Author: John Hibler

March 17, 2021 Weak upper level high pressure is currently building in from the eastern Pacific but will only control our weather for another 30 hours or so.  Much warmer air has already moved in above the valley floor.  The freezing level above Oakland has jumped up to 8,700 feet as the cold core low…

 March 16, 2021 A northwesterly flow aloft continues to develop upslope clouds against the Sierra Nevada foothills.  These clouds are arching out over the eastern half of the San Joaquin Valley.  Drier air embedded within this flow will begin to cause the clouds to dissipate overnight, although some cloudiness may last into Wednesday morning.  Currently,…

March 16, 2021 The cold core low has raced southeastward and is now centered in western Arizona and will reach the Four Corners region by this evening.  The northwest push of air behind the low continues to generate upslope clouds against the valley facing slopes of the Kern County mountains and the southern Sierra Nevada…

 March 15, 2021 The center of circulation of an extremely cold weather system is just above California at this hour.  No surprise that convective showers and thunderstorms are breaking out.  I’m already seeing reports of small hail in the northern San Joaquin Valley.  Winds are screaming over the Kern County mountains and the deserts of…

March 15, 2021 Welcome back to January.  The freezing level taken over Oakland this morning is as low as I’ve seen it all winter.  The balloon sounding pegged the level at just 2,900 feet.  Over Vandenberg AFB, the freezing level was dropping rapidly with a current level of 4,400 feet.  Most models underestimated the strength…

March 14, 2021 Clouds are increasing ahead of a very cold low pressure system which extends from its center over the Yukon Territory of Canada southward to off the northern California coast.  Showers are already spreading over northern California and will advance quickly into central California tonight and Monday morning.  There are models that place…

March 14, 2021 A very fast moving and very cold low is currently stretched from the parent low over the Yukon Territory of Canada with a trough extending southward to off the northern California coast.  The southern flank of the  trough will pinch off, forming a very cold low over northern California tonight.  it will…

We will be out of the office this afternoon.  Reports will resume Sunday morning.     March 13, 2021 Finally, the cold core low has moved far enough to the east to allow a temporary warming trend.  The low itself is now in  northern Arizona and will move into the Four  Corners region this afternoon. …

 March 12, 2021 The cold core low has now moved to a position over northwest Arizona.  The wrap around cloud deck from this storm is bumping up against the Sierra Nevada and the Kern County mountains, putting the southern San Joaquin Valley in a reverse rain shadow.  The airmass remains quite cold with temperatures at…

March 12, 2021 Heavy cloud cover remains over the southern half of the San Joaquin Valley this morning.  the center of the cold core low has now drifted to a position over southeast California.  The circulation pattern around the storm has winds aloft out of the northeast now.  Wraparound moisture will continue to affect the…