Wednesday, August 14, 2013

Watching the Tropics...

By Jay Grymes & Steve Caparotta

A cool front continues to sag slowly southward through the Bayou State.  The storms earlier in the day were the product of a pre-frontal line that has since moved out over the Gulf waters.

Those mid-day showers and storms took much of the storm energy out of the atmosphere over metro Baton Rouge.  While we are likely done with any strong storms for the day, scattered showers and a few t-storms can be expected through the late afternoon and evening as the front continues is southward drift.

The rains should taper off through the evening and overnight as drier air filters in from the north behind the cool front.  Most WAFB neighborhoods -- especially those along and north of the I-10/12 corridor -- can expect fair skies for Thursday’s wake-up.  In fact, WAFB’s northern viewers are likely to wake to temps in the 60°s!  We could still see a few showers along the coast, where the weak front will be positioned, but even there, rains are likely to be isolated and light in nature.

The front is likely to stall near the coast and meander a bit from Thursday afternoon into Saturday morning.  For most of us, that means a run of mainly fair skies, little rain, and less-humid conditions.  While baton Rouge afternoon highs will still get up around 90° to 92° for Thursday, Friday and Saturday, the lower dew points will mean less-oppressive afternoon heat and morning starts in the upper 60°s to around 70° for many -- not bad at all for mid-August!

But the drier air doesn’t last long.  By Sunday, the quasi-stationary front will have fizzled out, allowing for Gulf humidity to creep back into south Louisiana.

However, the bigger developing story is the outlook for the tropical disturbance in the western Caribbean -- currently labeled as ‘92L.’  The mass of clouds and convection in the western Caribbean has displayed slow consolidation through the day but a clear low-level center has yet to emerge.  The latest model consensus brings the ‘proposed’ center over the Yucatan tomorrow, with it moving into the Gulf of Mexico by Friday.

After that, all bets are off.  Until we have a defined center and sense of the system’s intensity, there will remain a number of possible scenarios that could play out.  Currently, some of the model runs take a developing system to the northwest into Mexico or Texas.  At the same time, a number of other models, including the American GFS, bring the system into the central Gulf Coast states over the weekend.

As if that isn’t confusing enough, the intensity forecasts are even more divided.  While the consensus keeps the system below hurricane strength (at least for now), there is no clear sense of just how well developed the system might become.  Most of the early forecast runs show peak intensities varying across the range of tropical-storm-force winds.  But remember, the forecast skill for intensity is only slightly better than “no skill at all” -- in other words, we are completely unclear as to what this system will do over the next three days.

The bottom line: this is one to keep tabs on.  No need to get overly concerned just yet, but be aware that this could become of threat for the Bayou State.  And if that does occur, it is most likely to arrive over the weekend.  Stay tuned!

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