Rain moving through; very warm Midwest/East

The first storm system in a series is moving through the Bay Area right now.  It brought light to moderate rain for much of the region with rainfall totals from near a half inch in San Francisco to over two inches in the North Bay, with generally a quarter inch or less south of SF.  These totals are a bit less than was forecasted but still respectable.  The latest radar image shows just a few light areas of rain slowly shifting southward across the area with the bulk of the rain remaining over far northern California.

One area of note though was the South Bay.  San Jose still has only reported a trace of rain from this system, despite radar imagery showing rain over the region for much of the day (not at present though).  A likely reason for this was strong southerly winds for much of the day.  Southerly flow enhances rain in parts of the North Bay mountains and the southward facing Santa Cruz mountains.  However, San Jose is north of the Santa Cruz mountains, so San Jose may have been in the rain shadow.  I haven't looked at enough data to support this hypothesis, but it is possible.  Also, the San Francisco/Monterey area radar is located on Mount Ununhum in the Santa Cruz mountains at near 3000 feet elevation, and thus is detecting rain/clouds well above sea-level.  So while it may have shown rain over the South Bay for much of the day, that precipitation was likely well above the surface and not reaching the ground.

We have a weaker system coming in Thursday afternoon and then a stronger, colder system for Friday and Saturday.  That one will bring much lower snow levels and still some possibility for a few thunderstorms. 

Meanwhile, unseasonably warm temperatures will cover much of the Midwest and East this week, with highs well into the 70s and even 80s.  These temperatures are extraordinarily warm for mid-March, over 30 degrees above normal in some spots.  Chicago, as an example, is expecting highs in the low 80s for Wednesday, which is more typical of June.  The average high for Wednesday is only 46º.  This will certainly be a new daily record, but this may go down as one of the warmest March weeks on record for many locations.  The table below shows a few cities and forecast highs for Wednesday.