11:00 AM | ***Occasional cold air outbreaks to last through the month of March...a favorable pattern for severe weather...and additional snow chances in the northern US***

There is the threat of severe weather next week in the Tuesday/Wednesday time frame (i.e., March 4/March 5) which may be centered over the Lower Mississippi Valley region. Map courtesy Colorado State University, NOAA

Overview

Today’s weather features above-normal temperatures across much of the nation and the next couple of days will remain on the mild side in the Mid-Atlantic region with high temperatures approaching 60 degrees in some areas. We are about to flip the calendar from February to March and it appears quite likely that there will be occasional cold air intrusions from Canada into the US during the next few weeks. Supporting evidence for additional cold air outbreaks during the month of March include the strong likelihood of a “disrupted” stratospheric polar vortex with significant warming near the North Pole by the middle of March and the movement of a tropical disturbance known as the Madden-Julian Oscillation (MJO). These occasional cold air outbreaks will contribute to an overall active weather pattern in the month of March and likely set the stage multiple severe weather outbreaks. In addition, the continuing cold air intrusions will certainly keep hope alive for snow lovers with multiple upcoming chances; especially, across interior higher elevation locations of the northern Mid-Atlantic and Northeast US.

Support for additional cold air outbreaks

Changes that are taking place in coming days across two vastly different parts of the atmosphere indicate to me that cold air outbreaks are likely to continue in the US through much of the month of March. One change has to do with temperatures at the highest levels of the atmosphere over the polar region that will become dramatically different by the middle of March. The other change involves the movement of a tropical disturbance known as the Madden-Julian Oscillation (MJO) which propagates around the globe on a regular basis.

A significant “disruption” is coming to the stratospheric polar vortex by the middle of March and this could lead to additional cold air outbreaks into the central and eastern US from later in March to early April. Maps courtesy NOAA

Stratospheric warming

The current stratospheric temperature pattern across the Northern Hemisphere features a rather typical looking (cold) polar vortex centered right near the North Pole with some “stretching” into the eastern part of Canada. There are reasons to believe that a major “disruption” in the stratospheric polar vortex will take place during the next couple of weeks leading to a “split” vortex by mid-March and significant warming right near the North Pole where temperatures can climb from around -60°C to -25°C. While not a guarantee, this kind of “disruption” in the location and magnitude of the stratospheric polar vortex often results in the movement of cold air masses from the polar region into the middle latitudes such as across the central and eastern US. In fact, a stratospheric warming event of this magnitude can have an impact on temperature patterns in the middle latitudes for several weeks to follow which would take us not only through the latter part of March, but into early April as well. In recent history, there have been several stratospheric warming events during the month of March (1984, 1993, 2014, 2015, 2018) and they were typically followed by colder-than-normal stretches of weather.

The MJO will push through “phases” 1 and 2 between now and the middle of March and these are typically correlated with below-normal temperatures across much of the central and eastern US. Maps courtesy NOAA

Madden-Julian Oscillation (MJO)

On the tropical scene, the movement of an area of convection (thunderstorm activity) known as the MJO can be predictive in upcoming temperature patterns across other parts of the world including here in the US. Specifically, when the MJO pushes into “phases” 1 and 2 during this stage of the winter season it if often correlated with below-normal temperatures across much of the central and eastern US. The forecast of the MJO into “phases” 1 and 2 between now and the middle of March provides support to the notion that there will be a continuation of cold air outbreaks into the US from Canada during the next few weeks.

Severe weather threats

The month of March certainly carries with it the increasing risk of severe weather in the US with increasingly warm and humid air flowing northward from the Gulf region at the same time winter-like cold air masses continue to drop south and east from Canada into the heartland. A “back and forth” type of temperature pattern is indeed in the cards for the next few weeks with periodic cold air outbreaks making their way from Canada into the US and this variability is likely to set the stage for multiple severe weather outbreaks. In some years, cold air can “overwhelm” the overall weather pattern during the month of March thereby limiting the chance for severe weather outbreaks; however, this does not look like it will be one of those more benign type of years.

A red flag in the upper part of the atmosphere for the possibility of severe weather during the month of March is one that features an upper-level trough of low pressure across the western states and a ridge of high pressure in the east. The zone in between these upper-level features can often be “battle zone” areas with cold, dry air advancing from the north and west into warm and humid air that may be positioned to the south and east. One such volatile setup is possible by the middle of next week raising the flag for severe weather in the Tuesday/Wednesday (March 4-5) time frame likely across the southern states. A similar setup (or two) can follow in the week or so to follow next week’s threat.

Two systems can bring significant accumulating snow to the interior, higher elevation locations of the northern Mid-Atlantic and Northeast US between now and the middle of the upcoming weekend. Map courtesy NOAA, tropicaltidbits.com

Upcoming snow chances

Additional cold air outbreaks through the month of March would certainly keep hope alive for snow lovers across the northern US and indeed, there appears to be multiple chances for snow in coming weeks. One part of the country that looks very favorable for accumulating snow is the interior, higher elevation locations of the northern Mid-Atlantic and Northeast US. In fact, one system is likely to produce accumulating snow from later tomorrow into tomorrow night across northern New York State and interior New England, and a second one quickly follows from later Friday into Saturday. There will be a quick shot of cold air into the northeastern part of the country on Friday following the first system and then an impressive cold air outbreak for Sunday and Monday following the passage of the second system.

Looking ahead, as mentioned earlier, there are signs of a severe weather outbreak across the southern states by the middle of next week and we’ll have to monitor the eventual movement of low pressure likely to be situated over the Deep South. The chances are high that this low pressure system will become a “cutter” and slide up to the north and west of the I-95 corridor which would favor rain in much of the East. However, it is not out of the realm of possibility that this storm system could make a move towards the east coast (instead of being a “cutter”)...potentially resulting in a snow threat for parts of the Mid-Atlantic/Northeast US. Even farther ahead, there may be a similar scenario around the 8th or 9th of March in which a southern system heads to or near the east coast from the southern states...perhaps bringing a threat of snow to the Mid-Atlantic/Northeast US in that time period.

Bottom line...March looks like it’ll be quite an active month of weather with the potential of multiple severe weather outbreaks and additional snow chances for many portions of the northern US.

Meteorologist Paul Dorian
Arcfield
arcfieldweather.com

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