Tuesday, May 7, 2013

Upper 70's Today, Showers Tomorrow

A warm dry Tuesday will be followed by a warm unsettled Wednesday.  For the first time in weeks rain is in the forecast.  While there is no need to build an Ark, it will be nice to get some water into the ground.  A cold front moving in from the west will drop more rain this weekend.

Observations/Short Term
WPC surface analysis 330 am
A surface low pressure is located in Western North Carolina.  At the upper levels this system looks like this
06z NAM 500 mb vort 8 am (image NCEP)
For another view here is the jet stream at 250 mb (way up in atmosphere) 
06z NAM 250 mb winds (image NCEP)
Underneath these cut off lows as they are called (notice the other low along the West Coast) temperatures are low.  For example yesterday it was much warmer in Massachusetts than it was in Atlanta, GA.  This really shows up in afternoon temperatures.  First here are the morning temperatures in New England
4 am 2 m temps (image weatherbell)
Precipitation is slowly creeping north on the radar, but it will not reach us until tomorrow.  
NWS Northeast Regional Radar 548 am
I expect mostly clear skies except along the immediate coast of CT, RI, and Cape Cod.  These areas will have an onshore Southerly flow.
06z NAM cloud cover 2 pm (image weatherbell)
Now here is the national temperature outlook this afternoon.  Remember where the two cut off low's were located
00z EURO 2 m temps Tues PM (image weatherbell)
Zoomed in to New England here is what to expect for us
06z NAM hires 2 m temp 3 pm (image weatherbell)
Nearly all of Southern New England will be in the mid to upper 70's.  No doubt a few places crack 80.  The cool spots will be where the clouds build along the coast.   Clouds will build in tonight as our low approaches from the south.  The clouds keep overnight lows in the 50's tonight.  The clouds linger tomorrow and rain will be approaching.
WPC surface forecast 8 am Wed 
The precipitation edge will be reaching Southwest CT right around 8 am.  Rain should build into Southern New England through Wednesday morning.  The precipitation will be convective in nature meaning several clusters of showers and thunderstorms will develop.  None the less until the rain falls on you temperatures will be in the low 70's
06z NAM hires 2 m temps Wed 1 PM (image weatherbell)
Around 0.25-0.50 inches of rain will fall.  SW CT looks to be the jackpot
WPC Day 2 precipitation outlook
On Thursday we have an interesting set up.  At the surface low pressure will still be affecting Southern New England
WPC surface forecast Thursday Morning
Guidance is indicating precipitation that looks like it could/should be convective.  In layman's terms I expect thunderstorm's on Thursday.  These upper level low's create a cold pocket aloft that is highly unstable.  With the low pressure providing a trigger, some isolated heavy rain during the day Thursday is likely.  Even the SPC has a chance of thunderstorms possible
Storm Prediction Center Day 3 thunderstorm outlook
As of now nothing severe looks imminent.  That said anytime there is a cold pool hail is always a possibility.  Friday looks to be similar to Thursday.  High temperatures will be around 70.  For the week, here is the 5 day precipitation outlook
WPC 5 day precipitation outlook
That's all for today.  First look at the weekend tomorrow morning and I'll be tracking the rain.














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