Tropical Storm Andrea forms; Will Impact Region

The first named storm of the 2013 North Atlantic Hurricane has developed in the Gulf of Mexico.  Her name is Andrea and she is not strong but she will be a vigorous rain producer.

Tropical Storm Andrea Advisory 1 (NHC)

Above is the official National Hurricane Center advisory and forecast track (& cone of uncertainty).  I have no quibbles with the track but I do expect it either over Cape Cod/SE MA or just offshore.  Andrea is no a symmetrical tropical system meaning most of the rain and thunderstorms are on the Eastern side of the storm

GOES_East Infrared Rainbow Image 645 PM (NOAA)

Notice the storm pulling moisture out of Central America, but also notice the dry air to the west of the storm.

GOES_East Water Vapor 645 PM (NOAA)

That dry air is a partial result of wind shear

 

SPC mesoanalysis 7 PM Effective Wind Shear 

The radar echos likely spend a few more miles out, but the radar bean cannot see any further from its location on land but you see the point.  There is abundant heavy rain with this system.  Winds are sustained at 40 mph and thats right about where Andrea will stay.  However a bump to 45 or 50 is still significant as the winds kinetic energy increases and thus the potential to snap some branches or topple some trees (http://hamradioskywave.blogspot.com/2013/04/kinetic-energy-factors-of-dynamic.html).  

A cold front is currently marching across the middle of the country

WPC surface analysis 5 PM

At the upper levels there is an area of low pressure driving the front east

12z EURO

By tomorrow afternoon Andrea will be making landfall in the Florida Panhandle and a warm front will be lifting north towards New England

WPC surface forecast Tomorrow 2 PM

By early tomorrow evening this boundary will set off showers and thunderstorms.  Here is this afternoons NAM hires simulated radar for tomorrow at 9 PM

18z NAM hires simulated radar 9 PM Thur

By Friday evening 0.25-0.50 inches of rain will have fallen in New England

WPC Day 1, 2 Precipitation Forecast

We will not have a pure tropical storm in the Northeast as Andrea will be transitioning into a Nor'Easter type system.  None the less overnight Friday into early Saturday morning the rain will be heavy in Southern New England and winds will gust up to 50 mph, perhaps 60 over the Cape and Islands, especially Nantucket.

WPC surface analysis 8 am Saturday

The good news about this track is the strongest winds will stay over the water.  The bad news is that the heaviest rains will be over New England and Upstate New York

WPC 1-3 day Precipitation forecast

This may be underdone slightly because the upper level low at 500 mb may help to energize the extratropical Andrea as she moves up the coast

12z EURO 500 mb heights Friday 8 am

More tomorrow morning, have a good night