Tuesday, February 18, 2014

Several Inches of Snow Today

A quick moving storm will drop several inches of snow across Southern New England today.  Most of the precip will fall early this afternoon and this will impact the PM commute in Eastern MA.  The National Weather Service in Taunton has issued a Winter Storm Warning for parts of the region (in pink) and a Winter Weather Advisory (in blue) for others.  The Cape, Islands, and SE MA are not included in the headlines as they will see mostly rain.
NWS Boston Headlines 02/18/14
Overview
A storm in the Great Lakes will move towards New England today and will strengthen south of New England.  Here is the surface chart
WPC 4 am Surface Analysis 
The regional radar shows some precipitation already streaming into Western New England.  A lot of this is not reaching the ground.  Expect snow to begin accumulating around 7 am in W CT/MA and by 9 in Boston.
NWS Northeast Regional Radar 528 am
It is cold in New England this AM.  SW CT and the Outer Cape are the only ones in the 20's.  This means snow will stick immediately and travel will become difficult.
4 am 2 m temperatures (image Weatherbell)
As the low track towards New England it will bring some low level warmth across CT/RI/SE MA.  Temperatures will climb to near 32 in those areas.  Temperatures are on track to remain in the upper 20's for the rest of MA/S NH.

Forecast
Latest HRRR (super short range/high resolution model) seems to have a good handle on the convection.  This would bring the moderate to heavy snow into CT by 10-12 PM and into MA around 12. 
09z HRRR simulated radar 12 PM (image Weatherbell)
Here is the projected surface chart at 1 PM
WPC Surface Forecast 1 PM Tues
The low deepens this PM and snow falls heavily until about 4 PM in Springfield-Worcester-Providence.  Snow hangs on through the evening commute in Boston.
09 HRRR Simulated Radar 4 PM (image Weatherbell)
By 7 PM the storm will continue to deepen in the Gulf of Maine but it will be clear of Southern New England
WPC Surface Forecast 7 PM tonight 
Here is my snowfall forecast
My Snow Expectation 
I could see some higher amounts in the 3-6" if thundersnow is able to develop this PM.  The snow will be fast & furious with any convection this afternoon.  

-Zack Green











Friday, February 14, 2014

Another Winter Storm Saturday Night

My neighbor accused me of enjoying all these snowstorms.  I enjoyed all the fluff bombs in January but I HATED the cement I shoveled for the last 36 hours.  Whether I like it, whether you hate, whether you are indifferent is irrelevant to mother nature.  Another snowstorm is on the way tomorrow night. Now if you live outside of 495 it may track far enough offshore so that only 1-3" of snow falls.  The Cape and Southeast MA will not be so lucky.   The details...

General Overview
Here is the 4 PM surface chart.  The low is located along the IL/IN/KY border
WPC 4 PM Surface Analysis
The upper level support is impressive.  Note yesterdays storm departing through Atlantic Canada
18z NAM 4 PM 500 mb heights, vorticity (image NCEP)
The Great Lakes Regional radar is impressive this afternoon
Central Great Lakes Regional Radar 508 PM
The water vapor satellite imagery is also impressive 
GOES_Composite Water Vapor 345 PM
This storm is going to explode when it reaches the coast.

Timing, Impacts, Accumulation
Light rain/snow will move across Southern New England between 1-4 PM tomorrow.  By 7 PM the storm will be located south of Cape Cod and will be gaining strength 
WPC Surface Forecast 7 PM Saturday
The radar at the same time shows moderate to heavy snow across Eastern MA, the Cape, and Martha's Vineyard.  Nantucket looks to be mainly rain for this event
18z NAM hires Simulated Radar valid 7 PM Sat (image Weatherbell)
It should be noted that several models are closer to the coast.  That would put Central MA in play for heavy snow.  As of now I think Bristol, Plymouth, and Barnstable Counties get the most snow/highest wind and the National Weather Service agrees, having posted Winter Storm Warnings and Blizzard Watch in these areas
02/14/14 NWS Headlines
Power outages are likely across SE MA.  Snow should be done by 5-6 AM on Sunday.  If the storm is closer it will linger longer.  I am in complete agreement with the NWS on this so here is their snowfall accumulation expectation 
NWS Snowfall Expectation Map
I will update as needed tomorrow

-Zack Green













Thursday, February 13, 2014

Another Batch of Precipitation Tonight

The first phase of this winter storm is over.  Nearly a foot of snow fell in Central and Western MA, Southern New Hampshire, and Eastern Connecticut.  The second phase is the lull in precipitation region wide.  The third and final phase will occur from 10-7 am.  This will occur as the storm center moves over SE MA and moves into the Gulf of Maine.  

Discussion
Here are the preliminary snow totals
NWS Boston 7 PM preliminary snow totals
Winds gusted 40-55 MPH in SE MA.   Winds will continue to gust close to 40 MPH especially in heavier precipitation.  Here is the regional radar as of 828 PM
NWS Northeast Regional Radar 828 PM
Here is the water vapor image with surface fronts from 815 PM
GOES_East Water Vapor Satellite 815 PM
This is a textbook satellite image.  This is driven by a strong upper level low
00z NAM 7 PM 500 mb Vorticity (image NCEP)
And also by a strong jet stream
00z NAM 7 PM 300 mb winds (image NCEP)
By 1 AM the low should be near the SE MA coast or over it
WPC Surface Forecast 1 AM Friday
High res guidance and radar trends suggest another 0.5 inch of precipitation for most of New England and perhaps some big time snowfall accumulations in the Berkshires.  This is likely rain in Eastern MA.  In Worcester County I see mainly snow north of the Pike with mixed precip  across Southern Worcester County.  I think the Berkshires end up as the big snowfall winners from this one.  Precip ends around 7 am.  

Enjoy the snow

-Zack Green




Pre Storm Observations

Good Morning.  Light snow is arriving in Southern New England as of 530 am.  Heavy snow, rain, sleet, ice, and wind will impact the region through early Friday morning.  Winter Storm Warnings have been extended into Essex and Suffolk Counties.
02/13/14 NWS Boston Headlines
Wind Advisories exist for the east coast of MA from the Cape up to Gloucester.  

Overview
First things first the current temps are in the 20's in SE MA, RI, and CT.  Temps are in the teens for the rest of MA and single digits in Central/Northern New England
4 am 2 m temperatures (image Weatherbell)
High pressure has scooted east into the Atlantic but as you can see there is impressive cold that remains.  Our storm is deepening already off the Carolina coast.  Here is the surface chart
WPC 4 am Surface Analysis 
Here is an awesome satellite shot of the East Coast.  This is the Water Vapor satellite 
NOAA GOES_East Water Vapor Satellite 515 am
Here is the radar this morning.  DC has 6" of snow already and it is still snowing there.  They will eventually change over to rain
NWS Northeast Regional Radar 538 am
It will not take long for the snow to become steady and it will accumulate rapidly.  Most of the snow South of the Pike and Inside 495 falls between 7 am - 5 pm.  Here is the 4 PM simulated radar
06z NAM hires 4 PM Simulated Radar (image Weatherbell)
It is raining from Boston-Providence-Hartford South and East.  Ice will be an issue near the Pike and 495 so communities like Marlboro, Northbridge, Lowell etc will likely see 6-10 inches of heavy wet snow and then a layer of sleet/ice on top.  

Winds will also increase this afternoon. With heavy wet snow and some ice accumulation there is a moderate chance for power outages.  The WPC expects 1.5-2.0" of precipitation to fall over the next 48 hours
WPC 2 day precipitation outlook
Overnight tonight a final band of snow will work SW to NE across Southern New England.  The low will be in the Gulf of Maine and with a sub 980 pressure 
WPC Surface Forecast 7 am Fri
So my final snow forecast is
SNE Snow Forecast 02/13/14
Questions, comments, complaints can be sent to twitter @zgreenwx or facebook if we are friends.

-Zack Green









Tuesday, February 11, 2014

Forecast Update

A strong winter storm will impact many in the Eastern US over the next 2-3 days.  The storm is expected to track over the Cape which means many South of the pike and inside of 495 will change to rain for a period on Thursday.  Heavy wet snow will fall before any changeover and this storm will pack strong winds.  

General Overview
The National Weather Service in Taunton has issued a Winter Storm Watch for inland areas in blue
NWS Boston Headlines
Temperatures remain cold across the Eastern 2/3 of the country
US 6 PM 2 m temps (image Weatherbell)
Here is the surface chart.  High pressure in the Great Lakes is allowing cold air to pour into the South.  This sets the stage for a major Snow/Ice event in the South tonight/tomorrow.  This situation is no joke for our friends down there.  Ice can be paralyzing for any community, no matter how use to winter.
WPC 4 PM Surface Analysis 
Here is the Southern Mississippi Valley radar 
NWS Southern Mississippi Valley Regional Radar 648 PM
There is plenty of juice in this system.  

Short Term Forecast
Not to be overlooked is another bitterly cold night ahead.  Its already down to the teens away from the coast with clear skies.  Many areas will dip below zero.  Boston likely won't and neither will the Outer Cape. Here is a short range high resolution model 
22z HRRR 2 m min temp 6 AM (image Weatherbell)
Wednesday is mostly sunny with highs in the low 20's. By Wednesday night the coastal low will be organizing off the Southeast coast.  The cold dome of high pressure will slide offshore and clouds will increase.  Lows Wednesday night will be in the upper teens.  By Thursday morning the storm will be deepening near the Outer Banks

Storm Forecast
Here is the projected surface chart 7 am Thursday morning
WPC Surface Forecast 7 am Thur
Everyone except starts with snow, even Nantucket and the Outer Cape but they will switch to rain quickly.  The initial burst of snow will be substantial, much like last Wednesday.  Snow breaks out around 7-9 AM and will be intense until early-mid afternoon.   At this point the low will be nearing the Cape.  It will draw warm air into the system and change the snow over to mix/rain.
Precipitation Type Expectation
The rain probably makes it to the Mass Pike for a time Thursday night.  That is where the battleground is likely to be  Thursday 7 PM projected surface chart
WPC Surface Forecast 7 PM Thursday
As the low pulls away cold air is drawn back into Southern New England to finish the event as snow.  So snowfall amounts
SNE Snow Expectation Thursday-Friday
Strong winds combining with a heavy wet snow will lead to scattered power outages.  1.5-2" of precipitation will fall out of the sky so isolated street flooding is also possible.  More in the AM.

-Zack Green






 

Monday, February 10, 2014

Another Winter Storm Thursday

Are you sick of winter yet?  It has been a remarkable winter so far for the Eastern 2/3 of the United States.   Another winter storm will impact Southern New England on Thursday.

Overview
A Polar Front has reached the Gulf Coast as a large dome of high pressure built up in the middle of the country.  Here is the 1 PM Surface Analysis
WPC 1 PM Surface Analysis
Here is the US temperature map as of 4 PM
4 PM 2 m temperatures (image Weatherbell)
The Jet Stream splits into a Northern and Southern stream in the west.  One stream is in Southern California through Arizona and New Mexico while the other enters the US in Washington.
18z NAM 1 PM 300 mb heights/winds (image NCEP)
Embedded within both streams are pieces of upper level energy.  These show up nicely on the 500 mb chart (I've circled the two pieces to watch)
18z NAM 500 mb vort 1 PM (image NCEP)
Both pieces also show up on the water vapor satellite 
GOES_WEST Western US water vapor image 5 PM
The Southern piece of energy will slide east through Arizona, New Mexico, and Texas towards the Gulf Coast while the Northern piece slides southeast through Montana, South Dakota, Nebraska, and Missouri.  The Southern piece will deliver quite a blow to the South on Wednesday.  This is after they get through several waves of low pressure tomorrow.  Locally the weather is quiet tomorrow and Wednesday.

Tuesday Cold tonight with mostly clear skies.  Low temps 5-10.  Mostly Sunny during the day, highs 20-25.  Very cold Tuesday night, expect low temps -2 to 4 above. West wind could gust 15-20 mph so wind chills around 0 are likely.  

Wednesday Cold again with mostly sunny skies.  Temps 20-25 with a light north wind.

By Wednesday morning a healthy storm will have formed along the Gulf Coast.  The Northern stream energy will not have combined with the Southern stream yet.  
Wednesday 7 am surface forecast WPC
Here is the 500 mb chart as of Wednesday 10 am
18z NAM 500 mb vort 10 am Wed (image NCEP)
By Thursday morning a coastal low will be moving up the Atlantic Seaboard
WPC Sutface Forecast Thursday 7 am
By 1 PM on Thursday here are the upper level charts
18z NAM 300 mb heights, winds 1 PM Thur (image NCEP)
Notice the blue streak off the Mid-Atlantic coast? That is driving a closed 500 mb low
18z NAM 500 mb vorticity 1 PM Thur (image NCEP)
This upper level set up favors a deepening area of low pressure moving just South and East of the Cape/Islands. A lot of precipitation will fall with this system and strong winds will move across Southeastern New England.

Snowfall Amounts
60 hours out is too far for me to make a map.  I am confident in heavy precipitation and at least 3-6 inches of snow for most outside of 95.  I'm also confident in strong winds gusting to 60 mph in Southeastern MA/Cape and Islands.  Where the rain/snow line sets up is a tough call.  There is no high pressure to the north to lock the cold in.  However there is a deep snow pack and the Atlantic is about as cool as it can get around here.  

Precipitation Type Expectation 02/13/14
The storm looks to start around 7 am on Thursday.  The morning looks to be all snow for everyone except the Outer Cape and Nantucket.  The storm will wind down early Friday morning.  I'll have the accumulation map tomorrow.  Have a good one.

-Zack Green













Rain Ending As Snow For The Blackstone Valley Tuesday

Tomorrow is Tuesday and surprise, surprise...precipitation is in the forecast.  WBZ went back and found that there has been measurable preci...