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Subtropischer Sturm Andrea

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Vorlage:Ongoing weather Vorlage:Infobox hurricane current Subtropical Storm Andrea is the first named storm and first subtropical cyclone of the 2007 Atlantic hurricane season. It developed out of a previously non-tropical low on May 9 about 150 miles (240 km) northeast of Daytona Beach, Florida, three weeks before the start of the season. The storm produced rough surf along the coastline from Florida to North Carolina, causing beach erosion and some damage.

Andrea is the first Atlantic named storm in May since Tropical Storm Arlene in 1981. Additionally, the storm is the first pre-season storm to develop since Tropical Storm Ana in April 2003.[1]

Storm history

In early May, a trough persisted across the western Atlantic Ocean in association with a back door cold front, which is a cold front that drifts southwestward due to a ridge to its north. For several days, hurricane forecast models had anticipated for the trough to evolve into a closed low pressure area,[2] and on May 6, a frontal low with a large and well-defined circulation developed about 90 miles (140 km) east of Cape Hatteras. The low maintained scattered convection around its circulation, and in conjunction with the strong high pressure to its north a very tight pressure gradient produced gale force winds near the coastline.[3] The low tracked south-southwestward[3] and intensified, though due to a lack of deep moisture its corresponding convection was minimal and scattered.[4]

The National Hurricane Center first mentioned the possibility of tropical cyclogenesis on May 8 while about 230 miles (370 km) east-southeast of the South Carolina coastline. Its associated convection had steadily increased as it tracked slowly westward at 5–10 mph (8–16 km/h).[5] The system changed little throughout the day,[6] though by the following morning hurricane specialists indicated the low was acquiring subtropical characteristics.[7] Early on May 9, a Hurricane Hunters flight into the system revealed winds of 45 mph (70 km/h) and a flat thermal core, which indicated the system was neither warm-core nor cold-core. In addition, satellite imagery indicated a consolidation of the convection near the center, as well as hints of upper-level outflow and a contraction of the radius of maximum winds from more than 115 miles (185 km) to about 70 miles (120 km). Based on the observations and the hybrid structure of the system, the National Hurricane Center classified the low as Subtropical Storm Andrea at 1500 UTC on May 9 about 150 miles (240 km) northeast of Daytona Beach, Florida.[8]

Upon first becoming a subtropical cyclone, Andrea was embedded within a large, nearly stationary deep-layer trough, leaving it moving westward. Drifting over sea surface temperatures of no more than 77º F (25º C),[8] the organization of the system deteriorated with a significant decrease in convection;[9] by early on May 10 much of the associated weather was located to the east of the cyclone within a band of moderate convection. Additionally, the center of circulation had become disorganized, with several small cloud swirls within the larger circulation.[10] This disorganization of the center, combined with increasing wind shear and dry air suppressing convective activity, caused Andrea to begin weakening later that morning.[11] Shortly thereafter, Andrea had weakened to a subtropical depression.[12]

Current storm information

As of 11 a.m. EDT May 10 (1500 UTC), Subtropical Depression Andrea was located near 29.9°N 79.9°W, about 100 miles (160 km) ESE of Jacksonville, Florida or about 80 miles (130 km) NE of Daytona Beach, Florida. It had maximum sustained winds of 30 knots (35 mph, 55 km/h), with stronger gusts. Andrea's minimum central pressure was 1003 mbar (29.62 inHg), and it was drifting to the south.

Warnings and watches

Vorlage:See also At 11 a.m. EDT (1500 UTC) May 10, all tropical storm watches were cancelled.

Preparations

Due to rough surf from the precursor low, local National Weather Service offices issued a High Surf Advisory for much of the coastline from Florida through North Carolina.[3] Upon first becoming a subtropical cyclone, the National Hurricane Center issued a tropical storm watch from the mouth of the Altamaha River in Georgia southward to Flagler Beach, Florida.[13] Additionally, a gale warning was issued for much of the South Carolina coastline.[14]

At Isle of Palms in South Carolina, workers prepared sandbags and dozens of firefighters in preparation for high tide after waves from the storm previously caused moderate beach erosion. As a precaution, officials there intentionally cut power and gas to multiple uninhabited buildings.[14] Officials closed schools in Dare County, North Carolina due to the threat for high winds from the storm. The North Carolina Department of Transportation also canceled ferry transportation to and from Ocracoke and Knotts Island, North Carolina.[15]

Impact

Prior to becoming a subtropical cyclone, the low produced gale force winds and dangerous surf near the coast from North Carolina through Georgia,[5] and later along the coast of Florida.[6] Significant swells were also reported in the Bahamas.[16] The waves caused beach erosion and washed up against coastal houses.[17]

Off the coast of North Carolina, the storm produced 34 foot (10 m) waves and storm force winds which damaged three boats; their combined nine passengers were rescued by the Coast Guard. All nine were injured to some degree; three endured hypothermia, one received a broken rib, and one Coast Guardsman experienced back injuries from the surf.[18] Another boat and its four occupants remain missing.[15] Onshore, winds reached 52 mph (84 km/h) in Norfolk, Virginia, with an unofficial report of 57 mph (92 km/h) near Virginia Beach. Similar observations occurred along the Outer Banks,[19] with the winds knocking some tree limbs onto power lines;[20] some isolated power outages were reported.[15] Wind damage included some roofs losing shingles from the winds.[19] In Elizabeth City, North Carolina, an outer rainband dropped 0.5 inches (10 mm) of precipitation in about 2 hours as well as several lightning strikes; one bolt of lightning injured two firefighters.[15] The winds covered portions of North Carolina Highway 12 with sand,[19] and for a day the route was closed after waves from the storm washed out about 200 feet (60 m) of roadway.[15] In some locations, the waves eroded up to 20 feet (6 m) of beach, leaving 70 homes in imminent danger.[21]

Rough waves from the precursor low left two kayakers missing near Seabrook Island, South Carolina. One was found the next day, while the other is currently missing.[22]

In Florida, waves of over 10 feet (3 m) in height capsized a boat near Lantana; the two occupants were rescued without injury. Additionally, the waves displaced a sailboat that had previously been washed ashore in Juno Beach. Large waves flooded a parking lot and destroyed several fences and tree branches at Jupiter Beach, which resulted in its temporary closure; nearby a maintenance shed was destroyed. Eight Leatherback Sea Turtle nests in Boca Raton were destroyed after the surf reached the dunes.[23] The waves forced the closure of the beach pier at Flagler Beach.[24] Strong winds from the storm spread smoke from local brush fires through the Tampa Bay area to Miami[25][26]

See also

Vorlage:Tcportal Vorlage:Wikinewspar

References

  1. ↑ Hurricane Research Division: Hurdat Data for Tropical Cyclones 1851-2006. National Oceanic and Atmospheric Administration, 2007, abgerufen am 11. Oktober 2006.
  2. ↑ Cangialosi: May 4 Tropical Weather Discussion. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  3. ↑ a b c Cangialosi: May 6 Tropical Weather Discussion. National Hurricane Center, 2007, abgerufen am 9. Mai 2007. Referenzfehler: Ungültiges <ref>-Tag. Der Name „57twd“ wurde mehrere Male mit einem unterschiedlichen Inhalt definiert.
  4. ↑ Cangialosi: May 7 Tropical Weather Discussion. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  5. ↑ a b Knabb: May 8 Special Tropical Disturbance Statement. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  6. ↑ a b Brown: May 9 Special Tropical Disturbance Statement. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  7. ↑ Franklin/Knabb: May 9 Special Tropical Disturbance Statement (2). National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  8. ↑ a b Knabb: Subtropical Storm Andrea Discussion One. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  9. ↑ Knabb: Subtropical Storm Andrea Discussion Two. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  10. ↑ Avila: Subtropical Storm Andrea Discussion Three. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  11. ↑ Mainelli: Subtropical Storm Andrea Discussion Four. National Hurricane Center, 2007, abgerufen am 10. Mai 2007.
  12. ↑ Knabb: Subtropical Depression Andrea Discussion Five. National Hurricane Center, 2007, abgerufen am 10. Mai 2007.
  13. ↑ Knabb: Subtropical Storm Andrea Public Advisory One. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  14. ↑ a b Jennifer Wilson: Forecasters: Subtropical Storm Andrea has formed. WIStv Columbia, South Carolina, 2007, abgerufen am 9. Mai 2007.
  15. ↑ a b c d e Lauren King and Kristin Davis: Season's first named storm unleashes band of rain. Virginia Pilot, 2007, abgerufen am 9. Mai 2007.
  16. ↑ Willis: May 8 Tropical Weather Discussion. National Hurricane Center, 2007, abgerufen am 9. Mai 2007.
  17. ↑ Jessica Gresko: Year's first named storm becomes Andrea, forms 3 weeks before hurricane season begins. Associated Press, 2007, abgerufen am 9. Mai 2007.
  18. ↑ Virginia Pilot: High drama on high seas, 8. Mai 2007. Abgerufen am 9. Mai 2007 
  19. ↑ a b c Virginia Pilot: Wind and chill chase away spring today's weather, 7. Mai 2007. Abgerufen am 9. Mai 2007 
  20. ↑ Francine Sawyer: Storm moving away from coast. New Bern Sun Journal, 2007, abgerufen am 9. Mai 2007.
  21. ↑ Bryan Mims: Offshore Storm System Raked N.C. Beaches. WRAL.com, 2007, abgerufen am 9. Mai 2007.
  22. ↑ Associated Press: First named '07 Atlantic storm forms near coast. 2007, abgerufen am 9. Mai 2007.
  23. ↑ Erika Pesantes, Sally Apgar and Chrystian Tejedor: Sweeping erosion hits Palm Beach County coast: Low-pressure system sucks swaths of sand; Jupiter feels brunt of it, South Florida Sun-Sentinel, 9. Mai 2007 
  24. ↑ Jacksonville, Florida National Weather Service: May 8 Preliminary Local Storm Report. 2007, abgerufen am 9. Mai 2007.
  25. ↑ Staff Writer: Subtropical storm Andrea is swirling off the north Florida coastline. Bradenton Herald, 2007, abgerufen am 9. Mai 2007.
  26. ↑ CNN Staff Writer: Atlantic's first named storm whips up wildfires. CNN, 2007, abgerufen am 10. Mai 2007.
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