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County Warning Area [CWA]: STO
Regional NWS Weather Office: Sacramento, CA
County Warning Area [CWA]: STO
Regional NWS Weather Office: Sacramento, CA
000 FXUS66 KSTO 230850 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 150 AM PDT Tue Apr 23 2024 .Synopsis... Cooler thru mid-week along with a chance for afternoon showers and thunderstorms over the mountains. Precipitation chances increase Thursday into Friday as a weather system moves through, best chances in the foothills and mountains. && .Discussion... A robust Delta Breeze is under way as the strong upper ridge of the past several days has weakened and begun to shift east. Stratus surged north along the coast on Monday and profiler data indicate the marine layer has deepened to around 3k ft or deeper. Surface pressure gradient has reversed from offshore to onshore and southwesterly gusts of 25-35 mph are common from the Sacramento area into the Delta. Mid-level moisture and instability has begun to get drawn northward ahead of the offshore trough. Forecast soundings indicate some elevated instability over the region this morning with the moisture increase, but the question is whether lift will be sufficient to pop some showers. Recent satellite imagery shows some mid clouds beginning to develop, and even some virga from these may be enough to seed some drizzle or light rain as marine stratus spreads inland this morning. Otherwise, in addition to the significantly cooler temperatures, we`re looking at mainly diurnal mountain showers and thunderstorms later today and Wednesday as the initial trough and closed low pass mainly to the south of us into SoCal. Behind that system, a couple stronger short-wave troughs are forecast to drop into NorCal later in the week reinforcing the cool and unsettled pattern and bringing a better chance for showers later Thursday into Friday. QPF is expected to be less than 0.10" in the valley with around 0.50" over the mountains. Snow levels will be around 7k ft or so with light snowfall accumulations possible over the higher peaks. Impacts to travel are expected to be minimal. && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... Saturday morning, the low pressure system that brought light snow and showers to the area late in the week moves south and east out of the Great Basin. Some lingering showers may impact areas in the foothills and mountains, though most precipitation will occur on Friday. A brief, broad and flat ridge will then move over the area, increasing the high temperatures on Saturday and Sunday afternoons. A developing low over the Pacific Northwest will keep temperatures from climbing any further on Monday and Tuesday though, with area high temperatures expected to remain near seasonable levels all four days. Valley high temperatures will reach around the low to mid 70s during this time, with foothill temperatures ranging from the mid 60s to low 70s, and the mountains from the 50s to 60s. Overall, conditions will be mild and dry throughout the extended forecast period. && .AVIATION... Areas of MVFR ceilings with drizzle expected to develop over the southern half of the Sacramento Valley early this morning and continue until about 18Z, otherwise mainly VFR conditions next 24 hours. Scattered thunderstorms develop over the mountains after 20Z with local MVFR conditions in the vicinity. Areas of southwesterly surface wind gusts 25-35 kts west Delta, and local southerly gusts 15-25 kts in the southern Sacramento Valley next 24 hours. Lighter winds elsewhere. && .STO WATCHES/WARNINGS/ADVISORIES...None. && $$
Forecast Discussion from: NOAA-NWS | Script developed by: El Dorado Weather |