Monday, September 6, 2010

Looking back at Tropical Storm Arlene



In June 1993, a tropical depression formed in the Bay of Campeche. This depression tracked northwest, then developed into Tropical Storm Arlene off the South Texas Coast, before making landfall in South Texas, between South Padre Island and Corpus Christi. This image, provided by Unisys Corporation, shows the track of this system as a depression (green) and as a tropical storm (yellow).

Arlene was a minimal tropical storm, generating maximum winds of 40 MPH. However, because this system moved very slowly in the 18 hours before landfall, it was still able to generate some noticeable storm surge. The SCIPP program identified a maximum storm surge of 4 feet in South/ Central Texas in association with Arlene.

Tropical storms Hermine and Arlene have several similarities and differences in relation to storm surge potential. Hermine developed into a tropical storm farther off the coast, likely enabling it to push more water than Arlene. Hermine's winds should also be stronger; the National Hurricane Center forecasts a most likely intensity of 58 MPH before landfall, whereas Arelene's winds never topped 40 MPH. These factors would lead one to expect a higher surge from Hermine.

However, Hermine is moving faster than Arlene, as the current forward speed is 10 MPH and the National Hurricane Center forecasts that Hermine should pick up forward speed today. Generally, faster moving tropical cyclones generate lower surges, so in this regard, Tropical Storm Arlene had a more favorable storm surge setup. Also, it is most likely that Hermine will make landfall in Northern Mexico, which would likely reduce the U.S. surge levels.

As all of these factors are taken into consideration, we might expect Hermine to produce a similar peak U.S. storm surge as Arlene- around 4 feet, if Hermine makes landfall in Texas. If Hermine makes landfall in Mexico, peak U.S. surges should be lower, perhaps between 2-4 feet.

Stay tuned to the 2010 Storm Surge Blog for updates twice daily until landfall. After landfall look for possible observation updates, which may include tide gage graphs and photos.

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