Monday, December 30, 2013

Snow Likely Thursday-Friday

Winter is poised to return to the Northeast this week after a brief spell of above average temperatures.  The timing is Thursday morning into Friday and the precipitation type is snow for everyone except the Cape/Islands.  The details...

General Overview/Short Term Forecast
Over the past week the East and West Coasts have seen above average warmth while the Central US has been mainly below average
NCEP Weekly Temperature Anomalies (image weatherbell)
Overall most of the nation was below average for December with the exception of the SE US
NCEP December to date Temp Anomaly (image weatherbell)
A tongue of cold water exists along the West Coast while the Atlantic remains warmer than normal.  This is consistent with the Cold PDO/Warm AMO ocean regime.  The PDO appears to be weaker than normal. 
NOAA/OSPO Sea Surface Temp Anomaly 12.30.2013
This is important because the warm Atlantic will likely juice up any storm that reaches the coast.  Today a cold front pushed offshore and temperatures dropped this afternoon.  Here is the current surface chart

WPC Surface Analysis 1 PM 
Temperatures tonight will fall to around 10 degrees
18z NAM hires 2 m temps 6 am Tue (image weatherbell)
Another front with a weak low pressure system will push through New England tomorrow
WPC Surface Forecast Tuesday 7 PM
This may fire off some snow squalls tomorrow afternoon. Temperatures tomorrow and New Years Day will be around 20-25 degrees.  So lets talk about the storm.

Thursday-Friday
A storm system will drop out of the Rockies while another storm develops in the Gulf.  By Thursday morning this is what the surface chart is projected to look like
WPC Surface Forecast 7 am Thur
The low in the Ohio Valley will begin to transfer energy off the East Coast.  Due to high pressure in an ideal position to the north, snow will break out well in advance of the storm Thursday AM.  As the storm moves up the coast it will deepen and winds will increase in Southern New England.

The snow will be fluffy for everyone except the South Coast/Cape Island.  This means snow will pile up and some significant accumulations are possible.  
First Guess Snowmap
Furthermore the winds WILL be a factor with the system.  Expect snow drifts.  Blizzard like conditions will be possible at times in certain locations.  I will make more specific forecasts tomorrow and Wednesday.  

-Zack Green










Thursday, December 19, 2013

Grinch Storm Threatens White Christmas; Surprise Xmas Eve?

The Grinch and Heat Miser will attempt to ruin a White Christmas in Southern New England.  However not all is lost; Snow Miser may have one more trick up his sleeve on Christmas Eve.  Do you believe?

The Grinch (via www.dragonart.com)

General Overview
Here is the the surface chart from 4 PM.  Notice the high pressure off the East Coast and the front to the north of New England
WPC Surface Analysis 4 PM est
This is a welcome change from the past week
NCEP 2 m temp anomalies past week (image weatherbell)
The melting began today and will continue.  Here is the upper level pattern which shows ridging over the east.  When we are in a ridge the atmospheric thickness increases and generally it warms.
SPC Mesoanalysis 5 PM 500 mb heights 
A storm will develop in the Southwestern US and eject into the Plains.  You can see the upper level energy that will drive this storm in So Cal.  It will also tap gulf moisture and make quite a mess in the Central US while also producing severe weather in Dixie.  No worries for travelers; this will clear the coast late on Monday (few showers possible in South Florida on Christmas Eve).  Behind the storm will be a another blast of Arctic air for the Midwest.  Not sure how strong this will be in New England at the moment.

Weekend Forecast
High temps tomorrow will soar into the 40's region wide.  Tomorrow morning will be around 30.  Expect partly to mostly sunny skies tomorrow.  On Saturday some precip will begin to work into New England 
WPC Saturday 7 am surface forecast 
Waves of low pressure will be riding along the front.  Check out the temperature gradient Saturday
18z NAM 2 m temps Sat 4 PM (image weatherbell)
Temps in New England will be in the upper 40s for most but low 50s looks good in SE MA including Cape and Islands. On Sunday the warm front will try to surge into Northern New England.  As a few veteran New England meteorologists mentioned this morning (Matt Noyes and Tim Kelley of NECN) good luck.  It should get close to Boston and Worcester, if not the MA/NH line.  So that means it could be in the upper 50s in Southern New England and around 30 in Portland, ME.  
18z NAM max 2 m temps Sunday 1 PM (image weatherbell)
In general we are looking at an inch of rain or so.  The timing is tricky because it will come in waves.  That needs to be fine tuned.  But over the next 5 days (until 7 PM Christmas Eve) here is what to expect
WPC 5 day Total Precip 
The warmth and rain will hurt the snowpack.  But the real snow killer is fog.  Expect fog throughout the weekend as the warm front moves over the snow.  Anyways on Monday temps will be around 50 as a cold front pushes through.  Tuesday is interesting.  It will be back to winter with temps around 30.  Also a wave of low pressure will likely develop along the front and move northeast.  It will probably get close enough to New England to drop a few inches of snow.  There is model support but its not a slam dunk.  My gut says YES SNOW.  
12z EURO CONTROL total snowfall (image weatherbell)
So Heat Miser will try to land a mean uppercut this weekend and ensure a Green Christmas.  Will Snow Miser have the last laugh?  
From "The Year Without A Santa Claus".  Not my video, all credit to who owns it.










Monday, December 16, 2013

Tuesday Winter Weather Event

A small to moderate snow event will impact New England tomorrow.  The snow begins after the AM commute but will impact the PM drive.  The National Weather Service has issued Winter Weather Advisories for much of the region
NWS Boston Watches/Warnings
Here is my forecast
Tuesday Snow Forecast

Click to enlarge
Short Term Forecast
High pressure in Southern Ontario has locked an Arctic air mass in place
WPC Northeast US surface chart
Here are the temperatures as of 7 PM
2 m temps 7 PM (image weatherbell) 
Temperatures tonight will drop near 0.  The storm approaches SW CT by 9 AM.  Will  take some time for the air to saturate due low temps/dew points.  Temperatures tomorrow west of 495 and North of the the Prov-Boston line should stay in the low 20's.  SE MA will warm up to near freezing while the Cape will go above freezing and change to rain.

This is not a major event by any means.  The trouble lies in the timing.  During these systems strong bands of snow can develop that drop 1-3 inches an hour.  That is difficult to drive in when caught on the highway.  It may only last a few minutes or it could sit an dump.  Therefore plan on a long commute tomorrow evening.  I'll update in the AM.

Thanks for reading 
-Zack






Winter Weather Event Tomorrow

A clipper system will impact the Northeast tomorrow.  It will be a quick burst of snow between 11 am - 7 pm tomorrow.  Temperatures will be very cold in the interior so expect a powdery snow.
Tuesday Snowfall Forecast
More later.


Friday, December 13, 2013

Winter Storm Watch Issued

The National Weather Service in Taunton, MA has issued a Winter Storm Watch for portions of Southern New England.
NWS Boston Winter Storm Watches
The watch will likely be upgraded to a warning tonight.  In general 6-12 inches of snow will fall.  Some areas will switch over to mix/freezing rain/rain Sunday morning.  North of the Pike and west of 95 its all snow.

The Storm
An Arctic front will push across New England today.  A cold high pressure system will be placed to our North.  Meanwhile a wave will develop in the Southern portion of the Jet Stream and track towards the Northeast.   Here is the storm moving through Texas, being driven by an upper level low in the Southwest.
GOES_Composite Water Vapor 445 am (image NOAA)
Today will be partly cloudy with high temps 20-25.  Tonight temps drop to around 10 degrees.  There is not much of a rebound on Saturday as high temperatures will be in the mid teens.  Snow will hold off until Saturday evening, though a few flurries or light snow showers will be possible during the day Saturday.  The main batch of precipitation arrives after 7 PM tomorrow night.
06z NAM hires simulated radar 10 PM Sat (image weatherbell)
There are differences in the computer models in regards to the temperature profile.  The NAM is cold with a track grazing the Cape and Islands.  The EURO runs over the Canal.  Either way a good thump of snow is on the way.  Here are the probabilities for 4 inches of snow
WPC Day 2 Snow Probs Snow > 4"
Northwest of the Boston-Prov-Hartford line has a real good chance at seeing 8 + inches of snow
WPC Day 2 Snow Probs > 8"
There is a decent chance someone in MA, S VT, S NH, S ME, or E NY gets over a foot.  Here is the projected surface chart Sunday morning
WPC Surface Forecast Sunday 7 am
By 10 am Sunday the storm will be winding down and should be out of Southern New England by 1 PM.  Perfect timing to get cleaned up and then watch the Pats.  Heres my forecast
Snow totals forecast
If the track is a bit further offshore the 8-12 will expand and push closer to the coast.  I don't like to update but I will tomorrow morning if need be.  Have a good one.









Wednesday, December 11, 2013

Update on Weekend Winter Storm

You may have heard about a winter storm potentially impacting Southern New England this weekend.  A plowable snowfall is likely for many.  Here's a breakdown with my thoughts.

The Big Picture
A series of Arctic fronts will push through the New England tonight and Friday.  This will keep temperatures in the teens and low 20's tomorrow.  The sun will be shining but that will just be for show.  Here is the current surface chart
WPC Surfce Analysis 4 PM EST
The main driver of the weekend storm is not even onshore yet in the Western US.  It will enter in Southern CA and track into Texas.  Once there the storm will split and one low center will decay as it moves up into Wisconsin.  Another low will try to run inland but high pressure to the north will force the low to reform off the New England coast.   Here is Saturday morning at 7 am
WPC Surface Forecast Saturday 7 am
Here are the 850 mb temps (5000 feet) Sunday 1 am
12z EURO 850 mb temps Sunday 1 am (image weatherbell)
These are plenty cold enough to support snow for all of New England through Sunday AM.  By 7 am some warm air will work in off the Atlantic changing the precipitation to sleet, freezing rain, and in some cases plain rain.  Here is the Sunday AM surface forecast
WPC Surface Forecast 7 am 
Timing & Impacts
Warm southern air will be running into a cold arctic high.  When this happens precipitation tends to break out hours before the storm is close.  I am seeing some signs that light snow could break out Saturday morning.  Steady accumulations begin after 7 PM Saturday night and will last into Sunday morning.  Don't believe the storm will be strong; but the dynamics are impressive.  Here is my current thinking
Saturday-Sunday storm outlook
Meanwhile bundle yourselves up tonight.  Lows drop down to around 10 tonight
22z HRRR 2 m temp 7 am (image weatherbell)
I'll have more as confidence increases.  Right now I'm curious as to how much snow will fall during the day Saturday.  This is NOT a repeat of February.  But it could be a decent December storm.  

-Zack Green










Tuesday, December 10, 2013

Light Snow Today

A disturbance passing south of New England will deliver 1-3 inches of snow South of the Mass Pike.  A dusting to an inch is likely from the Pike to the MA/NH/VT border.  Isolated 4 or 5 inch amounts appear possible in NE and NW CT into Western Worcester County as well as along the South Shore.  Winter Weather Advisories are up for CT/RI/SE MA
NWS Boston Advisories 12/10/13
The Big Picture
NWS Northeast Regional Radar 458 am
The radar shows moisture streaming Northeast.  The system is what we call "progressive".  In other words it moves quickly and is gone by this evening.  The upper level atmosphere behaves as a wave.  In the strongest storms the waves really dig deep; we do not have that in this pattern it is a shallow pattern with a bunch of quick hitting systems.  Here is the 500 mb chart
06z NAM 500 mb geo height 4 am (image weatherbell)
On the surface chart we see low pressure in the Southeast US riding along a stalled frontal boundary
WPC Surface Analysis 4 am EST
Now lets look at temperatures.  First at the surface
2 m temperatures 4 am EST (image weatherbell)
Its below freezing in much of Southern New England.  Temperatures will not rise much today.  Temperatures a few thousand feet up are running above freezing at the moment but that will change this morning
06z NAM hires 850 mb temps 5 am (image weatherbell)
The Forecast
Precipitation will break out in New England (starting in SW CT) between 9-11 am this morning.  Am expecting all snow.  Here are 850 temps at 10 am (850 is located in the snow growth zone.  Generally a good approximation of where the rain snow line will be).
06z NAM hires 850 mb temps 10 am (image weatherbell)
Surface temperatures will be around 30.  There are signals that a moderate band of snow will set up somewhere in SNE.  Odds favor this developing along the Southern Coast of Bristol County in MA.  The heaviest snow will fall between 11-4 PM today.  Total snow...I am using the NAM hires for accumulations as it seems to have the best handle on this system.  
06z NAM hires total accumulated snow (using 10-1 ratio) (image weatherbell)
Several points about this image.  The snow should be fluffy as one gets near the pike.  So we could be looking at higher amounts, but less liquid content.  Second I do think someone approaches 6 inches in Southern New England.  These are the snow storms that deliver surprises one way or another.  Should impact the afternoon commute from school and work so allow some extra time.

It looks cold for the rest of the week and there is potential for a storm this weekend.  More on that later, have a good one.

-Zack Green







Saturday, December 7, 2013

Saturday Morning Weather Thoughts

Will there be a white Christmas? Will it snow Monday?  I've heard the questions, now let me provide some answers.  I  took blogging off during football season.  Thankfully it was an awesome fall weather wise.  We were dry and warm most of the time. That is boring for meteorologists but wonderful for football and those who make a living working outside.

Short Term Forecast
A strong Arctic airmass has invaded the Western portions of the US.  Temperatures as of 9 am were below 0 in most of Iowa, Minnesota, North & South Dakota, Montana, and Wyoming.  This air mass will moderate as it moves east, but this is impressive early season cold.
US 2 m temps 9 am EST (image weatherbell)
See the strong high pressure system on the surface chart.  Also notice the front draped across the Southeast US.  See the temperature contrast?

US Surface Analysis
The warmth will try to lift north into New England by Monday. It will run into high pressure in Northern New England which sets up an interesting forecast tomorrow night into Monday. The 500 mb pattern is a bit odd, as it digs a trough in the west, but the ridge is more zonal in the the northeast.  The south is under the influence of a ridge in the Southwest Atlantic Ocean
12z NAM 500 mb geo heights 1 PM Sat (image weatherbell)
A weak area of low pressure will develop near the Gulf coast and track towards New England.  

Saturday Afternoon
Sunny and 38.  Winds out of the northwest 7-12 mph.  

Saturday Night
Clear skies.  Temps 17-22.  Light west winds 2-5 mph.  

Sunday
Partly Cloudy, temps 30-34.  Winds 4-7 mph.  Clouds increase throughout day

Sunday Night-Monday
Precipitation breaks out around 3 am.  Starts as snow, will slowly change to ice and plain rain.  Snowfall accumulations dusting to 2 inches (isolated 3).  Additional rain/ice less than 0.25 inches.  
12z NAM hires total snowfall (image weatherbell)
Not a big deal, just give yourself an extra hour or two.  This system looked more impressive a few days ago.  I don't believe there will be any school cancellations in Southern New England.  Temperatures will not get out of the 30's.  

Extended December Forecast
From USA Today, here are the odds of a white Christmas historically
USA Today Weather White Christmas Odds
Here is the 2 week total snowfall off the EURO control model ending at 7 PM on December 21
00z EURO control total snow (image weatherbell)
Most of this looks to fall around December 17.  The other long range models are also hinting at the possibility of something around this time frame.  Temperatures will generally be below average
GEFS 10-15 day temp anomaly (image weatherbell)
My prediction- a white Christmas and the ice will be safe enough to skate/ice fish by the 25th.  

One final thought- lows may be below 0 next weekend.  Temperature will be running 20-40 degrees below average 
00z EURO 850 mb temps Friday 8 PM (image weatherbell)
Another update tomorrow/Monday.  Have a good weekend.









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...