Flood Watch For Interior Southern New England

Light rain fell across much of Southern New England (SNE) yesterday as a cold front moved into the Atlantic.  The result is pretty nice Saturday morning as heights have risen in the northeast.  This will be short lived as a coastal low will creep slowly past the South Shore resulting in inches of rain.  The National Weather Service in Taunton has issued a Flood Watch for interior SNE

03/29/14 NWS Boston Headlines

Current Conditions

A look at the regional visible satellite shows some breaks of sun in the clouds this AM

GOES_EAST visible satellite 1002 AM (NOAA)

This has allowed some temperatures to jump into the low 50's

NWS Boston 10 am Temperature OBS (Mesonet)

Here is the 500 mb for 11 am off the 12z NAM (8 am model run).  

12z NAM 500 mb vort 11 am Sat (image NCEP)

Notice the ridge over the NE?  That will push offshore into the Western Atlantic today.  The dip in the Mississippi River Valley is driving our rainstorm and that will slowly push east.  The rain is right on doorstep of SNE 

NWS Northeast Regional Radar 1008 am

The Water Vapor Loop shows how much moisture is available 

GOES_East Water Vapor Satellite Loop 915 am (NOAA)

That moisture is moving directly up the east coast

SPC 14z 850 mb Moisture Transport

Now let's move forward and talk about the impacts and timing for SNE

Short Range Forecast

The latest high res NAM is bringing temperatures into the mid 50's across many areas by 1-2 PM

12z NAM Hires 2 m temps 1 PM (image Weatherbell)

By 2 PM the rain line will be approaching the MA border

13z HRRR Simulated Radar 2 PM (image Weatherbell)

It will rain heavily overnight today.  Here are the projected rainfall totals through 8 am tomorrow 

WPC 1 day precip forecast 

If we move this through 8 am Monday we are looking at widespread 2" + of rain, and scattered 3" + amounts

WPC Day 1,2 precip forecast 

The storm will move very slowly because of blocking upstream in the Atlantic.  We couldn't get any blocking for our snowstorms this winter which meant they dropped their snow and continued on their merry way.  This low will slowly move past the Cape.  Here is the projected surface chart for 8 am tomorrow

WPC projected Surface Analysis 8 am Sunday

Here is the projected surface chart Monday AM

WPC projected Surface Analysis 8 am Monday

It may be cold enough for freezing rain Monday AM.  I will keep an eye on that.  

Flooding

This is a very useful link for Southern New England River information .  You can track your local river right there.  My local river is the Blackstone River at Northbridge.  It is forecast to rise to 7.2 ft, which is below flood stage

NERF Blackstone River Hydrograph, forecast

2-3 inches of rain in the Blackstone Valley should keep the Blackstone in its banks,  However minor flooding is possible if some of the more aggressive short range models are correct and upwards of 4" fall.

09 SREF QPF Worcester (image Weatherbell)

There is a lot of information to digest but the bottom line is heavy rain is on the way for the next 2.5 days.  More as needed

-Zack Green