Friday, July 3, 2015

Scattered Storms Return for the Holiday Weekend

By Jay Grymes & Steve Caparotta

July 3rd WAFB First Alert Quickcast:

- back to scattered afternoon t-storms for the independence Day weekend
- drier and a little warmer for next week

Happy 4th to you and yours!

We doubt that anyone is complaining about our back-to-back dry days, thanks to high pressure at the mid and upper levels putting the clamps on afternoon thundershower development.

Unfortunately, the “lid” comes off the atmosphere over the weekend and we return to scattered afternoon showers and t-storms for both Saturday and Sunday. In fact, we’re leaning towards “rain likely” for Saturday (rain chances at 50% to 60% for Saturday afternoon), and there is a potential for a few strong to severe storms in the WAFB area over the two-day span.

The upper-level high (a mid/upper-air ridge, the “lid” on the pot) that put the brakes on afternoon rains yesterday and today will give ground over the weekend. That will let our moist and unstable Gulf air do its thing: build mid-day and afternoon showers and storms without an inhibitor to slow their vertical growth. Neither day will result in all-day rains for your backyard, but we expect a pretty active radar depiction for both afternoons as individual t-storms build, move and subside through the day. If you’ve got outdoor plans on either day, make sure that you have an indoor or under-cover option ready to go.

After muggy morning starts in the low to mid 70°s for both Saturday and Sunday around metro Baton Rouge, look for temperatures to climb into the upper 80°s to around 90° before the clouds and rains knock the temperatures back through the afternoon.

As for the Saturday evening “Fireworks on the Levee,” we expect the rains to have dissipated by showtime, but we could still have isolated rains in the area as late as 7:00 or even 8:00pm. We’re thinking that temperatures for the 9:00pm showtime will be in the upper 70°s to low 80°s on the levee.

Into next week, the ridge returns, taking rain chances back down into the ”isolated” category for just about every day next week -- yep, too bad the ridge had to retreat during the weekend. With the drier pattern in the forecast for next week, plan for muggy morning sunrises in the low to mid 70°s for most WAFB communities, with highs in the low 90°s just about every day.

Thursday, July 2, 2015

Mainly Dry Again for Friday

By Jay Grymes & Steve Caparotta

July 2nd WAFB First Alert Quickcast:
- hot, breezy and mostly dry for Friday
- scattered showers & t-storms expected for both weekend days

Okay, our “mainly dry” forecast for today took a big hit in a number of neighborhoods before 7:00am thanks to a band of mainly-light showers draped over the viewing area. Those showers fizzled out by or before mid-morning and the gray cloud deck had largely thinned before lunchtime. With the thinning clouds, mid-day and afternoon sunshine took temperatures into the 90°s for the afternoon.

Even as late as 3:00pm this afternoon, Doppler was “all clear” across the WAFB viewing area. A rogue, spotty shower or two might pop-up during the late afternoon or early evening, but we expect that just about everyone stays dry into the evening and overnight too.

Our Friday forecast calls for another mainly-dry day like today … with the big exception being no morning showers like some of us experienced this morning. After a muggy Friday morning start in the low to mid 70°s for many WAFB communities, we’ll climb once again into the low 90°s for Friday afternoon, with spotty showers, at best. Add in the afternoon humidity and that low 90° reading will ‘feel like’ 100° or more at the peak of the afternoon heat. Then it’s a warm and dry Friday evening and mostly fair skies into the night.

Out mostly-dry Thursday and Friday are courtesy of a western U.S. upper-air ridge building just a bit farther east. That ridge has pushed drier and slightly warmer air into the middle levels over the Bayou State -- and that serves as a rain-cloud inhibitor.

Unfortunately, the dry spell doesn’t hold through the weekend. The ridge softens and retreats westward allowing our locally-unstable air a better chance to build vertically during the afternoons: bigger afternoon cumulus clouds usually means more rain-clouds and better rain coverage. We’re still not too concerned about any kind of severe weather threat for either Saturday or Sunday, but we’ll go with rain chances at 40% to 50% or so for both days. Of course, with those elevated rain chances, we can’t rule out one or two strong storms on either afternoon.

So be ready to dodge the rains during both afternoons. We don’t anticipate all-day rains in either case and not everyone gets wet each day … but have a plan to get out of the weather should storms roll through your neighborhood. The good news is that we expect Saturday’s mainly-afternoon rains to be out of the way for Saturday evening’s fireworks and festivities.

Headed into next week, upper-level ridging builds back over the area, knocking rain chances back to around 20% to 30% for just about every afternoon. (Too bad that isn’t the cast for the weekend, eh?)