISCUSSION... Winds started to increase last evening in northern portions of our forecast area, and breezy conditions continue at this time, including gusts around 30-35 mph near Los Banos and Pacheco Pass as well as nearby areas along the west side of the San Joaquin Valley. Breezy conditions in these areas as well into the Kern County mountains and desert combined with low humidity will produce elevated fire weather concerns. In addition, a significant amount of grass fires have been occurring in quite a few areas during the last couple of weeks or so. At this time, clear skies prevail, and latest water vapor satellite imagery is depicting the offshore upper-level low offshore of Southern CA/Northern Baja, or around 30N/120W. This feature will move northeastward into Southern CA as we progress through today and will be over the Desert Southwest during the evening into the overnight hours. In the meantime, high temperatures are projected to lower in the San Joaquin Valley over the next couple of days, but more noticeable cooling occurs over the weekend into early next week. Mainly dry conditions persist, except for a slight (10-20%) chance of afternoon and evening showers and thunderstorms over the Sierra Nevada crest, mainly Yosemite to Sequoia NP, later today. A few strong thunderstorms remain possible. Temperatures will gradually lower through Friday with additional cooling over the weekend. Also, breezy conditions along with elevated fire concerns will continue along the west side of the SJ Valley each afternoon and evening through at least this weekend. However, the chance of triple digit heat in the Central Valley continues until Friday with a bit higher than today (20-40 percent, with the best chances from Fresno County to Kern County) on Friday. In addition, stronger gusty winds develop along the Mojave Desert slopes beginning Friday afternoon. Latest NBM (National Blend of Models) probabilistic data continues to show a high probability (mainly 60 percent and higher) of gusts above 45 mph for this area from Friday evening until early Saturday AM and again for Saturday evening into Sunday. The chances for a gust around 65 mph remain moderate (about 30-50 percent) for both Friday evening/Saturday morning and again Saturday evening through Sunday morning. Thus, we issued a High Wind Watch for these periods, though may need to extend beyond this period, including Sunday night into early next week as the overall pattern shows little change until Tuesday. Despite the increase in winds along the slopes, little changes in temperatures occur before Sunday in the Kern County desert, and triple digit heat will prevail until at least Saturday. Otherwise, mainly seasonal to below average (by around 3-6 degrees) temperatures prevail this weekend into Tuesday of next week. Afterward, or by Wednesday and next Thursday, a warming trend returns to the region, as high pressure ridging over the SW U.S. builds into Southern and Central CA. Highs will return to above average, though latest probabilistic data suggests temperatures rise to around 3 to 7 degrees above seasonal averages. Dry weather will continue. && .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... High Wind Watch from Friday evening through Sunday morning for CAZ338. Heat Advisory until 6 AM PDT early this morning for CAZ304>316- 319-332. && $$ BSO weather.gov/hanford