Winter’s Last Stand Begins Tonight

Hello everyone!

Our very tricky forecast remains a nail biter as the storm begins to develop off the Carolina coast. A large plume of moisture extends from the Eastern Pacific to the Western Atlantic and two disturbances are dropping in from the NW helping to form the storm. After careful analysis of Water Vapor satellite and observations as well as forecast model guidance, it seems that the more potent disturbance will likely arrive just in the nick of time for the Midcoast but a hair too late for everyone else.

A Comparison Of Observed Reality To Model Forecasts For The Same Time (5 PM This Evening). Image Credit: Accuweather and SPC
A Comparison Of Observed Reality To Model Forecasts For The Same Time (5 PM This Evening). Image Credit: Accuweather and SPC

This is the comparison I’m talking about with regards to the energy blasting through the Great Lakes. Notice the disturbance (marked here by the 534 dm contour line). It is a little farther behind the NAM forecast. These images are valid at the same time (5PM this evening). This is the critical energy that, when it gets here, will tilt the upper level trough negative which will intensify the storm and bring it west. This happens just a little too late for us. Model guidance has backed off on snowfall amounts today, probably as they are sniffing this out. Given that even the most up to date guidance (18Z NAM used here) is too fast with this energy, I’ve opted to go even lower with my snow totals. Without the trough tilting negative, moisture cannot be wrapped west and precip won’t get much past the coast.

HRRR Showing Precip Arriving This Evening. Credit: Weatherbell
HRRR Showing Precip Arriving This Evening. Credit: Weatherbell

In terms of how this all goes down, snow will move in late tonight and be light to moderate through midday tomorrow before tapering off. Really this one only impacts the coast with the mountains and NW foothills seeing but a few flakes. Take a look at the simulated radar above. Those not in the blue (snow) during this loop likely escape with a few flakes, if any at all. The Midcoast could see some heavy snow bands as the storm passes by.

Expected Snowfall Totals
Expected Snowfall Totals

In terms of accumulation, this is what I’m thinking as of now. The Midcoast will see the most as it could get into the heavy bands and will be closer to the center of the storm. A sharp cutoff will occur somewhere near Brunswick but it will be impossible to pinpoint that until the snow is actually falling. West of that cutoff, an inch or so is expected while east of that cutoff several inches are likely. Areas near Camden/Rockland/Belfast are pretty likely to see more than 4″ and up to 6 or 7″ is possible should the banding set up right. Farther north and west, little is expected and the mountains could escape without a flake.

NWS Best/Worse Case Scenarios From This Morning.
NWS Best/Worse Case Scenarios From This Morning.

To give you a sense of how this storm has puzzled even the pros (not just me!), here was what the NWS in Gray thought we could see in the ‘best case scenario’ and ‘worse case scenario’ this morning. This is absolutely not intended to criticize their forecast, this is to show you how uncertain this forecast is. It’s always a good idea to be prepared for the worst case scenario even if it only happens one in every ten times.

All snow wraps up from west to east early tomorrow afternoon with temps rising into the low to mid 30’s and northerly winds strengthening.

This sets up part two of winter’s last stand which will feature snow, sleet, freezing rain, and cold rain to end the week. More details on that tomorrow.

-Jack

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