Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
436 FXUS66 KHNX 191101 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 301 AM PST Sun Jan 19 2025 && .KEY MESSAGES... 1. Little change is temperatures are expected through the rest of the holiday weekend into next week. 2. Strong northeast winds are forecast in eastern Kern County between Monday afternoon and Tuesday morning. There is a 25 to 45 percent probability for wind gusts of 45 mph or higher along the Mojave Desert Slopes on Monday evening. 3. Sub-freezing temperatures will remain possible each night and morning through Friday across mainly rural areas in the southern San Joaquin Valley. There is up to a 75 percent probability for low temperatures of 32 degrees or lower across western Kern County. && .DISCUSSION... The upper level pattern is anchored by a strong upper low fixed over Hudson Bay with a strong longitudinal ridge poke all the way from the eastern Pacific to the North Pole along 145W. Shortwaves rotating around the upper low dive down the Canadian Rockies into the Great Basin and move into the southern plains. This keeps the surface high pressure over the Great Basin and general low pressure off the California Coast for northeast flow for the region through the week for more of the same cool morning with low end chances of fog for the San Joaquin Valley, breezy conditions for the Mojave Slopes and Kern County desert, and near to slightly below freezing temperatures in the lowest spots of the San Joaquin Valley. A rinse and repeat pattern through the weekend into next weekend where there is some hope for some mountain showers, but we will wait and see how that develops this week. This morning the prime issue is fog development in the San Joaquin Valley. The night fog satellite channel shows the fog attempting to organize this morning. There is some less than 5 mile visibility out there however dew point depression is still most 4 degrees C. The concern is a sunrise surprise event similar to yesterday morning. Yesterday morning at this time dew point depression was 2 degrees C or a little close at Merced. Going to keep a watch on highway cameras and observations before issuing a Dense Fog Advisory. The HREF probabilities of sub 1/4 miles visibility is 20 to 50 percent from Highway 99 west to the I-5. This puts Highways 41, 43, and 198 in the highest probability for seeing Dense Fog this morning. The probability of sub 32 degrees is right on the numbers with fog in the same area this morning. Monday fairly similar on temperatures and fog to this morning. The problem area focuses over on the Mojave Slopes. A 1046 MB high over southeastern Idaho and a 1018 MB low off the Channel Islands sets up a fair gradient for northeast wind across the Slopes and Kern County Desert. The issue is the HREF probabilities are much lower than the NBM. Comparing the two at 45 mph and above the HREF has, only at the very highest elevations, 25 to 50 percent probability. Now the NBM at the same time has 35 to 75 percent probability with high probabilities at the Highway 58/14 junction, a common trouble spot. The NBM 1D 25/75 whisker plot shows a better probability of up to 40 mph but not over, however does show the few members that run up the wind gusts higher. This is shown on the probabilities of the NBM of exceeding 60 mph at 10 to 20 percent in the common windy spots. The HREF is near zero. At this time the spread is large enough to avoid highlights for now. Will see if there is better agreement in the follow up runs of the HREF and NBM. Tuesday through Saturday the focus remains on freezing valley temperatures. 20 to 60 percent is the general rule with higher percentages in the lower part of the San Joaquin Valley. The highest probability of widespread freeze is Tuesday and Wednesday mornings. For now, will not go for a freeze watch. The probability of hard freeze at 28 degrees is down to 15 percent or less with the except of the southwestern valley with up to 30 percent. Next Sunday, a very low probability, the tiny cut off upper low zips through the area and spins up a Mojave Desert Low shifting the wind regime and giving a slim chance for precipitation in the Sierra. The CPC 6 to 10 and 8 to 14 days maintains the cooler and dry pattern for Interior Central California as we approach February. && .AVIATION...12Z: VFR/MVFR VSBY here at the start of the 12Z period across the valley with only KHJO falling into IFR VSBY. The LAMP probs favor the best probability of IFR at the rural terminal locations of KMCE and KVIS from 14-18Z with 40-60 probability and less than 20 percent probability of LIFR. NBM guidance favors the same and does for less than an hour drop to LIFR. Plan on holding MVFR VSBY and TEMPOing IFR for KMCE/KVIS. Otherwise, post 18Z VFR. VFR conditions will prevail elsewhere across the area for the next 24 hours. && .AIR QUALITY ISSUES... ISSUED: 01/18/2025 14:37 EXPIRES: 01/19/2025 23:59 On Sunday January 19 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... None. && $$ Operations...Proton DSS..........DCH weather.gov/hanford