Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
208 FXUS66 KHNX 050534 AAB AFDHNX Area Forecast Discussion...UPDATED National Weather Service Hanford CA 934 PM PST Tue Feb 4 2025 .UPDATE... Updated AVIATION section. && .KEY MESSAGES... 1. An atmospheric river event will continue to impact the through Wednesday morning. Moderate to heavy rain is expected for the Sierra Nevada foothills and heavy snow is expected for the mountains. 2. A Winter Storm Warning will remain in effect until 10 AM Wednesday. Total snow accumulations of 1 to 3 feet are expected with up to 4 feet of snow at the highest elevations. Wind gusts up to 55 mph are also anticipated along the Sierra Nevada crest with probabilities at 50 to 80 percent. 3. Moderate to heavy rainfall is expected to impact the Sierra Nevada foothills with 3 inches of rain likely to fall in the next 72 hours. Light to moderate rainfall is also forecast for the San Joaquin Valley, with heavier rainfall to the north. 4. The next system is expected to impact the region starting Thursday morning through Friday. Moderate to heavy snowfall is expected for the Sierra Nevada, along with moderate rainfall in the Sierra Nevada foothills. && .DISCUSSION... Current satellite over Central California shows lee wave clouds forming to the northeast of the Coastal Range Mountains, which are to the southwest of the San Joaquin Valley. These clouds herald the arrival of precipitation coming from the southwest into the interior of the state. Ensemble models had shown this precipitation arriving much earlier today, but the low pressure trough off the west coast has yet to move further south, which has lead to our region staying under the lower right-hand quadrant of the jet maximum aloft, which is not conducive to precipitation. The upper right- hand quadrant is currently over Northern California, and with that portion of the jet max being more allowing for precipitation formation, all the rain is to our north. As that trough and the jet with it moves south and more inland, our area will be in under the lower left-hand quadrant of the jet max, the other side of the jet max conceive to receiving precipitation. This is expected to occur later this afternoon and the heaviest precipitation can be expected tonight into Wednesday morning. As this moisture moves in later this afternoon, there is also the possibility for thunderstorms later this evening, with current probabilities at 15 to 20 percent. These chances are mainly along the Sierra Nevada Foothills and Lower Sierra Nevada Mountains, where orographic lifting would raise warm, moist air into cold, drier air, creating instability and producing thunderstorm cells.These cells would then lead to localized heavy rain and would be a risk to any burn scars in the mountains, especially the French Fire scar located in Mariposa. The moisture is also expected to fall as snow in the Sierra nevada above 6,500 feet later this evening. A Winter Storm Warning is currently in effect until 10 AM Wednesday, although current reports haven`t seen snowfall yet. This afternoon is also seeing increased Valley winds, mainly coming from the southwest. Recorded gusts are about 15 to 20 mph, and up into the 30`s north of Fresno. These winds are likely to continue through this evening. The next system is expected to come in Thursday morning as another wave of increased vorticity crosses Northern and Central California. This will provide more energy to bring moisture into the region, and thus more precipitation is likely to fall. Light rainfall is expected for the Valley, while the Sierra Foothills may see more moderate rainfall, with the Foothills having a 40 to 60 percent chance for an inch of rainfall overnight Thursday. There is also a 50 to 75 percent chance for a foot of snow in the Sierra Nevada Mountains at the same time. After the second system clears out, more of a ridging pattern will take over and a dry air mass is expected to set up over the Valley. This will lead to reduced fog potential and increased frost likelihood. Low temperatures currently have a 40 to 60 percent chance of reaching freezing from Saturday through next Tuesday. Long term ensemble models are beginning to show more precipitation chances late next weekend into next weekend, with current probabilities at 40 to 70 percent for a tenth of an inch in the Valley. && .AVIATION... Local MVFR conditions from precipitation across the San Joaquin Valley through 18z Wednesday. Widespread mountain obscuring IFR conditions in precipitation across the Sierra Nevada through 18z Wednesday then areas of IFR conditions until 00z Thursday while showers taper off. Areas of mountain obscuring IFR conditions in clouds and precipitation across the Kern County mountains until 06z Thursday. && .AIR QUALITY ISSUES... On Wednesday February 5 2025, Fireplace/Wood Stove Burning Status is: Burning Discouraged in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties, 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 through Wednesday morning for CAZ317-318. Winter Storm Warning until 10 AM PST Wednesday for CAZ323- 326>328-330-331. && $$ Public/Aviation/Fire Weather.....EW DSS/PIO..........................JWM/DAS weather.gov/hanford