[map courtesy Penn State eWall]
“Siberian-connection”, “polar vortex” and “omega-block” may become part of the weather dialogue in the eastern half of the nation as we close out the month of February and begin the new month of March since it appears winter will make a roaring comeback following the current brief mild spell. A strong cold front moves through the Mid-Atlantic region on Friday and it will be accompanied by brief downpours and possible strong thunderstorms. Temperatures on Friday will spike well into the 50’s ahead of the cold front in much of the Mid-Atlantic region, but a cooling trend begins later this weekend and then much colder air returns next week.
Last night’s 00Z GFS 500 millibar forecast map (above) for the 7-10 day time period supports the idea that a deep trough of low pressure will form in the southeastern part of Canada (blue) and a strong ridge of high pressure (red/orange) will extend northward along the west coasts of the U.S. and Canada [map courtesy Penn State eWall]. The combination of these two upper-level features will likely force numerous Arctic air masses to drop southward from central Canada into the central and eastern U.S. next week and beyond – just as it did earlier this winter. In fact, one such air mass that is destined to reach the northern U.S. later next week will cross the North Pole from Siberia in the next couple of days and then plunge southward through Canada towards the northern U.S. To make matters worse, the high pressure ridging that virtually surrounds the eastern trough is reflective of an “omega-shaped” blocking pattern in the upper atmosphere that promises to keep the cold air in place for an extended period of time in the central and eastern U.S. Yesterday’s GFS Ensemble 850 millibar temperature forecast map (below) shows the coldest air in North America centered over the western Great Lakes region during the middle of next week and this is reflective of a pattern in which the usual “polar” vortex is distributed to the mid-latitudes [map courtesy WeatherBell Analytics].
[map courtesy WeatherBell Analytics]
As far as snow is concerned, this upcoming pattern will produce multiple snow threats with more accumulating snow almost a certainty and there is an increasing chance for another major snowstorm in the Mid-Atlantic region. The first threat for snow will come in the Sunday night/early Monday time period when the initial batch of cold air arrives into the Mid-Atlantic region. A second threat comes late Tuesday into Wednesday as another wave of energy approaches the Mid-Atlantic region. Finally, a third threat could arrive late next week or early next week (Friday/Saturday) as a strong system looks like it may pull out of the Deep South and heads to the east coast, but it is way too early to tell how far up the coast this storm can go - certainly something to monitor. Today’s video discussion focuses in on the cold - and potentially snowy weather pattern - for next week and beyond.