Region Wide Wintry Precipitation Saturday

Temperatures dropped to 4 degrees in Boston this AM which made today the coldest morning in the city since 1989.  Worcester dropped to -1 which is impressive but it is tied with 12-21-2004 for the coldest morning this century,  The winds were strong but not as impressive as I thought they would be.  A warm front will lift north and kick high pressure offshore tonight.  With Arctic air firmly in place moisture will overrun the front and fall as snow.  Snow should begin to accumulate between 3-4 AM and it will continue until late morning.  Warmer air will then flow in aloft but it will remain below freezing at the surface and a round of freezing rain will complete the precipitation.  The storm finishes as rain everywhere south of Boston.

General Overview
The National Weather Service has issued a *Winter Weather Advisory* for most of the region from 1 AM until early afternoon.  The advisory expires in SE MA and RI at 1 PM.  Wintry precipitation lingers longer in Central/Western MA and NE CT so the advisory continues until 3 PM.  The advisory also continues until 3 PM in NE MA.

NWS Boston Headlines Friday 4 PM

Temperatures will remain in the upper teens to low 20's across SNE until 7 AM.  It will warm into the low 30's on the Outer Cape/Islands around daybreak.  Snow begins between 2-4 AM from SW to NE from CT to ME.  It will be slow to accumulate at first but by 7 AM it will be snowing steadily.

18z NAM hires parallel sim radar Saturday 7 AM (image Weatherbell)

At 10 AM the rain/snow line has advanced just north of route 44 in SE MA and route 6 from Providence to Hartford.  Snow may be thumping at 1"/hr between 9-11 AM in NE, C, and W Mass.

18z NAM hires parallel simulated radar Saturday 10 AM (image Weatherbell)

Between 11-12 sleet and rain will mix in with snow.  Warmer air aloft will turn all precipitation to rain.  Temperatures at the surface will remain below freezing so rain will freeze on contact.  This will add weight to snow but it will also make travel difficult for much of tomorrow AM/early PM.

18z NAM hires parallel simulated radar Saturday 12 PM (image Weatherbell)

I am in agreement with the NWS on snow and ice.  I do think we are closer to 6 in Northern CT, Western MA and Northern Worcester County.  Southern Worcester into Middlesex and Essex counties will be on the lower end.

Temperatures stay in the upper 20's but they will steadily climb into the 30's by midnight.  By Sunday morning temps will rise into the upper 40's/low 50's.  Winds will likely gust 40-50 mph on Sunday as a cold front passes offshore and a strong area of high pressure builds in the Central US.

WPC Surface Fronts/Precipitation Sunday 7 AM 

Up to a half inch of rain may fall with this.

-Zack Green

Perspective on December Arctic Assault

Can you hear that?  That's the Arctic hound knocking at the walls of your home.  The National Weather Service changed the Wind Chill Watch to a *Wind Chill Advisory*.  The High Wind Watch has been upgraded to a *High Wind Warning*.  Several records will be in reach tonight and tomorrow morning.  We are on track for the coldest December day in over 10 years in Boston, Worcester and Providence.  The coldest of the air looks to stay just north of Hartford.

NWS Boston Headlines Thursday December 15, 2016

Worcester has a chance to tie the record low for today December 15 just before midnight.  The record is 1 set in 1933.  The other 3 climate sites are safe for 12-15.

The record low max and record low temps for Dec 16 are in play.  The National Weather Service is forecasting several records tomorrow in Boston and Worcester.  

NWS forecast through 7 PM 

The latest high resolution computer guidance is forecast -3 in Worcester, -1 in Boston, 3 in Providence and 5 in Hartford.  Here is that models forecast for 7 AM.  This does not factor in the wind.

18z HRRR 2 m temps Friday 7 AM (image Weatherbell)

Here is the wind chills at 7 AM.  Most places are -10 to -15 below zero.

18z HRRR wind chill temps 7 AM (image Weatherbell)

Winds peak overnight, but the coldest air is at day break so the combination will be bitterly cold for the next 12-18 hours.  The winds will be strong enough to knock out power tonight so make sure all appliances (cell phones, lap tops, tablets) are charged.  Please be careful driving as I saw a lot of trash barrels flying around already this afternoon.   Also heads up for snow squalls tonight.  They will be isolated and the threat peaks this evening.

So how common or uncommon is this for December?  This chart shows the lowest max temps and lowest min temps for the month since 2000.  Blue reflects the coldest values during the 15 year period (16 seasons).

Boston, Worcester, and Providence are forecast to have their lowest temperatures in at least 16 years.  It looks like the minimum high temperature records will be close in Boston and Providence but Worcester and Hartford will lose out to 2004 and 2013 respectively.  Any way you slice it this is impressive and it will be one of the coldest December days this century.  I went back into the 20th century to find the last time we were this cold.  

December 27, 1993 was also very cold in Worcester (13, -1) but it was not as bad in the other cities.  This Arctic blast will stand along side some of the colder December days of the last 25-30 years.    December 22-23, 1989 deserves its own post.  Tune in for that but just know it snowed 14" in Myrtle Beach, SC and several communites in Northeat Florida had a White Christmas in 1989.

Saturday Snow

I believe a winter weather advisory will be needed Saturday AM.  Snow begins around dawn and continues through late morning.  The snow will change to rain around 11 AM and continue until 2 PM or so.  Winds pick up Saturday afternoon and evening as the region drys out.  Temperatures climb into the 50's on Sunday with rain before temperatures crash AGAIN.  We may finish as snow Sunday night/Monday AM so roads will have to be treated for snow/black ice.  More on this tomorrow.

I think 3-6 inches of snow Saturday AM.

-Zack Green

Bitter Arctic Blast On The Way

The National Weather Service Boston office has issued a *High Wind Watch* and a *Wind Chill Watch* for Thursday night into Friday.  Winds will gust 40-50 mph Thursday night into early Friday AM.  These wind gusts will combine with the Arctic air mass to produce wind chills -10 to -20 below zero.  Friday AM will be dangerous for anyone who has to be outside for extended periods of time.  Snow will fall overnight Friday into Saturday AM before changing to rain. By Sunday temperatures briefly return to the 50's.  Buckle up we are on a weather roller coaster.

NWS Boston Headlines 

General Overview
One cold front will cross New England tonight.  This front will drop temperatures 15-20 degrees from where they are today.  This is not the main Arctic front that will deliver the extreme cold and strong winds.  It will not arrive in time to deliver bitter overnight lows.

WPC Surface Fronts/Precipitation Wednesday 7 PM

Lows tonight are cold but manageable.  Temps drop into the upper teens in Worcester County out towards Springfield and into the lower 20's for E MA, RI and CT.

NWS minimum temps Wednesday PM to Thursday AM (image Weatherbell)

Thursday AM is the time to get any outdoor work complete.  Winds will gust 10-20 mph out of the west until about 2-4 PM when the true Arctic boundary closes in on the Northeast.  Here is the projected surface map as of 1 PM tomorrow.

WPC Surface Fronts/Precipitation Thursday 1 PM 

High temps tomorrow don't climb much from the overnight minimums.  There is a strong chance the low for Thursday occurs at 1159 PM tomorrow night.  The max temp will go into the books as 20-25 tomorrow even if temperatures reach that value before noon time.  Here are the 1 PM temps, 10 PM temps, and 7 AM Friday temps.

18z NAM hires 3 KM temps Thursday 1 PM (Image Weatherbell)

18z NAM hires 3 KM temps Thursday 10 PM (image Weatherbell)

18z NAM hires 3 km temps Friday 7 AM (image Weatherbell)

Most importantly here are the wind chills for 7 AM Friday.  Schools might have to be delayed as kids standing at a bus stop in these temperatures is insane.  If you are one of the people who think we have gone soft then feel free to stand outside for 15 minutes tomorrow AM.  If you can congratulations you are stronger than a school aged child.

18z NAM hires 3 km wind chill temps Friday 7 AM (Image Weatherbell)

Temperatures will moderate slightly on Friday but max temps will only be between 10-20 degrees.  Then we will turn our attention to a snow threat on Saturday.  Snow will begin after midnight as the low seen below in Kansas cuts northeast.

WPC Surface Fronts/Precipitation Friday 7 PM 

The low is riding along the cold/warm boundary as it crosses the US.  One might think that because it is so cold tomorrow and Friday it has to be all snow on Saturday.  Well that is not how it works.  The cold will make the beginning of the storm all snow and it will probably snow harder and further south and east Sat AM then Monday AM's event.  Warmth will surge in later Saturday into Sunday.  In Southern New England we need storms to move south and east of Nantucket to get big snows.  When storms cut west they bring the warmth with them.  Think of the counter clockwise flow around a low.  If that low is to the west our wind is out of the south.

I am putting together some stats to put the December cold in perspective.  I will post that tomorrow.

-Zack Green

Light Snow Tonight

A weak cold front will slide across New England tonight.  A weak ocean storm will pass well to our South at the same time.  These two features will produce some light snow tonight across Southern New England.  It appears the snow will set up north of the Pike and outside I-84 but some flurries are possible from 95 to 495 and some rain iis possible in SE MA/RI.  Little to no accumulation is expected.

Short Term Forecast
Here is the forecast surface fronts and precipitation for 8 PM tonight.

WPC Surface Fronts/Precipitation Tuesday 7 PM

The latest simulated radar returns for this evening show a decent band of snow moving through Southern New England around 10 PM.   By midnight it snow stretches from Lowell to Springfield.

20z HRRR simulated radar Wednesday 12 AM (image Weatherbell)

By 6 AM most of the precipitation is off the coast with the exception of the Cape/Islands.

20z HRRR simulated radar Wednesday 6 AM (image Weatherbell)

There will not be much wind as this front passes.  There also will not be much of an air mass change for tomorrow.  Low temps tonight are in the upper 20's tonight in the interior and low 30's in the coastal plain of SE MA.

NWS minimum temps Wednesday AM (image Weatherbell)

High temps Wednesday rebound into the upper 30's but look to the west to see the highs that are coming for Thursday and Friday.

NWS maximum temperatures Wednesday (image Weatherbell)

We will have a few more shots at snow this week but nothing major.  The big story will be the cold Thursday-Saturday AM. Some snow is likely Saturday AM before going over to rain.  How can it go from near 0 to rain in 36 hours?  I'll show you tomorrow.

-Zack Green

Pats-Ravens Forecast

Tom Brady leads the Patriots to victory in the 2011 AFC Championship (photo- Justin Lane European Pressphoto Agency)

For the first time since the 2014 AFC Divisional Playoffs (held in January 2015) the hated Baltimore Ravens return to Foxboro to battle the Patriots.  The Patriots won that game and the Super Bowl.  Many people in New England believe Johnny Harbaugh told on the Patriots for "deflating" footballs.  Temperatures tonight will drop into the 20's so the footballs will certainly deflate naturally thanks to the Ideal Gas Law (PV=nRT) but I am thinking the venom spewed from the Pats faithful tonight will be full of hot air.  Below is forecast for the game and some snow statistics from this morning's winter event.

Patriots-Ravens
The match ups are usually close and there is no weather advantage to be found by looking at the games in Foxboro since 2009 (Joe Flacco era)

It will be cold tonight but not as cold as the 2015 game.  I am expecting temperatures around freezing for kick off and dropping into the upper 20's by the end of the game.  Winds will not be a major factor as they blow out of the west at 5-10 MPH.  Crews will be out treating the roads tonight (hopefully before the black ice develops).

NWS Min temps tonight Eastern MA (image Weatherbell)

I like the Patriots 24-21.

Winter Event Wrap-Up
All of the snowfall totals can be found here.  Listed below are the totals for the big 5 SNE cities.

Northbridge ended up with 1-2".  The highest totals were in Northern Worcester County and Western MA.  I am happy with my forecast for this event but I was somewhat surprised Northbridge and Uxbridge held a full day of school.  The roads seemed fine so I have to agree with the call.  With these event Whitinsville is now up to 3" for the season, slightly below average for December 12.

 Short Term Forecast
High temperatures tomorrow will be around 40 with mostly sunny skies and light winds.

NWS max temps Tuesday (image Weatherbell)

Tuesday night a cold front will approach from the west which may touch off a few snow showers.  No accumulation is expected.  The front doesn't bring much in the way of a temperature change so Wednesday looks similar to Tuesday with temperatures just a few ticks cooler.  Big changes are on the way starting Thursday.  Here is the surface fronts and precipitation Wednesday evening.  See that cold front ready to enter the northeast?

WPC Surface fronts/precipitation Wednesday 7 PM

That is the Arctic hound!  Some like to call it the polar vortex which works as well.  Here is what it looks like in the middle of the atmosphere.

12z EURO 500 mb heights Thursday 7 AM (image Weatherbell)

At the surface this means temperatures near 20 for HIGHS on Thursday.

NWS Max temps Thursday (image Weatherbell)

Low temps Thursday night into Friday look to be near 0.  More on this cold to come tomorrow/Wednesday.

Go Pats!

-Zack Green

Update on Sunday PM/Monday AM Winter Event

Snow will begin to fall between 9-10 PM tonight as a weak weather system moves towards the Northeast.  Snow will begin to change to sleet, freezing rain and eventually plain rain in the morning.  Although this will be weak the storm will have a high impact on the AM commute.  The National Weather Service Boston office has issued a Winter Weather Advisory from 7 PM tonight until  1 PM Monday.

NWS Boston Headlines Sunday December 11

General Overview
Here is the surface fronts over the water vapor satellite.  High pressure has been in control for much of the week as temperatures were well below average.  Low pressure is tracking along a frontal boundary that is draped from Iowa to Maryland.

GOES Composite Water Vapor Satellite (Image NCEP/NOAA/NWS)

This boundary is advancing to the north and east into all of this cold air.  Here is a quick science lesson that many of you already know.  As the warm air meets the boundary it rises above the more dense cold air.  As the warm air rises it also condenses and falls as snow when the center of the storm is hundreds of miles away.    Here is the radar loop as of 330 PM.

NWS Northeast Regional Radar Loop

Snow will begin around 9-10 PM tonight across the whole region, including the south coast as temperatures initially are below freezing.  The Cape and Islands likely remain all rain.  As of 2 AM the mix/rain line is follows I-95 to Providence and then follows the coast to the Canal and up to Plymouth.

20z HRRR simulated radar 2 AM Monday (image Weatherbell)

By 6 AM the rain snow line is to the Southern MA border and pretty much to 495.  Snow flakes will be large and wet as the change to mix/rain.

20z HRRR Simulated radar Monday 6 AM (image Weatherbell)

Schools inside I-95 in Eastern MA and most of CT/RI should be fine for school with only minimal delays.    By 9 AM the rain/snow line will push all the way to Northern MA border.

20z HRRR simulated radar Monday 9 AM (image Weatherbell)

Any snow that falls in SE MA, RI, and CT will wash away quickly.  Snow will pile up the further north and west one goes in Southern New England.  The NW corner of the state will see 4-6 inches.
Elsewhere just a general 1-3, sometimes 4" event.  I think these NWS numbers are high.

NWS snowfall forecast Monday AM (image Weatherbell)

  I like the latest short range model best.

20z HRRR snowfall total through 9 AM (image Weatherbell)

Max temperatures surge into the 40's south of the Pike and near 50 in SE MA.

NWS max temperatures Monday (image Weatherbell)

Temperatures will steadily drop this week as another round of Arctic air arrives late week.  I'll post an update in the morning.  Brip, pack your lunch.

-Zack Green

Snow to Rain on Monday

Snow will move into Southern New England Sunday night into Monday AM.  A weak area of low pressure will pass over coastal SNE which will bring some warmer air into the system and change precipitation over to rain by midday.  This system showed more potential early in the week but atmospheric conditions just did not line up.  That said this is only a moderate confidence storm.  

Saturday-Sunday Forecast

High pressure will remain in control of our weather for the next 24-30 hours.  Temperatures crashed into the low teens last night.  Highs today will only max out in the upper 20's  That is a slow recovery.  Average max temps for December 10 are 38 in Worcester and 43 in Boston so we will be a good 10-15 F below normal today.

NWS max temps Saturday (Image Weatherbell)

Lows tonight will again drop into the teens.  There will not be much of a recovery on Sunday for interior SNE.  SE MA will warm into the low 30's while Worcester area is around 28-29.

NWS max temps Sunday (Image Weatherbell)

Clouds will increase Sunday afternoon into Sunday evening.  Here is the surface fronts/precipitation evolution from Saturday 7 PM to Monday 7 AM.  Watch as the snow tracks from the Midwest towards the Northeast.

WPC Surface fronts/precip 12/10 7 PM through 12/12 7 AM

The Bills-Steelers game in Buffalo and the Browns-Bengals game in Cleveland will be impacted by snow.  Cleveland has been a skidmark on the NFL's shield this season so hopefully the snow can cover up some of the stink and maybe the Browns can get their first win.  There are some conflicting signals about when the snow will start.  It may begin right around 9 PM or it will hold off until midnight or so.  I lean towards the earlier start.

06z NAM hires sim radar Sunday 10 PM  (image Weatherbell)

Temperatures overnight Sunday into Monday will fall into the 20's which easily supports all snow to start, even for the South Coast/Cape and Islands.

NWS min temps Sunday PM-Monday AM (image Weatherbell)

Notice those temperatures around Long Island in the low 30's?  These will surge north as the low passes by/over SNE.  In fact by 7 AM we may be over to sleet/mix for most of the region, especially inside 495 and south of the Pike.  The yellows in the sim radar image below are the  model picking up ice.

06z NAM hires sim radar Monday 7 AM (image Weatherbell)

Precipitation is done by noon time.  Total snow looks to be 2-4" before a changeover. 

NWS snow prediction next 72 hours (image Weatherbell)

These numbers will go up if the cold can hold on a bit longer which is possible and that is what I will track the next 36 hours before this hits.  I would imagine most school districts will go with a delay and not a closing on Monday, especially the further south and east one is.

-Zack Green