11:00 AM | ****Accumulating snow on the way for the DC-to-Philly-to-NYC corridor with several inches on the table****
Paul Dorian
The upcoming winter storm will feature heavy snow bands as depicted by this Sunday morning forecast map by the 12Z high-resolution NAM computer model. In fact, it’ll likely be some of the heaviest snowfall seen this year in many spots and it’ll happen during daylight hours for snow-lovers to enjoy. Map courtesy NOAA, tropicaltidbits.com
Overview
A moderately cold air mass has moved into the Mid-Atlantic region following the passage of a cold frontal system and now attention has turned to the Gulf of Mexico and the southeastern states where moisture is gathering. A storm will develop near the South Carolina coastline by early tonight and move to a position off the New Jersey coastline by mid-day Sunday. This system is going to generate a new round of accumulating snow in the DC-to-Philly-to-NYC corridor from late tonight into the mid-day or early afternoon hours on Sunday with several inches on the table for many spots. Looking ahead, the active weather pattern of recent days will continue beyond tomorrow’s storm with additional chances of snow and/or ice coming to the Mid-Atlantic from around mid-week into next weekend.
A wave of energy in the southern branch of the jet stream will be the catalyst for storm development and intensification along the east coast during the next 24-36 hours. Map courtesy NOAA, tropicaltidbits.com
Details
There are two waves of energy in the upper part of the atmosphere that will play a role in the development and intensification of a storm system along the east coast during the next 24-36 hours. One wave of energy is moving along in the northern branch of the jet stream and a second disturbance is pushing to the northeast from the southern states. It is the southern disturbance that is most important in this unfolding situation as it is quite strong and will be the catalyst for storm development and intensification along the east coast.
Unlike the long duration major winter storm of earlier this week, this next system will have no blocking pattern to deal with in the upper part of the atmosphere and it move along at a pretty good clip. The precipitation from this storm will move from southwest-to-northeast and will take place in about an 8-12 time period with the following timetable in the I-95 corridor for arrival and departure:
DC metro region: 3-5 AM to 11 AM-1 PM
Philly metro region: 5-7 AM to 1-3 PM
NYC metro region: 7-9 AM to 4-7 PM
“Total snowfall accumulation” map by the 12Z NAM computer forecast model for the upcoming storm with accumulating snow from DC-to-Boston and in surrounding areas. Map courtesy NOAA, Pivotal Weather
The air mass currently in place is “borderline” when it comes to its ability to support precipitation in the form of snow; however, the storm track will be quite favorable for snow in the I-95 corridor as this region will be on the northwest side of the system (i.e., on the cold side). While the bulk of this upcoming winter storm event should feature snow in the DC-to-Philly-to-NYC corridor, there can be a brief period of rain or a mix of rain and snow when the precipitation is on the light side such as at the onset of the storm and again near the end of the storm when the precipitation winds down.
Snow accumulation estimates are for a general 3-6 inch snowfall in the immediate DC-to-Philly-to-NYC corridor; but there are likely to be isolated higher amounts of up to 8 or 9 inches in those heavier snow band locations. The (wet) snow will come down heavily at times during this upcoming event; especially, in the morning-to-midday hours on Sunday (i.e., beginning a couple hours after arrival time). In fact, this event should feature some of the heaviest snowfall seen this year in many spots and it’ll happen during daylight hours for snow lovers to enjoy.
Looking ahead
The active weather pattern of recent days will continue after tomorrow’s storm with plenty of additional energy in the upper atmosphere across North America. This will result in additional chances for snow and/or ice in the Mid-Atlantic region beginning around mid-week and continuing into next weekend.
Stay tuned…an interesting weather pattern unfolding for the next couple of weeks.
Meteorologist Paul Dorian
Perspecta, Inc.
perspectaweather.com