Tropical Storm Debby (2006)

Infobox Hurricane
Name=Tropical Storm Debby
Type=Tropical storm
Year=2006
Basin=Atl
Image location=TS debby 2006.jpg


Formed=August 21, 2006
Dissipated=August 26, 2006
1-min winds=45
Pressure=999
Da

Inflated=
Fatalities=None reported
Areas=Cape Verde
Hurricane season=2006 Atlantic hurricane season

Tropical Storm Debby was the fifth tropical storm of the 2006 Atlantic hurricane season. Debby formed just off the coast of Africa on August 21 from a tropical wave. After passing near the Cape Verde islands, Debby moved generally northwestward for much of its life, reaching a peak intensity of 50 mph (85 km/h). Strong wind shear weakened the storm, and Debby dissipated on August 27 over the northern Atlantic Ocean.

Early in its life, Debby was forecast to pass through the southern Cape Verde islands as a tropical storm, potentially causing life-threatening flooding. Most computer models consistently predicted Debby to track to the northwest throughout its lifetime, though intensity was more problematic for forecasters. The National Hurricane Center continually predicted Debby to intensify to hurricane status, though strong vertical shear ultimately prevented the storm from becoming a hurricane.

Meteorological history

A vigorous tropical wave moved off the coast of Africa late on August 20, and almost convective banding and a broad circulation.Cite web|author=James L. Franklin|year=2006|title=Tropical Storm Debby Tropical Cyclone Report|publisher=National Hurricane Center|accessdate=2006-11-02|url=http://www.nhc.noaa.gov/pdf/TCR-AL042006_Debby.pdf] A broad area of low pressure formed within the wave the next day while located 260 miles (420 km) southeast of the Cape Verde islands. Though convection decreased early on August 21, the area of low pressure remained well-organizedcite web|author=Blake/Franklin|year=2006|title=August 21 Tropical Weather Outlook|publisher=NHC|accessdate=2006-09-05|url=ftp://ftp.met.fsu.edu/pub/weather/tropical/Outlook-A/2006082115.ABNT20] and the system developed into Tropical Depression Four late on August 21. Water temperatures remained warm enough for development, while upper level shear was minimal as the depression moved west-northwestward due to a ridge of high pressure to its north.cite web|author=Franklin|year=2006|title=Tropical Depression One Discussion|publisher=NHC|accessdate=2006-09-05|url=ftp://ftp.met.fsu.edu/pub/weather/tropical/Outlook-A/2006082115.ABNT20] Initial predictions by the National Hurricane Center also forecast a motion to the northwest based on consistent model predictions, though, as quoted by forecaster James Franklin, "The models have also been excellently wrong thus far".cite web|author=Franklin|year=2006|title=Tropical Depression Four Discussion Two|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.002.shtml?]

Despite a decrease in convection shortly after forming, the large depression remained well organized, with a wind field 575 miles (930 km) in diameter. On August 22, as it passed 140 miles (225 km) to south of the Cape Verde islands, deep convection developed over the center of circulation,cite web|author=Brown|year=2006|title=Tropical Depression Four Discussion Three|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.003.shtml?] and early on August 23 the depression intensified into Tropical Storm Debby about 300 miles (485 km) southwest of Cape Verde. Banding features continued to organize as the system slowly strengthened,cite web|author=Brown|year=2006|title=Tropical Storm Debby Discussion Seven|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.007.shtml?] and on August 23 Debby attained a peak intensity of 50 mph (85 km/h) over the open waters of the Atlantic Ocean. Forecasters predicted Debby to continue to intensify to attain hurricane status, while its projected path placed the storm in an area of warm water temperatures and moderate upper level shear.cite web|author=Franklin|year=2006|title=Tropical Storm Debby Discussion Eight|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.008.shtml?]

Shortly after reaching its peak intensity, Debby encountered an area of dry air, and subsequently weakened. The low level circulation detached itself from the diminishing convection while the system as a whole continued west-northwestward.cite web|author=Franklin|year=2006|title=Tropical Storm Debby Discussion Nine|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.009.shtml?] Convection redeveloped over a portion of the center, while banding features redeveloped as well.cite web|author=Stewart|year=2006|title=Tropical Storm Debby Discussion Ten|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.010.shtml?] Organization continued, and Debby again reached its peak intensity of 50 mph (85 km/h) on August 24.cite web|author=Franklin|year=2006|title=Tropical Storm Debby Discussion Twelve|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.012.shtml?] Southerly wind shear displaced the convection to the north of the center, and Debby weakened to a minimal tropical storm on August 25.cite web|author=Roberts/Beven|year=2006|title=Tropical Storm Debby Discussion Sixteen|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.016.shtml?] The center of the storm became asymmetric and elongated,cite web|author=Berg/Knabb|year=2006|title=Tropical Storm Debby Discussion Eighteen|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.018.shtml?] and on August 26 Debby weakened to a tropical depression.cite web|author=Blake/Avila|year=2006|title=Tropical Depression Debby Discussion Nineteen|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.019.shtml?] Convection remained minimal and it quickly degenerated into a remnant area of low pressure. The low turned to the north and north-northeast ahead of an approaching trough, and on August 28 the low dissipated.

Preparation and Impact

The government of the Cape Verde islands issued a tropical storm warning coinciding with the issuance of the first advisory on Tropical Depression Four, meaning tropical storm conditions were expected in the area within 24 hours. The National Hurricane Center stated that heavy rainfall, potentially as high as 10 inches (250 mm) in mountainous areas, would be possible in the territory, possibly causing life-threatening flash floods and mudslides.cite web|author=Franklin|year=2006|title=Tropical Depression Public Advisory One|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/pub/al042006.public.001.shtml?] However, due to a reformation further to the south, tropical storm warnings were discontinued as the depression moved from the area.cite web|author=Franklin|year=2006|title=Tropical Depression Four Public Advisory Four|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/pub/al042006.public.004.shtml?] While passing around 115 miles (185 km) to the southwest of the southwestern most islands, the depression produced a 35 mph (55 km/h) wind gust at Fogo and some rainfall, though no damage was reported.cite web|author=Associated Press|year=2006|title=Tropical Depression Reaches Cape Verde Islands|accessdate=2006-09-05|url=http://www.foxnews.com/story/0,2933,209786,00.html?sPage=fnc.specialsections/naturaldisaster]

Long range forecasts brought the storm near Bermuda. However Debby remained over 900 miles (1,450 km) from the island at its closest approach.cite web|author=Blake/Stewart|year=2006|title=Tropical Depression Debby Discussion 23|publisher=NHC|accessdate=2006-09-05|url=http://www.nhc.noaa.gov/archive/2006/dis/al042006.discus.023.shtml?] Though the storm was forecast to remain far away from the Gulf of Mexico, investors tracking the storm caused the price of crude oil to rise 60 cents a barrel due to the potential impact to oil installations.cite web|author=Agence France-Presse|year=2006|title=Oil prices up on new BP cut|accessdate=2006-09-05|url=http://www.news.com.au/dailytelegraph/story/0,22049,20246735-14334,00.html]

See also

* 2006 Atlantic hurricane season

References

External links

* [http://www.nhc.noaa.gov/archive/2006/DEBBY.shtml? National Hurricane Center's archive on Tropical Storm Debby]
* [http://www.nhc.noaa.gov/pdf/TCR-AL042006_Debby.pdf National Hurricane Center Tropical Cyclone Report on Tropical Storm Debby]