Sunday Discussion : Final Snowfall Forecast

A weak storm tries to come together over the mid Atlantic on Sunday, and as it looks now, it does not quiet become a significant storm.  Instead, we’re left with a rather minor, disorganized system… that still has the potential to cause some problems for our Sunday and Sunday night.

Timing:
– 11am to 3pm : Snow starts from SW to NE
– 3pm to 8pm : Steadiest snow expected
– 9pm to 1am : Snow ends from west to east

Impact:
– Temperatures 32° to 35° at the onset of snow
– Wet snow accumulation likely… even on paved surfaces, especially after dark
– Hazardous travel Sunday night likely, slick Mon AM commute possible

Snow Accumulation:
– Catskills, Mid & Lower Hudson Valley : 2 to 5 inches
– Upper Hudson Valley (Northern half of Zone 3 & Zone 4) : 1 to 3 inches

— Discussion —

Any time you have a storm trying to get it’s act together right over top of you, there is a high ‘bust’ potential in that storm.  This storm had 2 pieces of energy (an upper level low over the Ohio Valley, and a developing coastal low pressure), that were going to interact just soon enough to have a significant band of snow over the Hudson Valley.  Over the last 24 hours, we’ve seen a trend to keep those two features from interacting with the same intensity… and the result is a storm that looks less organized and less intense.

On the left is the model data from New Year’s Day.  Notice how there was a solid band of snow from Detroit to NYC.  The 1006mb low is tucked in near the tip of Maryland, and the system looks rather formidable.  On the right, is the model data from Saturday.  Just 24 hours later, the model depicts a storm that is weak and disorganized.  The precipitation shield is weak and broken, and the storm is weaker and further off shore.  This kind of development hints at the fact that this system is quite unpredictable.  This leaves a decent chance for error in the forecast.

Our forecast is based on the idea that the system is weak, but still organizes during the day on Sunday.  The snow shield will likely fill in on radar during the mid and late afternoon, and we should see a few hours of steady snow between 3pm and 8pm around the region.

Futurecast Radar for 9am to 11pm on Sunday

Despite being very disorganized early on Sunday… guidance suggests the snow really comes together by mid afternoon, so that a 2 to 4 inch snowfall occurs in the region.

Projected Snowfall per HRRR model

A widespread 2 to 4 inches would fall under this scenario, with the heaviest snow being west of the Hudson River and in the Catskills.  But this is significantly weaker than what was projected 24 hours earlier… so our concern is, ‘what happens if this trend continues on Sunday morning?’  We have some concern that the storm is even weaker than what is being projected above.  It’s possible the ULL (upper level low) is slower and weaker than projected… which would really limit the amount of available moisture.   If that happens, snow totals closer to 1 or 2 inches could be what we see.  At the same token… if the energy is stronger than currently expected, the snow totals could be on the higher end of the range, with 4 and even some 5 inch amounts being possible.

We’ll just have to monitor how it unfolds on Sunday.  Regardless, travel could be quite slick and hazardous Sunday after dark.  Make sure you factor that in to your plans.  We will try to update as frequently as possible on Sunday, to let you know if we think the data is trending one way or another.

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