March 2, 2022
Upper level high pressure has shifted eastward. Variable cloudiness is streaming over the northern half of California from a trough of low pressure stretching from the Pacific Northwest southwestward out to sea. Clearly there is a low center developing along the southern portion of the trough which continues to slow its eastward progress. It may be after midnight Thursday night before precipitation enters the valley. High resolution models, in estimating precipitation, are really not that impressive this afternoon. First of all, they now show a significant rain shadow developing along the western and southern flanks of the valley. Amounts will pick up closer to the Sierra Nevada. The main thrust of this first system will move through the southern half of California then into the Desert Southwest Friday night.
It will be closely followed by a much colder system out of the Gulf of Alaska which will arrive late Friday night and Saturday. This storm is much colder and will lower snow levels down to 2,000 to 3,000 feet. A pool of cold, unstable air will be above the valley floor Saturday afternoon. If there happens to be breaks in the overcast, the ground under those areas will warm, allowing warm currents of air to move skyward. this could trigger spring thunderstorms Saturday afternoon and early evening. The chance of showers will continue Saturday night, but will end by Sunday morning. Over the eastern Pacific, a large high will be running from southwest to northeast into the Gulf of Alaska, creating a northerly flow over California which will keep temperatures below freezing through the middle of next week. Local frost will be possible.
Upper level high pressure will slowly move in from the west by midweek for dry weather and a warming trend.
Forecast: Variable cloudiness tonight. Mostly cloudy Thursday. A chance of light showers after midnight Thursday. Periods of light showers Friday and Friday night. Scattered showers Saturday and Saturday night. There will be a chance of isolated thunderstorms Saturday afternoon and early evening which, should they develop, will be accompanied by small hail and heavy rain. Mostly to partly cloudy Sunday into Monday morning. Mostly clear Monday afternoon through Wednesday.
Wind Discussion: Winds will be generally at or less than 8 mph with periods of near calm conditions, mainly during the night and morning hours, through Thursday night. Winds Friday through Saturday will be out of the northwest at 8 to 15 MPH with stronger gusts.
Rain: a secondary low developing along the off shore trough continues to slow the trough’s eastward movement. It may be after midnight Thursday night before showers begin to spread into the valley. The latest high resolution models have reduced projections for precipitation for the valley. they clearly show a rain shadow developing along the west side and in Kern County. This first system will move through southern California Friday as a much colder system dives southward out of the Gulf of Alaska and right over central California Saturday. This will renew the shower activity with a pool of cold, very unstable air above the valley. This could generate isolated thunderstorms Saturday afternoon through the early evening. Should they break out they will be accompanied by small hail and heavy rain. Dry weather will return Sunday and continue for what appears to be most, if not all, of next week.
Rainfall amounts will range from a tenth of an inch or less around the west side and in Kern County to as much as a quarter to a third of an inch along the east side north of a Porterville/Tipton line.
Frost: all locations will be above 32 through Saturday morning. We are still on track for much colder weather arriving during the weekend. Low to mid 30s continue to be likely Sunday through Wednesday of next week. Any night with mostly clear skies and calm winds could potentially see winds in the upper 20s in those low lying frog pond areas. Most locations, however, should remain between 30 and 35 or so. After Wednesday, temperatures will begin to modify, pulling most locations above freezing.
Next report: March 3