Punxsutawney Phil’s prognostication of 6 more weeks of winter seems to be in line with a more scientific approach. NOAA released its Monthly Temperature Outlook for March. The Northwest and Northeast will likely be cooler than normal. Only the Southeast and western Alaska have a good chance of being warmer than normal.
After many cities experienced the warmest January on record and warm February, NOAA feels things will cool down.
NOAA meteorologists expect a pattern change, especially in the second two weeks of the month. The cooling trend is not unexpected weeks to 2 months after sudden stratospheric warming, which is a shift in the polar vortex.
A planetary wave in the troposphere at the end of January gave the polar vortex a minor bump from below, which caused some rapid but modest warming NOAA scientists explained. That event likely destabilized the polar vortex enough that a weaker disturbance in the stratosphere about a week later triggered a total disruption and sudden stratospheric warming event, they said.
“What the disruption will mean for weather down here in the troposphere is still uncertain, but sometimes these events lead to extreme cold air outbreaks in the mid-latitudes of the United States,” NOAA said in a blog post a few weeks ago.
SUDDEN STRATOSPHERIC WARMING, POLAR VORTEX DISRUPTION COULD MEAN COLDER WEATHER FOR EASTERN US
“A disrupted polar vortex tends to have its strongest tropospheric impact over the North Atlantic, which increases the odds for colder conditions across the eastern United States or northern Eurasia. But it’s not the only influence out there,” NOAA said in a recent blog post. “Other phenomena like La Nina, the Madden Julian Oscillation or the chaotic nature of the atmosphere can also affect how our atmosphere reacts to a disruption of the stratospheric polar vortex.”
And NOAA said in their outlook discussion, the Madden Julian Oscillation is going through phases that, “favors below-normal temperatures to expand eastward to include the north-central and eastern U.S. after the first week of March.”
NOAA maps show that three-quarters of the U.S. have a 50 to 60% chance of below-normal temperatures. A good chunk of the northwestern quadrant has a 70 to 80% chance of being cooler than normal.
That cold pool shifts east during the third week of March. The Northern Plains, Midwest and interior Northeast have a 70 to 80% chance of cooler-than-normal temperatures.
NOAA states that the cooling will come in the form of cold air outbreaks rather than a stagnant mass. Even so, they warn of a risk to early blooming vegetation over portions of the Southeast and Mid-Atlantic.
Only Florida and the immediate Gulf Coast have a 50 to 60% chance of warmer-than-normal temperatures. The rest of the Southeast and western Alaska are in the 33 to 60% likely category for above-average temperatures.
NOAA said in their Seasonal Forecast Discussion that the central Plains, Ohio Valley, mid-Atlantic and southern Plains will start out warm in March and end warm but have periods of cold during the middle weeks of the Month. That will average out to normal.