Tuesday Discussion : Final Snowfall Forecast 1/26

A weak storm system will push into the Hudson Valley on Tuesday and spread widespread accumulating snow into the region for the first time in weeks.  While not a major event, it could still cause some travel headaches and hazardous conditions across our area.

Timing (Tuesday):
– 10am to 1pm : Snow begins from SW to NE
– 12pm to 4pm : Period of moderate snow expected
– 4pm to 6am Wednesday : On and off periods of light snow
– 6am to 10am Wednesday : Snow showers taper off

Impact / Conditions:
– Steadiest snow likely at the onset, could fall up to 1″ per hour for a time
– By late afternoon Tuesday, lighter snow expected, could last into night
– Snow could mix with sleet south of I-84 late in afternoon
– Temps in 20s, snow accumulates to all surfaces, icy roads possible
– Tuesday PM and Wednesday AM commutes could be hazardous

Snow Accumulation:
– Catskills (Zone 1 & 2) : 4 to 8 inches
– Mid & Upper HV (Zone 3,4,5,6,7,8) : 2 to 6 inches
– Low Hudson Valley (Zone 9) : 1 to 3 inches

— Forecast Discussion —

A weakening storm pushing into the northeast will create a bit of a mess for the Hudson Valley on Tuesday.  Snow is likely to spread into the Hudson Valley between 10am and 1pm in most areas, and it could come down quite hard for a couple of hours…

Futurecast Radar : 10am to 4pm

The weakening system approaches disorganized, and then at the last minute, the atmospheric vorticity intensifies over NE PA, and snow should rapidly develop and become quite heavy for a brief time.  To get a visualization of what causes this moderate to heavy snow band to develop right over top of us, here is the 700mb vorticity loop for roughly the same time as the radar shown above.

700mb Vorticity 7am to 7pm

Vorticity is a measure of the rotation and lift of the air at this layer of the atmosphere.  The red and purple band develops over PA and moves NE, and that sudden rotation and lift of the air, should generate the moderate to potentially briefly heavy snow for Tuesday afternoon around the region.  For that reason, we’re concerned about a 1 to 2 hour burst of moderate to heavy snow across the region, close to the onset of the snow.  This could cause a quick 1″ of snow in spots, and create some very hazardous travel if people are caught off guard.

As the afternoon progresses, the back edge of the main area of moisture approaches between 4pm and 8pm.  As it does, some of the guidance wants to mix parts of the region with sleet and possibly even freezing rain.  We won’t discount it… but we have looked at projected soundings, and cannot see how this actually occurs.  All layers of the atmosphere are projected to be safely (3 to 6 degrees C) below freezing.  Either the sounding data is wrong… or the map above is wrong… because the soundings point to an all snow event.  We’ll see how it unfolds.  A wintry mix would reduce snow totals… so we’ll watch closely Tuesday afternoon.

By 6pm, the models show a widespread 2 to 4 inches of snow falling around the Hudson Valley.  If the front edge of the snow is as potent as latest data is suggesting, it is entirely possible that we have 2 to 4 inches on the ground by sunset.  The Tuesday PM commute is likely to be quite treacherous, so make sure to take it slow.

From there… the remainder of the event is a bit uncertain.  Some guidance keeps light snow showers in the region through the night Tuesday night, which could add an extra inch or so to the snow totals by Wednesday morning.  In addition, it would make for a potentially icy start to our Wednesday as well.  We’ll have more on that later on Tuesday, so check for updates.

An interesting, disorganized, and rather uncertain event on the way for Tuesday.  We’ll see what Mother Nature has in store for us.  Stay warm, stay safe… have a great day!

2 thoughts on “Tuesday Discussion : Final Snowfall Forecast 1/26”

  1. Thanks folks. I really appreciate the thorough, thoughtful analysis, and the presentation is great.
    The higher-anywhere-else-accuracy is also welcome!
    Happy snow day!


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