Monday, August 11, 2014

Another Summer 'Cool Front' Arriving on Tuesday

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:
- scattered rains for Tuesday
- ‘cool’ front arrives late Tuesday/early Wednesday
- hot but mainly-dry for Wednesday through Friday
The WAFB viewing area experienced quite a range rain totals over the past couple of days, with some 2” to 4” bull’s eyes dotting the region.  Fortunately, there have been no ‘severe’ storms lately although a few have been on the stronger side with gusty winds and even indications of small hail.

We started today -- the first day of school for many youngsters -- with gray skies and a muggy air mass, but the morning bus-rise and commute was generally rain-free for most WAFB communities.  The day was fairly typical for early-to-mid August: in and out of the clouds, with a hot-and-humid Gulf air mass fueling scattered afternoon showers and storms.
The weather picture gets a little tricky over the next 36 hours or so.  Two of our reliable short-term models, including the in-house RPM, are suggesting a band of southbound rains arriving later this evening -- essentially an outflow boundary running out ahead of a cool front currently draped through the ArkLaTex region.
For Tuesday, we expect a muggy morning start in the mid to upper 70°s for most WAFB neighborhoods, but we’ll also add in a slight chance of rain at roughly 20% for the morning commute and bus-ride.  As we head into the afternoon, expect a sun/cloud mix with scattered showers and a few t-storms but no serious threat for ‘severe’ storms.  However, a few t-storms could be on the stronger side with locally-heavy downpours possible for a few places.
The cool front currently to our north and northwest is expected to arrive late Tuesday.  It’ll be a ‘slow-mover,’ taking as much as another 24 hours to reach the BR metro area.  The current guidance shows the front moving south of Baton Rouge by late Tuesday or early Wednesday, delivering a welcomed dose of ‘drier’ continental air by Wednesday afternoon. 
So the question is, will the advancing ‘cool’ front be a good rainmaker as it approaches the area on Tuesday, or will the rains expected later this evening be the main “hurrah!” when it comes to wet weather and this week’s front?  It seems most of the computer models aren’t giving to much weight to a “wet” Tuesday and that this evening will be it.  So we’ll go with isolated to scattered rains on Tuesday with just about everything drying-out by Tuesday evening, if not before.
With the ‘cool’ front pushing through, we should enjoy a little relief.  Dew point readings for many WAFB communities -- especially those north of the east-west I-10/12 corridor -- could dip into the upper 60°s by Thursday -- that will mean noticeably lower humidity.  Sadly, it will only last for a day or so, but we’ll take it.
Unlike a couple of last month’s ‘cool’ fronts, this front will not sweep out into the Gulf.  Instead, it is expected to stall over the coastal parishes late Thursday, then begin retreating northward as a warm front on Friday.  This means three things:
(1) some WAFB coastal communities will not get to enjoy a significant drop in humidity,
(2) with the front stalled along the coast, we can’t rule out isolated showers for Wednesday and Thursday for our more southern viewers, and
(3) it’s back to more typical August weather for everyone by the weekend.
But, hey, it’s still the heart of summer, so we should be thankful for any relief from the heat-and-humidity that we can get.

In the tropics, the National Hurricane Center says “all quiet” through the next five days or more for the Caribbean and the Gulf, but they are currently watching a disturbance in the eastern tropical Atlantic for potential development later in the week.  For us, that system is too far east and too disorganized to worry about, at least for the time being.  So far, so good for Louisiana, but we are just now heading into the peak weeks for tropical development -- keeping fingers crossed!

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