121 FXUS66 KHNX 062058 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 158 PM PDT Wed Oct 6 2021 .SYNOPSIS... A Pacific storm system will bring much cooler temperatures and a chance of mainly light precipitation Thursday night into Friday. We will see unsettled weather continue across the Sierra Nevada on Saturday and again on Monday as a series of cold weather systems will drop out of the Great Basin and move south into the Sierra. && .DISCUSSION...One more relatively warm day will continue today with some high clouds at times. Southwest flow aloft has already set up over Central California. In addition, the westerly component associated with the winds will allow wildfire smoke to gradually pull away from the San Joaquin Valley. By Thursday, expect slightly lower temperatures, though much cooler on Friday. Daytime highs will likely fail to reach 70 degrees at most locations on Friday, or fall to about 15 degrees below average. Increased winds are possible by Thursday night and Friday, including over the mountains and near the ongoing wildfires. Otherwise, expect an increase in humidity and chances in precipitation. Rainfall amounts are expected to be less than one tenth of an inch in the Central Valley and West Side Hills, and amounts will be a little higher over the mountains, or between one quarter and one half inch. The probability for a tenth of an inch of rain at Fresno is around 40 percent, while there is a 40 percent chance that quite a few mountain locations will observe at least a quarter of an inch. Snowfall amounts above 8,000 feet will be around one to three inches. Snow levels during the beginning of the precipitation on Thursday night into Friday morning will be around 8,000 feet or higher and lower to around 7,000 feet by Friday evening. During Friday afternoon and early evening, there is the potential for isolated thunderstorms that could produce small hail and gusty winds. Ensemble and blended guidance suggest a small amount of CAPE while a fairly cold and unstable airmass moves overhead, so we can't rule out thunderstorms, at least over the mountains. Some lingering showers are possible over the Sierra Nevada on Friday night into Saturday, and snow levels will remain steady. Weak ridging will return for Sunday, so rising temperatures will briefly occur. Daytime highs could be a few degrees below average, or similar to what is forecast to occur on Thursday. Another low pressure system will bring the chance for precipitation over the mountains and potentially stronger winds on Monday and Tuesday of next week. The wind-prone areas may get a bit gusty, including towards the Mojave Desert slopes in eastern Kern County. More details will likely follow regarding next week's system, although it is more certain that cooler than normal temperatures will prevail into the middle of next week. && .AVIATION... Areas of MVFR visibilities along mainly the east and southern sides of the San Joaquin Valley will continue at times over the next 24 hours. Also, expect mountain obscuring IFR visibilities due to smoke and haze, especially near active wildfires. Elsewhere in the Central California interior, VFR conditions will prevail. && .AIR QUALITY ISSUES... On Wednesday October 6 2021... Unhealthy in Tulare County. Unhealthy for sensitive groups in Fresno and Kern Counties. Very unhealthy in Sequoia National Park and Forest. Further information is available at Valleyair.org && .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 an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ Public/Aviation/Fire Wx...BSO PIO/IDSS..................JEB weather.gov/hanford