Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
720 FXUS66 KHNX 310531 AAB AFDHNX Area Forecast Discussion...UPDATED National Weather Service Hanford CA 931 PM PST Thu Jan 30 2025 .UPDATE...Updated Aviation Section. && .KEY MESSAGES... 1. A pattern shift will occur for the weekend, bringing strong chances for rainfall to the northern areas of our CWA. THere is a 40 to 70 percent chance for 0.5 inches of rainfall int he northern San Joaquin Valley, with a 60 to 90 percent chance for 1 inch in the Sierra Nevada and Foothills. 2. A Winter Storm Warning has been issued for the Sierra Nevada from Yosemite National Park to Kings National Park as six to twelve inches of snowfall is expected above 8,000 feet; totals up to three feet are possible at the highest elevations. 3. Strong wind gusts are expected along the crests of the Sierra Nevada associated with the upcoming storm system. There is a 50 to 70 percent chance for wind gusts greater than 50 miles per hour. A Wind Advisory has been issued. 4. A stronger storm is favored during the next workweek with the storm total having a 50 to 80 percent chance for at least half an inch in the Valley and a similar chance of an inch or more in the foothills. && .DISCUSSION...An upper level ridge of high pressure is building into central California today, bringing about clear, dry conditions for the region. Freezing temperatures were observed once again in the San Joaquin Valley this morning, coming as the result of upper level flow from the north to northwest across the region. Temperatures will warm to near season averages this afternoon as weak upper level winds continue from the northwest through Friday morning. A pattern change will come Friday afternoon, but not before there is another chance for freezing lows in the southern San Joaquin Valley. The National Blend of Models expresses a 50 to 80 percent chance for temperatures less than 32 degrees in the rural valley areas of Kern County tomorrow morning. As the day progresses, a low pressure trough moving through the Pacific Northwest region will pair with the high pressure ridge, allowing zonal flow to propagate across central California. A slight warmup is expected to occur as much of the incoming flow will be from the southwest. These warmer conditions will continue through the weekend and into early next week, with a 40 to 80 percent chance for afternoon temperatures to exceed 70 degrees Sunday in the San Joaquin Valley, and a 15 to 55 percent chance on Monday. Along with the warmer conditions, the funneling of moisture into northern and central California is anticipated to bring likely chances for precipitation to our area, especially in the northern San Joaquin Valley and Sierra Nevada. There has been a slight southerly shift in the approaching system, increasing the probabilities for excessive rainfall, particularly in the mountains and foothills in Mariposa, Madera, and Merced Counties. The following are probabilities from the NBM for increasing precipitation totals in these areas through 4 AM PST Sunday. Inches: 0.01 0.1 0.5 1.0 2.0 Tioga Pass 90% 88% 79% 68% 44% Yosemite Valley 99% 97% 93% 87% 71% Mariposa 99% 97% 90% 81% 61% Oakhurst 95% 94% 87% 76% 53% Merced 98% 91% 68% 40% 11% Chowchilla 94% 87% 60% 34% 9% Los Banos 95% 86% 48% 18% 3% Madera 89% 79% 46% 23% 6% Fresno 87% 70% 40% 19% 4% Due to moderate rainfall rates and totals up to 3 to 4 inches, a Flood Watch has been issued for the central Sierra Nevada foothills, including Yosemite Valley, Mariposa, Catheys Valley, Oakhurst, and Coarsegold valid from 12 PM Friday through 4 AM Sunday. Snow levels are expected to be above 8,000 feet resulting from the warmer nature of this system, and subsequently snowfall will largely be confined to the higher elevations of the Sierra Nevada. However, due to the amount of moisture, intense snowfall rates will be observed, especially in and around Yosemite National Park and extending south to Kings Canyon National Park. A Winter Storm Warning has been issued for this area valid from 10 AM Friday morning through 4 AM Sunday morning. Accompanying the snowfall in the higher elevations, the strong pressure gradient between the aforementioned trough and ridge will bring strong winds to the crests of the Sierra Nevada, with a 50 to 70 percent chance for maximum gusts Saturday to exceed 50 miles per hour. Wording for these elevated winds is included in the Winter Storm Warning, however a Wind Advisory has been issued for the remainder of the Sierra Nevada through Fresno and Tulare Counties valid 4 AM Saturday through 10 PM Sunday. Conditions are favorable to improve on Monday as the focus of this band of moisture progresses eastward away from the region, with only up to a 50% chance for 24 hour measurable precipitation greater than 0.01 inches Monday across central California. However, a secondary trough, mentioned in previous days forecast discussion, is anticipated to phase with the trough located over the Pacific Northwest region. The phasing of these systems will cause the atmospheric flow aloft to become north-south oriented, tapping into more tropical moisture. As a result, there is another chance for widespread precipitation Tuesday through Thursday for the region. Early estimates give a 50 to 80 percent chance for 0.5 inches of precipitation in the San Joaquin Valley between 4 AM Tuesday and 4 AM Thursday of next week. There are similar probabilities for one inch of precipitation in the Sierra Nevada, however with snow levels lowering near 6,000 feet, there are better chances for this area to receive snowfall. Much like the valley rainfall, early estimates from the NBM show up to a 90% chance for 18 inches of snowfall in the 48 hours ending Thursday morning. && .AVIATION...06Z Update: In the San Joaquin Valley and West Side Hills, VFR conditions will prevail thru 21Z Fri then local MVFR in low clouds and rain between 21Z Fri and 03Z Sat. areas of MVFR in low clouds and rain between 03Z Sat and 06Z Sat. In the Sierra Nevada and adjacent foothills, VFR conditions will prevail thru 15Z Fri the increasing areas of MVFR with local mountain obscuring IFR in low clouds and precipitation between 15Z Fri and 21Z Fri. After 21Z Fri, mountain obscuring IFR becoming widespread in low clouds and precipitation. In the Tehachapi Mountains and the Mojave Desert in Kern County, VFR conditions will prevail thru 06Z Sat. && .AIR QUALITY ISSUES...On Friday January 31 2025, Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno, Kern, Kings, Madera, and Tulare Counties. Burning Discouraged in Merced County, and Kern (Greater Frazier Park Area) and Sequoia National Park and Forest. && .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... Flood Watch from Friday afternoon through late Saturday night for CAZ317-318-324. Winter Storm Warning from 10 AM Friday to 4 AM PST Sunday for CAZ323-326-328. Wind Advisory from 4 AM Saturday to 10 PM PST Sunday for CAZ330-331. && $$ public...SM aviation...DAS weather.gov/hanford