Storm system makes a quick exit, thunderstorms possible today

March 25, 2020 – Scattered showers today with mountain snow gradually tapering off. A few showers linger into Thursday, otherwise dry and milder late this week with unsettled weather returning this weekend.

Discussion

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The upper trough is settling over the region as the main frontal zone has shifted south into central California. Radar shows most of the lingering showers over NorCal early this morning are to the south of Sacramento and over the northern Sierra where light snow continues to fall at KBLU (7 inches has accumulated so far since early Tuesday). To the north of Sacramento, satellite shows mainly clear skies across the Sacramento Valley.

NorCal will be under the cool positive-tilt upper trough today as it continues to slowly edge south and east. Scattered showers and a few thunderstorms will become a little more numerous across the Central Valley by this afternoon as instability increases with the trough axis moving overhead (-32C at 500 mbs). Showers expected to taper off rather quickly this evening as instability wanes following sunset, and the upper trough edges a bit further east.

Dry and milder weather expected for most of the area on Thursday and Friday, though scattered showers likely to redevelop across the southeast corner of the forecast area (Sierra Nevada south of Lake Tahoe) Thursday afternoon on the backside of the departing trough. Next upstream weaker short-wave may bring a return of a few showers to the region Friday night and Saturday.

Extended discussion (Sunday through Wednesday)

Digging upper trough drops into interior NorCal Sunday into Monday continuing a threat of showers, mainly over the mountains and in the Northern Sacramento Valley. Deterministic models and ensemble solutions then point towards drier weather Tuesday into Wednesday as upper level ridging dominates. Warming trend expected through the extended forecast period with high temperatures climbing to about 10 degrees above normal by the middle of next week.