February 8-9, 2025 southern New England Winter Storm (Overnight)

 We have entered an active stretch of weather with multiple winter storm threats between Super Bowl weekend and the upcoming week. Let's get right to it and discuss the Super Bowl weekend winter storm potential. 

Low pressure develops within eastern Colorado and central Plains Saturday along a baroclinic zone evolving into a frontal system as it rapidly tracks east-northeast across the country. Meanwhile an abundance of shortwave energy embedded within a fast zonal jet stream aloft traverses the northern Plains. This shortwave energy is expected to give a bit of a boost to the system as this shortwave energy has some interaction with the frontal system:

Moving into Saturday evening, computer forecast model guidance indicates very strong upper-level diffluence (faster jet stream winds moving into slower jet stream winds) with increasing upper-level divergence across the Northeast (evident by the wind barbs moving away from each other). The increasing upper-level divergence will help precipitation blossom within the region Saturday evening which will be further aided by increasing warm-air advection (supplying moisture) and strengthening area of surface low pressure:

Increasing precipitation Saturday afternoon and evening across the Northeast:

As the system lifts northeast and then east across the Northeast, we'll see a several hour window of strong upward vertical motion (lift) traverse the region:

Latest bufkit profiles across the region from the 18z/06 run of the GFS show a several hour period where omega values range between -20 to -30 ubar/s within the dendritic snow growth zone with snowfall ratios in excess of 10:1 and potentially greater than 15:1. This is suggestive of heavy snowfall rates (perhaps in excess of 1inch per hour) with excellent snow growth. Below is an example from Worcester, MA (ORH):

So, what can we expect? This will be another fast-moving, quick hitting winter storm with the brunt of the storm impact occurring in a 3-5 hour window. 

• Snow arrives from southwest to northeast across the region, beginning first across western Connecticut between 6:00-8:00 PM EST Saturday evening and 8:00-10:00 PM EST across northeastern Massachusetts. 
• Heaviest snowfall occurs between the hours of 11:00 PM - 4:00 AM EST. This is when snowfall rates could approach 1 inch per hour under the heaviest echo's. 
• Snow begins tapering off southwest-to-northeast during the pre-dawn hours southwest and around or shortly after daybreak Sunday northeast. 
• The fast forward speed of this storm limits accumulations. 
• Outside of the immediate coastal Plain and outer Cape, precipitation will be all snow. Sleet is expected to mix in across the immediate shoreline of Connecticut and Rhode Island and outer Cape Cod. This holds down totals slightly in these areas.
• Below is what I am currently expecting:

Sunday, January 19, 2025 Winter Storm

 Technical Discussion:

Low pressure develops within the mid-Atlantic region Sunday afternoon ahead of a southeastward advancing cold front. Computer forecast models are all in great agreement in shortwave energy rounding the base of an amplifying upper-level trough aiding in the development and strength of the low pressure. However, there are some uncertainties on the strength of this shortwave energy, however, there is a consensus towards this piece of energy to be on the stronger side:

Low pressure is then expected to pass to the south and east of Connecticut, a very favorable track for moderate-to-heavy snow to traverse much of the state. However, with some warmer in place out ahead of this system; particularly along the shoreline and southeastern Connecticut, this will ultimately cut down on snow potentials there:

Despite being so close to the storm, there are some uncertainties regarding the overall track and this could have a big impact on snowfall totals; particularly across south and eastern sections which are on the line between colder and warmer temperatures and where the heaviest banding and subsequent totals may reside. One of the more consistent forecast models with the evolution of this system has been the GFS. The GFS advertises potential for some heavy banding to traverse much of southern New England:

In fact, the latest 12z GFS bufkit for Worcester, MA (ORH) exhibits a crosshair signature with as much as -40 to -50 ubar/second within the dendritic snow growth zone. This is indicative of tremendous lift and would likely result in snowfall rates in the 2-3 inch per hour range with snowfall ratios of 15:1:

Forecast:

• Light snow begins to breakout across western Connecticut and western Massachusetts between 1-3 PM Sunday and the remainder of the region by 5-6 PM. 
• Snowfall rates intensify rapidly during the evening with the heaviest snowfall rates between 7-10 PM (hold on as late as 12-1 AM across northeast Massachusetts). Snowfall rates will approach 1 inch per hour and as much as 2-3 inches per hour under the heaviest banding. 
• Snow tapers off during the early overnight. 
• This will be a quick hitting and fast moving storm.
• There are some uncertainties; particularly around the Boston market and where the heaviest banding occurs. 
• Where the heaviest banding occurs, we will likely see a swath of snowfall accumulations more in the 8-12 inch range. 
• There will also be some mesoscale subsidence zones where snow growth and intensities struggle. Where this occurs totals will end up closer to the lower ends of the ranges. 
• Frigid temperatures and dangerously cold wind chills build in for Sunday night and Monday behind the system. 
• Below is what I am currently thinking. Keep in mind, where the heaviest banding snowfall occurs, totals will be in the 8-12 inch range, however, it is very difficult to determine where that will occur.