FIRST ALERT FORECAST: Beta heads to Texas; local focus remains on rain

FIRST ALERT FORECAST: Monday, Sept. 21 - Noon

BATON ROUGE, La. (WAFB) - Dry air and wind shear have continued to take a toll on Tropical Storm Beta as it tracks toward the Texas coastline today.

Maximum sustained winds were listed at 50 mph as of the 10 a.m. advisory and no strengthening is forecasted before Beta potentially makes landfall along the mid-Texas coast by tonight.

Excessive rainfall outlook from NOAA’s Weather Prediction Center valid from 7 a.m. Tuesday – 7 a.m. Wednesday. A ‘moderate’ risk of flooding is posted for much of our area
Excessive rainfall outlook from NOAA’s Weather Prediction Center valid from 7 a.m. Tuesday – 7 a.m. Wednesday. A ‘moderate’ risk of flooding is posted for much of our area (Source: WAFB)

Our local focus will continue to be on the potential for some heavy rainfall well removed from the center of Beta over the next couple of days. Thus far, most of the heavy rain has been confined to coastal locations and that trend will likely continue through the day on Monday. But there is some concern that heavier rains could translate farther inland beginning on Tuesday, resulting in an increased flood threat.

NOAA’s Weather Prediction Center (WPC) echoes that sentiment by placing much of our area under a ‘Moderate’ risk of flooding from Tuesday into Wednesday morning.

Excessive rainfall outlook from NOAA’s Weather Prediction Center valid from 7 a.m. Tuesday – 7 a.m. Wednesday. A ‘moderate’ risk of flooding is posted for much of our area
Excessive rainfall outlook from NOAA’s Weather Prediction Center valid from 7 a.m. Tuesday – 7 a.m. Wednesday. A ‘moderate’ risk of flooding is posted for much of our area (Source: WAFB)

The concern is that some north-south oriented bands of rainfall could develop over southeast Louisiana on Tuesday, resulting in ‘training’, or a pattern where heavy rains repetitively move over the same areas. The National Weather Service has also placed the majority of our viewing area under a Flash Flood Watch through Wednesday evening.

A Flash Flood Watch is in effect for most of the WAFB viewing area through 7 p.m. Wednesday.
A Flash Flood Watch is in effect for most of the WAFB viewing area through 7 p.m. Wednesday. (Source: WAFB)

While our level of concern trends a little higher over the next 24 hours, the overall confidence in heavy rain potential is low. Take, for example, the range of model rain forecasts centered on Baton Rouge through Wednesday evening. Plotting 5 different models gives us a range of potential rainfall from as little as 0.26″ to over 10 inches from the Euro!

While the Euro forecast is a red flag and gets some added attention because the model has been consistent in showing this potential for a few days, I’ve also noted that the Euro has consistently been too fast in bringing the heavy rains inland.

Given the huge model spread on potential rainfall, the best approach for now is probably to lean closer to the WPC guidance which relies on a blend of multiple model solutions.

Rainfall outlook from NOAA’s Weather Prediction Center through Saturday morning. The outlook as of Monday morning suggested average rain totals of 3” to 7” over the next 5 days for most of our area.
Rainfall outlook from NOAA’s Weather Prediction Center through Saturday morning. The outlook as of Monday morning suggested average rain totals of 3” to 7” over the next 5 days for most of our area. (Source: WAFB)

The latest outlook from WPC shows 3″-7″ of rain on average for most of our area through Saturday morning. But if heavy rain bands do develop at any point over the next couple of days, those amounts could go higher.

One other thing we’ll be monitoring through the week is the coastal flood threat due to Beta’s persistent east and southeast winds across our area. Water levels as much as 2 to 3 feet above normal along the eastern facing shores of SE Louisiana and into Lakes Pontchartrain and Maurepas and surrounding areas.

Coastal Flood Advisories & Warnings are posted along the Louisiana coast and for areas around Lakes Pontchartrain and Maurepas. Water levels are running 2 to 3 feet above normal in many areas due to Tropical Storm Beta.
Coastal Flood Advisories & Warnings are posted along the Louisiana coast and for areas around Lakes Pontchartrain and Maurepas. Water levels are running 2 to 3 feet above normal in many areas due to Tropical Storm Beta. (Source: WAFB)

Gauges along the lower reaches of the Amite & Tickfaw rivers were still showing a steady climb as of Monday morning and people in these areas should plan on high water being around all week due to the slow movement of Beta.

We do eventually expect a drying trend by the weekend as Beta moves to our north and weakens. Temperatures will also rebound to near-normal levels by late in the week and into the weekend.

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