April 8, 2020 – Lingering showers possible in the southern CWA into Thursday, mainly over the Sierra Nevada. Otherwise dry and warmer with locally gusty northerly wind at times in the Central Valley.
548 DM closed upper low off the SoCal coast is progged to slowly shift inland later today. This will keep a threat of wrap around showers over southern portions of the CWA. Main threat will be over the Sierra Nevada. Meanwhile, EPAC high builds into the PacNW and sets up low level N-S pressure gradient over the Central Valley today with some locally breezy northerly wind. 1000-500 mb thicknesses on the rise today with downslope flow results in warming AMS. Guidance suggests high temperatures this afternoon will be upwards of 15 degrees warmer in northern portions of the Sacramento Valley with lower 80s expected.
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Low level flow turns more upvalley Thursday resulting in slight cooling as suggested by guidance. In the northern mountains, AMS continues to warm as heights/thicknesses trend up. Max temperatures expected near to slightly above normal. Minor cooling and threat of showers continues Thursday in the southern CWA, with best chances over the Sierra Nevada.
Shower threat shifts south of the CWA Friday as upper ridging increases over NorCal. AMS warms under increasing subsidence with high temps 5 to 15 degrees above normal by the weekend.
Extended Discussion (Sunday through Wednesday)
To finish out the weekend, a broad upper ridge will extend over the east Pacific while heights begin to lower across the Intermountain West. Weak ascent in response to the passing trough could spark a few showers over the Sierra on Sunday. Otherwise, the ridge/trough configuration will foster a period of breezy northerly winds across the Valley which extends into Monday. The offshore ridge should gradually re-establish its presence over the region based on the latest global ensembles. This enforces additional warm, dry weather into next week. Daily high temperatures across the Delta and Valley will sit in the mid/upper 70s, locally into the low 80s over the northern Sacramento Valley. This is roughly 5 to 10 degrees above mid-April climatology.