Posted by: splillo | March 19, 2012

Like getting a blizzard in October

My forecasts from the last two posts have certainly verified. The heat is on!

Yesterday, Concord, NH started off at 29 and rose an incredible 52 degrees during the day to reach a high temperature of 81. This absolutely demolished the old record of 64. The average is 44. The high of 81 is the normal for June 21st!! Concord was just one of many cities that broke records yesterday.

This is just the beginning.

Heat has overtaken much of the nation, and the core of the warmth is still yet to come. Look at some of the departures from yesterday (courtesy of weather.com):

Temperatures only continue to climb for the next three days. For central New England this means highs consistently reaching the 70's and 80's through Thursday. For coastal areas, we always need to keep an eye on the seabreeze. Especially this time of the year, the cold marine layer can penetrate well inland and result in low level clouds, stiff easterly winds, and temperatures plummeting from the 70's to the 50's.

What is especially remarkable today is that in Boston, the seabreeze kicked down the door around noon, and yet they still were able to reach another record high. This is a testament to the extraordinary magnitude of this warm air mass.

Thursday is expected to be the warmest day of this period. Temperatures start out in the 50's for most (already well above the normal highs!) and will soar into the 80's across the entire region. A few areas could even take a shot at 90! In March!! To give a little more perspective, these temps are around 40 degrees above normal for this time of the year, and would be above normal even in the middle of the summer.

So what does it take to reach 90 in March?

  • Lack of foliage on the trees promotes warmer temperatures, because less heat is taken away for evapotransporation.
  • No snow cover around the region at all, which is unusual for March in New England. So the albedo is lower, and less heat is taken away for evaporation.
  • Rainfall has been running below normal, so the ground is relatively dry, so again less heat is taken away for evaporation.
  • Increasing westerly winds help "mix" the atmosphere which results in low level compression warming ... just another factor that bumps the mercury up a notch.
  • Finally, the airmass itself! The best measure of the airmass is the temperature aloft (around a mile above the surface). This air then mixes down to the surface, warming through compression. In this case, the temperatures aloft are in the 50's, which is extremely rare for March.
All of these factors will come together to support one of the warmest days ever recorded in the month of March on this Thursday. The statistical rarity of an event like this is perhaps comparable to getting a 20" snowstorm in October...
... as if that could ever happen 😉

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