Monday, August 13, 2007

Record heat continues in Alabama

The heat has been historic in Alabama this month. All time records have already been set and it appears likely that more will fall this week.

On Friday August 10, Tuscaloosa tied their all-time record high temperature of 107, which was previously reached in 1952.

As of Sunday August 12, Montgomery had reached 100 degrees or higher seven consecutive days which ties the previous record which was set in 1881, 1954, and 1990.

Birmingham has reported six consecutive days at 100 degrees or higher. The record is eight from 1980.

Anniston has also reached the century mark six consecutive days and their record is eight, set back in 1952.

Tuscaloosa has been at 100 or higher six consecutive days and their record is eight.

If forecasts are correct, all of these records will be broken this week.

Many folks are wondering what is causing these extremely high temperatures. I would suggest that it is a combination of at least two factors. First, Alabama is situated beneath a strong ridge of high pressure. This ridge is keeping the atmosphere capped, reducing the possibility of scattered storms and it is inhibiting any upper level winds from transporting modified air into the area.

The second factor, I believe, is the extreme drought conditions that we have been experiencing. Many areas in North and Central Alabama are over 20” below normal rainfall. The dry ground heats much quicker and this heat is transferred to the air near the surface. If the ground was moist, much of that heat energy would be absorbed by the moisture rather than radiating back into the air. Tim Coleman wrote an interesting piece about this phenomenon here.

We have experienced 10 days in a row with high temperatures exceeding 97 degrees in northern Cullman County.

Date Reading Rounded Rainfall
Friday 8/3/07 97.7 (98) .16”
Saturday 8/4/07 97.0 (97)
Sunday 8/5/07 97.9 (98)
Monday 8/6/07 97.9 (98)
Tuesday 8/7/07 99.1 (99)
Wednesday 8/8/07 100.9 (101)
Thursday 8/9/07 101.0 (101)
Friday 8/10/07 97.7 (98) .04”
Saturday 8/11/07 102.6 (103)
Sunday 8/12/07 102.9 (103)

One interesting note about these temperatures is that the weather felt more comfortable this weekend despite the highs of 103. After a round of storms blew through Friday afternoon, the air became much drier. This reinforced my belief that humidity is a bigger factor than heat in making the air uncomfortable.

It looks like we are in for several more days of excessive heat in Alabama. Records will be the only thing falling around here related to temperatures.

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