1:20 PM | *Still monitoring significant coastal storm threat for DC, Philly, NYC*
Paul Dorian
The latest NAM computer forecast model has consolidated and moved farther north the upper-level wave of energy on Monday morning compared to prior runs and this will be a key factor in the development of low pressure near the east coast. Map courtesy NOAA, tropicaltidbits.com
Overview
There have been two major coastal storms in the Mid-Atlantic/Northeast US during the past several days and there is the chance for another significant one early next week. After a couple of relatively quiet days, multiple short-waves of upper-level energy will slide towards the Tennessee Valley by Sunday and begin to consolidate resulting in the formation of surface low pressure in the Southeast US early next week. This storm will then intensify as it begins to head towards the Mid-Atlantic coastline. It is a bit too early to tell exactly how far up the coast this system will travel, but the overall weather pattern certainly allows for an impact on the DC-to-Philly-to-NYC corridor in the late Sunday night/Monday time period.
The 06Z GEFS forecast map of 850 mb temperature anomalies averaged over the current five day period with colder-than-normal conditions focused on the Mid-Atlantic region; map courtesy NOAA, tropicaltidbits.com
Details
One key to our overall cold and stormy March weather pattern has been strong high-latitude blocking over northern Canada and that will continue to exist come early next week. This is crucial in not only allowing for cold air to penetrate into the Northeast US, but also for the cold air to stick around which is a necessary requirement for snow this time of year. The average 850 mb temperature anomalies over the next five days focus the colder-than-normal temperatures right in the Mid-Atlantic region (06Z GEFS). In fact, it looks like we’ll continue with colder-than-normal weather on average not only for the next five days, but for much of the month of March in the eastern US.
In addition to the high-latitude blocking to our north, key players in the upcoming storm threat will be multiple upper-level short-waves that will slide into the eastern half of the nation on Sunday. These waves will consolidate and ultimately set off the formation of a strong surface low pressure system in the Southeast US by the end of the weekend. This system will then make an attempt to ride northeastward towards the Mid-Atlantic coastline by early Monday, but exactly how far north it’ll progress is still uncertain. Given the cold air mass in place, if this storm does come up this far north then snow would likely be the favored precipitation type in areas N and W of I-95, but rain could be involved in areas to the south and east of I-95 and closer to the coast.
Stay tuned, details still need to be ironed out on this significant threat, but it remains on the table.
Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com
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