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Tropical Storm Laura

Tropical Storm (SSHWS/NWS)
Tropical Storm Laura at peak intensity on September 30 2008.
Formed	September 29, 2008
Dissipated	October 1, 2008
Highest winds	1-minute sustained: 60 mph (95 km/h)
Lowest pressure	994 mbar (hPa); 29.35 inHg
Fatalities	None
Damage	None
Areas affected	Netherlands, British Isles, Norway (when post-tropical)
Part of the 2008 Atlantic hurricane season

Tropical Storm Laura was the twelfth named storm of the 2008 Atlantic hurricane season. Laura formed out of a large non-tropical low pressure area located 1015 miles (1635 km) west of the western islands of the Azores on September 29. Laura slowly developed tropical characteristics throughout the day as it moved over warmer waters. On the afternoon of September 30, Laura had acquired enough tropical characteristics to be designated a Tropical Storm. Shortly after being declared tropical, Laura began to undergo an extratropical transition, which did not fully take place until the morning of October 1. Laura degenerated into a post-tropical cyclone later that morning, and the final advisory by the National Hurricane Center was issued.

Meteorological History

In late September, a large non-tropical system located over the north-central Atlantic slowly moved westward away from the Azores. The low produced hurricane-force winds, but did not exhibit the characteristics of a tropical cyclone. The storm steadily weakened over the following days, but developed tropical characteristics as it moved over slightly warmer waters. By September 29, the low had developed sufficient convection and was declared Subtropical Storm Laura. Upon being upgraded, cold cloud tops began to wrap around the center of Laura and consolidate near the center of circulation. The convection organized around the center quickly and a satellite pass over the storm revealed that it could be intensifying. A later satellite pass disregarded the possibility of intensification as the intensity was confirmed to be at 60 mph (95 km/h). The overall structure of Laura remained subtropical but there were indications that it was acquiring tropical characteristics.

During the afternoon, satellites revealed that Laura had developed a deep warm core, a characteristic of a tropical cyclone, but the wind field remained subtropical in nature. By the nighttime hours, the radius of the strongest winds contracted to 80 mi (130 km), much smaller than what is typical of a subtropical cyclone. However, Laura was still under the influence of an upper-level low and cloud tops remained shallow. However, the cloud tops became colder overnight and Laura was on the verge of becoming a tropical cyclone by the morning of September 30, but strong interaction with the upper-level low meant it was still subtropical. Despite moving over colder waters, a water vapor satellite image determined that Laura had separated itself from the upper-level low, signifying it had developed into a tropical cyclone. Laura was upgraded to a tropical storm at a relatively high latitude, 41.2°N. Not long after being declared tropical, early signs of an extratropical transition appeared. Cold air began to enter the storm on the west side and forecast models showed Laura becoming extratropical the next morning and non-tropical later the next day.

Overnight, convection associated with Laura began to diminish and lose tropical characteristics, but still retained its status. Early on October 1, the extratropical transition was fully apparent. Laura remained tropical but the cloud pattern was becoming frontal and there was little convection around the center of the system. Laura later degenerated into a post-tropical cyclone, a term that had been previously used by the Canadian Hurricane Centre to describe a storm that has lost tropical characteristics, but is not subtropical or extratropical. The transition was forecasted to be complete by the end of the day.

Impact

As a tropical cyclone, Laura never approached land, and no effects, damages, or fatalities occurred. However, the storm's remnants were caught in an upper-level jet stream, and steered towards Europe. Heavy rain fell across portions of Britain, causing localized accumulation of flood waters. As a result, Glebe Road near Windermere, England was closed in both directions, and along the A65 road between Old Hutton and Kirkby Lonsdale, previously saturated soil, combined with overwhelmed storm drains resulted in localized flooding. Traffic on the M6 Motorway was slowed due to poor driving conditions.

After the remnants of now extratropical Laura made final landfall on the southern coast of the Netherlands, its rain bands started interacting with a cold front associated with a well-developed low west of Norway, dropping up to 113 mm (4.5 in) of precipitation in the Northwestern Netherlands, flooding streets and homes in the village of Hippolytushoef. More than 10,000 people lost electricity in southern Norway because of damage to the electrical system caused by the remnants of the storm.

See also

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• 2008 Atlantic hurricane season

References

1. NHC (2008). "12L 2008 Trackfile". National Hurricane Center. Retrieved 2008-09-29.
2. Stewart (2008). "Subtropical Storm Laura Public Advisory One". National Hurricane Center. Retrieved 2008-09-29.
3. Stewart (2008). "Subtropical Storm Laura Discussion One". National Hurricane Center. Retrieved 2008-09-29.
4. Berg/Pasch (2008). "Subtropical Storm Laura Discussion Two". National Hurricane Center. Retrieved 2008-09-29.
5. Berg/Franklin (2008). "Subtropical Storm Laura Discussion Three". National Hurricane Center. Retrieved 2008-09-30.
6. Franklin (2008). "Subtropical Storm Laura Discussion Four". National Hurricane Center. Retrieved 2008-09-30.
7. Beven (2008). "Subtropical Storm Laura Discussion Five". National Hurricane Center. Retrieved 2008-09-30.
8. Berg/Pasch (2008). "Tropical Storm Laura Discussion Six". National Hurricane Center. Retrieved 2008-09-30.
9. Berg/Pasch (2008). "Tropical Storm Laura Discussion Seven". National Hurricane Center. Retrieved 2008-10-01.
10. Avila (2008). "Tropical Storm Laura Discussion Eight". National Hurricane Center. Retrieved 2008-10-01.
11. Beven (2008). "Tropical Storm Laura Discussion Nine". National Hurricane Center. Retrieved 2008-10-01.
12. Franklin (2008). "Post-Tropical Cyclone Laura Discussion Ten". National Hurricane Center. Retrieved 2008-10-01.
13. Paul Simons (2008). "Weather: torrential rain expected as strong winds hit Wales and the South West". The Times. Retrieved 2008-10-05. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
14. Staff Writer (2008). "Tropical storm brings floods". The Westmorland Gazette. Retrieved 2008-10-05. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
15. Rob Sluijter (2008). "5 oktober 2008: Wateroverlast in het noordwesten". KNMI. Retrieved 2008-10-08. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
16. Meteo Consult (2008). "De Noord-Hollandse 'zondvloed' nader bekeken". Meteo Consult. Retrieved 2008-10-08. {{cite web}}: Italic or bold markup not allowed in: |publisher= (help)
17. NRK.no: Kraftig uvær på Østlandet

External links

• The NHC's Archive on Laura

v t e Tropical cyclones of the 2008 Atlantic hurricane season
Timeline
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Category

• 2008 Atlantic hurricane season
• Atlantic tropical storms
• 2008 in Europe