The odds of a hurricane spoiling the Republican National Convention in Tampa

By: Dr. Jeff Masters , 4:48 PM GMT on August 14, 2012

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On September 25, 1848, the Great Gale of 1848, the most violent hurricane in Tampa's history, roared ashore as a Category 3 or 4 hurricane with 115 - 135 mph winds. Major R. D. S. Wade weathered the storm in Fort Brooke, in what is now downtown Tampa. Here is what he wrote this to his commanding officer in Washington D.C.: "The waters rose to an unprecedented height, and the waves swept away the wharves and all the buildings that were near the Bay or river." A 15-foot storm surge was observed at Fort Brooke, and the peninsula where St. Petersburg lies in Pinellas County was inundated "at the waist" and "the bays met," making St. Petersburg an island. After the hurricane, "Tampa was a scene of devastation. Magnificent old oaks were toppled by the hurricane's winds. At Fort Brooke the barracks, horse shed, and other structures were gone. The pine forest north of the garrison was filled with wreckage and debris. The hurricane's powerful surge had shifted sand all along the coast and reshaped many of the keys near Tampa Bay. Navigation routes were filled in and closed, making charts of the area produced before 1848 almost useless after the hurricane. In terms of intensity and destruction, the 1848 storm remains perhaps the greatest in Tampa's history" (Barnes, 1999.)


Figure 1. Pencil sketch of the Captains' Quarters, drawn by one of the officers stationed at Fort Brooke in 1845. Fort Brooke was one of the largest military establishments in the United States at the time. Image Credit: The Tampa Bay History Center.

Fort Brooke today
Fort Brooke is the current site of the Tampa Bay Convention Center, which hosts the Republican National Convention on August 27 - 30 this year. The convention center is in Evacuation Zone A, which is evacuated for Category 1 hurricanes. The Tampa Bay Times Forum and two major convention hotels--the Tampa Marriott Waterside and the Embassy Suites--are in Evacuation Zone B, which is evacuated for Category 2 hurricanes. In a worst-case Category 4 hurricane, the Convention Center could be immersed in 20 feet of water. Clearly, even a Category 1 hurricane would be enough to spoil the convention. So, what are the odds of a mass evacuation order being issued for Tampa Bay during the convention?


Figure 2. Predicted height above ground of the water from a worst-case Category 4 hurricane in the Tampa Bay region, as computed using NOAA's SLOSH storm surge model. The Tampa Bay convention center would go under 20 feet of water, and St. Petersburg would become an island, as occurred during the 1848 hurricane.


Figure 3. Perhaps the most spectacular hurricane image ever captured: view of Hurricane Elena on September 1, 1985, as seen from the Space Shuttle Discovery. At the time, Elena was a Category 3 hurricane with 125 mph winds, located just 80 miles offshore from Tampa Bay, Florida. The hurricane prompted the largest mass evacuation in Tampa Bay history.

Two mass evacuations in Tampa in the past 25 years
Two hurricanes have prompted mass evacuations of more than 300,000 people from the Tampa Bay area over the past 25 years. The first was Hurricane Elena of 1985, a Category 3 hurricane that stalled 80 miles offshore for two days on Labor Day weekend, bringing a 6 - 7 foot storm surge, wind gusts of 80 mph, and torrential rains. On August 13, 2004, another mass evacuation was ordered for Hurricane Charley. Thanks to a late track shift, Charley missed Tampa Bay, and instead hit well to the south in Port Charlotte as a Category 4 storm with 150 mph winds. More limited evacuations of low-lying areas and mobile homes in the 4-county Tampa Bay region were ordered for three other hurricanes in the past fifteen years--Hurricane Georges of 1998, Hurricane Frances of 2004, and Hurricane Jeanne of 2004. Other historical storms which would likely trigger mass evacuations were they occur today include:

The 1921 hurricane. One of only two major hurricanes to hit Tampa, this Category 3 storm brought a storm tide of 10.5 feet.

Hurricane Easy of 1950. The hurricane parked itself over the west coast of Florida, drenching residents with record-breaking rains, and brought a 6.5 ft storm surge to Tampa Bay.


Figure 4. Damage to Bayshore Boulevard after the 1921 Tampa Bay hurricane. The road leads to the Tampa Bay Convention Center from the south.


Figure 5. Track of the Tampa Bay Hurricane of 1921, one of only two major hurricanes ever to hit the city. This Category 3 storm with 115 mph winds brought a storm tide of 10.5 feet to Tampa Bay.


Figure 6. A near miss: just a slight deviation in the path of Hurricane Charley of 2004 would have brought the Category 4 hurricane into Tampa Bay.

Tampa Bay's vulnerability to hurricanes
Tampa Bay doesn't get hit very often by hurricanes. The last time it suffered a direct hit by any hurricane was 1946, when a Category 1 storm came up through the bay. The Tampa Bay Hurricane of October 25, 1921 was a the last major hurricane to make landfall in the Tampa Bay Region. At that time, there were 160,000 residents in the 4-county region, most of whom lived in communities on high ground. Today there are 2.75 million residents in the region, most of whom live along the coast and low-lying areas or in manufactured housing. About 1/3 of the 4-county Tampa Bay region lies within a flood plain. Over 800,000 people live in evacuation zones for a Category 1 hurricane, and 2 million people live in evacuation zones for a Category 5 hurricane, according to the 2010 Statewide Regional Evacuation Study for the Tampa Bay Region. Given that only 46% of the people in the evacuation zones for a Category 1 hurricane evacuated when Category 4 Hurricane Charley threatened the region, the potential for hundreds or thousands of people to die when the next major hurricane hits the region is high. In the long run, I expect a multi-billion dollar sea wall will be built to protect Tampa Bay from storm surges, since sea level rise will make storm surge damages increasingly problematic. A 2007 study by Tufts University titled, Florida and Climate Change, found that a 2.25 foot increase in sea level--which many sea level rise scientists expect will happen by the end of the century--would put 152,000 people in Pinellas County (where St. Petersburg is located) at risk of inundation.

The hurricane forecast for the Republican National Convention
Given that there have been two mass evacuations of Tampa during the past 25 years during the peak three-month period of hurricane season--August, September, and October--history suggests that the odds of a mass evacuation order being given during the 4-day period that the Republican National Convention is in town are probably around 0.2%. Any tropical waves which might develop into hurricanes that could hit Tampa during the convention would have to come off the coast of Africa next week. Looking at the latest 16-day forecast from the GFS, all of the tropical waves coming off of Africa next week are predicted to exit too far north to make the long crossing of the Atlantic and threaten the Gulf Coast. While something could develop in the Gulf of Mexico from the remains of an old cold front, it is rare for such storms to grow strong enough to deserve mass evacuations. So far, early signs point to a hurricane-free Republican National Convention at the end of August.

References
Barnes, J., 1999, Florida’s Hurricane History. The University of North Carolina Press.

Weisberg, R.H, and L. Zheng, 2006, "Hurricane storm surge simulations for Tampa Bay", Estuaries and Coasts Vol 29, No. 6A, pp 899-913.

History of Pasco County: The 1921 Hurricane

The 2010 Statewide Regional Evacuation Study for the Tampa Bay Region

The Tampa Bay Catastrophic Plan for a Category 5 $250 billion hurricane

Jeff Masters

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Quoting kwgirl:
Imagine that. While I was working, Dr. M was working on the answer to the question he posed concerning Tampa, a hurricane and the RNC. So I go into the previous blog to check it out, put some person on ignore and I come back with this. So I am torn. Do I stay here or go back to the old one to read up. I might have to put more people on ignore if I do that LOL!



aha, so glad i saw this comment when i came on...

there is no point to just ignoring people like that....i really dont see the point.
Member Since: February 11, 2012 Posts: 0 Comments: 9731
.........................hmmmm wonder if any of these coming off africa would build up in the caribbean?, just something to watch for now
Member Since: August 6, 2011 Posts: 4 Comments: 39144
Member Since: August 6, 2011 Posts: 4 Comments: 39144
Quoting kwgirl:
Imagine that. While I was working, Dr. M was working on the answer to the question he posed concerning Tampa, a hurricane and the RNC. So I go into the previous blog to check it out, put some person on ignore and I come back with this. So I am torn. Do I stay here or go back to the old one to read up. I might have to put more people on ignore if I do that LOL!


Why do you think anyone would care if you put them on ignore?
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LOL
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Member Since: August 6, 2011 Posts: 4 Comments: 39144
Quoting shfr173:
If anything was to develop in the carribean, any chance of it getting pulled up in gulf? With trough setting up there?
..as of right now there is still a high sitting in the gulf..but we'll see a week from now
Member Since: August 6, 2011 Posts: 4 Comments: 39144
Been doing research about hurricanes in Baldwin County in
Alabama. Two storms hit this area in 1916. Would it be possible to discover whether this would have occurred during an elnino, lanina,or neutral conditions?
Thanks
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Quoting ILwthrfan:
93L may not be a fish. Models want to crank it up to 83 knots. I am not buying that, but it could pose a problem for the Azores Islands I wouldn't say it is a guaranteed fish storm.

..93L is a british isles worry, not ours, the high out there is too strong for it to keep going west towards the USA
Member Since: August 6, 2011 Posts: 4 Comments: 39144
Quoting Neapolitan:
So at best there's only a 1-in-500 chance that there'll be a mass evacuation order given in Tampa during the 4-day duration of the convention. Not bad. Weather-wise, then, the bigger concern would seem to be the inundation by tens of thousands of people unfamiliar with Florida's midsummer heat, humidity, and lightning. (Of course, there are many other dangers lurking in Tampa for careless conventioneers, but they have nothing whatsoever to do with the climate there...)
Leave it to you Nea to point out that the holier-than-thou people have faults like everyone else. They just have more money to spend!
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Well, I hope that any storm crossing the Everglades doesn't cause something like this guy to pay a visit to my town. Yikes...I'll take the alligators every time.
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If anything was to develop in the carribean, any chance of it getting pulled up in gulf? With trough setting up there?
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Quoting Waltanater:
With or without hook?
Without hook, looks generally heading west.
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..hmmmm Nam has something off the northern gulf coast in the 5 day outlook
Member Since: August 6, 2011 Posts: 4 Comments: 39144
Quoting kshipre1:
.02 is two hundreths


Yeah, I know. I already changed it. Thanks :p
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93L may not be a fish. Models want to crank it up to 83 knots. I am not buying that, but it could pose a problem for the Azores Islands I wouldn't say it is a guaranteed fish storm.

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Quoting WxGeekVA:


93L is producing organized convection, and banding is becoming apparent on most sides. Also, latest RGB suggests that there is a closed LLCOC in the middle of the convective area. If the convection can keep up, we may well be looking at a TD later today, and at the very least an upgrade to code red on the TWO at 2:00.

Convection has waned, a little though...
NHC will go with 50%
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Imagine that. While I was working, Dr. M was working on the answer to the question he posed concerning Tampa, a hurricane and the RNC. So I go into the previous blog to check it out, put some person on ignore and I come back with this. So I am torn. Do I stay here or go back to the old one to read up. I might have to put more people on ignore if I do that LOL!
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.02 is two hundreths
Quoting VAbeachhurricanes:


.2% is two hundredths. If he just would have said .2 without the percentage sign then it would be 20%.
Member Since: July 12, 2010 Posts: 0 Comments: 1130
Quoting GTcooliebai:
GFS Loop and Joyce comes rolling off of Africa like a bowling ball in the long range.
With or without hook?
Member Since: May 16, 2010 Posts: 0 Comments: 1472
the Doc has opened Pandora's box..I will be back later as its getting ugly in here..LOL
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting sar2401:
Doc, is that 0.2%, as in 20%, or 2 hundreths of one percent. I'm math challenged. Thanks for getting the new blog up so quickly. Things were getting up to about a cat 3 on the earlier blog. :)
.2 would be 20%; .02 is 2% so .2% is less than 1%
Member Since: May 16, 2010 Posts: 0 Comments: 1472
Quoting ncstorm:
Interesting day for the Eastern US..





Gahh, not again. Have had enough of severe weather to last a whole year here in Richmond.
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60. bio4
Seeing as how the largest representation of climate change deniers are from the Republican camp, they should be the last to be evacuated from the Tampa area in the event of a hit by a major hurricane.
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Quoting WxGeekVA:


That is 93L...



What the heck, ya know the NHC may just upgrade this to TD status. Will be fun to track this one as it will be a fishy ;).
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XX/AOI/XX
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Quoting StormHype:
To be fair, what are the odds of a major cane affecting DC? Does Obama know how to swim?
Thx.
What are the odds he will be in HI during that time?
Member Since: May 16, 2010 Posts: 0 Comments: 1472
Quoting ChaseyChasinStorms:
Good afternoon all. Well I guess the Farmer's Almanac was wrong afterall about a storm hitting the Gulf Coast August 15-20.........



figured that a while back
Member Since: February 11, 2012 Posts: 0 Comments: 9731
I'm betting the Doc will do a hurricane blog for the DNC he's just that kind of guy fair and balanced. He reports you decide. I'm just wondering how he is going to put a pro liberal spin on it, can't wait. Like I predicted this morning 93l goes code Red, 70% I say.
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GFS Loop and Joyce comes rolling off of Africa like a bowling ball in the long range.
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Quoting CosmicEvents:
Thanks Doc.
Looks like my 500/1 odds were spot on.
Too low!
Member Since: May 16, 2010 Posts: 0 Comments: 1472
Good afternoon all. Well I guess the Farmer's Almanac was wrong afterall about a storm hitting the Gulf Coast August 15-20.........
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Interesting day for the Eastern US..



Member Since: August 19, 2006 Posts: 13 Comments: 15666
Looks like another entity in SW Caribbean might be merging with ex TD7

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1.6% - 3.2% chance of a hurricane forcing an evacuation in Tampa during that time.
Member Since: May 16, 2010 Posts: 0 Comments: 1472
Thanks Jeff. LOL!! If there was any doubt about intent, it's gone now...
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Quoting VAbeachhurricanes:


.2% is two hundredths. If he just would have said .2 without the percentage sign then it would be 20%.


Thanks, VA. Like I said, I'm amth challenged. :) BTW, what's the deal with that quasi-stationary blob of the lower east coast of the US? That thing has been there about a week.
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XX/INV/93L
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Quoting WxGeekVA:


That is 93L...



So what is that in the centre of the atlantic





Umm unless I am Mistaken is that not 93L as well oh well if I am wrong I am cool with it
Member Since: March 1, 2012 Posts: 0 Comments: 6927
12z CMC out to 144 hours..Mexico and Africa

Member Since: August 19, 2006 Posts: 13 Comments: 15666
Thanks Dr. Master

Cos, you sure called it! Way to Go!
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12z Nogaps at hour 156
Member Since: August 19, 2006 Posts: 13 Comments: 15666
Quoting sar2401:
Doc, is that 0.2%, as in 20%, or 2 hundreths of one percent. I'm math challenged. Thanks for getting the new blog up so quickly. Things were getting up to about a cat 3 on the earlier blog. :)


.2% is two tenths. If he just would have said .2 without the percentage sign then it would be 20%.
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Quoting stormchaser19:



How certain is Modiki Nino, because we have 2004 year but which others years were modiki apart of 2004?


Other years that where a 'Modoki' El Nino was to my memory only 2002 during peak hurricane season.
Member Since: July 8, 2005 Posts: 259 Comments: 24169
Quoting StormHype:


The local news was talking about 300-500 visiting protesters that may be clueless regarding the affects of dehydration in the Florida August heat.. I believe a water canon can help with hydration quite effectively in this situation w/o much cost to the city of Tampa.
Yeah, because why not violently brutalize people peacefully exercising their First Amendment rights?
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Thanks, Doc. I was just going to post that! :)
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93L is producing organized convection, and banding is becoming apparent on most sides. Also, latest RGB suggests that there is a closed LLCOC in the middle of the convective area. If the convection can keep up, we may well be looking at a TD later today, and at the very least an upgrade to code red on the TWO at 2:00.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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