1:45 PM | *Now attention turns to the weekend threat*
Paul Dorian
Overview
Now that the latest Arctic frontal system that generated the first snowflakes of the season for many of us has pushed off the east coast, attention turns to the weekend possibilities. It looks like there will be one system that affects the I-95 corridor with rain from Friday night into early Saturday, and then a second – and far less certain – system could impact the region late Sunday. The second threat carries with it a bigger concern since - if it were to reach this area late Sunday - it would encounter much colder air than the initial system and snow would likely be the result.
Friday night/early Saturday
Moisture will advance our way from the southern states at the end of the week and rain is likely to break out in the I-95 corridor Friday night and last into Saturday morning. Despite the fact that it is very cold today in the Mid-Atlantic region, temperatures will modify noticeably tomorrow and Friday ahead of the arrival of this southern moisture. As a result, rain is likely in the immediate I-95 corridor from this early weekend system although a changeover to snow is possible in interior sections of the Northeast US. The surface pressure pattern by the early weekend should feature one low pressure system over the Great Lakes region which will ultimately transfer its energy to a developing coastal low. This coastal low will then move northeastward on Saturday just off the New England coastline.
12Z GFS forecast map for Sunday night (blue=snow); map courtesy tropicaltidbits.com
Late Sunday
Following the early weekend system, much colder air will filter into the Mid-Atlantic region. At the same time, strong upper-level support will be dropping to the southeast from Canada and it is likely to spin off new low pressure in the Gulf of Mexico. It is at this point that questions continue as far as the storm track is concerned. This low pressure could then ride to the northeast to a position just off the Mid-Atlantic coastline later Sunday or it could move harmlessly out to sea. It is still too early to determine just how much of an impact this potential coastal storm will have in the DC-to-Philly-NYC corridor, but snow would likely be the precipitation type given the fresh cold air mass.
The most bullish computer forecast model for snow around here is NOAA's GFS. Indeed, the latest (12Z) operational version of the GFS model produces a surface forecast map (above) that is showing lots of blue (i.e., snow) in the I-95 corridor for Sunday night (7pm) with a powerful nearby coastal storm. Furthermore, the 12Z GFS “ensembles” model run backs up the operational version of the model also hinting at a potential Sunday snowstorm for the Mid-Atlantic region. However, other computer forecast models (Euro, Canadian) are not yet supporting the idea of a “close-in” coastal storm. The potential is certainly there and we’ll closely monitor it over the next few days. Brutal cold air will follow the late weekend system for the early part of next week – probably the coldest air yet - and another storm will likely threaten by the end of next week. Stay tuned.
Meteorologist Paul Dorian
Vencore, Inc.