Wednesday, March 11, 2015

Flash Flood Watch Continues...

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:
- FLASH FLOOD WATCH extended through Friday 6:00pm for areas east of the Atchafalaya
- FLASH FLOOD WATCH canceled for areas west of the Atchafalaya
- still a potential for an additional 1” to 3” of rain between now and Friday evening

It was unquestionably quieter today in terms of area rains today compared to yesterday. In fact, a few neighborhoods even got some glimpses of faded blue skies and streaks of sunshine. But all of our model guidance -- as well as our latest radar trends -- indicate that our run of rainy days is far from over.

Both of our high-resolution, short-term models -- the HRRR and our in-house RPM -- are showing a broad swath of rain moving into Louisiana form the Gulf this evening and staying with us through most of the night. After that, we could see another quiet spell with limited rains through the first half of Thursday before the next wave makes it into the viewing area later in the day.

Regional rains will continue to arrive in periodic waves through a good bit of Friday, with rains tapering off during the latter half of the day. Although we could spend a good bit of Saturday under mostly cloudy skies, we expect the weather to be just fine for “The Wearing of the Green” in Baton Rouge.

From a temperature standpoint, our recent run of mild days will continue. We’ve got afternoon highs posted in the 70°s right through the weekend and into next week. As for lows, we expect the Gulf air mass currently in place will keep our morning starts in the 60°s for Thursday and Friday. Be ready for patchy fog on both mornings too.

As we head into the weekend, the upper-air pattern and series of disturbances that have kept skies gray and yards wet will shift to the east. With that shift, a slightly drier and less humid (lower dewpoints) air mass from the west and northwest will be moving into the lower Mississippi Valley. That should mean morning minimums in the 50°s for the weekend and continuing into next week.

So what about the rains? Admittedly, totals for most WAFB communities through this afternoon are lower than what we had anticipated earlier in the week. While several waves of rains have arrived over the past few days, thankfully they have not been as “productive” as we expected. Still, there are lots of WAFB neighborhoods that have received more than 1” of rain thus far, and we still have two potentially “wet” days ahead -- Thursday and Friday. 

As of this morning, the NWS Weather Prediction Center was still showing a 4” bullseye for the upcoming three-day total (from this morning through early Saturday) centered right over South Louisiana. We’re thinking that number may be on the high side for our area, although we won’t rule out the possibility of one or two spots topping 4” in the coming days. However, something more like widespread 1” to 2” -- with some scattered totals of 3" or more -- seems a bit more likely given the forecasted rain patterns through Friday.

These lower multi-day forecasted rain totals are obviously good news. We’ll still be watching for street flooding and excess water problems in the usual places, but we are a little less concerned about flooding along area rivers and bayous. That said, we still need to watch our local waterways closely over the next few days as we await the arrival of additional periods of rain. 

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