Gordon became a category one hurricane on the Saffir-Simpson Hurricane Scale over the eastern Gulf of Mexico, but eventually made landfall in the Florida Big Bend area as a weakening tropical storm.
a. Synoptic History
A tropical wave moved off the west coast of Africa on 4 September and tracked westward across the tropical Atlantic. Little or no deep convection was associated with the wave until 8 September when the wave was located about 600 n mi east of the Lesser Antilles. The tropical wave moved through those islands on 9-10 September bringing locally heavy rainfall and wind gusts of 25 to 30 kt. The wave tracked west-northwestward and developed centralized convection near the vorticity center over the central Caribbean Sea on the 12th.
Satellite classifications from the Tropical Analysis and Forecast Branch (TAFB) and the Satellite Analysis Branch (SAB) began around 0000 UTC 13 September. They indicated the convection was poorly organized. However, by 1800 UTC surface observations indicated a broad low pressure area had developed along the wave axis about 100 n mi southeast of Cozumel, Mexico. At 0000 UTC 14 September, Dvorak satellite intensity estimates from the TAFB, SAB, and the Air Force Weather Agency (AFWA) suggested the broad low pressure system was near tropical depression strength, but the overall convective pattern was still poorly organized.
Tropical Depression Eleven formed about midway between Cozumel and Chetumal, Mexico on the morning of 14 September based on a U. S. Air Force Reserve (USAFR) reconnaissance aircraft report of a broad closed circulation and 31 kt flight-level (1500 ft) winds. By 2100 UTC, the depression's low-level center had moved inland over the eastern Yucatan Peninsula, while the more pronounced mid-level circulation was located about 10 n mi to the northeast. This decoupled pattern persisted for more than 24 hours while the depression tracked slowly northwestward across the northern Yucatan Peninsula.
Late on 15 September, an Air Force Reserve reconnaissance aircraft indicated the depression had moved off the north coast of the Yucatan and over the warm waters of the Gulf of Mexico. Aircrew reported the low- and mid-level circulations had become vertically aligned, 59 kt flight-level (1500 ft) winds, and a minimum pressure of 1003 mb. At 0000 UTC 16 September, the depression had strengthened into Tropical Storm Gordon. Once over the warm Gulf waters, Gordon moved steadily northeastward toward the Florida Big Bend area and slowly intensified. A report of easterly winds of 64 kt from ship MYMX5 located about 30 n mi northeast of the center indicated that Gordon had become a hurricane by 0000 UTC 17 September. Only slight strengthening continued for another 6 hours and Gordon eventually peaked at 70 kt. Figure 1 is a NEXRAD/WSR-88D radar image at 0803 UTC 17 September, from Tampa Bay, Florida (KTBW) when Gordon was near its peak strength.
After peaking on the 17th about 165 n mi southwest of Tampa, Florida, slow weakening began as moderate southwesterly upper-level winds ahead of an approaching mid-tropospheric trough began to increase the vertical shear across the hurricane. Water vapor imagery and surrounding upper-air data indicated that mid-level dry air entrainment from the south also helped the weakening process. The dry air helped erode the outer cloud and precipitation shield and gradually wrapped into the inner core of the hurricane. This is depicted in Figure 1 by the large rain-free or "dry slot" area located in the eastern semicircle between the eye and the outer convective bands near the Florida west coast. Within a few hours, the dry slot had worked its way counter-clockwise completely around the eye and by 1328 UTC reconnaissance reports indicated the minimum surface pressure had risen sharply to 990 mb.
Gordon was downgraded to a tropical storm at 1800 UTC 17 September. It continued to track northeastward and eventually made landfall just northwest of Cedar Key, Florida, at 0300 UTC 18 September, as a tropical storm with 55 kt winds. After landfall, interaction with land and cool, stable air north of a weak frontal boundary hastened the weakening process. At 1200 UTC the same day, Gordon weakened into a tropical depression. By 1800 UTC, it merged with the front and extratropical transition occurred over southeast Georgia. Gordon's remnant low-level circulation then moved northeastward up the east coast of the United States for the next 3 days before being absorbed by a large extratropical low pressure system over eastern Canada around 1200 UTC 21 September. Owing to the lack of any significant baroclinic effects, only modest rainfall totals and no significant flooding were observed over the mid-Atlantic and northeast regions of the United States.
b. Meteorological Statistics
Table 1 lists the best track positions and intensities of Gordon at six-hour intervals. Figure 2 is a display of this track. Observations in Gordon (Figure 3 and Figure 4) include satellite-based Dvorak technique intensity estimates from TAFB, SAB, and AFWA. In addition, flight-level observations were available from flights of the USAFR 53rd Weather Reconnaissance Squadron and the NOAA Aircraft Operations Center.
As a result of Gordon weakening well offshore the Florida west coast, only a few reports of tropical storm force winds were received. Table 2 and Table 3 consist of all ship and buoy reports, respectively, of tropical storm force winds (> 34 kt) associated with Hurricane Gordon. Table 4 consists of selected surface reports from Automated Surface Observing System (ASOS) and Coastal-Marine Automated Network (C-MAN) observation stations from Florida for Hurricane Gordon.
During Gordon's intensification stage, the maximum reconnaissance flight level (850 mb) wind measured was 89 kt (71 kt surface wind using an adjustment factor of 80%) at 0544 UTC 17 September, whereas the minimum surface pressure of 981 mb was observed at 0805 UTC -- 11 mb lower than the pressure when the maximum wind was observed.
Dry air entrainment further reduced the amount of rainfall that typically occurs with a land falling tropical cyclone moving at a forward speed of 10 to 12 kt. The largest rainfall amounts were reported in Florida and ranged from 4.83 in at Cedar Key on the west coast to 3.02 in at Vero Beach on the east coast. No significant flooding was reported.
Gordon's weakened state also reduced the amount of storm surge flooding that otherwise could have occurred. Maximum storm tides (i.e., water height above National Geodetic Vertical Datum [1929 mean sea level]) occurred along the Florida west coast and generally ranged from 3 to 5 ft from the Tampa Bay area northward to Cedar Key.
c. Forecast and Warning Critique
There are no error statistics available at 72 h due to the short time period that Gordon existed as a tropical storm or hurricane. Average official track errors for Gordon (with the number of cases in parentheses) were 32 (8), 37 (6), 40 (4), and 75 (2) n mi for the 12, 24, 36, and 48 h forecasts, respectively. These errors are significantly lower than the average official track errors for the 10-yr period 1990-1999 (46, 85, 122, and 158 n mi, respectively) at all times. The official forecast errors were better than all available forecast guidance at all times, except slightly worse than the CLIPER (CLImatological and PERsistence) model at 12 h and the GFDL model at 48 h.
Average official intensity errors for Gordon were 8, 9, 20, and 18 kt for the 12, 24, 36, and 48, respectively. Unlike the track errors, the intensity errors were greater than the average official errors for the 10-yr period 1990-1999 (7, 11, 13, and 16 kt, respectively), and were over-forecasts at all times, especially at 36 and 48 h. The SHIPS (Statistical Hurricane Intensity Prediction Scheme) intensity forecast model had similarly poor intensity forecasts.
Table 5 lists watches and warnings issued for Hurricane Gordon.
d. Casualty and Damage Statistics
There were 23 deaths reported in Guatemala due to heavy rainfall-induced flooding in mountainous areas. Many of the deaths may have occurred during the pre-depression stage while the system was moving slowly over the western Caribbean Sea and Yucatan Peninsula of Mexico. One death occurred in the United States when a surfer drowned in heavy seas near Pensacola, FL while Gordon make landfall in the Florida Big Bend area.
Most of the damage was due to downed tree and power lines. In addition, more than 20,000 Florida customers lost power for more than six hours during Gordon's passage. Also, numerous homes along the immediate Florida west coast from the Tampa Bay area northward to Cedar Key experienced some minor roof damage. Some coastal roads and highways experienced flooding from the storm surge and had to be temporarily closed. Damage estimate for the United States is $10.8 million. No damage estimates have been received from Guatemala in association with the heavy rainfall and flooding.
There were also two confirmed tornadoes. The first tornado (intensity unknown) occurred around 1845 UTC 17 September, in Cape Coral along the Florida west coast. At least 1 home received major damage and 2 other homes received minor damage. A second tornado (F0) touched down later that down around 2030 UTC near the town of Ponce Inlet in Volusia County along the Florida east coast. Damage was minimal and mainly confined to downed trees and power lines, although a few homes received minor damage.
Figure 1. 0803 UTC, 17 September 2000, NEXRAD/WSR-88D Base Reflectivity (0.5o elev.) radar data from Tampa Bay (KTBW), Florida. Image is at approximately the same time the minimum pressure of 981 mb was observed. Eye is located about 140 n mi west-southwest of the radar site at an altitude of approximately 22,000 ft ASL.
Table 1. Best track for Hurricane Gordon, September 2000. Date/Time
Stage Lat. (°N) Lon. (°W) 14/1200 19.8 87.3 1008 25 tropical depression 14/1800 20.4 87.4 1007 25 " 15/0000 20.7 87.7 1007 25 " 15/0600 21.0 88.0 1006 25 " 15/1200 21.4 88.7 1004 25 " 15/1800 21.6 87.8 1004 30 " 16/0000 22.5 86.7 1000 40 tropical storm 16/0600 22.9 86.6 997 50 " 16/1200 23.5 86.3 992 55 " 16/1800 24.3 85.9 983 60 " 17/0000 25.2 85.4 985 65 hurricane 17/0600 26.1 84.9 981 70 " 17/1200 27.1 84.3 987 65 " 17/1800 28.0 83.8 985 60 tropical storm 18/0000 28.9 83.4 992 55 " 18/0600 29.8 83.0 1000 40 tropical storm 18/1200 31.0 82.3 1006 30 tropical depression 18/1800 32.3 81.5 1011 25 extratropical 19/0000 33.5 80.2 1011 25 " 19/0600 35.0 79.0 1011 20 " 19/1200 37.0 78.2 1010 20 " 19/1800 38.5 76.0 1008 25 " 20/0000 40.0 74.0 1007 25 " 20/0600 41.5 72.0 1005 25 " 20/1200 42.0 69.5 1005 30 " 20/1800 42.5 67.2 1005 30 " 21/0000 43.0 65.0 1004 30 " 21/0600 43.5 63.0 1003 30 " 21/1200 absorbed by extratropical low 17/0600 26.1 84.9 981 70 minimum pressure 18/0300 29.3 83.2 991 55 landfall near Cedar Key, Florida
Table 2. Ship reports with winds of at least 34 kt for Hurricane Gordon. Ship Call Sign Date/ Time
Lat. (°N) Lon. (°W) Wind dir/speed
16/1500 WPWH 25.8 86.9 120/35 1010.5 16/1800 MYMX5 25.5 85.9 110/45 1004.4 16/1800 VRWK5 25.6 87.0 110/42 1009.0 16/2100 MYMX5 25.1 85.0 090/64 999.9 17/0000 KGBE 24.9 83.8 150/52 1004.2 17/0000 MYMX5 24.7 84.5 170/60 1001.3 17/0300 MYMX5 24.6 83.5 170/54 1006.8 17/0600 WCOB 24.9 84.1 210/45 1006.8 17/0600 MYMX5 24.1 83.4 190/45 1008.3 18/1200 H3GQ 27.3 88.5 090/36 1011.0
Table 3. Buoy reports with winds of at least 34 kt for Hurricane Gordon. Buoy Call Sign Date/ Time
Lat. (°N) Lon. (°W) Wind dir/speed
17/0020 42003 25.9 85.9 345/43(57b) 999.6 17/0200 42003 25.9 85.9 998.5 17/1722a 42036 28.5 84.5 340/51 b 1002.7 17/1800 42036 28.5 84.5 010/37 1005.5 17/2000 41009 28.5 80.2 130/35 b 1010.8 17/2100 42036 28.5 84.5 340/37(41b) 1003.8 18/0900 41004 32.5 79.1 090/35 b 18/1700a 41008 31.4 80.9 200/37b
* 8-min average wind, moored buoys
alast of several occurrences
Table 4. Selected surface observation reports (ASOS and C-MAN stations) from Florida for Hurricane Gordon. Minimum
Maximum surface wind speed
(mb) [Date/Time, if different]
17/1529 St. Petersburg (KSPG) 130/38 17/1552 Punta Gorda (KPGD) 160/32 17/1650 Titusville (KTTS) 150/15 30 1011.8 [17/2250] 17/1800 St. Petersburg (KPIE) 180/39 18/1855 Patrick AFB (KCOF) 120/27 39 17/1908 Leesburg (KLEE) 130/35 18/0015 Keaton Beach (KTNF1) 36 1003.7 [18/0500] 18/0110 Cedar Key (CDRF1) 110/45a 59 999.3 [18/0300] 18/0229 Cross City (KCTY) 040/29 37 997.6 [18/0543] 18/0242 Perry-Foley (K40J) 360/24 34 1005.1 [18/0612] 18/0540 St. Augustine (SAUF1) 160/32a 40 1008.2 [18/0900] 18/0604 Gainesville (KGNV) 1004.4 18/1302 Jacksonville (KCRG) 36
*2-min average wind
a10-min average wind
Figure 2. Best track positions for Hurricane Gordon. Track during the extratropical stage is based on analyses from the Tropical Analysis and Forecast Branch and the NOAA Hydrometeorological Prediction Center.
Figure 3. Best track maximum sustained surface wind speed curve for Hurricane Gordon, and the observations on which the best track curve is based. Aircraft observations have been adjusted for elevation using 90%, 80% and 85% reduction factors for observations from 700 mb, 850 mb and 1500 ft, respectively. Estimates during the extratropical stage are based on analyses from the Tropical Analysis and Forecast Branch and the NOAA Hydrometeorological Prediction Center.
Figure 4. Best track minimum central pressure curve for Hurricane Gordon, and the observations or estimates on which the best track curve is based. Estimates during the extratropical stage are based on analyses from the Tropical Analysis and Forecast Branch and the NOAA Hydrometeorological Prediction Center.
Table 5. Watch and warning summary for Hurricane Gordon, September 2000. Date/Time
Action Location 16/0300 Hurricane Watch Issued Florida west coast from Bonita Beach northward to the Suwanee River 16/1500 Tropical storm warning issued Florida west coast from Bonita Beach northward to the Suwanee River 16/1500 Hurricane watch extended Florida west coast from Suwanee River northward and westward to Apalachicola 17/0300 Hurricane warning issued Florida west coast from Anna Maria Island to Ochlockonee River 17/0300 Tropical storm warning Florida west coast from Bonita Beach northward to south of Anna Maria Island, and from west of Ochlockonee River westward to Indian Pass 17/0300 Tropical storm watch issued Florida northeast coast and Georgia southeast coast from Flagler Beach, Florida northward to Brunswick, Georgia 17/0900 Tropical storm watch upgraded to tropical storm warning Southeast U.S. coast from Flagler Beach, Florida northward to Brunswick, Georgia 17/0900 Tropical storm watch issued Brunswick, Georgia northward to the South Santee River, South Carolina 17/1500 Tropical storm warning extended Southeast U.S. coast from Flagler Beach, Florida northward to Little River Inlet, South Carolina 17/1500 Tropical storm watch extended north of Little River Inlet, South Carolina to Cape Hatteras, North Carolina 17/1800 Tropical storm warning extended Florida east coast from Flagler Beach south to Titusville 17/2100 Hurricane warning downgraded to tropical storm warning Florida Gulf Coast from Anna Maria Island northward to Indian Pass 17/2100 Tropical storm warning discontinued Florida west coast south of Anna Maria Island 17/2100 Hurricane watch discontinued Florida Gulf Coast 18/0000 Tropical storm watch extended Cape Hatteras, North Carolina northward to the North Carolina-Virginia Border, including Albemarle and Pamlico Sounds 18/0300 Tropical storm warning discontinued Florida Gulf Coast west of Saint Marks and south of Anclote Keys 18/0300 Tropical storm warning discontinued Florida east coast south of Flagler Beach 18/0900 Tropical storm warning discontinued All of Florida Gulf Coast 18/0900 Tropical storm watch discontinued All of North Carolina coast 18/1200 Tropical storm warning discontinued All coasts of North Florida, Georgia, and South Carolina