Tuesday, June 26, 2012

More Record Highs Falling...

By Jay Grymes & Steve Caparotta

Another hot one today … it was 97° by 1PM at Metro Airport, with the day’s high topping out at 101°F, setting a new record for the date and topping a record that has stood since 1930 (more than 80 years).

As hot as it was, at least the dewpoints were in the 60°s through the day for most of us.  Not that dewpoints in the 60°s means “comfortably dry” air, but at least it wasn’t so overwhelmingly oppressive.  But from what we are seeing, that is going to change as well in the coming days.
The northerly flow that has delivered “drier” continental air to most WAFB neighborhoods over the past two days is expected to come to an end on Wednesday, with a more traditional southeasterly flow setting up by Wednesday afternoon and evening.  That will ultimately mean a return of Gulf moisture to our area, rising humidity and a muggier feel to the air as the week progresses.
There is a trade-off:  “drier” air heats up more easily and generally produces less cloud cover (which translates into more sunshine). The effect is that in many instances, summer days with a slight reduction in humidity will end up with higher afternoon temperatures.  By contrast, Gulf air with its higher water vapor content tends to generate more cloud cover, helping to block some of the solar loading.  In addition, “moist” air heats more slowly, so that afternoon temps during a more traditional summer day may not get quite so high.
So what will it be: very hot and slightly less humid or our traditional hot-and-humid weather?  From a “feels like” standpoint, very hot days with low humidity often end up with Heat Index numbers that are comparable to the days with higher humidity but not as hot (on the thermometer).
There are a couple of other issues to consider.  Those “drier” air days, with the northerly flow are often a little breezier than our traditional “return flow” days (days with windflow from the Gulf) – those breezes can make the heat slightly more bearable.  However, as generally sunnier days, those “drier” air days offer little or no respite from the intense sunshine, and the sun can add from 5° to 10° to the “feels like” temperature.  So for those stuck in the sunshine all day long, the lack of clouds can really take an additional toll!
Bottom line: most summer days in the WAFB viewing area are tough on anyone when too much time is spent without relief from the heat.  And this week is shaping up to be a bit more brutal than most summer days.  Take breaks, get into the air-conditioning occasionally if it is available, and try to limit direct exposure to the sunshine.  Don’t forget: loose-fitting, light-colored clothes, lots of fluids, even a hat or yes, an umbrella, helps!
T.S. Debby continues to weaken and made landfall this afternoon along the shores of the Florida ‘Big Bend’ region.  Debby picked up a little east-bound speed today, and now looks like she could be across the Florida Peninsula and into the Western Atlantic by late Wednesday or early Thursday.  The forecast still calls for Debby to return to tropical-storm strength after reaching the Atlantic, thanks to a little energy boost when she reaches the Gulf Stream.

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