Figure 1. Best Track analysis of Hurricane Alex, which affected portions of the outer banks of North Carolina during the 2004 hurricane Season .1
Light Red=Category 1-2 Hurricane
Dark Red=Category 3-5 Hurricane
Hurricane Alex* was the first hurricane of the 2004 Atlantic Hurricane Season, which developed into an unusually strong Category 3 Storm while accelerating northeastward into the Northwestern Atlantic. Alex never officially made landfall, but his center passed within 15 miles of Cape Hatteras, North Carolina on 3 August.
Because Alex was a relatively small tropical cyclone, the hurricane-force wind radii never exceeded 25 miles from the storm’s center during his closest approach to the Outer Banks2. Alex, therefore, caused minimal structural damage to homes, with reported sustained winds topping out at around 80 mph, with gusts nearing 105 mph. Most of the damage was caused by flooding along the coastline associated with Alex’s 3-5 foot storm surge. Total damages from Alex are estimated to be around $5 million (2004 USD).3
* “Alex” replaced “Andrew” in the 1998 Atlantic Hurricane Season. “Alex” will be used in the 2010 Atlantic Hurricane Season
An area of disturbed weather well east of the Bahamas likely played a role in Alex’s genesis on 31 July. From 26-28 July, a surface trough of low pressure interacted with an upper low to the west, spitting out spotty showers and thunderstorms east of the Bahamas. On 30 July, convection began concentrating around a broad area of low pressure while moving slowly to the northwest. By 31 July, the area of showers and thunderstorms about 175 miles south-southeast of Charleston, South Carolina developed into Tropical Depression One4.
No significant development occurred within the following 24 hours due to a large amount of sinking air (i.e. subsidence, which does not favor cloud and thunderstorm formation) and strong upper-level shear around the tropical cyclone.
By the afternoon on 1 August, however, the cyclone’s low-level center had shifted farther south, becoming embedded in deep convection 80 miles southeast of Charleston, South Carolina5, and was upgraded to the season’s first Tropical Storm. Alex began to accelerate as shear weakened and the overall environment grew more favorable for intensification. Early on 3 August, Alex had become a hurricane, and began lashing the Southeast coastline with gusty winds, rip currents, and intense rain squalls embedded within the cyclone’s rotating feeder bands. During the afternoon, several reports of sustained winds near 75 mph and gusts nearing 100 mph around the Cape Hatteras area were received by the Hurricane Center associated with then Category 2 Hurricane Alex6.
Alex proceeded to move away from the North Carolina coast during the evening, and began accelerating towards the east-northeast under an increasingly fast steering current. Unexpectedly, late on 4 August, Alex strengthened into a 120 mph Category 3 Hurricane—the strongest hurricane on record to move north of 38 degrees latitude7. Alex maintained this intensity for roughly 18 hours, before passing over cooler Sea Surface Temperatures, where he weakened into a Tropical Storm. Alex’s remnants became extratropical for a short while in the North Central Atlantic.
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MODIS Terra RGB using the MOD02HKM product. This image is of the swath data from Aug 04 at 1505 hrs. More images like this and parameters animation created from other datasets can be seen in our Archive Image Gallery for hurricaneAlex
1. Image courtesy of the NOAA coastal Services Center Http://hurricane.csc.noaa.gov/hurricanes
2. Franklin, James. “Hurricane Alex Forecast/Advisory Number 13.” 3 August 2004. http://www.nhc.noaa.gov/archive/2004/mar/al012004.fstadv.013.shtml? (13 July 2006).
3. Franklin, James. “Tropical Cyclone Report: Hurricane Alex.” 26 October 2004. http://www.nhc.noaa.gov/pdf/TCR-AL012004_Alex.pdf (13 July 2006).
4. Beven, Jack. “Tropical Depression One Advisory Number 1.” 31 July 2004. http://www.nhc.noaa.gov/archive/2004/pub/al012004.public.001.shtml? (13 July 2006).
5. Franklin, James. “Tropical Storm Alex Intermediate Advisory Number 4A.” 1 August 2004. http://www.nhc.noaa.gov/archive/2004/pub/al012004.public_a.004.shtml? (13 July 2006).
6. Franklin, James. “Hurricane Alex Intermediate Advisory Number 13B.” 3 August 2004. http://www.nhc.noaa.gov/archive/2004/pub/al012004.public_b.013.shtml? (13 July 2006).
7. Stewart, Stacy. “Hurricane Alex Discussion Number 19.” 4 August 2004. http://www.nhc.noaa.gov/archive/2004/dis/al012004.discus.019.shtml? (13 July 2006).