Monday, July 1, 2013

Enjoying the Reduced Humidity!

By Jay Grymes & Steve Caparotta

A quasi-stationary front continues to linger along and near the Louisiana coast, but we’re enjoying the benefits of being on the north side of the boundary and that means a little relief from the normal summer humidity. Dew point temperatures have been in the 60°s at Metro Airport since late Sunday morning, even dipping into the very comfortable low 60°s around lunchtime today. And those lower dew points mean below-normal morning temps, with many WAFB neighborhoods starting out in the mid to upper 60°s on Monday morning.

And we’ll enjoy a bit more of the “drier” air, with dew points expected to remain in the 60°s into Thursday. Tuesday morning should start off quite comfortable by July standards for WAFB country, with wake-up temps in the mid to upper 60°s under mainly clear skies. Like we saw today, we could see some mid- to high-level clouds on Tuesday afternoon, so we’ll post a “fair to partly cloudy” forecast for Tuesday afternoon with highs in the upper 80°s to near 90°. Still, with the afternoon dew points in the 60°s, it won’t feel like a typical July day in the Red Stick.

Now understand: even with the “drier” air we expect into Thursday, that doesn’t mean “no rain” until then. But it does suggest that rain chances will remain on the low side, at least through Wednesday and into early Thursday. We’ll call for rain chances at 20% or less for Wednesday and set those chances at 30% to possibly 40% for Thursday afternoon with highs both days at or just above 90°.

There are two main drivers for this “drier” air: a huge upper-level ridge over the western U.S. and a persistent upper low centered over the middle Mississippi Valley. These two features are combining to produce a steady northerly and northwesterly flow of low-humidity air into the lower Mississippi Valley. The western U.S. ridge continues to generate record highs across much of that part of the country, but it’s the upper low over that mid-Mississippi Valley that is the real oddity. We don’t normally see such features in the middle of summer and the current thinking is that it will hang around until Wednesday before finally exiting to the north-northeast.

By Thursday -- July 4th -- we expect a return to something more typical for July rain probabilities, with rain chances for Independence Day posted at around 30% to 40%. Although we can’t rule out a lingering shower or storm by “Fireworks on the Levee” time this Thursday evening, we think that most of the showers and storms should be out of the way soon after sunset. 

After that, rain chances rising rapidly as we go into Friday and the weekend. In fact, for the time being we’re calling for “rain likely” for all three days.

The same rains that will make for a wet weekend locally will also mean a less than ideal 4th of July weekend for many of our Gulf Coast beaches. Showers and t-storms are likely each day from Wednesday through Friday along the Alabama and Florida beaches.

And finally ... the tropics remain fairly quiet. While there is an area of convection in the eastern Gulf, it shows no serious potential for developing at this time. However, given that it’s right outside the “back door,” we’ll keep a watch on it. Elsewhere, there are no other areas in the Atlantic Basin with any immediate potential for organization. 

No comments:

Post a Comment