Cold & Dry First Half of January Likely on Tap
First Chance for Significant Snowfall Possible Mid-Month
It appeared last weekend as though there was a slight chance for a significant snow event this Sunday night into Monday, followed by a greater threat centered around January 11th, however, it now appears as though any major snowfall will be delayed until the second half of the month.
Trough Axis Ultimately Proves Unfavorable for Major Snowfall Across the Region
The potential system for this Sunday night and Monday was always a low percentage likelihood. This is due to the fact that the developing -NAO block over Greenland is preventing the timely exit of the storm system that provided the region with rainfall on New Year's Eve and into the early morning hours of New Year's Day.
Frequently these blocked up patterns can lead to prolific storms along the east coast, but in this instance, the predecessor storm is so close that it not only prevents the approaching storm system from gaining sufficient latitude to greatly impact southern New England, but the flow around it shreds the follow up wave apart.
Although it is not uncommon for guidance to extend the confluent flow around systems in these situations too far to the south, it is now exceedingly unlikely that any such error would be large enough to allow for anything other than light snow across southern most New England given the decreasing lead time.
Thus while a major regional impact can be ruled out at this stage, accumulations of up to an inch or two over especially southwestern Connecticut cannot as of yet, as unlikely as that is to actually occur.
In addition to the inauspicious positioning of the NAO block (from the perspective of a winter weather enthusiast) later this week, there are also nuances within the larger long wave pattern that are making a major winter storm next weekly more unlikely, as well.
Major System Next Week Less Likely But Still Possible
The larger potential outlined last weekend remains a viable possibility, but it now appears more dubious due to some nuances within the long wave pattern that have become more evident. Namely, there is an emergent strong consensus that the PNA ridge/eastern trough couplet will be too positively tilted to allow for major cyclogenesis quickly enough and close enough to the coast to allow for a major winter storm.
However, unlikely the first threat, there is still time for this to change given the ample lead time between now and January 10th. One of the most likely ways that the storm prospects would grow again is if the energy over in the vicinity of Baja, Mexico were to eject quickly and increase the amplitude of the entire trough.
Regardless of what happens next week, a cold pattern will remain anchored in place and it looks to grow more active as the NAO block relaxes on approach to the identified January 21-February 4 major east coast winter storm window.
Stay tuned throughout the week for any updates-
