Tropical Storm Fay<br>
September 4-6, 2002<br>
Written by Derek Ortt on December 21, 2002
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<b>I. Synoptic History</b>
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	Tropical Storm Fay originated from an area of disturbed weather in the north central Gulf of Mexico that persisted for many days in early September 2002. This area of disturbed weather was associated with a surface trough that had persisted in the area for several days. The convection was able to persist due to the very warm sea surface temperatures in the north central Gulf of Mexico, and due to a large upper level anti-cyclone centered over the area of disturbed weather. The area slowly organized and a recon aircraft that investigated the system discovered that the system had become a tropical depression. Based upon this data, the area of disorganized weather is analyzed as a tropical depression at 1900 UTC, September 4. Surface observations from oil rigs and data buoys indicated that the depression had intensified into Tropical Storm Fay near 300 UTC, September 5.
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	The motion of Fay while it was over the Gulf of Mexico was very slow and erratic. The vast majority of the motion was caused by center reformations. Steering currents were weak due to a high to the northwest and a trough to the east. This left Fay in a col area, which prevented any true motion from occurring. However, the center reformations tended to bring Fay to the WNW, which brought the system closer to the Texas coast. 
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	As Fay approached the Texas coast, it continued to organize. Recon indicated that the system had intensified into a 50KT tropical storm near 1200 UTC, September 5. However, after this time, Fay did not increase any further in intensity. The reason for this was an upper low that formed to the SW of the system. This prevented any outflow in the SW quadrant and resulted in some dry air being entrained into the center. The result of this was Fay was never able to make the transformation into a purely tropical cyclone; thus, it was not able to intensify into a hurricane. Instead, Fay remained a 50KT tropical storm until it made landfall along the central coast of Texas early in the morning of September 6 (for more information regarding the landfall, please see the landfall analysis section of this report).
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	After landfall, Fay began to accelerate to the WNW as it came under the influence of the high to its north. This track continued until Fay weakened into a remnant low later on the 6. Fay completely dissipated a couple of days later.
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<b>II. Forecast Analysis</b>
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	The track forecasts for Tropical Storm Fay were tricky due to the numerous center reformations that Fay underwent while it was in the Gulf of Mexico. However, for the most part, the errors were below the NHC 10-Year Average errors. The track forecasts indicated a slow motion. The final center reformation, that brought Fay inland was not anticipated; thus, the forecast errors were magnified over what they would have been otherwise. The landfall in Texas was correctly forecast, and the location along the Texas Coast was also fairly well forecast. This was to the south of the forecast model landfall forecasts, which forecast a landfall near the Houston/Galveston location. However, the timing of the landfall was off. Landfall occurred about 24 hours before it was forecast to occur. 
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	While the absolute intensity forecast errors for Fay were well above the NHC 10-Year Averages, the intensity forecasts were not all that poor. The reason for the errors was that the track forecasts indicated that Fay would remain over the Gulf of Mexico for about 24 hours longer than it actually did. As a result, the intensity forecasts called for an increased intensification into a hurricane before landfall. This may have occurred had Fay had been over water for about 24 more hours as atmospheric conditions were becoming more favorable for development as Fay was making landfall.
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	Due to system problems, the precise watches and warnings that NWHHC recommended are not available. However, there was a tropical storm warning/hurricane watch recommended about 24 hours before landfall. This was upgraded to a hurricane watch/tropical storm warning, then to a hurricane warning. For more information regarding these differing levels of alert, please visit the <a href="http://www.nwhhc.com/gpage4.html">NWHHC Alerts Page</a>.
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	All forecast errors are given in the table that follows this report.
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<b>III. Landfall Analysis</b>
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	Tropical Storm Fay made landfall as a 50KT tropical storm. This is based upon recon data from the 34 hours prior to landfall. About 24 hours prior to landfall, recon indicated 68KT 850mb flight-level winds. This was the highest flight-level wind value reported from Fay. In fact, the other obs indicate winds in the upper 50KT range. This may indicate that the 68KT was either a transient event, or an error. The 68KT wind was the basis for operationally increasing the wind speed to 50KT. Recon indicated that the pressure feel from 1001mb from the time of the 68KT flight-level wind report to 999mb at the time of landfall, suggesting that Fay did not weaken. It is possible that Fay was a 45KT tropical storm throughout the time period; however, the data is inclusive. Therefore, it is best to keep Fay as a 50KT tropical storm at the time of landfall.
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	Over land, the greatest effects from Fay were the heavy rainfall and associated flooding. Up to 15 inches of rainfall was recorded over parts of Texas. However, the flooding was not as severe as has been experienced with previous landfalling tropical cyclones along the Texas Coast. Flood damage to structures was minor. Along the coastline, wind and surge damage was also minor with only a few structures being destroyed or suffering serious structural damage.
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<b>Forecast Errors</b> (Cases are in parenthesis and errors are in knots)
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12 Hour (3): 38/6.7 NHC 10-Year Average: 44/7.0<br>
24 Hour (3): 76/20* NHC 10-Year Average: 82/10.8<br>
36 Hour (2): 93/20* NHC 10-Year Average: 118/13.7<br>
48 Hour (1): 154/35* NHC 10-Year Average: 151/16.3
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*These represent the absolute intensity errors. The errors for the time periods while the system was over water are much lower than the errors given in this report.
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Data from this report came from the NHC products, HPC storm assessments, as well as operational NWHHC products.
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