Hurricane Sally Grinds Slowly Toward the Gulf Coast

Hurricane Sally ground its way slowly toward the Gulf Coast on Monday night.  At 11:00 p.m. EDT on Monday the center of Hurricane Sally was located at latitude 28.9°N and longitude 87.6°W which put it about 90 miles (145 km) east of the Mouth of the Mississippi River.  Sally was moving toward the west-northwest at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 100 m.p.h. (160 km/h) and there were wind gusts to 120 m.p.h. (195 km/h).  The minimum surface pressure was 986 mb.

A Hurricane Warning was in effect for the portion of the coast from Grand Isle, Louisiana to Navarre,, Florida including New Orleans, Lake Pontchartrain and Lake Maurepas.  Tropical Storm Warnings were in effect for the portions of the coast from Morgan City, to Grand Isle, Louisiana and from Navarre to Indian Pass, Florida.

After intensifying rapidly earlier on Monday, Hurricane Sally exhibited a more steady state on Monday evening.  There was a circular eye with a diameter of 16 miles (26 km) at the center of Sally.  The eye was surrounded by a ring of strong thunderstorms and the strongest winds were occurring in that ring of storms.  There was a break in the south side of the ring.  The circulation of Hurricane Sally pulled some drier air around the southern side of the core.  The drier air may have contributed to the break in the eyewall.  Storms near the core generated upper level divergence which pumped mass away to the north and the east of the hurricane.

The circulation around Hurricane Sally was relatively small.  Winds to hurricane force extended out 45 miles (75 km) from the center of circulation in the northeastern quadrant of Sally.  Elsewhere, hurricane force winds were occurring mainly in the eyewall.  Winds to tropical storm force extended out 130 miles from the center of circulation.  The winds were weakest in the southwestern quadrant of the hurricane.  The Hurricane Intensity Index (HII) for Hurricane Sally was 16.5.  The Hurricane Size Index (HSI) was 9.5 and the Hurricane Wind Intensity Size Index (HWISI) was 27.0.  Sally was capable of causing localized serious damage.

Hurricane Sally will move through an environment mostly favorable for intensification during the next 12 hours.  Sally will move over water where the Sea Surface Temperature is near 30°C.  It will be in a region where the upper level winds are weak and there will be little vertical wind shear.  Two other factors could inhibit further intensification of Hurricane Sally.  The drier air in the southern part of the circulation could limit the development of thunderstorms in that part of Sally.  The fact that Hurricane Sally is moving slowly means that it could mix cooler water to the surface which might reduce the energy available to drive the hurricane.  Even with the two inhibiting factors, Sally could intensify again on Tuesday.

Hurricane Sally will move around the western end of a subtropical high pressure system during the next 36 hours.  The steering currents are weak in that region and Sally will move slowly.  The slow movement of Hurricane Sally near the Gulf Coast means that any slight wobbles could affect the location of landfall.  On its anticipated track Hurricane Sally could approach the coasts of Mississippi and Alabama on Tuesday night.  A wobble to the left could bring Sally ashore in southeastern Louisiana while a wobble to the right would bring it closer to Northwest Florida.

Hurricane Sally will bring strong winds to the coast of Mississippi and Alabama.  Where the winds blow water toward the coast, Hurricane Sally could cause a storm surge of up to 12 feet (4 meters).  Hurricane Sally could drop nearly a foot (0.3 m) of rain on parts of southern Mississippi and Alabama.  Flash Flood Watches have been issued for parts of southern Mississippi, Alabama and Northwest Florida.

Elsewhere, Hurricane Paulette was speeding away from Bermuda, and Tropical Storms Teddy and Vicky organized over the eastern Atlantic Ocean.  At 11:00 p.m. EDT on Monday the center of Hurricane Paulette was located at latitude 35.7°N and longitude 62.3°W which put it about 275 miles (440 km) north-northeast of Bermuda.  Paulette was moving toward the northeast at 17 m.p.h. (28 km/h).  The maximum sustained wind speed was 105 m.p.h. (165 km/h) and there were wind gusts to 125 m.p.h. (200 km/h).  The minimum surface pressure was 965 mb.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Teddy was located at latitude 13.2°N and longitude 45.0°W which put it about 1100 miles (1770 km) east of the Lesser Antilles.  Teddy was moving toward the west at 13 m.p.h. (20 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1002 mb.

At 11:00 p.m. EDT on Monday the center of Tropical Storm Vicky was located at latitude 19.5°N and longitude 29.9°W which put it about 455 miles (735 km) west-northwest of the Cabo Verde Islands.  Vicky was moving toward the mprthwest at 7 m.p.h. (11 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1000 mb.

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