Wednesday, July 17, 2013

Headed towards "normal" July weather
Looks like we got just about what we expected for today: a little less cloud cover and fewer showers which translated in a return to afternoon temps in the 90°s. Still there were some pockets of stronger t-storms during the afternoon across the WAFB viewing area -- a reminder that just because it is “quiet” over your backyard doesn’t mean that the weather is behaving throughout the viewing area!
The drier day also came with a slight drop in the mid-day and afternoon humidity, as dew points dropped a couple of degrees -- from the mid 70°s to the low 70°s -- into the afternoon. Unlike air temperature, a drop of just a few degrees in the dew point temperature can make a very noticeable difference in how “hot” the air feels.
Still, afternoon Heat Index values (HIs) climbed up to near the 100° mark for many WAFB neighborhoods. And don’t forget, direct sunshine from mid-morning into the mid-afternoon can add as much as 5° to 15° to the “apparent temperature” (what the heat ‘feels like’ to the skin).
We think we’ll have another mostly-dry day on Thursday as the dome of mid/upper-level high pressure (“ridging”) over the eastern U.S. continues to influence our area, keeping a modest cap on the development of afternoon rains. Let’s plan on rain chances in the 20% to 30% range for Thursday afternoon.
But by the latter half of Thursday and early Friday, the upper ridge will have begun to weaken and shift east. At the same time, it looks like a weak low pressure (non-tropical) over the Gulf could be approaching the central Gulf Coast. That should provide at least a modest increase in our rain chances for Friday and keep the weather “wetter” through the weekend.
At this point, we’ll go with scattered showers and t-storms for Friday, Saturday and Sunday -- setting rain chances at about 30% to 40% for Friday and then running about 40% for the weekend. And for the time being, we’ll keep rain chances running at about 40% for Monday through Wednesday too.
Does that seem too wet? Well, not really. In fact, that’s just about “normal” for July across WAFB Country.
To put it in perspective, long-term statistics for the metro area during July tell us that we record “measurable rainfall” (0.01” or more) an average of 12-13 days during July -- that works out to be roughly 40%. In fact, records from Metro Airport (BTR) show that there is a thunderstorm somewhere within view of BTR on half of all July days, although not all of those t-storms actually produce rain at the airport.
So get ready for a run of “average” July weather by the weekend: morning lows in the low to mid 70°s, afternoon highs in the low 90°s, and somebody somewhere getting some rain!

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