A very complex upper level low pressure system diving in from Canada will bring some much needed rainfall to the Hudson Valley, and the season’s first snowstorm for the Catskills.
Timing:
– 12am to 4am Thursday: Rain develops from SW to NE
– 3am to 12pm : Period of heaviest rain
– 12pm to 8pm : Periods of light to moderate rain showers
– 8pm and after : Possible valley rain mix with / change to wet snow
Impacts:
– Soaking rain could cause slick commutes on Thursday
– Catskills: Heavy wet snow, treacherous roads possible
– Valley: very close call, enough cold air for wet snow Thu night?
– Dynamic system with variable conditions based on elevation & location
Snow Accumulation:
– Catskills : 4 to 8 inches, localized 12″+ in higher peaks
– Hudson Valley : Slushy coating to 1″ away from Hudson River
– Hill towns above 800ft elevation: slushy coating to 3″ (west of Hudson)
Discussion:
With the Hudson Valley officially in a ‘Severe Drought”, this storm system is exactly what the doctor ordered. An intensifying Upper Level Low pressure (ULL) is pushing into the Great Lakes, and it will impact the Hudson Valley in multiple phases over the next 48 hours.
To begin, the ULL will develop a surface low pressure that spreads a soaking moderate to heavy rain into the Hudson Valley, beginning shortly after midnight. The heaviest rains are likely to fall just before sunrise and last through the Thursday AM commute. It’s possible that many of us see around an inch of rain by noon on Thursday. The deepening of the ULL will likely keep rain showers spread across the Hudson Valley for most of the afternoon Thursday… as the upward motion in the atmosphere generates and enhances precipitation over the Hudson Valley and Catskills.
This deepening will also pull cold air from the mid levels of the atmosphere, down to the surface. This will cause temperatures to tumble Thursday evening. As it does, rain will begin to mix with wet snow. The Catskills will change over to snow early Thursday morning, and the rain/snow line will be elevation dependent… becoming lower and lower after dark on Thursday. The biggest uncertainty with this system will be exactly how much of the valley sees a period of wet snow Thursday night into Friday… and where does it accumulate. Computer guidance is pretty confident that most of us will see wet snow fall from the sky at some point, but with temperatures expected to be 33° to 37°, accumulations will be tough. We’ll have a separate post to discuss this potential in more detail.
For now, the “Preliminary Snowfall Projection” map provides a good representation of our current thinking. We’ll keep working on the details over the next 24 hours, but the concern about wet snow for the valley areas doesn’t begin until after sunset on Thursday.
A complex storm system brings our potential for the first wet snow accumulation of the year in some places. We’ll see what Mother Nature has in store for us. Check back for more updates…