Wednesday, September 11, 2013

Staying Hot, Slim Rain Chances

By Jay Grymes & Steve Caparotta

There were a couple of blips on Titan9 Doppler this afternoon including showers that passed over Denham Springs and downtown Baton Rouge.  But for most of us, it was just hot and dry ... and that’s just what we expect for Thursday and Friday.  Yes, a pop-up afternoon shower or two are still possible over the next couple of days -- that’s the nature of even “dry” summer days along the Gulf Coast.  But any showers that do develop through Friday will be spotty at best and probably very short-lived.  Besides, if you are lucky enough to get one of them, your yard will be thankful.
Although it will be quite warm, all looks good for Friday’s “Live After 5” in downtown BR.

Our forecast remains essentially unchanged for the next two days: morning lows near 70° to the low 70°s for most of the BR metro area with afternoon highs generally in the low 90°s with some WAFB  neighborhoods flirting with the mid 90°s.  Rain chances will be next to nil for Thursday and Friday.
We’re keeping rain chances for Saturday at under 20%, so LSU Tiger and Jaguar Nation tailgating should be okay for the most part -- just be ready for a quick sprinkle through the course of the afternoon.  We’ll go with 20% rain chances for Sunday afternoon.
The upper-level ridge that has dominated much of the eastern half of the U.S. over the past couple of days will retreat to the west over the next two days.  At the same time, a trough will dig southward over the eastern U.S. and try to push a front to the Gulf by Saturday.
For now, we think a weak cool front will make its way into the viewing area on Saturday.  It will only mean a slight increase in rain chances for Saturday afternoon and won’t deliver a  significant cool-down, although it may drop afternoon readings a couple of degrees around the area.  The lingering remnants of the front could help with low-end rain chances for Sunday too.

In the extended outlook, there is promise of a somewhat stronger cool front -- essentially a “backdoor” front -- arriving late Monday or Tuesday.  It’s a little too early to say, but that front currently offers a better chance for some needed rains by Monday, Tuesday and into Wednesday.
In the tropics, we’re focused on three features -- ‘Cat 1’ HUMBERTO in the eastern Atlantic, T.S. Gabrielle in the western Atlantic, and “Invest 93L” in the western Caribbean. 
HUMBERTO was officially upgraded to hurricane status at 4AM (CDT) this morning, the first hurricane of the 2013 season and just three hours shy of tying the record for the “latest-forming first hurricane” since the satellite-era of tropical cyclone tracking.  The National Hurricane Center (NHC) expects HUMBERTO to continue on a north-to-NNW course for the next couple of days, then turn to the west over the weekend. HUMBERTO is forecast to reach ‘his’ peak intensity later today or tonight, with the system dropping to tropical-storm strength by the weekend.

GABRIELLE has been weakening while drifting slowly to the west and NW for much of the day.  The system is barely maintaining ‘her’ tropical-storm structure due to shear, with much of the convection to the east of the defined low-level circulation.  It has been slowly moving away from Bermuda and is expected to begin accelerating to the NW, then north, and finally to the NNE in the coming days, eventually transitioning to a post-tropical (extra-tropical) system.  Those in the Canadian Maritimes and Newfoundland should monitor GABRIELLE into the weekend. 
And for Gulf interests, models suggest that “93L” could quite possibly become INGRID once the disturbance makes it across the Yucatan and enters the Bay of Campeche.  The next question will deal with its “residence time” over those warm waters.  While some of the computer forecasts take the system (T.S. INGRID) directly into Mexico, several other models are hinting at the system stalling over the Bay and lingering there -- possibly through the weekend.

While we do not anticipate a strengthening INGRID becoming a threat for the central Gulf Coast, the longer the system remains over water the more uncertain we are about ‘her’ final destination.  Stay tuned ...

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