Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
361 FXUS66 KSTO 132027 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 127 PM PDT Tue Aug 13 2024 .SYNOPSIS... Near to slightly below normal temperatures persist this week alongside periodically breezy diurnal winds. && .Discussion... GOES-West visible satellite imagery shows smoke from the Boise fire moving over the northern Coast Range and funneling into portions of the northern Sacramento Valley, otherwise mostly clear skies prevail across Northern California. Temperatures are on track to be a few degrees warmer today and tomorrow, but remain approximately 2 to 10 degrees below normal. The trough that brought enhanced diurnal winds to the region yesterday/Sunday, will continue to weaken and shift eastward today. Entraining dry air left in its wake will lead to a brief downtrend in relative humidity values through Wednesday before values increase by late week. Wednesday into Thursday, a weak shortwave trough will travel along the California-Oregon border. An isolated shower developing over the northern Shasta County mountains during the afternoon hours cannot be ruled out, but probabilities are low (around 5-10%). This feature then quickly phases with a deepening trough off the Pacific Northwest coast that looks to remain fairly stationary as building high pressure over the Four Corners prevents it`s eastward advancement. As the trough deepens, enhanced onshore flow will return to interior NorCal with the NBM showing a 20-50% probability of Valley winds gusting 25 mph or greater on Saturday, with a 70-95% chance across the Delta and mountains. Troughing influence will keep high temperature near to below normal through this week, as a gradual cooling trend persists through the weekend. && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... Latest cluster analysis continues to highlight the stationary nature of a deepening trough off the coast of the Pacific Northwest through the weekend. There are some indications of the trough weakening, but still remaining stationary, into early next week. A few solutions do suggest increasing heights over NorCal early next week as the aforementioned Four Corners ridging expands westward. Temperatures will continue to gradually cool through the weekend with a 70-100% chance of high temperatures less than 95 deg F. However as that ridging sets in temperatures will gradually increase (still remaining near or slighly below normal) with the NBM indicating a 20-40% chance of Valley high temperatures greater than 95 degF Monday and Tuesday. && .AVIATION... VFR conditions prevail across interior NorCal next 24 hours except isolated MVFR in HZ/FU in vicinity of fires. Surface winds generally less than 12 kts, although late day gusts to 20 kts possible in Delta vicinity and upper elevations in mountains. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$