Wednesday, February 27, 2019

Winter Weather Advisory Wednesday Night, Thursday AM

A *Winter Weather Advisory* has been issued from 7 PM tonight until 7 AM Tuesday morning.  A light, fluffy snow will begin to fall this evening.  Snow rates will not be all that intense, so snow removal technicians will be able to keep up with it.  Most cities and towns will see 3-6".  The highest amounts will be along and north of the Pike. 

NWS Wednesday AM Headlines 

Snow falls lightly from 6 PM until 9 PM.  The roads will start to become snow covered quickly, with temperatures between 15-20 degrees.  Snow may fall moderately at times between 9 PM and 5 AM.  It will quickly taper to just snow showers between 5-8 AM, ending just before or during the AM rush. 

12z NAM 3km HiRes Simulated Radar Wed 5 PM to Thurs 11 AM (Image
 You can use a backpack blower or a broom to get rid of this stuff tomorrow AM.  Compared to the frozen slop we have had to clean up so far this winter, this is a welcome change.  If a heavy band of snow does indeed set up, some localized communities could see over 6".  This will be the exception, not the rule. 

NWS Boston Expected Snowfall 
I don't think this is the last snow chance of the winter.  There are several snow chances in the next 1-2 weeks.  I'll keep you posted.


Monday, February 25, 2019

Strong Winds to Bitter Cold to...A Real Snow Event?

It has been a wild day so far across Southern New England.  Snow squalls caused some travel issues this morning but the main story is the strong winds.  A *High Wind Warning* continues until 7 PM this evening.  The wind will relent somewhat this evening and overnight.   Temperatures will fall into the low teens by Tuesday morning and will only rebound into the low to mid 20's Tuesday afternoon.   The coldest air of the week arrives on Wednesday morning with lows in the single digits.  It will help set the table for a probable plowable snow event Wednesday evening into Thursday morning.  

NWS Boston Skywarn Twitter Post of Damage in Springfield, MA

As of 402 PM, 63926 customers were without power in Massachusetts.  The worst is happening right now.  You can find the latest wind reports here and the latest wind damage reports here.  The highest gust I have seen so far is 69 MPH in Cambridge, MA.  Worcester has reached 60 MPH and Mendon has reached 59 MPH.   The strongest wind gusts will diminish shortly after sunset.  Winds will remain gusty, but the power outages and tree damage should begin to slow down.  

NWS NDFD Minimum Temperature Forecast Tuesday AM (image
It will be sunny and breezy tomorrow.  Although the threat for damaging winds decrease tomorrow, garbage and recycling bins will likely be blown around again.  The coldest air of the week arrives Tuesday evening into Wednesday morning.  By 7 AM Wednesday, wind chill temperatures will -10 to -15 below.

12z EURO 2 m Wind Chill Temperatures Wed 7 AM (Image

We then turn our attention to a clipper system them will emerge out of the Great Lakes, and perhaps strengthen as it passes South of New England.  Most storms have moved through New England this season, which means a change over to rain, warm aloft, and other negative snow factors.  Although this system may be moisture starved, the most recent computer guidance has a up to a 0.5" of precipitation by Thursday morning.

WPC Surface Fronts/Precipitation Wednesday 7 PM

That works out to 3-5" of snow.  However, with temperatures in the teens Wednesday evening and favorable snow growth in the lower and mid levels of the atmosphere, that 3-5" could turn out to be more like 5-10".  There will be no mixing concerns and this snow will be powder.  The biggest questions is how much moisture/forcing will be available to produce snow.  The NAM is on the lighter side, while the EURO is on the juicer side.

18z NAM 3km Hi-res Simulated Radar Wednesday 9 PM (image
 I will have more on this tomorrow and Wednesday.  


Sunday, February 24, 2019

High Wind Warning Headlines Sunday Weather Discussion

NWS Northeast Regional Radar 

With most of Sunday's precipitation behind us, a soggy Southern New England now must prepare for strong winds tonight through Monday evening.  Winds out of the W and NW will be sustained at 20-40 MPH with gusts as high as 65 MPH possible.  There is a real threat for damage to trees, power lines, and property.  For that reason, the National Weather Service in Norton, MA has issued a *High Wind Warning* from 10 PM this evening until 7 PM Monday evening.  Traveling will be difficult, especially for high profile vehicles. 

NWS Boston Sunday Early PM Headlines (click to enlarge)
General Overview
Surface low pressure is moving through Southeastern New England.  Winds out of the northeast are allowing for the continuous drizzle this afternoon.  This low is part of a larger storm system that is responsible for severe weather and flooding deaths in parts of the south, along with blizzard conditions in the Midwest and Great Lakes.  This is part of the same storm system that brought snow flurries to Los Angeles and Las Vegas during the week. 

WPC Surface Fronts/Precipitation Sunday 7 PM
As the parent low decays in Southeastern Ontario, the secondary low (which is really an open wave) that brought the rain to New England will begin to absorb energy from the parent low as it tracks in the Canadian  Maritimes.  The secondary low will deepen into a strong storm with a pressure of around 970 mb.  At the same time, strong, broad high pressure will descend into the Upper Midwest.  It will have pressure around 1040 mb. 

WPC Surface Fronts.Precipitation Monday 1 PM
Winds have not been a major problem so far this winter because temperatures have often increased from the surface into the lowest levels of the atmosphere.  This is known as an inversion and acts as a barrier to keep the strongest low-level winds above our heads.  This will not be the case tomorrow.  Cold, dry arctic air will begin spilling in from the Northwest this evening.  This is an efficient way for the low-level winds to reach the surface. 

Timing & Impacts
Temperatures this evening will fall from the low 40's to the upper 20's by morning.  Temperatures will stay in the 20s for most of the day in Worcester County and Northeast MA.  Temperatures will rise into the low 30's across Southeast MA.  It will feel much colder thanks to the roaring winds.  Wind chill values will be in the mid to upper teens in Western and Central MA and low 20's across Eastern MA.

12z EURO(1 hr) 2 m Wind Chill Temperatures Monday 2 PM (image

Winds tonight will begin to increase around 10 PM.  Light sleepers are in for a rough night as wind gusts will slowly increase from 30 MPH to 45 MPH by morning.  The potential overnight is for isolated to perhaps scattered power outages from downed tree limbs.  There is also the potential for snow squalls that will hit at various times overnight through the morning commute.

20z HRRR Simulated Radar Monday 5-9 AM (Image

The snow squalls will not only cause briefly hazardous travel conditions but also will serve as the entrance music for the main event.  The main event is sustained winds of 20-30 MPH with winds gusts of 45-65 MPH from 10 AM to 6 PM.  Scattered to widespread tree and powerline damage is likely.   Wind gusts of 60+ MPH are most likely between 1-4 PM. 

NWS Max Wind Gusts Forecast

The winds will only relent somewhat on Tuesday.  Temperatures will also be colder, with wind chill temperature near or just below 0 in the morning and will not improve much during the day.  The coldest day of the week is Wednesday, with wind chills -10 to -15 below Wednesday morning.   If your power does go out, it may be a few days for it to come back on.  These cold temperatures will be living in unheated buildings unrealistic so you may want to consider a backup plan, just in case. 

Other Thoughts
I think tomorrow's event will be more widespread in magnitude thanks to the amount of precipitation that has fallen in Southern New England since last summer.  Just in Southern Worcester County, observations taken at Worcester Airport and the Blackstone River at Sutton Street/Providence Road in Northbridge show anomalies of + 15.00" since July 1, 2018.

These anomalies exist all across Southern New England.  The Quabbin reservoir is 100.6 % full and the Wachusett reservoir is 93% full.  It wasn't all that long ago (2-3 years) that moderate to major drought conditions were widespread in New England. 

MWRA Quabbin Water Levels Jan 2000-2018
While that is good, the water table is nearly full.  The soil has lots of moisture.  Again, that is positive on the agricultural side it will also make trees uproot more easily.  March and April are also months where we tend to get a lot of rain.  It will be interesting to see if the precipitation trend continues.  If it does, big river flooding trouble is in our future.  In the meantime, stay safe tomorrow. 

-Zack Green

Wednesday, February 20, 2019

This Is Not A Recording; Snow to Ice to Rain Tonight

Stop me when you've heard this forecast lead before; a fast moving winter storm will start as snow tonight before changing to sleet, freezing rain, and plain rain after midnight.  Light snow and ice amounts are expected but the Thursday AM commute is likely to be slippery in Central, Metrowest, and Northeast Massachusetts.

NWS Headlines
The National Weather Service in Norton, MA has issued a *Winter Weather Advisory* from 7 PM this evening until 7 AM Thursday morning for all of Southern New England except for the Cape and Islands. 
NWS Boston Headlines 
A Winter Weather Advisory means periods of snow, sleet, and freezing rain will cause travel difficulties.  Expect slippery conditions and use caution when driving. 

General Overview
Strong high pressure is control today.  Temperatures started in the single digits and teens and they will rebound in the low to mid 20's.  Fun fact- the jet stream is ripping along above our heads.  A flight was measured at 801 mph as it got embedded in 200+ mph winds around 35,000 feet up.  This is good if you are flying to Europe, bad if you have to fly to the west coast.

00z EURO 300 mb winds Tuesday 7 PM (image
The fast jet will keep traffic in the atmosphere moving along.  The high pressure will slide east today as a storm system develops along the Gulf Coast, lifts northeast, and reforms near the Mid-Atlantic coast.  High level clouds will increase throughout the day, but precipitation will hold off in Central and Eastern MA until after 7 PM.

WPC Surface Forecast Fronts, Precipitation Wednesday 1 PM, 7 PM, Thursday 1 AM, 7 AM
Cold surface temperatures will linger in Central and Northeast MA all night so it is likely that all precipitation that falls will be frozen north of a Brockton to Foxboro to Smithfield, RI line.   However, temperatures on Thursday will rise into the 40's across most of Southern New England so we aren't worried about everything turning to cement.

Snow will begin after 7 PM in Worcester and Boston.  Snow will be light from 7 until 10, increasing around 11, and peaking from 12-2 AM.  Between 2-3, snow will transition to sleet, freezing rain, and rain.  All precipitation ends around 6 AM. 
12z HRRR Simulated Radar Wed 4 PM to Thur 7 AM (Image
Although surface temperatures will be in the mid 20's across Central and Northeast MA, warm temperatures aloft will limit the ability for snow growth in the mid layers, limiting snow totals on the ground.  That said, a general 2-4" is likely followed by up to 0.10" of ice.  Some communities closer to the NH/MA border could see up to 4". 
12z HRRR total snow *click to enlarge (Image
For the Thursday AM commute, traffic is lighter than normal this week thanks to school vacation.  That will help keep congestion down, but it will still be a slow go.  Unlike last weeks storm, precipitation will end closer to 6 AM, which will delay the clean up.  I anticipate the main roads being fine, but untreated side roads will be slippery.  If you have the option to work from home, it is a not a bad idea to exercise that right.  The roads will be fine by the afternoon, but why spend the time commuting when you can be working? (Practicing for my boss). 

I will update again if needed.


Monday, February 11, 2019

Winter Storm To Significantly Impact Tuesday PM Commute

A winter storm will bring snow, sleet, freezing rain, and rain to Southern New England Tuesday afternoon into Wednesday morning.  Snow will begin Tuesday afternoon and will fall moderately to heavy at times through the evening commute.  Snow will transition to sleet and freezing rain after 7 PM and will change to rain after 1 AM.  The rain will end before the Wednesday AM commute. 

NWS Headlines

NWS Headlines
A *Winter Storm Watch* is in effect.  Some parts of this watch will be converted to a warning, while others will be converted to an advisory.  Either way, the impact to the evening commute remains the biggest threat. 

General Details

WPC Surface Fronts/Precipitation Monday 7 PM, Tuesday 7 AM, PM, Wednesday 7 AM, PM

High pressure is currently building to the north.  Light northerly winds will bring cold, dry air into Southern New England this evening.  By morning, temperatures will be in the low to mid-teens.  Temperatures will be in the low to mid 20's when precipitation arrives as snow Tuesday Afternoon.  Snowfall rates of 1-2"/per hour are possible between 3-7 PM. 

18z HRRR Sim Radar/P Type Tuesday 7 PM (image
Snow transitions to sleet and freezing rain from south to north starting after 6 PM.  Warm air will begin to move in aloft.  It should reach the Worcester and Boston area after 7 PM.  Frozen precipitation will fall until 1-2 AM before finishing as a bit of rain Wednesday morning as surface warming finally catches up to the warming aloft. 

Storm Totals
A general 3-6" of snow will fall before the changeover to sleet and freezing rain.  

NWS Expected Snowfall (Click to enlarge)
A total of 0.1 to 0.2" of ice accretion is expected, which is below damage thresholds.  

NWS Expected Ice (click to enlarge)
Overall, this is not a huge deal except for the snowfall during the Tuesday PM commute.  It also adds more water to the system, which is near capacity.  If this weather pattern continues, spring flooding is going to be a story around here. 

-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...