Wednesday, February 15, 2012

Wet Tonight, Again Saturday

By Jay Grymes & Steve Caparotta

The rains have been a little slower to arrive for much of the WAFB viewing area than we had anticipated yesterday, but a look at Titan9 Doppler radar this afternoon makes it clear that the showers and t-storms are on their way!

For metro Baton Rouge, there is a “Slight Risk” for severe storms late this evening and into the pre-dawn hours of Thursday -- the threat arrives a little earlier for communities west of the ‘Red Stick’ and later in the morning for areas south and east of metro BR.  That severe threat will mainly be in the form of localized high winds, but we can’t entirely rule out the potential for isolated tornadoes.  And while hail doesn’t look to be a widespread issue, don’t be surprised by pockets of hail through the night.

A cool front will be working its way through Louisiana tonight and into Thursday morning, and that will be the lifting mechanism that fires-up some strong to severe t-storms and prompts our severe weather risk.  The rains should be over for most, if not all, WAFB neighborhoods by mid-morning on Thursday, but clouds will linger into the afternoon.  In addition, the so-called cool front won’t cool things off much at all, as we expect highs to return to the 70°s again on Thursday.

Unfortunately, Thursday’s advancing front will slow and eventually stall along our coastal waters and linger there into Friday.  That set-up, coupled with some upper level support, will keep the weather unsettled through most of Friday – that’s why we keep a 40% to 50% rain chance in our Friday forecast.

As we head into Saturday, the forecast guidance suggests that a low will develop along that same front over the northern Gulf.  At the same time, that front will begin to retreat to the north as a warm front with the Gulf low tracking towards the SE Louisiana coast.  With an upper-air disturbance adding to the equation and helping to boost regional instability, it sure looks like the better part of Saturday will be “wet.” 

In fact, at this point, the questions are, “how wet and how stormy?”

The answer will eventually be determined by the exact track of the Gulf low.  If that low moves up and over the coastal parishes, they could see rain on the order of an inch or more with thunderstorms.  Should the surface low stay along the coast or out over the water and move east, rain totals and the stormy-weather threat will be reduced.

Top-left: Titan9 RPM model projection for Noon Saturday. Top-right: GFS model projection for Noon Saturday. Bottom-left: ECMWF model projection for Noon Saturday. Bottom-right: NOAA/HPC rain projection from 6 p.m. Friday through 6 p.m. Saturday showing 1" to 3" of rain for most of south Louisiana.

Regardless, periods of rain seem to be a sure bet across the WAFB viewing area through most or all of Saturday and right into the evening.  And given Saturday’s expected cloud cover and cool temps -- topping out in the low 60°s -- let’s just say it won’t be the best weather day! 

But we’ll still salvage some good weather for the extended Mardi Gras holiday.  After morning clouds and a lingering shower or two early on Sunday, skies should be clearing for Sunday afternoon with highs in the 60°s.  Monday looks good -- under fair to partly cloudy skies -- with highs in the upper 60°s.  We bring a 30% to 40% chance of rain back into the forecast for the latter half of ‘Fat Tuesday’ as our next front approaches the region, with the weather clearing by Wednesday afternoon.

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