12:00 PM | *Next coastal storm threat comes late Sunday night/Monday, but it is too early to say if it'll come this far north*
Paul Dorian
12Z GFS operational model surface forecast maps for Monday morning (left) and Monday evening (right) with the next storm skirting the I-95 corridor; maps courtesy NOAA/EMC, tropicaltidbits.com
Overview
There have been two major coastal storms in the Mid-Atlantic region and Northeast US during the past six days and there is the chance for another one early next week. After a few relatively quiet days, a couple of waves of upper-level energy will slide towards the Tennessee Valley and Southeast US by the latter part of the weekend. This combination of energy will help to set off the formation of a strong surface storm near the Carolina coastline by late Sunday night or early Monday morning. At this time, the storm will then begin a turn up the east coast; however, it is just a little early to say how far north it will go. Many computer forecast models tend to push the system to the south and east of the DC-to-Philly-to-NYC corridor, but the overall weather pattern and teleconnections (e.g., -NAO) certainly warrants the close monitoring of this system over the next few days.
12Z GFS 500 mb height anomaly forecast map for Monday morning with high-latitude blocking - a key factor - still in place across northern Canada (boxed region); map courtesy NOAA/EMC, tropicaltidbits.com
Details
One key to the overall cold and stormy March weather pattern here in the eastern US has been strong high-latitude blocking over northern Canada and that will continue to exist into early next week. This is crucial to not only allowing for cold air masses to penetrate into the Northeast US, but also for sustainability of the cold air - a necessary requirement for snow this late in the season. In fact, it looks like we’ll continue with colder-than-normal weather on average not only for the next week to ten days in the Mid-Atlantic region, but perhaps for the remainder of the month of March.
12Z GFS 500 mb forecast map for Monday morning with two important waves of energy (indicated by arrows) in the upper-atmosphere. One wave is headed into the Southeast US and the other is moving over the Tennessee Valley. The ultimate interaction of these two systems will be crucial to any surface storm development. Courtesy NOAA/EMC, tropicatidbits.com
In addition to the high-latitude blocking to our north, two key players in the upcoming scenario will be upper-level waves pushing into the eastern half of the nation late in the weekend. Exactly how these two waves interact will ultimately determine the strength and positioning of surface low pressure near the Mid-Atlantic coastline come early Monday – and it is just a little early to be certain.
12Z GEFS 500 mb height anomaly forecast map for Tuesday morning with deep upper-level troughing extending all the way up the coast with a negative tilt to the orientation axis; map courtesy NOAA/EMC, tropicaltidbits.com
The latest operational forecast by the 12Z GFS model features a strong system near the Mid-Atlantic coastline early Monday that then skirts the DC-to-Philly-to-NYC corridor and recent European operational model runs have actually suppressed this potential coastal system even farther to our south and east of here. However, upper-level height anomaly forecast maps by ensemble runs of the same computer forecast models tend to develop deep troughing along the east coast early next week that expands to the north of here and it is just a bit too early to write it off.
Stay tuned.
Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com
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