Thursday, August 22, 2013

Sct'd T-Storms into the Weekend

By Jay Grymes & Steve Caparotta

To put it simply: our thinking hasn’t changed for the coming days in terms of the forecast.  Surface high pressure to our east will help maintain a steady flow off the Gulf through the weekend.  To our west and northwest, a building upper-level ridge may become a more dominant player for our weather, especially by next week.
Don’t be looking for any relief from the heat and humidity through the coming 7 days or so.  While a “backdoor” cool front will approach our area from the northeast over the weekend, the current thinking is that the front stalls and fizzles out over Mississippi.
That means our current August weather continues -- expect more of the same.
Morning lows will run in the low to mid 70°s for metro Baton Rouge, with occasional morning showers closer to the coast.  Don’t be surprised to see some patchy sunrise fog, but not so much as to be a problem for the morning commute.  Afternoon temps will rise into the 90°s for most WAFB neighborhoods just about every day, and that daytime heating will combine with the moist-and-unstable Gulf air to fuel scattered afternoon and early evening showers and t-storms.  For many communities, much as we’ve seen over the past several days, early afternoon 90°s will drop into the 80°s -- possibly even the 70°s -- later in the day thanks to the clouds and showers.  We’re setting daily rain chances in the 30% to 40% range through the weekend and into next week.
There are some hints that we could see a modest dip in those rainfall probabilities by the middle of next week as an upper-level ridge expands over the central U.S. -- while at the same time, weak surface high pressure tries to take hold over the Gulf Coast states.  We’ll have to watch to see how all this plays out, but should that combination of features come to pass, we could see a notable warm-up by the middle to end of next week.
As for the tropics, all remains relatively quiet over the Atlantic Basin, especially give that we are in late August.
A modest tropical wave (easterly wave) located over the northeastern Gulf may add a bit to our Friday rain chances but its impact will mainly be limited to the coastal parishes.  The National Hurricane Center is currently giving the wave only a 10% chance of development in the coming days as it moves from east to west across the northern Gulf.  Farther to the south and southeast, a broad disturbance continues to move across the west-central Caribbean and appears headed for the southern Gulf in the coming days.
While there is nothing to suggest a quick spin-up of either of these features right now and there is no cause for concern at this time, both are deserve watching.  Let’s face it, (1) it is late August and (2) the Gulf and Caribbean waters are plenty warm.
Over the open tropical Atlantic, dry air and unusually-persistent stability (for this time of year) have put the clamps on eastern Atlantic wave development.  What’s more, most of the guidance suggests that this pattern will continue for the next several days, at least.  Could we get through the month of August without a hurricane?  Uncommon, but not unheard of.  A quick scan of the record books suggests that the last hurricane-free August was back in 2002; what’s more, hurricane-free Augusts have occurred a handful of times over the past 50 years.
So maybe you’re thinking, “What happened during the 2002 season?”  12 ‘named’ storms by season’s end, including 4 that visited Louisiana: Bertha, Hanna, memorable Isidore and even-memorable Lili!  In fact, the 4 Louisiana ‘hits’ in 2002 are the most for any season on record for the Bayou State!

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