Thursday, August 7, 2014

No Relief from the Heat Anytime Soon

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:

- summer-like heat-and-humidity continues 
- rain chances at 20% to 30% through Sunday 
- NOAA updates their tropical forecast

Baton Rouge’s Metro Airport (BTR) hit 95° this afternoon, matching July 26th with the highest temperature of the summer thus far.

Our weather for the next couple of days will be much like the last few days: muggy mornings with sunrise temperatures in the mid 70°s for metro Baton Rouge followed by awfully hot and very humid conditions for the mid-afternoons as highs climb into the mid 90°s for many WAFB communities. And that heat-and-humidity will combine to drive Heat Index values into the triple digits for most neighborhoods. But in the end, our daily temperatures won’t be all that much above normal -- maybe a couple of degrees at best. Yes, this heat is normal for August in and around the Red Stick.

What is also normal are near-daily hit-or-miss afternoon and early evening showers and storms. Long-term statistics show that metro area daily rain chances in August average at close to 40%, with most of that occurring in the afternoon and early evening hours.. So, if anything, our weather over the last few days has been -- and our forecasts for the next few days are -- on the drier side of normal from a rainfall standpoint. 

But what has been a bit different -- at least during the previous three days -- was that the rains waited until around 6:00pm or so before really getting cranked-up. It is more typical in the summer months for those heating-enhanced showers and storms to start popping by or even before the mid-afternoon and subside around sunset. Instead, during the previous days, the action started later and lingered well past sunset. And you may have noticed that some of those storms over the past few days were highly charged with cloud-to-ground lightning. What’s more, they tended to be slow-movers, so that some neighborhoods caught under the core of those evening cells received from 1” to 2” of rain in relatively short periods.

What about the upcoming daily rain chances? We’ll keep them in the 20% to 30% range for Friday and the weekend - in other words, more of the same. The upper-level ridge centered over the Southern Plains will maintain just enough of an influence over the lower Mississippi Valley to keep our daily coverage below the ‘August 40% norm’ .. but not enough to shut-off the rain chances completely. So the majority of the WAFB viewing area stays rain-free each day through Sunday -- but over the course of the next three days, more than half of the area should get at least a shower or two. And a few folks could again be dealing with lightning-charged storms and locally-heavy downpours.

NOAA’s hurricane experts released their August “update” to their Hurricane Season Outlook. While we’ve already seen two hurricanes this season, including a ‘hit’ along the East Coast by ARTHUR, the NOAA team seems confident that this will not become an overly-active season. Their forecast calls for a 95% likelihood that storm activity will be near-normal (25% chance) to below-normal (70% chance). Their outlook is based on expectations that ‘hostile’ atmospheric and oceanic conditions over the tropical Atlantic will serve to suppress tropical system development. However, they acknowledge their forecast does NOT address landfall probabilities and that ‘low activity’ hurricane seasons still have the potential to be extremely destructive -- as was the case in 1992 when Andrew struck Florida and Louisiana.

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