Weekend Weather Take 5.19.13

An unsettled week of weather is shaping up for Southern New England.  A stagnant boundary will allow temperatures to warm into the upper 70's when the sun is out, but will also usher in periods of showers and thunderstorms.  Bear with me, this is likely to be a frustrating forecasting week. 

Current Conditions/Short Range Forecast

The best way to start out this morning is by looking at 3 different levels of the atmosphere.  Usually I like to work from the surface on up but first here is the 250 mb jet stream.  

06z NAM 250 mb jet 8 am (NCEP)

A streak is digging into the Southern Plains as warm moist gulf air is being pulled into the Central US.  A ridge is in place over much of the east; in New England we are on the edge of the ridge and a departing trough.  This is easier to see at the 500 mb level

06z NAM 500 mb vort 8 am (NCEP)

A boundary exists across Northern MS, AL, GA and Southern TN, NC.  Another boundary exists near the Mid Atlantic.  The National radar is busy this morning

NWS National Radar 838 am 

Finally here is the surface analysis

WPC surface analysis 617 am

Several surface low pressure systems have developed along the boundary in the Midwest.  A significant severe weather outbreak is likely across much of the region.  Check out the US temperatures as of 8 am

US 2 m temps 8 am (image weatherbell)

Keep in mind it is 5-6 am in the west but as we can see from the surface chart a large thermal gradient should exist across the US.    None of these features are in a hurry to move which makes the forecast complex. 

Short Range Forecast

Today the stationary boundary to the south will try to work north as a warm front.  High pressure in the Gulf of Maine will act as resistance.  Temperatures at 8 am were in the 50's in SNE but climbing

8 am 2 m temps (image weatherbell)

The Northeast radar shows shower activity in SW CT 

NWS Northeast Regional Radar 918 am

These showers are moving southeast (in the direction of the upper level flow) but guidance suggests more showers develop in Western New England and move east this afternoon as the warm front pushes Northeast.  Here is the NAM hires simulated radar early this afternoon

06z NAM hires simulated radar 2 pm (image weatherbell)

The rainfall will be mainly light. I wouldn't cancel any outdoor plans.  Temperatures will likely peak late this morning before cloud cover spreads over the entire region

GOES_East Southern New England visible sat 915 am

When the rain falls temps will settle around 60.  When the sun shines most will be around 70

Tonight due to cloud cover temperatures will remain in the mid to upper 50's.  The clouds will begin to break apart around 10 am and temperatures will soar to the upper 70's/low 80's.  The warm front is expected to push into Central New England

WPC surface analysis Monday 8 pm

Temperatures surge into the low 80's tomorrow afternoon

12z NAM hires 2 m temp 1 pm Mon (image weatherbell)

Under a set up like this much of New England has a chance of thunderstorms

SPC day 2 outlook

On Tuesday the warm front will sag back south of New England.  It will surge north again on Wednesday

WPC Surface forecast 8 am Tuesday

Temperatures Tuesday should be in the low 70's.  I think the place to look for a scattered shower on Tuesday will be the CT River Valley.  Wednesday is a transition day as the warm front lifts north again

WPC surface forecast Wed 8 am

Thursday may be a major severe weather day in the Northeast.

WPC surface forecast Thursday 8 am

We have an active pattern right now.  Keep an eye to the sky tomorrow evening as the short range models build up some nice looking storms on the simulated radar.  Talk to you in the morning