THEWEATHERMOGIL:: Out of balance temperatures rule the eastern U.S.
When the upper level winds (I’m talking altitudes of four to eight miles above the Earth’s surface) take on a high-amplitude wave pattern (Fig. 1), strong low-pressure systems often develop. Given the counter-clockwise wind flow around such lows in the Northern Hemisphere, surface or near-ground temperatures typically take on a similar wave-like pattern. One can argue cause and effect here, but suffice to say that these weather patterns are linked
.
It’s important to realize that cold air masses tend to form over higher latitude regions due to snow cover, shorter days and lower sun angles. Similarly, warm air masses develop over lower latitudes. Air masses are just large volumes of air with similar temperature and moisture characteristics.
When upper-level troughs and associated storm systems develop, these air masses get transported far their homes. This means that cold air travels far south from its “source” region and warm air travels far north from its origin location. Such was the case early this Thursday morning.
Fig. 1 shows the upper level wind pattern at 7:00 p.m. E.D.T. yesterday that was associated with the low-pressure (or storm) system responsible for the deadly and destructive severe weather events of the past two days. Early this morning, that double-barreled surface low (with its counter-clockwise wind flow) was centered near western New York State.
To the east of the low, winds were blowing from the south and temperatures across southern New England were in the upper 50’s to lower 60’s. Fig. 2 shows that at 4:00 a.m. E.D.T., Boston, MA (BOS) was reporting a 61-degree reading (with thunderstorms). Far to the south of the low, where colder air had moved southward on northerly and northwesterly winds, Tampa, FL (TPA) was only at 57 degrees.
A similar scenario existed between Minneapolis, MN (MSP) and Amarillo, TX (AMA). Both cities had readings in the upper 20’s this morning.
© 2016 H. Michael Mogil
Originally posted 2/25/16