Meteorological winter may be officially over, but spring isn’t exactly around the corner. Following a major warmup, another Arctic blast could send temperatures plunging across the U.S. in mid-to-late March, meteorologists warn.
Experts are monitoring a sudden stratospheric warming event—when temperatures in the Arctic stratosphere rise drastically over just a couple of days—that may cause the polar vortex to stretch southward. This large area of low pressure and frigid air swirls around the North Pole, keeping Arctic temperatures locked within the upper latitudes. When it stretches, those temperatures spill down into the mid-latitudes, bringing an intense cold snap to North America.
This atmospheric phenomenon has helped fuel the coldest and snowiest winter the Eastern U.S. has seen in years. It’s too early to know the exact timing, extent, or severity of this potential Arctic blast, and most of the country will get to enjoy some unseasonable warmth this and potentially next week, but meteorologists advise against stowing away your winter coat just yet.
According to the National Weather Service, above-average temperatures will become widespread across the southern half of the U.S. this week, with daily record highs stretching from the southern Plains to the Southeast. Over the next week, forecasters expect more than 500 temperature records to be neared, tied, or broken across parts of 40 states, meteorologist Ben Noll reports for the Washington Post.
In the Southeast, afternoon highs could climb into the mid-70s and 80s Fahrenheit (into the 20s Celsius), the NWS states. As the warmth extends northward into the Mid-Atlantic and Ohio Valley, highs could hit the upper 60s and 70s (low 20s Celsius).
The warm spell will help fuel an active early spring weather pattern that will persist across the continental U.S. through the end of the week, bringing ongoing showers and thunderstorms to the Ohio Valley. These storms may produce areas of heavy rainfall and localized flash flooding in central Indiana and southern Ohio, where the NWS has issued flood advisories and watches.
A transition back to winter temperatures would feel extra painful following this period of remarkable warmth, but unfortunately, forecasters are growing increasingly confident in a polar vortex split next week. This occurs when the vortex separates into two lobes of Arctic air. These lobes, weakly contained by a significantly disrupted vortex, can then spill southward.
Following a sudden stratospheric warming event, it typically takes a couple of weeks for an Arctic blast to reach mid-latitudes, which is why meteorologists are anticipating a return to colder temperatures in mid-March. Again, the timing of this cold snap remains uncertain, but the forecast should become clearer over the next week or so.
It certainly looks like most of the U.S. will be riding the weather rollercoaster this month. As always, be sure to monitor your local forecast for the latest updates.
Source: Gizmodo