X hits on this document

57 views

0 shares

0 downloads

0 comments

5 / 30

1748

MONTHLY WEA

to several buildings. It then hit a mobile home park, damaging at least 20 homes. There was a total of 30 tornadoes from Louisiana through North Carolina. The Property Claim Services Division of the American In- surance Services Group, the Insurance Services Office, Inc., reports that insured losses due to Bill totaled 22 million dollars in Louisiana. Total losses for Louisiana and Mississippi are estimated at 50 million dollars.

4) WARNINGS

A tropical storm watch was issued from San Luis Pass, Texas, to Morgan City, Louisiana, at 1500 UTC on 29 June. A tropical storm warning was issued from High Island, Texas, to Pascagoula, Mississippi, includ- ing Lake Ponchartrain, at 2100 UTC on the same day. Bill made landfall near the middle of the warning area about 22 h after the warning was issued. However, the landfall location was just east of the eastern limit of the watch area.

c. Hurricane Claudette, 817 July

Hurricane Claudette made landfall on the northeast- ern Yucatan Peninsula of Mexico as a tropical storm, and as a category-1 hurricane in Texas.

1) SYNOPTIC HISTORY

Claudette formed from a tropical wave that moved westward across the coast of Africa on 1 July. The wave showed signs of convective organization on 6 July and was well enough organized on satellite imagery to be classified as a tropical depression on 7 July near the Windward Islands. However, the wave was moving westward at 2025 kt at the time, and neither surface observations nor an investigative flight by the U.S. Air Force Reserve Hurricane Hunters indicated that the system had a closed surface circulation.

The wave continued rapidly westward with a further increase in organization. Satellite intensity estimates suggested the system was near tropical storm strength by 1500 UTC 8 July. However, a second investigative flight could not find a closed center at that time. Finally, near 1800 UTC the plane found a small area of south- westerly winds that indicated a closed circulation and the wave is estimated to have become Tropical Storm Claudette while located about 200 n mi south of His- paniola.

Claudette continued quickly westward through 9 July while slowly strengthening, and then turned northwest- ward with some deceleration on the following day. It formed a small eye and strengthened to a 70-kt hurri- cane for a few hours on 10 July, but became disorga-

THER REVIEW

VOLUME 133

nized and weakened to 50 kt before making landfall on the northeastern Yucatan Peninsula of Mexico near 1000 UTC 11 July.

The storm moved northwestward into the southern Gulf of Mexico on 11 July. A north-northwestward jog occurred on 12 July while Claudette became a little better organized. The storm meandered erratically northwestward on 13 July, then turned northward later that day. These track changes were likely due to a com- bination of 1) weakening of a mid-upper-level ridge along the northern Gulf Coast caused by a developing trough over the eastern United States, and 2) reforma- tion of the center caused by strong but asymmetric con- vection to the northeast. This change in motion was accompanied by some decrease in the shear, and while the center remained mostly exposed, Claudette slowly strengthened on 13 July.

A building deep-layer ridge over the western United States and the western Gulf Coast states forced Clau- dette to gradually turn west-northwestward late on 14 July. An eyewall formed and Claudette again became a hurricane at 0600 UTC 15 July. A faster west-north- westward motion brought the center of Claudette to the Texas coast at Matagorda Island (just east of Port OConnor) at 1530 UTC that day (Fig. 2). Strengthen- ing continued up to landfall, with estimated maximum winds increasing to 80 kt and the central pressure fall- ing to 979 mb.

Claudette turned westward just after landfall and weakened to a tropical storm at 0000 UTC 16 July. It then turned west-northwestward again while moving into northern Mexico later that day. This motion con- tinued until dissipation. Claudette was slow to lose or- ganization, as the radar and satellite presentations of its structure remained distinct for more than 24 h after landfall. Surface data indicate the system maintained tropical storm strength until 0000 UTC 17 July. The low-level circulation dissipated over the mountains of northwestern Mexico later that day. However, the mid- and upper-level moisture and vorticity continued west- northwestward, eventually crossing southern California into the Pacific.

2) METEOROLOGICAL STATISTICS

The maximum flight-level winds observed by the air- craft were 85 kt at 0334 UTC 9 July (at an altitude of 457 m) and at 1517 UTC 15 July (at 700 mb). The latter observation was made as the eye of Claudette was crossing the Texas coast. Global positioning system (GPS) dropsondes deployed by the aircraft reported surface winds of 73 kt at 1526 UTC 10 July and 70 kt at 1516 UTC 15 July.

Early on 9 July, in the central Caribbean, an aircraft

Document info
Document views57
Page views57
Page last viewedFri Dec 02 18:51:54 UTC 2016
Pages30
Paragraphs1627
Words16885

Comments