Nice Wednesday, Increasing Clouds as Storm System Approaches Thursday

A tropical low is trying to organize itself in the Gulf of Mexico.  At the same time a trough is approaching from the Midwest and this will pick the system up and lift it along the east coast.  Heavy rain will lead to localized flooding and winds may gust close to 50 MPH at the coast.  Since this is the major weather during the short-medium, will focus on this today.

Observations/Short Term Forecast
As of 4 am temperatures were in the upper 40's in the higher elevations of MA, low 50's elsewhere

4 am 2 m temps (image weatherbell)

Here is the surface chart

WPC surface analysis 330 am

While high pressure along the VA coast is in control of our weather, the front along the US/Canadian border will allow for some mid level clouds to work into the region today.  The kicker is it will be warmer today than it was yesterday

06z NAM hires 2 m temps 4 PM (image weatherbell)

Tonight lows drop into the low to mid 50's.  Here is the surface chart tomorrow morning

WPC surface analysis 8 am Thursday

Currently the National Hurricane Center gives the low in the Gulf a 40% chance of development.  Again it doesn't really matter to us as a tropical connection is going to be established either way.  But here it is on infrared radar

GOES_East Rainbow IR image 545 am (NOAA)

Good convection which is the first clue that this system will produce a lot of precipitation.  It is also being sheared as the thunderstorms are all to the east of the center.  In a well developed tropical cyclone the heavy rain is west of the center, the high waves and high winds are on the east side.  Anyway the name will be Andrea and I'd say she becomes at least a depression today, possibly a storm.   Thursday high temperatures are in the low 70's

06z NAM hires 2 m temps Thur 2 PM (image weatherbell)

By Thursday evening the rain will begin to push into New England.  The surface chart

WPC surface forecast Thursday 8 PM

The simulated radar shows plenty of rain which is largely unrelated to the tropical disturbance 

06z NAM hires simulated radar Thur 8 pm (image weatherbell)

On Friday the low will be working into the Florida panhandle.  All precipitation Thursday evening/early Friday will be related to the surface front working towards the coast, driven at the 500 mb level by a trough diving east.  

WPC Friday morning surface forecast

But as Friday evolves and the tropical disturbance moves Northeast, an event called a Predecessor Rain Event is likely to break out somewhere in the Northeast.  The most likely spot is Upstate NY/Western New England.  We have a strengthening jet streak, a trough west of the tropical cyclone, and a ridge to the east.  There is also a low level boundary present (Cote, Bosart, Keyser 08).

00z CMC 250 mb jet Friday 8 pm (image weatherbell)

There should be a lull Friday morning in Southern New England.  However all in all 2-4 inches of rain will fall with isolated higher amounts.  The overnight models have consistently printed out less precipitation than the morning models.  The night shift at the WPC is less bullish than the day shift accordingly

WPC 5 day precipitation totals

My advice and what I will do is split the difference.  More on the winds and specific timing in the next post.  Have a good Wednesday.

Quiet & Dry Next 3 Days

Yesterday's cold front has pushed offshore and high pressure over the Great Lakes has introduced flow out of the northwest dropping temperatures and dew points.  High pressure will remain in control for the next several days before several systems converge on the Northeast for Friday/Saturday.  The potential exists for 2-4 inches of rain this weekend.

Observations
The current surface chart

WPC surface analysis 330 am

With the passage of the front temperatures are cool enough for a jacket is parts of Western MA this morning

2 m temps 4 am (image weatherbell)

The water vapor image shows the upper level flow into New England.  Air is wrapping around an upper Low in Quebec and around the high pressure in the Great Lakes

GOES_East Water Vapor Sat 515 am (NOAA)

By 11 am most of Southern New England will be over 60.  Exceptions include Northern Worcester County and the Berkshires.  High temperatures should be just around 70 and that will be around 3-4 PM

06z NAM hires 2 m temps 5 pm (image weatherbell)

Skies remain mostly cloud free all the way through the evening

06z NAM simulated Satellite 8 PM (image weatherbell)

Temperatures tonight will be similar to last night.  Berkshire County will be the coldest, in the low 40's.  Most of Eastern Southern New England will be around 50, warmer along the coast.  Here is the forecast surface chart tomorrow morning

WPC surface forecast Wed 8 am

There will be a few more clouds, but temperatures will also be warmer.  The Connecticut River Valley will approach the upper 70's as well as interior SE MA

06z NAM hires 2 m temps 5 pm Wed (image weatherbell)

Tomorrow night is warmer with lows in the mid 50's. There will be more cloud cover tomorrow night which will trap some heat and not let it radiate back to space.  On Thursday morning a disturbance will begin to approach from the Ohio Valley.  

WPC surface forecast Thur 8 am 

It should be in the mid 70's for most of Southern New England on Thursday.  If the rain works into Western New England in the afternoon temperatures will be held down a bit there.  As of now I expect the majority of Thursday to be dry

06z NAM hires 2 m temps Thur 2 pm (image weatherbell)

Most guidance works the precipitation into Western/Northern New England around 8 PM

00z EURO Precip Fri 2 am (image weatherbell)

Tropical Watch

Disorganized low pressure in the Gulf of Mexico has been given a 30% chance of developing into a tropical/subtropical storm in the next 48 hours.  While I think development will slowly occur and a weak tropical storm will form, its almost irrelevant to us in the northeast as it will impact our weather regardless.  

NHC Outlook, issued 1 am 

A frontal boundary and associated low waves of low pressure will be moving toward the east coast which will force the low pressure to move up along the east coast.  

WPC surface forecast Friday 8 am

Temperatures Friday will be warmest in SE MA.  Most of the region will be in the upper 60's while SE MA will be in the low 70's.  Here is the surface chart Saturday Morning

WPC surface forecast Sat 8 am

Heavy rain, gusty winds, and some isolated severe weather possible on Saturday as this low morphs into a late season Nor'Easter.  As of now the WPC likes the axis of heavy rain to be mainly in Vermont and Upstate New York

WPC 5 day precipitation outlook

Someone will approach 5-6 inches of rain but it will ultimately depend on the jet stream configuration.  Winds will depend on the ultimate track and strength.  I'll know more tomorrow, have a good Tuesday.

Surges of Rain This Morning

A slow moving cold front which brought severe weather to the western parts of New England yesterday will finally push across the region today.  We were able to break the heat yesterday and today we will break the humidity.  There is a trade off; multiple bouts of rain will move across Southern New England this morning.  Already there has been heavy rain with embedded thunder and lightning over the Cape.  There has been a lull in Southern Worcester County but this will fill in during the next hour or two.

NWS Northeast Regional Radar 538 am

This rain has tropical connections.  Here is the water vapor satellite image with the surface fronts super imposed.

GOES_East Water Vapor Satellite 515 am

We can also look at the precipitable water which measures the heavy rainfall potential

SPC Precipitable Water 5 am

With values up around 1.7 and 1.8 inches there is a high chance for urban flooding if one of these waves sit over the same area for an extended period of time.  Western MA, Western CT, an SE MA are most likely to see this.  Here is the radar estimated rainfall total since noon yesterday

NWS Boston radar precipitation estimate 6/02/13 12 PM-present

That's nearly 3 inches near Springfield with more to come today.  Here are the temperatures this morning

2 m temps 5 am (image weatherbell)

Here is a look at the dew points

2 m Dew Points 5 am (image NCEP)

This combination will result in sticky conditions and of course rain as temperatures and dew points are about the same.  

Short Term Forecast

Rain will continue to work northeastward as the cold front pushes towards the coast.  The front may get hung up over the CT/RI border and through Worcester County.  This will keep SE MA in the rain for most of the day.  Nantucket and Martha's Vineyard will see storms work in off the Atlantic

WPC surface forecast 2 pm Monday

Here is the simulated radar for 2 PM

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

The tropical connection will continue to send waves along the front.  With it stalling out in Central New England that leaves Eastern MA under the fire hose.  Temperatures at 2 PM

06z NAM hires 2 m temp 2 pm (image weatherbell)

It should get to 70 in Eastern MA.  Most of us stay in the 60's, but it is a sticky feeling.  So how much additional rainfall to expect?  Here is the WPC day 1 outlook

WPC Day 1 Precip Outlook 

In general another 0.3-0.7 inches but I think isolated areas over the Cape may see over an inch.  The good news is that this front is going to be offshore by tomorrow morning.  Overnight lows will drop into the upper 40's across Southwestern New England and will be near 50 in Southeastern New England.  Here is the forecast surface chart

WPC surface forecast 8 am Tues

High pressure over the Great Lakes will introduce a Northwesterly flow into the region.  Tomorrow is dry, the humidity is low, and temperatures are in the upper 60' to low 70's.

06z NAM hires 2  m temp 5 pm Tues (image weatherbell)

Lows tomorrow night will be in the low 50's for everyone except those in the Berkshires; there we can expect temperatures in the low to mid 40's.  On Wednesday it will be warmer with temperatures in the mid 70's.  

Tropical Update

Hurricane Season officially began on Saturday and will run through November.  There is something to monitor in the Gulf of Mexico near the Yucatan.  

NHC Atlantic basin outlook

There is a low chance (20 %) of this system developing in the next 48 hours.  Guidance is sensing development but it should be fairly weak and slow to occur.  It is possible that something subtropical emerges on the east coast of Florida and tries to run the Eastern Seaboard at the end of the week.  I'm not really worried about wind but I am about more heavy rain moving into the area.  If named it will be Andrea

WPC Day 5 surface forecast

For the week the WPC is predicting almost 3 inches of rain in Southern New England

WPC 7 day precip outlook

Have a good Monday.

Severe Thunderstorm Watch Issued for Most of New England

The Storm Prediction Center in Norman, Oklahoma has issued a severe thunderstorm watch until 8 PM

SPC WW 271

Isolated tornadoes will be possible, but the most likely effects will be severe damaging winds and hail over an inch in diameter.  Right now the storms are in Eastern New York and Maine.  In fact Maine has the highest tornado threat in the country today

SPC tornado probabilities 

The wind threat is much more widespread

SPC severe wind probabilities 

The hail threat is lower than the wind threat, but greater than the tornado threat

SPC severe hail probabilities 

Here is the current (as of 155 PM) radar out of Albany, NY

NWS Albany Radar 151 PM

Surface based energy is increasing rapidly with the heating of the day.  There are several pockets of 3000 J/kg of CAPE, or convective available potential energy.  

17z SPC CAPE

As of noontime many areas in New England had dew points in the upper 60's/low 70's.  

16z NCEP RTMA Dew points

Temperatures as of 1 PM

2 m temps 1 PM (image weatherbell)

Cloud cover will not save us today, as it has several times in the past few weeks.  Here is the visible satellite as of 115 PM

Northeast Regional Visible Satellite (GOES_East, NOAA)

A strong surface cold front is pushing east toward the coast.  The warm sector is feeding right into New England

WPC surface analysis 1230 PM

At the upper levels a 500 mb trough is driving low pressure in Southern Ontario 

12z NAM 500 mb heights, winds (image weatherbell)

These storms will enter Western MA before 3 PM.  They reach Springfield around 5-6, and Worcester around 7-8.  Will update this as necessary