Wednesday, May 13, 2015

Fairly Dry Again on Thursday

By Jay Grymes & Steve Caparotta

May 13th WAFB First Alert Quickcast:

- only a few showers today, much the same for Thursday
- higher rain chances for Friday and the weekend

After back-to-back afternoons (Monday & Tuesday) with weather warnings posted for parts of the WAFB area, today’s quieter pattern was welcomed by most.

We started the day under the clouds, and even the afternoon was marked by more clouds than sun.  We didn’t go through the day entirely rain-free, but weak upper-level ridging placed a “cap” on the atmosphere, inhibiting the ability for afternoon clouds to develop vertically.  (It’s the upward growth that allows our morning cumulus clouds to become afternoon thunderstorms.)

What showers that did develop today were located mainly to the west of metro Baton Rouge.  Just about all of today’s showers should be gone by sunset.  Later tonight, like last night, we’ll stay under mostly-cloudy to cloudy skies with Thursday morning lows dipping to the upper 60°s to around 70° for the Baton Rouge metro area. 

Thursday morning’s commute will be a dry one, with a pocket or two of mainly-light fog.  Headed into the afternoon, temperatures will climb into the mid to upper 80°s around the area under a mostly cloudy sky. Today's atmospheric "cap" will be slightly weaker tomorrow, so we'll post rain chances at 20% to maybe 30% for Thursday afternoon -- the majority of WAFB neighborhoods will remain dry once again. Plan for afternoon highs in the mid to upper 80°s.

By Friday, the “cap” should be gone and daytime heating will work with our humid Gulf air to get afternoon showers and storms going again.  In addition, our guidance is showing a fairly healthy disturbance tracking from the west across the lower Mississippi Valley on Friday, adding a big boost to the already unstable air mass.  Right now, it’s not looking like an all-day rain, but showers and t-storms are likely for Friday afternoon.  With the clouds and rains, highs on Friday may only make it into the low to mid 80°s for most of us.

The outlook for the weekend may not be quite as wet as our thinking for Friday, but unsettled weather remains the forecast for both Saturday and Sunday.  Expect scattered afternoon showers and storms for both days with Capital area morning lows in the low 70°s and afternoon highs in the mid 80°s, with a few neighborhoods sneaking up into the upper 80°s.

Headed into next week, we don’t see much in the way of significant changes to the afternoon weather pattern.  Although the NWS Weather Prediction Center (WPC) is currently showing a cool front approaching South Louisiana on Tuesday, the WPC has the front stalling over the southern parishes on Wednesday -- a situation not too different from what we’ve seen the past 24 hours or so. 

That means more of the same: scattered mainly-afternoon showers and t-storms for Monday through Wednesday, with some potential for stronger storms next week as the front draws near.

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