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

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

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


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 36 - 1

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 — Blog Index



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.
Member Since: Posts: Comments:
Hurricane Easy of 1950:




Hurricane Easy and Dog:

Member Since: Posts: Comments:
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. :)
Member Since: Posts: Comments:
Quoting victoria780:
What are the odds of a Tornado hitting the Democratic Convention?
Far, far less than they are for a hurricane striking the DNC. First, peak tornado season in Charlotte is between March and May, aso that's obviously long past. Second, and more importantly, even the largest tornadoes are seldom wider than a few hundred yards, while a hurricane can cover a few hundred miles, so the chances for a particular building--say, a convention center--being hit a far less. I don't have time to do the math now, but the odds are probably about 1-in-500,000.
Member Since: Posts: Comments:
Daily SOI: -15.1
30 Day SOI: -8.8
90 Day SOI: -7.7
Member Since: Posts: Comments:
It is of note that the convention center requires evacuation in event of a Cat 1. Thanks Doc.
Member Since: Posts: Comments:
Well if a Tornado hits the DNC I hope there aren't any protesters out there.Some of those people probably don't know how to come in from the rain.
Member Since: Posts: Comments:
Thanks Dr. Masters, the SLOSH model is a telling sign that if you live in and around the Tampa Bay area to GET OUT, especially in Pinellas County because all access would be blocked off from bridges being overwashed and the area would be inundated with water, not to mention the Phosphate Plants we have in the Port of Tampa that can cause an environmental disaster.

Tampa Bay Catastrophic Plam: Project Phoenix

Video
Member Since: Posts: Comments:
Thanks Dr Masters...good afternoon everyone!
Member Since: Posts: Comments:
Thanks Dr. Masters
Member Since: Posts: Comments:
Quoting VR46L:
Hmmm interesting blob south of X TD7 and 93l looks as good as it has done for quite a while

Funktop Image


Rainbow Image


That is 93L...

Member Since: Posts: Comments:
Quoting yoboi:
wow the last blog was short....is that a record for the shortest blog time????


I don't think so, probably only when the comments really start to get silly.
Member Since: Posts: Comments:
Very interesting and informative post Dr. Masters - thank you!!
Member Since: Posts: Comments:
Ocean barrier layers - effect on tropical cyclone intensification

Karthik Balagurua,b, Ping Changb,c,d,1, R. Saravananc, L. Ruby Leunga, Zhao Xub,d, Mingkui Lid, and Jen-Shan Hsiehc

Edited by Kerry A. Emanuel, Massachusetts Institute of Technology, Cambridge, MA, and approved July 13, 2012 (received for review January 25, 2012)

Abstract

Improving a tropical cyclone's forecast and mitigating its destructive potential requires knowledge of various environmental factors that influence the cyclone's path and intensity. Herein, using a combination of observations and model simulations, we systematically demonstrate that tropical cyclone intensification is significantly affected by salinity-induced barrier layers, which are "quasi-permanent" features in the upper tropical oceans.

When tropical cyclones pass over regions with barrier layers, the increased stratification and stability within the layer reduce storm-induced vertical mixing and sea surface temperature cooling. This causes an increase in enthalpy flux from the ocean to the atmosphere and, consequently, an intensification of tropical cyclones. On average, the tropical cyclone intensification rate is nearly 50% higher over regions with barrier layers, compared to regions without.

Our finding, which underscores the importance of observing not only the upper-ocean thermal structure but also the salinity structure in deep tropical barrier layer regions, may be a key to more skillful predictions of tropical cyclone intensities through improved ocean state estimates and simulations of barrier layer processes.

Link

As the hydrological cycle responds to global warming, any associated changes in the barrier layer distribution must be considered in projecting future tropical cyclone activity.
Member Since: Posts: Comments:
Quoting victoria780:
What are the odds of a Tornado hitting the Democratic Convention?


fair is fair..I would be interested to know as well..would be slim but there is always a chance..
Member Since: December 31, 1969 Posts: Comments:
I am not sure if the 1921 hurricane season is an anlaog season for this hurricane season. reason I say that is because if it is, then possibly similar tracks from 1921 could be present this season. maybe I am thinking too much...sorry
Member Since: Posts: Comments:
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...)
Member Since: Posts: Comments:
Hmmm interesting blob south of X TD7 and 93l looks as good as it has done for quite a while

Funktop Image


Rainbow Image
Member Since: Posts: Comments:
Thanks Dr. Great history and stats. Only statement you might want to mull over is the following; . 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.

That is great long-term advice but, neither does Florida or the Feds have the funds for a project of this magnitude. Arguably, it "might" happen after such a catastrophe, as we saw with some of the rebuilding of the walls around New Orleans, but preventive measures of this size are not going to be on the front burner anytime soon. Further, given the historical trend for Tampa, I would think that cites more prone to shorter return periods on major hurricanes would get first dibs on funds for these type of projects based on what happens in the future (whether from obvious sea level rises or following a catastrophic hurricane event).
Member Since: Posts: Comments:
oh boy.......
Quoting victoria780:
What are the odds of a Tornado hitting the Democratic Convention?
Member Since: Posts: Comments:
That was cosmic. CosmicE
Member Since: Posts: Comments:
Would be cool to have Gordon,Helene,Isaac and Joyce for this month and it looks that 3 of them are going to be cape verde base on the gfs.
Member Since: Posts: Comments:
What are the odds of a Tornado hitting the Democratic Convention?
Member Since: Posts: Comments:
Thanks DRM.
Member Since: Posts: Comments:
Nice! Like the historical context.....thanks!
Member Since: Posts: Comments:
Thanks Doc.
Looks like my 500/1 odds were spot on.
Member Since: Posts: Comments:
good news that nothing bad is supposed to happen. I could not imagine a storm of this size especially right now.
Member Since: Posts: Comments:
Thanks Doc.Calm down with the blogs XD.Been spitt'in them out like crazy.
Member Since: December 31, 1969 Posts: Comments:
SO BIASED! jk, thanks Dr. Masters for a great history lesson.
Member Since: Posts: Comments:
that was a short season!
Member Since: Posts: Comments:


Link

Member Since: Posts: Comments:
thanks doc ! nice blow up in caribiean
Member Since: Posts: Comments:

Viewing: 36 - 1

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 — Blog Index

Top of Page

Category 6™

About

Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather