{"id":2610,"date":"2020-05-30T18:40:35","date_gmt":"2020-05-30T23:40:35","guid":{"rendered":"http:\/\/oceanweatherservices.com\/blog\/?p=2610"},"modified":"2020-07-11T15:00:36","modified_gmt":"2020-07-11T20:00:36","slug":"tampa-bay-hurricane-storm-surge","status":"publish","type":"post","link":"https:\/\/oceanweatherservices.com\/blog\/2020\/05\/30\/tampa-bay-hurricane-storm-surge\/","title":{"rendered":"Tampa Bay Hurricane Storm Surge Scenarios"},"content":{"rendered":"
\"\"<\/a>

Hurricane Isaac Storm Surge along the Gulf Coast. Image Credit NOAA<\/p><\/div>\n

The 2020 hurricane season is off to an early start so it is not too early to prepare for the possibility of the Tampa Bay area experiencing a direct hurricane hit. Tampa has experienced strong storm surges in the past and the question is when will it happen again?<\/span><\/p>\n

Will History Repeat?\u00a0<\/strong><\/h3>\n

Since Tampa was a small town associated with a <\/span>US Army post, Fort Brooke<\/b><\/a> in the 1820s, there have been only two major hurricanes that directly impacted the Tampa Bay area with high winds and storm surges.\u00a0 <\/span>The highest reported storm tide in Tampa Bay occurred in September of 1848 during the \u201c<\/span>Great Tampa Gale<\/b><\/a>\u201d when the tide was reported to have been 15 feet above low tide or about 12.75 feet above MHHW.\u00a0 During the <\/span>October Hurricane of 1921<\/b><\/a> the tide was reported to have reached 10.5 feet above low water or about 8.25 feet above MHHW.\u00a0 Both of these storms were category 3 hurricanes and so far, Tampa Bay has escaped a direct hit from any category 4 or 5 storms. \u00a0 Hurricane Elena,\u00a0 in August of 1985, although not directly hitting Tampa Bay, did create a storm surge that was 4.0 feet above Mean Higher High Water (MHHW) or 6.26 feet above Mean Lower Low Water (MLLW) as Elena hovered offshore over the Gulf of Mexico to the northwest of Tampa Bay.\u00a0<\/span><\/p>\n

Although these catestrophic events are rare, they can and will happen again.\u00a0 I would estimate that there is a 1-2% risk for a major hurricane impacting the Tampa Bay area in any given year and the question is will it be this year?\u00a0 Even though there has never been a Category 4 or 5 hurricane to directly hit Tampa Bay, it is not impossible and the devastation would be extreme.<\/span><\/p>\n

Storm Surge Simulations<\/strong><\/h2>\n

In the paper:\u00a0\u00a0Hurricane Storm Surge Simulations for Tampa Bay (1)<\/i><\/b>, <\/i>authors<\/span> Robert H. Weisberg and Lianyuan Zheng\u00a0\u00a0<\/span>took a close look at the flooding potential caused by wind stress and atmospheric pressure induced storm surge for a category 2 hurricane and for a catastrophic category 4 hurricane where storm surges of 4-6 meters (13-20 ft) are likely. The paper describes 11 different scenarios with 8 different tracks.\u00a0 Storm tracks E1, E2, E3, and E4 are for eastward moving hurricanes making landfall at Indian Rocks Beach, Sarasota, Tampa Bay mouth, and Tarpon Springs, respectively. Tracks D2, D3, D4, and D5 are for hurricanes paralleling the axis of the bay or paralleling the coastline from the northwest or the southeast, respectively.<\/span><\/p>\n

\"Storm<\/a>

Proposed Hurricane Track Scenarios Image: (Weisberg and Zheng (1))<\/span><\/p><\/div>\n

Most people believe that a hurricane moving northeastward directly up Tampa Bay would be the <\/span>\u201cworst case scenario\u201d<\/i><\/b>, however, this is not the case. The paper, in fact, shows that a storm transiting up the bay axis from southwest to northeast actually results in the smallest surge!<\/span>\u00a0\u00a0<\/span><\/p>\n

\"\"<\/a>

Storm Surge (meters) associated with a category 2 storm moving up the axis of Tampa Bay.\u00a0 Image: (Weisberg and Zheng (1))<\/span><\/p><\/div>\n

While no storm scenario is a good one for the Tampa Bay area, the worst case is when the hurricane center is located north of the Tampa Bay entrance such that the maximum winds associated with the eye wall occur at the mouth of the bay with storms making landfall farther north result in lower surges.\u00a0 Storms that make landfall to the south of the bay tend to reduce storm surge along Pinellas County beaches, although localized surges can still occur within the bay.\u00a0\u00a0<\/span><\/p>\n

Storm surge is also sensitive to the direction that storms approach the bay.\u00a0 Storms that approach from the south produce lower surges than those approaching from the north. The speed at which the hurricane approaches is also important.\u00a0 If a storm moves fast enough, the surge may not have enough time to reach the full storm surge potential.\u00a0 Wind speed is also key as surge height tends to increase with the square of the wind speed.\u00a0 A category 2 storm might produce limited flooding, while the flooding potential for a category 4 storm could be \u201ccatastrophic\u201d.\u00a0<\/span><\/p>\n

Additional factors in surge development include the effects of tides, rivers, and waves. Tide\u00a0<\/span>ranges for Tampa Bay tend to be small (0.5 m to 1 m) when compared to the surge potential by winds and pressure. Flooding by heavy rains can be locally important with additional inundation and damage caused by waves.\u00a0\u00a0<\/span><\/p>\n

Below is the storm surge expected by a Category 2 hurricane, approaching from the west at 5 m\/s (10 knots)\u00a0 and making landfall at Indian Rocks Beach. The asterisk denotes the landfall location while the filled circles show the storm center. The bold lines are surge elevation contours at 1-m intervals.<\/span><\/p>\n

\"Cat<\/a>

Storm surge expected by a Category 2 hurricane making landfall at Indian Rocks Beach\u00a0 Image: (Weisberg & Zheng (1))<\/span><\/p><\/div>\n

\u00a0<\/span><\/p>\n

Cat. 4 Hurricane Scenari0<\/strong><\/h3>\n

Below is the storm surge associated with a Cat 4 hurricane making landfall at Indian Rocks Beach. The asterisk denotes the landfall location while the filled circles show the storm center. The bold lines are surge elevation contours at 1-m intervals.<\/span><\/p>\n

\"Cat.<\/a>

Storm surge associated with a Cat 4 hurricane making landfall at Indian Rocks Beach\u00a0 Image: (Weisberg & Zheng (1))<\/span><\/p><\/div>\n

How do Waves add to Storm Surge?<\/strong><\/h3>\n

During hurricanes Ivan in 2004 (Alabama) and Katrina in 2005 <\/span>(<\/span>SE <\/span>Louisiana<\/span> and <\/span>Mississippi<\/span>) <\/span>heavy waves combined with storm surge destroyed sections of bri<\/span>dges. The contributions of the waves to the storm surge and the increased water elevation by storm surge to the waves was described in another paper:\u00a0<\/span>Coupling of surge and waves for an Ivan\u2010like hurricane impacting <\/i><\/b>the Tampa Bay, Florida region (2)<\/i><\/b><\/p>\n

The paper describes the important\u00a0 interaction between waves and storm surge in shoaling water where the surge height will be elevated by the wave\u2010induced forces and where changes in water level by storm surge will greatly impact the wave field. It was found that storm surge is increased by wave stress by 0.3\u20130.5 m.\u00a0 In addition, the greatest surge enhancement by waves occurs in advance of the actual peak in the storm surge because the wave speed exceeds the storm speed of advance.\u00a0<\/span><\/p>\n

On the other hand, there is also an effect of storm surge on waves. The <\/span>Significant Wave Height<\/b> <\/a>\u00a0(the average of the \u2153 highest waves) can increase with surge elevation by about a 1.0\u20131.5 m and hence perhaps as much as a 2\u20133 m increase in the maximum wave height.\u00a0 Such enhancement of waves for a major hurricane could be sufficient to initiate large\u2010scale damage within the Tampa Bay region prior to the onset of hurricane strength winds. About 3 hours prior to landfall, both the inundation and the significant wave heights would be high enough to begin causing massive damage to low-lying buildings that are open water exposure.\u00a0<\/span><\/p>\n

How Vulnerable is Tampa Bay?<\/strong><\/h3>\n

Particularly vulnerable would be the northeast section of St. Petersburg and the northern sections of Old Tampa Bay, including the Courtney Campbell Causeway, the Howard\u00a0<\/span>Frankland Bridge, and the Gandy Bridge. As the storm makes landfall, the situation worsens\u00a0<\/span>as the inundation continues to increase along with the significant wave heights, even until the\u00a0 center passes Tampa Bay.\u00a0<\/span><\/p>\n

Therefore, it is not only the wind speed (<\/span>Saffir\u2010Simpson category<\/b><\/a>) that matters, rather it is the complex mix of wind, tide, surge and waves that combine to cause major destruction. The entire coastline of Tampa Bay with low elevation and open to water exposure is susceptible to such damage. The eastern shore of Tampa Bay is at risk, even after the storm center passes beyond the Bay since the bay would already be filled with storm surge water and waves which would then shift direction to attack the eastern shore.\u00a0\u00a0<\/span><\/p>\n

It is also very likely that the wave forces acting vertically beneath bridge spans would destroy spans of the Courtney Campbell Causeway, the Howard Frankland Bridge, and the Gandy Bridge that are closest to the water. McDill Air Force Base and Tampa International Airport would be damaged along with Tampa General Hospital, as well as some other critical areas of infrastructure.\u00a0<\/span><\/p>\n

References:<\/strong><\/h4>\n
    \n
  1. Weisberg, R.H., Zheng, L. Hurricane storm surge simulations for Tampa Bay.\u00a0Estuaries and Coasts: J ERF<\/i>\u00a029,\u00a0<\/b>899\u2013913 (2006).
    \n    https:\/\/www.researchgate.net\/publication\/226176569_Hurricane_storm_surge_simulation_for_Tampa_Bay<\/a><\/li>\n
  2. Huang, Yong & Weisberg, Robert & Zheng, Lianyuan. (2010). Coupling of surge and waves for an Ivan\u2010like hurricane impacting the Tampa Bay, Florida region. J. Geophys. Res. 115. 0.1029\/2009JC006090.
    \n    https:\/\/www.researchgate.net\/publication\/228973196_Coupling_of_surge_and_waves_for_an_Ivan-like_hurricane_impacting_the_Tampa_Bay_Florida_region<\/a><\/li>\n<\/ol>\n

    Other Links:<\/strong><\/h4>\n

    Hurricane Storm Surge Simulations for Florida\u2019s Tampa Bay Region\u00a0 \u00a0<\/span>http:\/\/ocgweb.marine.usf.edu\/Posters\/TBHurricane.pdf<\/span><\/a><\/p>\n

    Mariner\u2019s Wave Guide\u00a0 <\/span>http:\/\/oceanweatherservices.com\/featured_blog_posts\/a_mariners_guide_to_waves<\/span><\/a>Storm<\/p>\n

    Surge Overview, NHC:
    \n    https:\/\/www.nhc.noaa.gov\/surge<\/a><\/p>\n

    NOAA Blog Inside the Eye
    \n    Storm Surge–Plain and Simple (Part 1)<\/a><\/p>\n

    Ocean Weather Services
    \n    http:\/\/www.oceanweatherservices.com<\/a><\/p>\n

     <\/p>\n

     <\/p>\n","protected":false},"excerpt":{"rendered":"

    While no storm scenario is a good one for the Tampa Bay area, the worst case is when the hurricane center is located north of the Tampa Bay entrance such that the maximum winds associated with the eye wall occur at the mouth of the bay with storms making landfall farther north result in lower surges. Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[73,4,152,158,10,15,102],"tags":[157,41,18,27,80,155,66,65,111],"_links":{"self":[{"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/posts\/2610"}],"collection":[{"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/comments?post=2610"}],"version-history":[{"count":29,"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/posts\/2610\/revisions"}],"predecessor-version":[{"id":2652,"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/posts\/2610\/revisions\/2652"}],"wp:attachment":[{"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/media?parent=2610"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/categories?post=2610"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/oceanweatherservices.com\/blog\/wp-json\/wp\/v2\/tags?post=2610"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}