WINTER SLAMS INTO THE REGION THIS WEEKEND WITH MODERATE TO HEAVY SNOW SATURDAY NIGHT INTO SUNDAY MORNING, CHANGING TO MODERATE TO HEAVY SLEET FOR A TIME IN PORTIONS OF WMASS AND CMASS, WITH SLEET AND FREEZING RAIN POSSIBLE IN N.CT BEFORE CHANGING BACK TO SNOW FROM WEST TO EAST SUNDAY AFTERNOON INTO THE EVENING… JACKPOT IS NORTHERN BERKSHIRES/TACONICS, SVT, AND WESTERN FRANKLIN AND NORTHWESTERN HAMPSHIRE COUNTIES WHERE 1-2+ FEET SHOULD FALL BY MONDAY MORNING… WIDESPREAD PLOWABLE SNOWFALL AND TERRIBLE TRAVEL EXPECTED ACROSS THE REGION SUNDAY… LIGHT SNOW MAY CAUSE SLIPPERY SPOTS FOR TOMORROW MORNING’S COMMUTE… BRUTAL COLD AND DANGEROUS WIND CHILLS MONDAY MORNING… (7:25PM Thursday)
Good evening everybody, I’ve been poring over and reading tons of data and info and wanted to get my evening report out to you with an idea of snowfall accumulations for our major winter storm Saturday night through Sunday.
This is going to be a long-form report with capitalized section headers, so do a quick scan-scroll up and down the length of this vertically-oriented wintry and nerdy diatribe to find what you need, and leave the rest as my musical hero Levon Helm used to croon.
In other words, if you just want the onset timing of snow and amounts, there are sections below for you.
So allow me to dust off my brain, finger tips and eyeballs and let’s get down to business!
FRIDAY AM LIGHT SNOW THROUGH SAT. NOON
We’ll watch a whiff of a weakening low pressure center glide south of Long Island tomorrow, which will bring a coating to an inch or two of snow in the morning. Some slippery spots will develop, but this is more of a table-setting event for the real deal on Sunday.
Highs Friday will be in the low to mid 30s with lows in the teens as we clear out. Saturday starts of partly sunny and we’ll cloud up by noon with highs in the 20s.
STORM SETUP
A moisture-laden low pressure system crosses the Rockies on Friday and dives east-southeast into the southern Plains, which will form a moisture tap down into the Gulf of Mexico so our storm system can gas back up, so to speak.
Our sopping low will then push east-northeast toward the Mid-Atlantic coastline on Saturday, and likely spawn a secondary system that will pass to our south along the southern new England coastline, destined for Cape Cod and the Canadian Maritimes through Sunday.
STRONG TEMPERATURE GRADIENT
At the same time, an upper level low will be dropping off the western fringe of a lobe of the polar vortex and diving southeast, which will strengthen the secondary low by pushing truly Arctic air from northwest to southeast through southern New England. With this super cold air to the north, and much milder air south of the storm, this clash of air masses is what causes a sharp gradient (i.e. change) of temperatures over a short distance that helps winter storms to form, strengthen and precipitate out in the form of snow and ice over WMass and surrounding counties.
SNOW ONSET TIMING
Clouds will quickly increase Saturday afternoon, lower and thicken. Snow showers will be possible as early as 2-4pm along and north of the MassPike into SVT/SWNH. Then snow will in through the reset of the region further south between 6-8pm.
With very cold temperatures in place in the low to mid 20s, after a very cold night with lows in the teens, snow will stick to the roads and travel will become slippery before midnight.
FRONT-END SNOW THUMP
As snow becomes steady and heavier before midnight, a lower level jet streak about a mile up out of the south will start to crank and meet up against truly Arctic air draining from north to south.
The term for the leading edges of two very different air masses meeting together is called “frontogenesis”, which literally means the “birth of a front”.
Frontogenesis is produced by the converging of two air masses, and when this happens, air has nowhere to go but UP. This intense lift is indicated in the attached FGEN graphic with dark magenta/purple over WMass.
This will occur late Saturday night into Sunday morning as the lower level jet is maximized over our region, and will produce intense areas of lift, and the result will be periods of snow, which will accumulate at 1-2″ per hour during the pre-dawn hours of Sunday morning. I do believe that most of our snow will fall overnight from this system for those of us that change to some form of ice.
CHANGE TO HEAVY SLEET SOMEWHERE BETWEEN RT. 2 TO NORTHERN CT… FREEZING RAIN POCKETS MOST LIKELY IN A LINE FROM HARTFORD TO WORCESTER AND POINTS SOUTH
It is this lower level jet that will also be pushing a milder nose of air northward up against this super cold air draining down from the north. You can see a graphic of the LLJ attached to this post.
How far north it is able to push before running out of gas against the Arctic cold dome in place will be a function of the strength of the jet and the longitude of the low center passing east-northeast to the south of the CT and Long Island coastlines.
The way I see things transpiring, I think this warm nose aloft will turn some of us over to heavy sleet for a time on Sunday morning, around or after sunrise, which is when the jet will be at its strongest over our region.
As the low center tracks east, it will not only take the low level jet streak with it to the east, but also start to wrap in much colder air from the WEST, as well as from the north.
CHANGE BACK TO SNOW IN AFTERNOON
Any sleet or freezing rain will change back over to accumulating snowfall sometime by early afternoon on Sunday. The precipitation shield’s western/back edge should be approaching the Hudson River Valley by that time, so additional light to perhaps moderate snow accumulations will be possible before it quits by sunset or early evening.
I do have concern that the upper level jet stream will be positioned overhead as we change back over which may produce some extra lift and lean towards more moderate snow accumulations on the back end, but we shall see. A graphic of the upper level jet stream is attached to this post.
SNOW AMOUNTS
For north-central CT (Hartford and Tolland Counties) up into central and eastern Hampden County I think 6-10″ of snow and sleet will accumulate from this system.
For northeast CT (Windham County) up into Worcester County along and south of the MassPike I think we could see more like 4-8″ of snow with a longer period of sleet and some freezing rain briefly mixed in.
For northwest CT (Litchfield County) up into the southern Berkshires/Taconics, into the western hilltowns of Hampden County, as well as through central and eastern Hampshire, central and eastern Franklin County, and northern Worcester County south of the Rt. 2 corridor, I think 10-16″ of snow with a period of sleet looks plausible right now.
Where I believe it will remain all snow in the northern Berkshires, northern Taconics, the western hilltowns of Franklin and Hampshire County, as well as north of the Rt. 2 corridor up into southern VT and southwest NH, I think we will see 12″-24″, and I would not be surprised at all to see some highs 20s readings to perhaps even 30″ in spots like the high ski peaks of the southern Greens.
Skiers, you have got to LOVE LOVE LOVE this forecast!
BLOWING AND DRIFTING
In the areas where mostly or all snow falls, northwest winds gusting 25-40mph will whip through the region behind the departing storm system late Sunday night into all of Monday and cause blowing and drifting of the newly-fallen powdery snow.
FLASH FREEZE
Across the entirety of southern New England, surface temperatures are going to plummet into the single digits below zero to single digits above zero.
Everywhere.
If you see any standing water, sleet, slush, slop and snow kicking around after the storm?
REMOVE IT, lest you want ice stalagmites and undesirable slippery zones all up in your business. Nobody has any time for that.
WIND CHILL AND BRUTAL COLD MONDAY
Wind Chill Advisories and Warnings will likely be posted for early Monday morning as northwest winds and plummeting air temps combine to create wind chills of 15-30 below zero.
Ok, so that about does it for the upcoming major winter storm for our region.
I hope you’ve enjoyed reading the report, and if you’d share it to help get the word out I’d be most appreciative.
STORM-RELATED QUESTIONS
I will try to answer as many questions as I can, and remember: this is how it looks as of this writing. It’s the future, and things are subject to change.
BUST POTENTIAL
I have a VERY hard time believing that this storm would bust to the warm side, meaning a much more robust intrusion of mild air at all levels cutting snow totals way down even into SVT and bringing plain rain way up into CT.
I just think this Arctic air is too strong, too entrenched and established, with polar origins, with not enough lower level jet sustained power to do other than something like what I’ve painted above.
Regardless of what transpires, I will keep you abreast of any changes as we near this impactful winter system for western Mass and surrounding counties, regions and states.
Have a great night, and thank you for reading!
——-
WINTER STORM WATCHES HAVE BEEN HOISTED ACROSS THE ENTIRE REGION, FROM THE TACONICS, TO S-VT, TO SW-NH, TO ALL OF WMASS, ALL OF CMASS, AND ALL OF N-CT FOR SATURDAY EVENING THROUGH SUNDAY NIGHT… THE LIKELIHOOD FOR A MAJOR SNOW AND ICE STORM CONTINUES TO INCREASE… LIGHT SNOW ACCUMULATIONS TO IMPACT TOMORROW MORNING’S COMMUTE… (7:05am Thursday)
Good morning folks, my sleep deprivation begins as my excitement increases around the prospects for a major winter storm in our region this weekend. Hard to turn the mind off with the way this event is presenting ahead of time.
I will put together a more comprehensive report for this evening with post sections and will do my best to paint a proper picture of all the elements involved with this storm, so look for that this evening. There’s a little section on the uncertainty that remains below, but if you just want the Summary, scroll below it.
UNCERTAINTY REMAINS
To be clear, we are still 3 days away from the brunt of this storm’s impact, and WMass south of Rt. 2 down into northern CT still carries uncertainty regarding exact precip types, durations, changeovers to sleet and possibly freezing rain, changebacks to snow, but we should start to get a much more clear picture as today wears on, and into tomorrow morning. I really do think that along and north of Rt. 2 this is going to be mostly or all snow, and where it stays all snow, it could be a 10-20″ type snowfall, with up to 2+ feet in the snowbelt southern Greens of SVT.
Tomorrow morning will be a nice warm-up (cold-down?) to the main event over the weekend, a setting of the winter table, if you will. Ok, put your big boy and big girl suits on and let’s jump into the details!
TODAY THROUGH FRIDAY NIGHT
–For today, we start off mostly sunny but clouds will build in later in the day
–Any morning breezes will slacken and become light by afternoon
–Expect highs in the low 20s in the high terrain, and the mid to upper 20s in the valley floor
–High pressure quickly departs this evening as clouds build into the region as weak low pressure approaches from the west
–Lows tonight will drop into the teens and light snow will begin to fall sometime after midnight and before sunrise tomorrow morning
–This is a moisture-starved system, so we can expect about a coating to 2″ by noon tomorrow
–The timing is of the Stinkpot McGee variety, given that it will occur before and during the morning commute
–Given a very cold start in the temperature department tomorrow morning, snow will readily stick to the road ways, so it will be slippery on untreated surfaces
–It’s possible a change to rain could occur south of the Rt 9 corridor before the precip quits around noon or so, but it will be negligible
–Highs tomorrow will be in the upper 20s to mid 30s, with lows Friday night in the teens under clearing skies
SATURDAY AND SUNDAY
–Any brief subsidence between systems will allow partly sunny skies to start Saturday morning, with clouds quickly advancing into the region by noon
–Highs will crest into the teens over the high terrain and low to mid 20s in the valley as Arctic high pressure to the north drains cold south into WMass
–As I posted above, Winter Storm Watches are up for the entire region from 4pm Saturday to 7pm Sunday, a 27 hour period
–Snow showers will be possible by late afternoon to near sunset on Saturday
–Snow will become steady, and heavy at times late Saturday night and into Sunday morning across the entire region. Lows will be in the teens, with highs in the 20s on Sunday
–Then things get tricky, as the exact surface storm track, along with the strength and orientation of a lower level jet streak (i.e. faster moving river of air a mile above our heads) will decide who mixes, for how long, with what types, and where
–I will post a full report later this evening with more details, but suffice it to say, I think along and north of the Rt. 2 corridor sees all snow from this system, the way it looks now
–This means those areas could see over a foot of snow, and in some cases like the high terrain of SVT, up to 2 feet, and maybe a little more
–For areas south of Rt. 2 into northern CT, plowable snowfall is likely, with varying amounts of heavy sleet, with freezing rain possible south of the Pike
–If a freezing rain zone sets up, it could accrete up to a half inch of ice glaze on EVERYTHING, and possibly a touch more, which would cause major problems, and scattered to widespread outages in a narrow ribbon of geography that sees such conditions
–I do think the mix line sets up somewhere between the Rt. 9 corridor to the MA/CT line, possibly as far north as Rt. 2
–We all change back to snow late Sunday afternoon into early evening as low pressure passes by to our south and east heading towards Cape Cod
–Arctic air will PLUNGE into the region Sunday night with lows in many places below zero as northwest winds pick up, along with high terrain upslope snow showers producing additional light accumulations there
MONDAY AND BEYOND
–Monday morning is going to be brutally cold. Wind Advisories may be needed, as some gusts up to 40+mph will be possible
–At the same time, wind chills will likely plummet to between 10-25 BELOW ZERO, which means Wind Chill Advisories and Wind Chill Warnings will be posted later
–Air temp highs on MLK Day will only be in the single digits!
–Monday night lows will be below zero
–Tuesday “rebounds” into the teens and 20s with fair weather, and then another storm of snow and mixed precip is possible for mid week, with another storm next weekend
Busy pattern folks!! Stay tuned for this evening’s report, we gotta stahm comin’!
Ayup.