Storm Update #1 : Monday – Wednesday Nor’easter

Light snow (mixed with rain) 6am to 6pm Monday
… Snow Intensifies : 6pm to 10pm Monday
… Stop : 6pm Tuesday to 6am Wednesday
– Wind gusts 25mph to 40mph
– Low Confidence on Details due to storm track
– Heavy Snow rates, over 1″ per hour
– Blowing & drifting snow = low visibilities
– Heavy wet snow expected, temps 29° to 34°
– Long duration event
Accumulation (subject to change):
– Eastern Catskills: 12 to 24 inches
– Upper & Mid Hudson Valley: 8 to 16 inches
– Western Catskills & Lower HV: 6 to 12 inches
– Extreme Lower Hudson Valley: 2 to 6 inches
STORM SYNOPSIS: An area of low pressure will emerge off the NC coast on Monday AM and progress Northeastward. As the storm tracks NE an Upper Level Low (ULL) will be tracking in from the west, these two pieces will phase off the coast and undergo a rapid deepening or bombogenesis off the coast of New England dropping from 1003MB down into the 970’s by Tuesday. This storm will have copious amounts of moisture associated with it, and thanks to the capture of the energy by the ULL it will be slow to depart and may even loop off Cape Cod. The combination of Atlantic moisture, gusty winds, and it’s slow departure, will be the recipe for a long duration event with potentially severe impacts on parts of the region.
Light snow and rain showers are expected to develop during the day on Monday. Due to the airmass being marginal, and this being a mid March storm, valley temperatures may be in the mid to upper 30s Monday, causing the storm to begin as rain. As the coastal storm begins to deepen and phase with the ULL, surface temperatures will fall into the low 30s, and any rain will transition to snow after dark on Monday. Snow will intensify overnight with snowfall rates of 1-3” per hour, this will overcome any surface temp issues with snow rapidly accumulating on all surfaces. Localized banding will develop, while its exact location cannot be predetermined, where these bands do occur amounts will exceed upper ends of forecasted amounts.
The combination of winds gusting 20-40 MPH with extremely high snowfall rates will lead to treacherous to impossible travel in the hardest impacted parts of the region. The combination of this being a long duration event with snow possibly not tapering off until early Wednesday, and this being a heavy wet snowfall, combined with gusty winds, will lead to significant to severe impacts to travel a commerce.
—- Wildcards —-
One of the key components to this storms evolution is the phasing of the two pieces of energy, the GFS model is a bit later on the phase. This results in the low pressure being captured later and deepening further east. By the time the system retrogrades back to the west it is beginning to occluded and it’s western precipitation is collapsing east. This results is heavier snowfall focused slightly NW with lesser impacts west and south. This could very well be a part of the SE bias of the GFS Model. The European model continues to project all of the components of a blockbuster HECS “Historic East Coast Storm”. The storm is captured, it makes a full loop over the cape and slowly departs NW, if the Euro model proves correct in its handling of the players on the field, then our prelim snow-map would be underdone, region wide.
Our current snow-map is reserved and blended with multiple model data and ensemble data, it is strong enough to highlight the need for preparation, but cautious with the knowledge that there are some things can alter the outcome of this storm. We will have very heavy coverage on this storm over the next few days, we will issue additional snow-maps as confidence continues to increase. As of now, north of i84 and away from the valley floor west of the river on the eastern facing slopes of the higher terrain, confidence is highest for 18”+. As stated above, if the dynamics all align, parts of the Catskills may exceed 24” of snowfall.
This is going to be a very complex situation as it develops, expect regular updates over the next 48 hours as we continue to hone in on what may be instore for the Hudson Valley Monday through Wednesday.
-Alex, Todd & Bill-

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