Thursday, July 4, 2013

Wet Weekend Ahead!

It wasn’t an entirely rain-free day across WAFB-land, but it was certainly “quieter” weather-wise compared to what we saw on Wednesday, especially across the Baton Rouge metro area. Isolated showers this afternoon should wind down nicely as we head towards sunset, leaving us with a mainly-dry window at dark for enjoying the local fireworks, no matter where you are.
At the surface, a weak, quasi-stationary front continues to meander over southeast Louisiana, but that front is losing some of its definition and is slowly fizzling out. At the same time, the unusual upper-air trough over the center of the U.S. remains in place. On Wednesday, these two features teamed up to focus showers and storms over metro BR. By contrast today, the trough is pulling less “dry” northern air into the Gulf Coast region -- instead, in its current position it is tending to enhance a warmer and more humid southwesterly flow aloft. At the same time, the weakening front is less of a factor for generating afternoon rains, even though the air across most of the WAFB viewing area is moistening up.
After a run of days with dew point temperatures frequently in the low to mid 60°s, it’s looking like upper 60°s to low 70°s are returning -- something closer to July norms. Yes, our traditional Gulf humidity is on the way back.
Your attention likely will turn to the Gulf over the coming days after a look at the satellite loops. A broad area of low pressure extends across the entire Gulf, from the Florida Panhandle all the way to the Yucatan Peninsula. We’ve talked about this situation already this week: one could argue that it was two distinct areas of low pressure that have essentially merged into one large rain-making mess. That mess will continue a slow march towards the west and northwest along the central Gulf Coast over the coming days, and that means very good rain chances for Friday and the weekend.
The National Hurricane Center continues to post the southern portion of this area -- along and over the Yucatan Peninsula -- with a 10% chance for tropical development over the next 48 hours. We’re good with that probability -- there is too much shear over the northern and western Gulf for development there ... and simply too little organization or definition over the southern Gulf for anything to develop anytime soon down there. 
But get ready for some rainy weather, especially our coastal communities. The Florida Panhandle has been hammered these past few days, with estimates of 4” to as much as 10” of rain - - localized totals there potentially top a foot of rain! While we are not expecting anything quite like that over south Louisiana, we should prepare for a run of wet days. Plan on scattered-to-numerous showers and t-storms on Friday with rain likely (60% to 70% chances or better) for Saturday and Sunday.
I’m thinking rains of 1” to 2” -- with locally higher totals -- along and north of the I-10/12 corridor by the end of the weekend. Totals will be greater as you get closer to the Gulf: coastal communities should plan on 2” to 4” or more, with some localized big bull’s eyes as the Gulf low pressure region moves from east to west.
And elevated rain chances will probably continue into the first half of the upcoming work week. Oh well, I suppose that the backyards and gardens will love it?

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