Nicholas Archives - Reduce Flooding

Nicholas, Now a Hurricane, Expected to Slow to a Crawl Near SW Louisiana

As of its 10 PM CDT update on 9/13/2021, the National Hurricane Center (NHC) upgraded Tropical Storm Nicholas to a hurricane.

Nicholas a Minimum Cat 1 Hurricane

A weather station at Matagorda Bay reported sustained winds of 66 kt (76 mph) with a gust to 83 kt. NHC expects no additional strengthening before the system makes landfall. Gradual weakening is expected during the next 2-3 days while Nicholas moves over southeastern Texas and southwestern Louisiana.

The minimum sustained winds for a Category 1 hurricane are 74 mph.

Light Steering Currents Will Slow Nicholas

According to NHC, “Nicholas is currently moving through a weakness in a mid-level subtropical ridge. Within 12 to 24 hours, after Nicholas has moved inland, the ridge should weaken and leave Nicholas in an area of light steering currents. As a result, during the next couple of days, the cyclone should turn eastward and slow to a crawl near southwestern Louisiana.”

*Nicholas should now reach the Houston Area with tropical-storm-force winds on Tuesday before slowing near the Louisiana border on Wednesday as a tropical depression..*

The current 10 PM official forecast shows Nicholas moving more slowly than the previous forecast.

Key Messages

Heavy rainfall will impact portions of southeastern Texas, Louisiana, and southern Mississippi through the middle of the week. Significant rainfall amounts are expected, potentially resulting in areas of life-threatening flash and urban flooding, along the eastern Texas coast into southwestern Louisiana. Minor to isolated major river flooding is also possible in smaller river basins and urban areas.
There is the danger of life-threatening storm surge inundation along the coast of Texas from Port Aransas to Sabine Pass. Residents in these areas should follow any advice given by local officials.

Wind Force Probabilities Increasing

*The probability of experiencing tropical-storm-force winds in the north Houston Area is very high.*

Rain Forecast Less Extreme in North Houston Area

*However, the Weather Prediction Center now shows major rain accumulations only near the coast and to the east of Houston.*

I already have 1.47 inches in my rain gage for today. The estimates above are for three days.

Flash Flooding Risk Now Mostly Along Coast

*The risk of flash flooding mirrors the rainfall map above. The Lake Houston Area now has only a slight chance of flooding.*

All in all, if the maps above are accurate, the Lake Houston Area could still see 2 to 6 inches of rain tomorrow, but that’s far better than previously predicted.

*This infrared image shows the areas of heaviest rainfall as of 11:26 PM CDT 9/13/2021*

Areas near the coast remain under a storm surge warning.

So far, none of the streams or bayous in Harris County have come out of their banks. To stay on top of potential local flooding on Tuesday, visit the Harris County Flood Warning System.

Posted by Bob Rehak at 11 PM Monday, 9/13/2021 based on information from NHC and HCFCD

1476 Days since Hurricane Harvey

Cone of Nicholas Shifts East, Now Includes Houston, Hurricane Watch Expanded

The 10 AM update from the National Hurricane Center shows that the eye of Nicholas is reforming yet again – further east from where it first reformed earlier today near Brownsville. This means that the cone of uncertainty for Nicholas has expanded. It now includes the entire Houston Area. And although chances of a hurricane are low, the hurricane watch has been extended northward to San Luis Pass.

Nicholas’ Cone Now Includes All of Houston

*Remember that every place within the cone has an equal change of having the storm pass over it.*

Main Threats from Tonight to Tomorrow Night

Bands of heavy rainfall and gusty winds continue to spread inland from the coast and will increase in frequency and intensity this afternoon into tonight. Core of Nicholas will move across southeast Texas….especially areas south of I-10 overnight into Tuesday with significant rainfall likely.

Harris County Meteorologist Jeff Lindner warns that while Nicholas is not forecasted to become a hurricane, it is possible that it could landfall as a minimal hurricane….but this does NOT change the impacts.

Impact Predictions Remain Unchanged Since Last Update

Rainfall, wind, and storm surge impacts remain unchanged from my post earlier this morning.

Significant rains will begin early this evening and likely continue into Tuesday morning.

Rainfall rates of 2-4 inches per hour will be possible yielding rapid street flooding and significant rises on bayous and creeks.

Lindner’s main concern is watersheds south of I-10 (Clear Creek, Armand Bayou, Vince and Little Vince Bayous, Keegans Bayou, and possibly Brays Bayou). However, Lindner still sees risk north I-10.

Some bayous and creeks may overflow their banks. Structure flooding is possible tonight. The majority of the rainfall is going to be tonight into Tuesday morning.

Residents should stay where they are after 6:00 PM this evening and remain there through the duration of Nicholas.
Jeff Lindner, Harris County Meteorologist

Best Ways to Monitor Nicholas

Closely monitor bayou and creek conditions and rainfall trends. The best way to do that is through the Harris County Flood Warning System.

Also, closely monitor the National Hurricane Center website. This page contains their latest satellite image updates. During storms like this, they update them hourly. Here’s one from 11:46 AM Houston time.

*Nicholas as of 11:46 AM on Monday, 9/13/2021.*

Posted by Bob Rehak on 9/13/2021 at 10:30 AM and again at Noon

1476 Days since Hurricane Harvey

Tropical Storm Nicholas Forms in Gulf

A USAF mission this morning found low-level circulation and a large area of 40-50mph winds over the western Gulf. Additionally, satellite images show an expansion of the scattered deep convection associated with the system. Based on this, the system has been upgraded to Tropical Storm Nicholas. The storm is moving NNW at 13mph and this motion is expected to continue today.

Tropical Storm Warnings have been issued from the Mouth of the Rio Grande to Port Aransas TX
Tropical Storm Watches have been issued from Port Aransas TX to High Island TX including Matagorda and Galveston Bays.
Storm surge watch has been issued from the mouth of the Rio Grande to High Island TX
Flash Flood Watch from 7PM tonight through Tuesday night for most of Houston region

*NOAA satellite image of Nicholas as of 10AM CDT Houston time.*

*Nicholas’ track should bring the storm onshore near Matagorda Bay.*

Jeff Lindner, Harris County Meteorologist, predicts, “Nicholas will be moving over warm waters of the western Gulf of Mexico in fairly favorable upper level conditions and steady intensification is likely up to landfall. Most models predict the system to become a mid-range tropical storm. The National Hurricane Center forecasts a 65mph tropical storm at landfall. A reasonable worst case potential is a category 1 hurricane, but at this time that looks unlikely.

Nicholas’ track places southeast Texas on the “dirty” side of the system with onshore winds and bands of heavy rainfall,” says Lindner.

Rainfall Starting Later Today

By late today, heavy rain is expected to reach portions of the Texas and Louisiana coasts, with a heavy rain threat continuing across coastal areas through the middle of the week. Localized significant rainfall could produce areas of flash, urban, and isolated river flooding.

Hourly rainfall rates could be high during this time with 2-3 inches possible, which would lead to some flooding in more urban areas.

How far this storm moves inland will determine how far heavy rains advance on Monday. Says Lindner, “Certainly the coastal counties (Chambers, Galveston, Brazoria, Matagorda, and Jackson) will see heavy rainfall, but this could extend inland into southern Liberty, southern Harris, Fort Bend, and Wharton counties also.” He predicts:

Coastal Counties: widespread 5-8 inches (isolated areas 10-15 inches)
South of I-10: widespread 3-6 inches (isolated areas 8-12 inches)
North of I-10: widespread 2-4 inches (isolated areas 6 inches)

*The NWS Weather Prediction Center shows heavy rain and flash flooding are possible for most of the upper Texas coast through mid-week.*

Flood Potential

Lindner says, “Given the tropical moisture in place hourly rainfall rates of 2-4 inches will be possible under the stronger cells which will lead to quick accumulations. While grounds are dry initially, waves of rainfall will gradually saturate the soils leading the increasing run-off. Flooding will be possible, especially across the coastal counties and areas south of I-10 where the greatest rainfall is most likely at the moment.”

*Most of the Houston area will have a slight (10%) chance of flash flooding for the next three days.*

Tropical-Storm-Force Winds Should Arrive in Houston Tuesday Morning

*Tropical storm force winds should hit the Houston area Tuesday morning.*

2-4 Feet of Storm Surge Likely in Galveston Bay

*Nicholas should bring 2-4 feet of storm surge to the upper Texas coast.*

Posted on 9/12/2021 by Bob Rehak based on Information from NHC and HCFCD

1475 Days since Hurricane Harvey

Tag Archive for: Nicholas