Tuesday, April 14, 2015

Flash Flood Watch Extended Through Wednesday

By Jay Grymes & Steve Caparotta

April 15th First Alert Quickcast:

- Flash Flood Watch extended into Wednesday for much of the WAFB viewing area
- a bit of a break in the rains tonight
- NWS forecast still suggesting another 3” to 6” of rain between now and the weekend!

What a mess!  The rains got into the viewing area sooner this morning than we expected and they came with a vengeance -- prompting one of the most widespread arrays of Flash Flood and Areal Flood Warnings that we’ve seen in a long, long time.  Thankfully, as we ease into the late afternoon and evening, those Warnings have been allowed to expire.

Radar estimates are showing an extensive area of more than 3.0” of rain for today - - focused across WAFB communities to the south of metro Baton Rouge.  Those big rain totals are highlighted by a bull’s-eye of roughly 5.0” to 6.0” or more along and near the Iberville/Ascension parish line. 

Thanks to our viewers, we’ve received numerous photos of street flooding throughout the WAFB viewing area with reports of water in homes in some locations south of the Baton Rouge metro area.  Those living along and north of the I-10/12 corridor have been far more fortunate today, with radar showing most of these areas with roughly 1.0” to 1.5” for the day.

Thankfully, we should get a break from the heavy rains over the next 18-24 hours.  We’re going with isolated showers for most of the viewing area overnight and scattered rains for Wednesday.  Rain totals for just about everyone should be less than one inch for Wednesday, with many coming in at well under one-half-inch for the day.

Unfortunately, our Thursday and Friday outlooks return to a “rain likely forecast” ... and it doesn’t get a whole lot better for the weekend either.  Our two main extended-range forecast models -- the American ‘GFS’ and the European ‘ECMWF’ -- are both indicating that the much of our area could see another 3.0” to 5.0” of rain between tonight and Sunday evening, with isolated higher totals.

Now ... let’s factor in the radar estimates and raingage reports since last Friday.  They show as much as 6.0” to 8.0” has fallen across portions of WAFB’s southern parish zones already with some radar bull’s eyes topping an estimated ten inches of rain in the Iberville/Ascension area.  Add in the forecast for the coming five days and we could be dealing with some serious high-water problems, especially for areas already pounded by heavy rains over the past five days.

We’ll keep an eye on the Florida Parish rivers too.  So far, with the heaviest rains to the south, we don’t anticipate any serious river flooding -- for the Amite, Comite, Tickfaw and Tangipahoa -- even with the “wet” five-day forecast.   Rains have generally been under two inches across the upper parts of these river basins, thus far.  However, one or more of these rivers could climb out of its banks should the forecasted rains come in one big dousing.

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