Wednesday, August 15, 2012

Rain Chances on the Rise...

By Jay Grymes & Steve Caparotta

Much like we saw on Tuesday, afternoon showers and t-storms were limited in coverage.  Most of Wednesday’s showers and storms moved along west-to-east paths in response to the zonal flow at mid levels.  And also like Tuesday, the daytime heat-and-humidity was the main weather story for most WAFB neighborhoods.
Our forecast for Thursday reads much the same, with slightly better chances for a cooling rain shower or t-storm over your backyard: set Thursday afternoon’s rain chances at about 30% to 40%.
The current quasi-stationary front draped over Louisiana is expected to begin a slight northward retreat tonight and tomorrow and effectively dissipate to our north, keeping the WAFB viewing area under the influence of this very warm and very humid Gulf air mass through the remainder of the week.
By Friday, a deepening upper-level trough over the eastern U.S. will help drive a cool front south-southeast across the U.S. Plains -- that front will become the main weather feature for us as we head into Friday and the weekend.  We’re going with 50-50 rain chances for Friday afternoon.  That same front is expected to slowly work its way southward through the state, providing lift for the unstable air mass during Saturday, Sunday and Monday. 
With the slow-moving front over us, we’ll keep high rain chances - - 60% to 70% - - through the weekend forecast and carry a 50% to 60% chance through Monday!  By Monday afternoon, many WAFB communities could be dealing with multi-day rain totals on the order of 2” to 4” or more!

The latest guidance suggest that the weekend front will eventually pass to the south of Baton Rouge, possibly making it into the northernmost coastal waters early next week where it is likely to stall.  This should give us a brief break from the very-high humidity we’ve endured this week, with morning lows possibly dipping below 70° for communities along and north of the I-10/12 corridor.
But if that relief from the humidity does develop, it only lasts a day or so.  By mid-week, the humidity of the Gulf air mass will quickly return.
The disturbance over the central Atlantic -- roughly 600 miles ESE of Bermuda -- has really taken shape over the last 12-18 hours or so and has been upgraded to Tropical Depression #8 as of 4PM.  The NHC forecast calls for additional strengthening, with TD #8 potentially becoming T.S. Gordon later tonight or tomorrow.  Regardless of what does become of TD #8, virtually all of the computer guidance has it taking a hard turn to the east in the next day or two, which means it stays out over the open water with no threat to land.

The remnants of T.D. #7 still has our attention even though the core of the wave is over the Central American landmass.  There remains a slight bit of concern that some of the energy associated with this tropical wave could emerge into the Bay of Campeche in the next day or two.  Even if this did occur, it appears as though its current WNW track and forward speed -- at 15-20 mph -- would give it little time for significant development before moving back over land along the Mexico Coast.  Regardless, the system looks like it will continue to be a troublesome rainmaker for Belize, Guatemala and southern Mexico in the coming days.

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