Thursday, July 24, 2014

A Little Drier .. and a Little Hotter ..

WAFB First Alert Quickcast:
- getting even “drier” in the coming days
- could see some mid 90°s over the weekend
- all “quiet” in the tropics

Yesterday we mentioned the slow breakdown of the upper-low that has been skirting from east-to-west along the Gulf Coast .. and as of this afternoon that feature is just about gone. What we did see in the way of rainmakers today was a bit of a combination of the last “hello” form the upper-low -- mainly over Acadiana -- and something a little more like a summer sea-breeze for the southeastern parishes.

As is usually the case at this time of year, the area rains will dissipate as we lose the energy of daytime heating. So it’s fair skies tonight and into Friday morning, with sunrise temperatures in the low 70°s for metro Baton Rouge. As we head into Friday afternoon -- and throughout the weekend -- the upper-level ridge to our west will expand and shift a bit eastward. That means its influence on our regional weather will increase in the coming days.

You know that ridges aloft (upper-level high pressure) tend to inhibit vertical cloud growth. In simple words, not only does upper-air ridging reduce rain chances, but it usually means more sunshine. And in the summer, more sun often means higher temperatures.

We won’t go completely “dry” over the next few days. In fact, I must acknowledge that our in-house RPM model wants to make things rather wet for Friday, apparently picking up on a weakness along the Gulf Coast under the eastern fringe of the upper-air ridge. But I’m not buying that, at least not the RPM’s 40% to 50% coverage for Friday afternoon -- nor are some of our other reliable short-term models. So I’m going with rain chances at about 20% or so for Friday, then on the order of 20% for Saturday too. I expect the ridge to be most dominant by late Saturday into Sunday, so for Sunday, I’m thinking rain chances at 20% or less.

Bottom line: the weekend is looking pretty good for some outdoor fun or work, but be ready for temperatures in the low to mid 90°s. Heading into next week, the upper ridge begins to shrink and retreat back to the west again, along for increasing rain chances. In fact, some of the extended guidance is trying to drive a summer ‘cool’ front down to the Gulf Coast around mid-week. Nothing to get excited about just yet -- that’s a little too far down the road for confidence -- but it will certainly be something to watch.

And in the tropics, there are a couple of weak waves floating in the Atlantic -- one being the remnants of TD #2 -- but that’s about it. Neither wave shows any potential for development in the near-term. So, no threats for now and none anticipate by the NHC in the next five days or more.

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