Tuesday, February 28, 2017

Lion Like Start to March

3/1/17 640 AM Update-  Multiple rounds of showers/thunderstorms for SNE today.  The next batch arrives around lunch time. 
9z HRRR Simulated Radar Wednesday 12 PM (Image Weatherbell)
Another batch looks to follow late afternoon, especially in CT, RI and SE MA.  A third and final batch is likely tonight around 11 PM.  Of more immediate concern is fog in SE MA/RI and a wind threat.  The NWS has issued a *Wind Advisory* region wide and a *Dense Fog Advisory* for said areas.
NWS Wednesday AM Headlines
Winds will gust 40-50 MPH AFTER the cold front passes overnight.  Thursday will be very windy across SNE.  Temperatures are still forecast to rise into the mid 60's today, which puts us in striking distance of the record highs for the date.
More later.

Previous Discussion Below (Tuesday 530 PM Post)

In 1732, a proverb appeared in Thomas Fuller's book Gnomologia: Adagies and Proverbs; Wise Sentences and Witty Sayings, Ancient and Modern that reads "Comes in like a Lion, goes out like a Lamb".  Some smarty used this saying to describe the weather in March in mid-latitude climates.  The "roar" is that of the Arctic wind and the snow hounds that are often present in early March.  In New England we know that early spring is really just an extension of late winter.   The 3rd ranked storm on the Northeast Snowfall Impact Scale (NESIS) is a crippling snowstorm from March 3-5, 1960 that dropped 20-30" of snow in Eastern MA.

(h/t Sadie Stein, The Paris Review)
March 2-5, 1960 snow accumulation (NESIS)
The top ranked storm on the Northeast Snowfall Impact Scale (NESIS) is the famous March 1993 Superstorm, which occurred in the middle of the month.
March 12-14, 1993 snow accumulation (NESIS)
Then there is the matter of March 31-April 1, 1997.
March 31-April 1, 1997 storm accumulation (NESIS)
There are some flaws in the proverb but the general point remains the same.  Early March is still winter while early April is spring.  I can safely say there will be no snow tomorrow.  But I can say that March will come in like a lion with thunderstorms roaring from Louisiana to Massachusetts.

Short Term Forecast
There are a few showers entering Western MA/CT as of 5 PM.  These showers will remain fairly weak through early evening as they track to the ENE.
NWS Northeast Regional Radar Loop
We will have to watch this precipitation entering Southern PA.  The atmosphere is primed for precipitation, especially across South Coastal New England.  I am expecting this rain to slide mostly south of SNE, but showers and possibly a thunderstorm will form between 11 PM-5 AM.  I expect more radar coverage than this model currently depicts. 
20z HRRR sim radar Wed 2 AM (image Weatherbell)
Temperatures stay in the mid to upper 40's tonight.

Multiple rounds of thunderstorms are possible tomorrow, but forecasting severe thunderstorms for March 1 in Southern New England is something NO ONE is good at.  The majority of communities may not hear a single rumble or thunder or see a bolt of lightning.  There are signs that the one or two ingredients for severe weather may be missing.  That said of the ingredients needed are off the charts.  As a result most of Southern New England is under a "Marginal" or "Slight" severe risk.
SPC Wednesday Severe Thunderstorm Outlook
Temperatures will be plenty warm enough for late winter thunderstorms.  Most are in the mid to upper 60's with a shot at the record high for March 1.
NWS Max Temps Wednesday.   Potential record high temps circled (image Weatherbell)
One batch of showers and storms will move through between 11 AM and 2 PM.  I am concerned (for my forecast) that energy in Northern New England may rob these showers of their energy.  This will become clear tomorrow AM so I'll mention the chance of precipitation at lunch.  The next shot, mostly for W MA/CT, is between 5-7 PM.  A final round of thunderstorms is possible as the cold front crosses the region tomorrow night.

Repeat- odds of seeing a thunderstorm tomorrow are low, but if you do see one damaging winds and perhaps a tornado.  Hell it happened on Saturday.  It also happened on March 1, 1966 in Berkshire County, although reports are hard to find. 

I'll update in the morning.

-Zack Green

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

Sunday, February 26, 2017

February 25 is a Big Severe Weather Day in Southern New England

Update 6:52 PM The NWS has just confirmed that an EF-1 tornado did touch down in Conway, MA last night.  This is the first recorded tornado in state history during the month of February.  WOW!  Max wind is estimated at 110 MPH.

Like any good spring warm up, the Northeast was cooled off by severe thunderstorms yesterday afternoon and evening.  As is often the case in the early part of the year the storms fell apart long before they got to Eastern MA and N RI.  The difference yesterday is that the calendar still reads February and the National Weather Service is sending out storm survey teams to determine what caused this kind of damage in Conway, MA.  Conway is up in Franklin County near Greenfield, a little west of 91 and south of Rt 2.
WWLP photo of damage in Conway, MA on 2/25/2017
 I don't conduct storm survey's but that looks like a microburst to me.  There is significant structural damage to some homes but it is confined to a small area.  The severe reports in the northeast are impressive.
SPC Preliminary Storm Reports Saturday, February 25, 2017
Believe it or not, this isn't the worst severe weather outbreak on February 25 in New England history.  Just last year most of Southern New England woke up to heavy rain, lightning, and damaging winds.  Most of the severe weather occurred on February 24. 2016 including tornadoes in Pennsylvania.  The storms reached Southern New England after midnight.
February 24-25, 2016 7 AM to 7 AM Severe Weather Reports (SPC)
These were two different weather systems as the 2016 storm had origins Texas while this year's storm was born out of the Rockies.  This year the storm lifted well to our west as high pressure offshore protected the region until a cold front finally brought an air mass change.  In 2016 Candian high pressure to the north was in charge.  Some light snow fell the morning before the thunderstorms thanks to a good overrunning setup.  A subtropical high has been anchored in the Western Atlantic for the past few days.
Daily Weather Map February 24-25, 2016
Compare this to 2017 when the storm is further west.  The upper atmospheric set up is much different in the NE Pacific as well.  The parent low-pressure system driving the frontal system was closer and much stronger in 2016 which is why the entire SNE region saw the severe weather.
Daily Weather Map February 24-25, 2017
Suffice to say there are multiple ways to get severe weather in Southern New England, apparently! A list of all watches and warnings from the 2016 event can be found here. At first glance, the temperatures on 2/24 and 2/25 of 2016 look impressive (prior to this week).

It was only over 50 degrees from approx 10 PM on 2/24/16 until 2 PM 2/25/16 in Worcester.  The 2016 warmth was brief but it was enough to produce wind gusts 50-80 MPH across Southern New England.  I remember most rare weather events that happen in Southern New England but this one slipped my mind until this morning.  The storms raged from midnight until 5 AM so most people slept right through it.

Once the NWS is done their storm survey in Conway I think they will estimate winds of a similar magnitude last night.  Here is the radar image from 730 PM when the storm was bearing down on Conway.
NEXRAD radar image 730 PM Saturday
I'm still processing and reviewing the warmth we saw last week.  It was historic and will take a bit longer to break down, but I'm already working on it.  We are going back to the 50's and potentially 60 by Wednesday.
ECMWF 10 day max/min temps

Take days 6-10 with a grain of salt but it does look like a return to seasonably cool weather is on the table.  It will be breezy tomorrow with temps in the 50s but sunny skies.  Showers for Tuesday and Wednesday with thunder also possible Wednesday afternoon.  Mid spring in late winter continues.

-Zack Green

Friday, February 24, 2017

All Time Warmest February Day in 145 Years (Boston)

Standing ovation for this weather pattern.  It has delivered one of the warmest (the warmest? project time!)  stretches in 145 years of record keeping.  Worcester is at 66 as of 1 PM, just one degree off.  The HRRR last night nailed this.
8 PM HRRR 2 m max temperatures Friday 2 PM (image Weatherbell)
Here is where we stand in regards to warmest Feb days.
I'd like to think we can break tomorrow's records as well before late afternoon/early evening rain overspreads the region.   If minimum temperatures don't get below 50 tonight we will tie or break the warmest minimum temperatures in February.

-Zack Green

Thursday, February 23, 2017

A Record Setting Day in Southern New England

Boston, Providence, and Worcester each set a new maximum temperature record for the date.  The record run continues through Saturday as several more records may fall.  A boundary across Southern New England will be the focus for some showers/downpours in the pre-dawn/early morning hours.

Short Term Forecast
Clouds will increase tonight as a boundary to our north sags south.  It will lift back north between 3-7 AM.  This is when some rain showers will be possible.  Here is the current northeast surface analysis.
WPC Surface Analysis Thursday 4 PM
  Temperatures are well above average to the east of the cold front and south of the warm front.   Records were set throughout the northeast today, including the all-time February record in Burlington, VT.
NWS Northeast Maximum Temps Thursday, Feb 23, 2017 (image Weatherbell)
Here are the simulated radar runs from 4-7 AM tomorrow AM.  Given the warmth, I wouldn't be shocked if someone hears a rumble of thunder or two with these.
22z HRRR Sim Radar Friday 4-7 AM (image Weatherbell)
This is thanks to this boundary lingering in our air space.
WPC Surface Fronts, Precipitation Friday 7 AM 
A fog bank will envelop the South Coast tomorrow morning.  Minimum temperatures will be in the mid to upper 40's!  The average high temperature for the date is around 40.  You can see the effect the boundary has on temperatures in the Northeast.  Northern NY and New England will be in the 30's (which is still very warm for late Feb).
NWS Minimum Temperature Forecast Thursday night into Friday AM (image Weatherbell)
Tomorrow holds all the all-time February record in all four climate sites.  It will take some good clearing tomorrow afternoon to approach these.
Most guidance stays below these values but if the warm front lifts further north than anticipated we may give it a go.
NWS Max temperature forecast Friday record highs circled (image Weatherbell)
It stays warm again Friday night as we remain in the warm sector.  Temperatures fall to the upper 40's.  Clouds and moisture increase ahead of the cold frontal passage Saturday night.
WPC Surface Fronts/Precipitation Saturday 7 PM
This spring preview ends with the possibility of thunderstorms in the northeast on Saturday.  It is not often the SPC has a severe thunderstorm area shaded in this part of the country in February.
SPC Thunderstorm Outlook Saturday
I'll be watching.

-Zack Green

Tuesday, February 21, 2017

Near Record Warmth Possible Thursday

A sequence of storm systems moving through the Great Lakes will escort rounds of seasonably warm temperatures into the Northeast.  Temperatures Wednesday-Saturday will rise well above normal.  This round of above average temperatures comes to a close this weekend when a strong cold front brings heavy rain to the region.

General Overview/Short Term Forecast
The warmth is centered in the Plains and Midwest today.  Record highs are forecast to be tied or broken in Chicago, Milwaukee, Green Bay, Minneapolis, Denver, and Omaha, to name a few.
NWS Max temps Tuesday. Circled values are forecast to tie or break daily record (image Weatherbell)
Look at the huge difference the snowpack makes.  Temperatures are in the mid 70's in South Dakota while just over the border in North Dakota temps remain in the 30's and 40's,
National Snow Analysis, Snow Depth 2-21-2017 (NOAA)
Meanwhile in the Northeast high pressure remains in control.  An advancing warm front will bring some showers tonight and the leading edge of the mild air.  Temperatures today will rise into the mid 40's further helping to reduce the snowpack in Southern New England.  I think this is critical to approaching record highs on Thursday, as we see in the Midwest today.
WPC Surface Fronts/Precipitation Tuesday 7 PM
Some freezing rain is possible in the higher elevations of Worcester and Franklin Counties tonight.  I will still keep an eye on temp trends this evening in case it gets slick in the lower elevations as well.  Forecast minimum temperatures are close to freezing even in the Blackstone Valley.
NWS Minimum temps Tuesday PM into Wednesday AM (image Weatherbell)
The precipitation threat is between midnight and 4 AM.
13z HRRR sim radar Wednesday 2 AM (image Weatherbell)
The cold front will fall apart as runs into the influence of the Atlantic high.  As a result morning clouds will thin and depending on how much sun we get, temperatures will rise into the mid to upper 50's.
NWS Max temps Wednesday (image Weatherbell)
Wednesday PM-Saturday PM
Although I am confident Wednesday's records are safe in SNE, here are the record high temperatures for the next 4 days (starting tomorrow).

Here is the projected surface analysis for 7 AM Thursday.  Note the developing snow storm in Wyoming and Nebraska.  Today's max temps in Nebraska are the mid to upper 70's!  That's the beauty of the weather on the open plains.  It can go from 75 and sunny to 20 and blizzard in 12-24 hours.
WPC Surface Fronts/Precipitation Thursday 7 AM
This storm will head towards the Great Lakes.  This means the flow in the Northeast is from the Southwest and our air is warm and moist, especially this time of year.   The moisture hanging around the northeast is a concern for forecasting record temperatures on Thursday.  Low-level clouds may keep temperatures in the upper 50's/low 60's.  Worcester and Providence have a shot at the 60 and 61.  Boston and Hartford should be safe.
NWS Max temp forecast Thursday with forecast record max circled (image Weatherbell)
Some 25-30 mph wind gusts are possible on Thursday, especially near the South Coast.  It sure looks glorious in the Mid-Atlantic.  Now on Friday, a backdoor frontal boundary may settle across New England.  That would keep temperatures in the 50's with a chance of showers.  It is possible it will be 48 in Gloucester but 65 in Hartford.  The front will lift back through Southern New England as a warm front late Friday.  If that happens early look at the warmth lurking in the Ohio Valley.
NWS max temperature forecast, max temp records forecast to be tied./broken circled (image Weatherbell)
February 24 has the monthly temperature record at each climate site so it will be hard to set any records on Friday.   We get into the 60's again Saturday as the front swings through in the afternoon/early evening.  Rain is likely Saturday AM ahead of the front as tropical air surges north.  0.5 to 1" of rain by midnight and then the system is long gone and seasonable weather remains.

I'll be evaluating the temperature trends for Friday.

-Zack Green

Biggest Snow Storm Of The Season Heads To Impact Region Tonight

The National Weather Service (NWS) in Norton, MA has issued a * Winter Storm Warning * from 7 PM tonight until 10 AM Wednesday.  A widesprea...