Monday, February 27, 2017

Brief Cool Down Concludes Monday AM

After multiple days of record breaking weather, temperatures have briefly returned to seasonably average levels.  This will not last long as a storm system will pass to our west midweek.  Combining with high pressure in the Western Atlantic, a moisture-rich air mass will stream into Southern New England.  Severe weather will once again be possible in the Northeast on Wednesday when a cold front pushes towards the coast.  The greatest threat for storms will be to our west and south.  The mere threat of thunderstorms means temperatures will once again rise into the 60's/70's.

General Overview/Short Term Forecast
PM temperatures in SNE are expected to rise into the low to mid 50's.  Winds will be from the southwest this afternoon with gusts as high as 25-30 MPH possible.  Despite abundant sun this PM, this will take some of the shine out of the nice temps.
NWS Max temps Monday PM (image Weatherbell)
There are no precipitation chances this afternoon or this evening.  High pressure is slowly sliding to the east into the Atlantic.  That will bring the mild air back into our parts.
WPC Surface Fronts/Precipitation Monday 7 PM 
Despite the lack of precipitation, a *Flood Warning* has been issued for the Connecticut River at Hartford.  Remember, the first two weeks of February featured a lot of cold and snow, especially in Northern New England.   The warmth of last week released a lot of water into the CT River system.  Some minor flooding in the low-level areas is likely tonight through Tuesday before the river crests.
NWS CT River forecast at Hartford
Ice jams left parking lots at Plymouth State University in NH under several feet of water yesterday.
Siobhan Lopez WMUR photo of cars submerged on 2/26/17 in Plymouth. NH
  Tornadoes, record warm temps, and flooding.  What the heck is next?!?  Well, a weak cold front will try to edge south from Northern New England tonight.  At the same time, a ridge will try to advance NE with warmer temps.  Temperatures tonight fall into the low 30's with a threat of precipitation between 5-9 AM tomorrow, mainly north of the Pike. I expect some mid-day clearing on Tuesday which should help get temperatures into the mid 50's.
NWS Max temps Tuesday (image Weatherbell)
Some light drizzle/showers will move back into the region around 4 PM.  This is in association with a warm front lifting northeast.  The warm temperatures are behind this boundary and this is what we will see Wednesday.

Tuesday PM-Wednesday PM
WPC Surface Fronts/Precip Tuesday 7 PM
I expect the showers to pick up in intensity after 9 PM.  Here is the simulated radar for 11 PM tomorrow night.  These showers will drop around 0.25" on average, with isolated higher amounts.
12z NAM hires 3km sim radar Tuesday 11 PM (image Weatherbell)
Temps stay in the mid to upper 40's thanks to the warm front lifting north.  The rain lets up around 4 AM.  Then it's time to watch how the atmosphere evolves.  The parent cold front to our west is primed to deliver a moderate severe weather event in the South, Ohio Valley, and Mid-Atlantic.
Current Day 3 Severe Weather Outlook (Wed 7 am to Thur 7 am)
Damaging winds, hail, and tornadoes are on the table for our friends to the south.  How much of that can get into PA, NY, NJ, and New England?  I think NY and PA will be facing a widespread damaging wind threat.  Cloud debris left over from AM showers will limit the atmospheres ability to destabilize in New England.  We thought the same thing on Saturday and that did not happen.  If skies clear max temperatures will soar into the upper 60's.
NWS Max temps Wednesday (image Weatherbell)
The latest American high-resolution model is indicating a nasty line of storms in Central PA on Wednesday PM.  We have time to watch this but please be aware of the possibility of some storms Wednesday.
12z NAM hires 3 km sim radar Wednesday 2 PM (image Weatherbell)
Temps fall for Thursday.  More on this tonight or tomorrow AM.

-Zack Green

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