Saturday, May 11, 2013

Rain Clearing, Thunderstorms Later

A cold pushing towards the east coast will bring showers this morning and thunderstorms this afternoon.
WPC surface analysis 630 am
The water vapor satellite looks like this
GOES_E water vapor satellite 645 am
Here is the current regional radar
NWS Northeast Regional Radar 728 am
A break in the precipitation will last until around 930 am before another round of showers and embedded thunder move in.  That batch of rain will last a few hours and then the sun may break out in Western/Central MA, RI, and CT.  Here is the 3 PM simulated radar
06z NAM hires simulated radar 3 pm (image weatherbell)
Temperatures at 4 PM
06z NAM hires 2 m temps 4 pm (image weatherbell)
And finally the simulated radar at 5
06z NAM hires simulated radar
The storm prediction center thinks the main severe threat will be in the Mid Atlantic, but still sees the thunderstorm threat for New England
SPC day 1 outlook
The SPC is a world class meteorological center.  However New England is different when it comes to thunderstorms.  Some of the usual parameters meteorologists use to forecast severe weather do not hold in our part of the country.  Take Thursday for example; an EF-0 tornado touched down in Stoughton, MA.  Many small localized thunderstorms developed and packed a strong punch.  Now the dynamics were different on Thursday- those storms were triggered through an anomalous cold pool aloft.  Today will be a more classic set up.

Here are the surface winds around 5 pm
06z NAM 10 m winds 5 pm (image weatherbell)
Here are the winds a few thousand feet up
06z NAM 850 mb winds, temps 5 pm (image weatherbell)
The winds are southerly at the surface, southwest at 850 mb.  That is low level wind shear which is one ingredient for strong thunderstorms.  Western MA and CT will face the biggest threat.  By the time this cluster gets close to Boston it should be falling apart.  I'll be watching throughout the day and will update with any watches and warnings.  









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