Thursday, February 28, 2013

Unsettled Pattern Through Weekend

Yesterday's storm brought over an inch of rain to most of Southern New England along with wind gusts in excess of 50 mph.  There was also snow in the highest elevations of Massachusetts and New Hampshire.  Here is a list of storm reports from the NWS.  Due to an upstream block in the atmosphere the system is taking its time to exit the Northeast but its not strong.

NWS Northeast Radar
At the surface we see several low pressure centers
SPC Surface Analysis 5 am EST
We see low pressure north of Lake Ontario and along the Maine coast.  There is a another low pressure center developing near Maryland, which is picked up on the HPC surface analysis
HPC Surface Analysis 530 am EST
This system has been largely driven by the upper level energy and that continues this morning.  Here is the 500 mb chart from 1 AM
06 NAM 500 mb vort valid 1 AM (image NCEP)
As this spins toward the coast more weak low pressure centers should form and these will have the potential to drop some locally heavy rain.  It will be rain as its not all that cold this morning
5 AM Temperature Analysis (image weatherbell)
By afternoon we are jumping into the mid to upper 40's
10z RAP 2 m T 2 PM EST (image weatherbell)
Short range guidance is indicating a band of rain for most of Southeast New England around 1 or 2 PM today.  Moving on to tonight the same threat will exist BUT temperatures will fall to around freezing.  This will potentially allow for snow.  Accumulations are likely light but a quick inch or two is not out of the question for CT/RI/SE MA.  Here are the temperatures for 4 am Friday Morning
06z NAM Hires 2 m T 4 am (image weatherbell)
Basically you can take this forecast and repeat Friday, Saturday, Sunday, and Monday.  Precipitation at night is more likely to fall as snow.  Daytime temperatures look to be in the upper 30's/low 40's.  The reason is a slow moving upper level low.  These are difficult to forecast so I will be paying attention to the short range models in case there are any surprises.  Here is the 500 mb on Sunday Afternoon
06z NAM 500 mb vorticitiy (image weatherbell)
If you scroll back up you can see the closed low over New England has not moved much.  In late April or May its these type of systems that can sit and we don't see the sun for days (think May 05, 06).  Actually most of you probably won't remember that unless you are a weather weenie like me.  None the less here is the 5 day precipitation totals
HPC 5 day precipitation totals
It doesn't look impressive, but that max off the Cape is worth watching.  Finally there is a rumor about a storm next week.  I'm not on board for a storm but its going to be close.  Have a good day.









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