Just a quick update on some concerns we have with freezing rain and it’s potential impacts on the morning commute. As I type this update moderate to heavy snow has pushed about as far North as Kingston and is continuing its trek North. The high pressure the was over our region this weekend has moved offshore and this has put our region under its southerly flow. The record breaking cold airmass that was in place the last few days is anchored firmly over the region. Temps today have risen from just below zero to about the mid teens and will continue to rise overnight. Colder air is heavier and denser, meaning its quite comfortable holding its position from about a few thousand feet above our heads to the surface at the moment. Meanwhile from about 5k feet and up where the precipitation is born, the atmosphere is quickly being warmed from nearly -30 degrees celsius on Sunday to near zero to our south in NJ.
The second image depicts temps at 5k feet, as you can see our entire region is above freezing or 0 degrees celsius and above by 11PM tonight, at that point snow can no longer form and we will transition to sleet. As the warmer air continues to erode the surface locked cold from the top down, the ability for raindrops to freeze into sleet pellets will eventually end, as the layer of air below freezing reduces itself down to only a few hundred feet or less, and all surfaces on the ground. This is the point where rainfall begins to freeze on contact, otherwise known as freezing rain. The first image shows surface temps at 4AM, you can clearly see the Hudson Valley, Wallkill River Valley, and smaller sheltered Valley’s within the Catskills, reason for this is the valleys are helping to lock in the colder air with their natural topography. You can also clearly see the Connecticut river valley to are east, also note it is colder there, that is because a deeper snowpack further aids in anchoring the cold surface air.
These areas will likely have glazing of ice by the morning commute and may still be actively seeing icing conditions by the morning commute. Remember freezing rain looks and feels like liquid rain, it is the ice it becomes on the sub freezing surfaces it comes in contact with that makes it a hazard. The silver lining is that due to the storm track we will not be in the heaviest of precipitation after midnight as we will be in a bit of a dry slot so ice accretion will be not be as bad as it could have been. Nevertheless, only small amounts of freezing rain can result in hazardous travel, travelers should be prepared for the potential for icy travel across the region tomorrow morning. Again, these icing conditions will be focused to the lower elevations and travel conditions will vary widely across the region with some areas seeing plain rain with others still icing.