The lazy snowfall of the day was really a secondary feature and not a feature of our main developing storm, over the next few hours we will gradually see it escalate in both precipitation intensity and wind.
As you can see from the current radar below, moisture is really beginning to stack up to our south as low pressure begins to deepen just NE of Cape Hatteras NC. Currently that low pressure is at about 1002MB’s. As it heads NE and up the NJ coastline, it will undergo Bombogenesis, and rapidly deepen into a fully mature mid latitude cyclone with central pressure dropping to near 970mb’s in the next 12 hours as it continues NE and just southeast of Cape Cod Monday AM.
As this storm deepens, the pressure gradient between the cyclone and high pressure over the Great Lakes will pack isobars tightly and increase gusty ENE winds region wide. The reason the NWS has expanded Blizzard Warnings further inland to now include the entire state of NJ, parts of PA, the entire mid and lower Hudson Valley, NYC, Coastal New England and all Long Island is due to increased confidence in atleast three hours of less than 1/4 mile visibility and winds sustained at 35 miles per hour or higher. Blizzard warning are more wind and visibility driven than accumulation driven. This is the most expansive issuance of blizzard warning in recent memory and a testament to the depth of this storm system.
As precipitation begins to pick up in intensity, the combination of dynamic cooling from falling snow and the deepening low pulling colder air into its circulation, we will see temps drop from near and slight above the freezing mark to the upper 20’s and low 30’s. This will lead to a very quick cover over of roadways and surfaces, so please conclude or avoid unnecessary travel later this evening and tonight.
We target the step up of precipitation rates to begin south to north between 4pm and 10pm. The period between midnight and 10am tomorrow may feature the most extreme period of both snowfall rates and wind gusts. During this period rotating mesoscale bands of snowfall rates between 1-3” per hour will push into the region, these snow bands may be accompanied by claps of thunder and flashes of lightning. Where these bands rotate, stall and eventually pivot will be the areas that maximize their snow totals. Just north and west of these bands we will see areas of sinking air, these areas of subsidence will have the opposite effect and cause snow to light and taper. Throw in the fact that this is a somewhat compact storm and we expect a very sharp gradiant between substantial snowfall amounts and light to moderate amounts.
In looking back and reading old storm reports and leaning into historic analogs, storms of this strength a tracks that are just east of the benchmark position we have found a common theme of very sharp cutoffs. This cutoff WILL occur within our forecast zones. We have painstakingly tried our best to account for where we believe this will occur in our final snow maps. Realize that these cutoffs will be sensitive to the final track if the system. If you live along or near the difference between a 3-8” contour or a 10”-16” contour this applies to you. For areas south and east, the confidence remains high for an accurate forecast.
This snow will be heavy and wet in consistency, blowing and drifting will maximize the impacts on roadways and travel. Expect drifts that may exceed 5’ in the areas that see the most consistent and highest gusts. Even areas with lower totals will have the effects maximized by winds.
Short range models continue to suggest that mesoscale banding will set up somewhere within our region, and may persist as late as 1-3pm tomorrow. Where these bands persist the longest- the higher ends of our forecast totals will be crested, we added a plus to the areas we fell this is most likely. This is an impactful storm, and we wanna shout out our plow drivers, linemen, emergency personnel who’s will be putting in long hours away from family to keep our communities running, cheers to you all.
We will be here all night into tomorrow trying our best to to keep you all ahead of the weather and feeding you weather geeks enough to scratch that meteorological itch! Love that you’re all hear and love that we have sparked so much new hobbyist to the science. It’s a wild and stressful ride this weather thing, thanks for letting us do it for yall!
Keep Calm & Weather On!
-Alex