Black Friday Storm – Update

Rain totals are way underperforming thanks to some mesoscale banding that really messed things up. Strong deformation zone in western New England was the focal point of heaviest rain so far today while overnight convection focused heavy rain in portions of E CT. Eastern New England is getting dry slotted at the moment with closed mid level low overhead. Winds are picking up as the low strengthens and pulls past… expecting winds up to 50 mph by tomorrow morning!

At least this wasn’t snow!

More later..

Black Friday Nor’easter

It’s certainly not the most exciting storm but it is something to talk about!! Pressures are starting to fall off the Mid Atlantic coast and convection is firing south of ACK. Big time cyclogenesis is about to get underway. A strong vort max rounding the base of a strong and negatively tilted trough is interacting with a baroclinic zone along the coast. In a few hours – BOOM!

On the water vapor loop you can see the shortwave on the North Carolina/South Carolina border. As it moves offshore things are going to get going in a hurry. Pressures are dropping east of Long Island (about 3mb/3 hours) but will really start dropping quickly when the upper level energy moves off the coast. Rain is already breaking out south of New England and this will continue tonight. I’m expecting 0.5″-1.0″ of rain – though over well an inch is possible in eastern Connecticut depending on how close to the coast the storm tracks.

Big wind is likely as the storm wraps up (I’m seeing 60 knots at 850mb Saturday morning). This should mean widespread 40-50 mph wind gusts. Some snow is possible Friday night as temperatures crash as the storm pulls away in the hills. The boundary layer seems too warm in the valleys but above 1000 feet it should be cold enough for snow. Up to an inch is possible in some towns northeast and northwest of Hartford. Several inches of “upslope” snow late Friday and Friday night is likely in the Berkshires and up to a foot in some parts of Vermont.

Here’s my call for Friday/Saturday:

  • 0.75″ rain / 40 mph wind gust at BDR
  • 0.80″ rain / 45 mph wind gust at BDL
  • 1.00″ rain / 48 mph wind gust at BOS
  • 1.20″ rain / 45 mph wind gust at PVD
  • 1.20″ rain / 50 mph wind gust at ORH (snow: 0.5″)

Ryan

Lots of Wind

Check out the 12z GFS and how windy it gets by 15z on Saturday. 50-60 knot winds around 850 mb (thanks to a stronger and further south low pressure) with a mixed boundary layer to about 875mb. This would mean wind gusts up to 50 mph in a few towns Saturday morning especially if the sun can come out and mix up the atmosphere. A strong pressure rise (isallobaric component) should promote strong winds as well. As for the risk of accumulating snow, a few of our models still have a wound up CCB which may promote some accumulation in the hilltowns (no more than an inch) Friday night. We’ll see how this plays out but it’s not looking like a big deal for 95% of us thanks too warm boundary layer temperatures. Big time snows though in the upslope regions of VT! Skiers and riders are saying hallelujah to that!

Have a good Thanksgiving!!

Ryan

Whoa 12z GFS

That’s a sweet looking damaging wind signal Saturday morning. Easily 50+ gusts with that setup. Notice the difference between the 12z run and the 06z or 00z run. The biggest is how fast the low closes off and stall. The 12z run closes the low off faster, keeps the storm stronger, and stalls it along the Maine coast like last night’s Euro. The overnight GFS runs pushed the storm further north toward northern Maine and New Brunswick.

We’ll see what develops but I’m becoming more confident in a major upslope snow event along the spine of the Green Mountains in Vermont and even in northern New Hampshire and northwest Maine. Jay Peak, for example, shouldn’t have much of a problem picking up a foot. A coating of snow seems like a possibility in elevated towns in SNE with the exception of the Berkshires where a few inches are possible.

Ryan

Friday/Saturday Storm – Wind But No Snow?

Most of our computer models this morning have some good news for travelers Friday. The GFS and NAM both show the storm that develops will stay far enough offshore on Friday to spare us from any appreciable rainfall during the day. On the 6z GFS you can see one batch of precipitation over Cape Cod and Maine associated with some DCVA (differential cyclonic vorticity advection) and some low level warm advection (look at the thermal packing at 850 mb along the eastern Massachusetts coast). A second batch of precipitation from Watertown, NY south toward Sussex County, NJ is associated with a strong 500mb vorticity maximum. The 6z GFS does slide some precipitation into CT after 10pm Friday night which could fall as a little bit of light rain/mixed with snow in the hills.

One important difference in the GFS/NAM from the Euro is that at 12z Saturday the Euro has the surface low in the Gulf of Maine while the GFS and NAM have it north of Caribou in New Brunswick. If the surface low gets captured by the mid/upper level lows and it stalls south of Maine then there is a greater chance at seeing some accumulating snow in southern New England.

The GGEM and UKMet agree more or less with the American models and keep this thing far enough north to spare us from a more significant wraparound event. That said, the 00z GGEM does bring in some moderate rain during the day on Friday. As is sometimes the case the far outlier/wrapped up Euro solution doesn’t seem to be the way to go. A consensus forecast approach keeps this storm progressive and out of our hair (with limited snowfall) by Saturday morning.

One other issue for Saturday will be the winds behind this storm. On the 6z NAM BUFKIT sounding you can see a well mixed boundary layer tapping into some of the strong winds just off the earth’s surface. A strong pressure gradient in the storm’s wake should lead to gusty winds over 30 mph and possibly 40 mph on Saturday. Notice the lapse rates to the left from 850mb to 950mb is nearly dry adiabatic (9.1ÂșC/km). If the storm trends stronger or cuts off further south these winds may be stronger.

Bottom line – here’s what I’m expecting

  • No snow accumulation in SNE outside of the Berkshires (some upslope)
  • Wind gusts to 40 mph Saturday morning
  • No precipitation after 12z Saturday (dry at BDL/ORH/BDR/PVD/BOS)
  • Rainfall through 12z Saturday of 0.25″ to 0.5″ at BDL

Ryan