Monday, February 28, 2011

Subtropical Visit?

After a fantastic couple of days of skiing, a bit of a pattern change is in store for this week.  In particular, over the next couple of days, cyclogenesis will occur over the eastern Pacific, leading to a surge of subtropical moisture into California and the Sierra Nevada late Tuesday and Wednesday.  As this occurs, we will see the large-scale flow over Utah shift to southwesterly with a strong connection into the subtropics.  Note the surge of high precipitable water air into California late in the loop below.

0600 UTC 28 Feb initialized GFS sea level pressure
(black contours), preciptable water (color fill) and 250-mb
(jet level) wind vectors (red).
The Sierra in in store for a round of storminess for sure, although snow levels may rise to as high as 6000 feet near Lake Tahoe during the storm.

Due to the large-scale southwesterly flow, this will be a good case to examine the transformation (drying and warming) of the airmass across the Sierra Nevada and the evolution of the "leftovers" over the Intermountain West.

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