Wednesday, August 27, 2014

Rains Returning to the Forecast

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:
- rain chances rising into the weekend
- still eyeing the disturbance in the western Gulf

For most of us, today was another relatively quiet weather day, with a prolonged run of NE to easterly breezes thanks to the circulation around the low-pressure area in the Gulf. After a morning start in the low 70°s for the Red Stick, most WAFB neighborhoods climbed into the low 90°s for the afternoon, but rains were fairly limited and the humidity was quite tolerable for an August day.

Of course, most of the local weather attention remains focused in the western Gulf. Admittedly, the area of low pressure tried to ‘kick up its heels’ overnight with another round of convection popping up in the early morning. The low-level circulation was (and is still) evident, but throughout most of today the main storm energy with this system remained to the north and east of the low-level spin. As of this afternoon, the National Hurricane Center (NHC) remains unimpressed with the disturbance -- listing it with only a 20% chance for development in the next two days. However, the NHC did concede that it deserves attention, dubbing it “Invest 98L” and scheduling today’s visit by aircraft. 

So, the real question for 98L: will it stay out over the water long enough to get its act together and earn tropical cyclone classification (as a depression or tropical storm)?

Well, there is no question that the Gulf is ‘warm’ enough to support intensification and the mid-level shear has appeared to relax a little today. Given the time of year, we won’t rule out a brief upgrade to depression strength, especially if 98L slows its westward movement. However, “space is limited” for the system -- if it doesn’t slow to a crawl or stall soon, it will be over the Texas coast before you know it. Regardless, high pressure to our north should keep 98L well to our south and southwest and west-bound into Texas. And for “droughty” central Texas, a dose of tropical rains would be welcomed.

For us, the drier pattern we’ve enjoyed is coming to a quick end. Winds will start to swing back around from the SE by mid-day Thursday, pumping Gulf moisture back into the viewing area. And as we head into the weekend, the Gulf moisture looks like it gets a bit of a boost (added lift) from both the north and the south. An upper-air trough will be sliding west-to-east across the central U.S. this week, breaking down the high-pressure ridge that has persisted over the Southern U.S., while northbound energy coming out of the Caribbean heads towards the central Gulf Coast by the weekend. 

In short: a rainmaker’s sandwich.

For Thursday and Friday, we’ll call for morning lows in the BR metro area in the low to mid 70°s, with afternoon highs in the low 90°s. Set afternoon rain chances at about 30% under an afternoon sun/cloud mix for Thursday, then 40% for Friday afternoon and early evening.

At this stage, the Labor Day weekend is shaping up to be a fairly soggy one. Showers and t-storms are likely for Saturday, with rain chances on Sunday at 50% or better. The rain and clouds should keep most at or below 90° over the weekend, but the trade-off could be localized nuisance flooding. (Note: localized .. not widespread)

With a little luck, Monday should be a bit better, but even then we’re carrying scattered afternoon showers and storms in the outlook.

Elsewhere in the tropics, ‘Category 1’ Cristobal is holding strong but is no threat to the U.S mainland nor to Bermuda. While Cristobal will still be on the weather maps this weekend, ‘he’ is headed towards the northeast and will be tracking over cooler Atlantic waters. A weak tropical wave about 400+ miles east of the Lesser Antilles (formerly labeled as “Invest 97L”) offers no serious threat for development, at least not over the next several days. (We will keep an eye on this wave, however, as some of the guidance suggests that it might re-fire over the western Caribbean or southern Gulf. Lastly, the NHC is also watching a healthy tropical wave about to enter the eastern Atlantic from the African continent, but it is simply too far away to worry about.

As for the Saturday night football outlook, whether you are headed to Houston for LSU’s match-up with Wisconsin (8pm kick-off), following the Jags to Lafayette to take on the Ragin’ Cajuns (6pm kick-off) or catching the SLU Lions at home in Hammond (7pm) against Jacksonville, fans will want the raingear handy. We’ve got scattered-to-likely rain chances at all three locations, especially during the afternoon tailgating hours.

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