Weather

Flood Event Unfolding along the Upper Texas Coast

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September 18, 2019

Training of heavy thunderstorm bands along the Upper Texas Coast on Wed Sep 18

Very serious situation unfolding along the Texas Coast this morning…
Training of intense thunderstorms will bring flash flooding to areas such as Freeport, Galveston and Beaumont/ Port Arthur…

DETAILS

1) Areas from Freeport to Galveston should already have saturated surface soil. Galveston has picked up around 6.5 inches of rain so far as of 0600AM this morning. Training of heavy rain over these areas can produce flash flooding…Parts of Sargeant…near Freeport were observing roads under water earlier…

2) League City/ Friendswood area experienced numerous hours of heavy rain yesterday afternoon and evening, but the training of thunderstorms should be south of you this morning. Nonetheless, some periods of heavy rain could hit you off and on this morning and the ground is already saturated…expect street flooding in heavy rain…

Flooding in Galveston on Wed Sep 18 near 45th Street and Avenue O….source Sara Asocar Facebook

3) Bolivar/ Chambers County- I have received reports of 5-7″ of rain already….the training of heaviest thunderstorms may mostly stay south of you this morning but will lift back up to you this afternoon….ground should be saturated…and periods of heavy rain this morning could quickly produce localized flooding…Parts of Hwy 87 were already underwater yesterday from heavy rain and high salt water levels.

4) Beaumont/ Port Arthur/ Orange Golden Triangle…you’ve been later to get into the game. As of 0600AM this morning much of the metro area saw only around 2 inches of rain so far. That will change in a hurry this morning, as training of intense thunderstorms could drop 2-3″ of rain per hour…

Even though surface soils are relatively dry, that much rain so quickly can cause flash flooding…

As I forecast yesterday, the Golden Triangle area could be the bullseye for heaviest rain totals with Imelda….expect very heavy rains and flooding this morning..

Flooding in Galveston on Wed Sep 18 near 45th Street and Avenue O….source Sara Asocar Facebook

5) Be very careful about many of the graphics/ maps and news reports spreading. Many maps plot out the center of circulation- and this implies that the areas near circulation center are most dangerous. This is not true!

The center of circulation is near metro Houston now. I marked it with an “L” (low pressure) on the map. However, the training of intense thunderstorms is offset to the south and east of this circulation center.

I drew arrows where the training of intense thunderstorms are setting up this morning….as you can see it’s offset to south and east of center of circulation.

Be careful not to be deceived by reports that say Imelda has weakened or is “only” a tropical depression. These classifications are based on wind speeds, but our biggest hazard here is heavy rain….it doesn’t matter how “strong” this storm is…if you see training of intense thunderstorms, flash flooding can happen quickly…it doesn’t matter if the storm is a hurricane, tropical storm or tropical depression.

I think the areas with training of intense thunderstorms could start to lift north through the day today, so League City, Friendswood, Kemah, Pasadena and metro Houston may all see training of thunderstorms later today…for now these areas should expect periods of steady rain with some downpours.

Stay safe everybody! Please comment on this post to share any local observations of what you are seeing.I will try to send another update later.

-HH