re: Tropical Storm Nicholas - Flash Flood Watch for South Louisiana

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Meteorologist Nick Mikulas
The story on Tropical Storm Nicholas is starting to clear up a bit. After having a nice center to track on radar all night, it appears there is yet another center realignment going on. The current center is weakening and moving northeast, and should align more with the mid level center this afternoon. For our purposes, this relocation means we will probably see a pretty direct hit from Nicholas, but with a quicker forward speed. That means more of a concentrated heavy rain event, over a shorter period of time. There will be rain before and after, but the main show will likely be from late tonight through early Wednesday. And the highest chance for really nasty weather will be late Tuesday morning through Tuesday around midnight. Here are the latest numbers on Nicholas.

LOCATION...26.4N 96.8W
ABOUT 45 MI...70 KM NE OF MOUTH OF THE RIO GRANDE
ABOUT 140 MI...225 KM S OF PORT OCONNOR TEXAS
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...N OR 5 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES

I’m going to continue with a timeline over a parish by parish breakdown. This doesn’t look like a massive wind event, and the heavy rain will be distributed over the entire area. There will be stripes of excessive rain, but saying exactly where that happens is impossible. But you need to be prepared for a flood threat. Rapides, Vernon, Avoyelles, Beauregard, Allen, Evangeline, and St. Landry Parishes are all under a flash flood watch until Wednesday.

Through midnight Monday…

Cloudy skies, and off and on light rain are likely. Rain could start to increase a bit this afternoon with a few scattered storms, but there won’t be flooding problems or wind problems today. Just dreary and humid.

Midnight Monday through 6:00 AM Wednesday…

This is when things kind of let loose around here. The good news is, models are showing at least slow northeastward motion through this time frame. That means it doesn’t look like this storm will stall out and produce biblical amounts of rain. It will produce plenty, and there will be flooding, but I don’t see some crazy Harvey-like scenario happening. In fact, I’m upping my rain totals, but only to a general 4-8 inches. I’d considered going a bit higher, but with the system not stalling, I’ll keep them just a bit lower than what I initially thought I might do. There will be stripes of 12+ inches of rain, and I still wouldn’t be stunned to see an isolated report approaching 20 inches. So if you have flooded in extreme rain events, you’ll want to be as prepared as you can be by Monday evening. There will be some wind, but I’m thinking 20-40 mph, with a few higher gusts. That probably means some isolated power outages, but nothing long term. The rain is the main problem with this storm.

Wednesday morning through Friday…

With more of a hook to the right on Tropical Storm Nicholas, we might actually catch a break from most of the rain during the day Wednesday and Thursday. Moisture should return by Friday, and at least scattered storms will return. But this shouldn’t be a huge issue.

So at this point, it looks like a 24-30 hour window where we see most of our action. Rain is by far our main concern. Wind will be gusty, but doesn’t look like it’ll bring widespread problems. Being near, and east of the center in most of the area means there is a low threat for tornadoes, but those should be quite isolated if we see any at all. So strap in for some rain. I’ll update later today.

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