Tropical Storm Cristobal Moves Toward Louisiana

Tropical Storm Cristobal moved toward Louisiana on Friday night.  At 11:00 p.m. EDT on Friday the center of Tropical Storm Cristobal was located at latitude 22.7°N and longitude 90.1°W which put it about 440 miles (705 km) south of the Mouth of the Mississippi River.  Cristobal was moving toward the north at 14 m.p.h. (22 km/h).  The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h).  The minimum surface pressure was 998 mb.

A Tropical Storm Warning was in effect for the portion of the coast from Morgan City, Louisiana to the Okaloosa/Walton County Line in Florida including Lake Pontchartrain and Lake Maurepas.  A Tropical Storm Watch was in effect for the portion of the coast from Intracoastal City to Morgan City, Louisiana.

Tropical Storm Cristobal strengthened slowly after the center of circulation moved over the southern Gulf of Mexico.  Cristobal moved under the western side of an upper level ridge.  The flow around the ridge created upper level divergence which pumped away mass and caused the surface pressure to decrease by several millibars.  Cristobal strengthened back to a tropical storm when the wind speed increased in response to the decrease in pressure.  The distribution of thunderstorms and the wind field around Tropical Storm Cristobal remained asymmetrical.  The strongest rainbands wrapped around the eastern and northern sides if the circulation.  Winds to tropical storm force extended out 240 miles (390 km) on the eastern side of Cristobal.  Winds to tropical storm force extended out 140 miles (220 km) northwest of the center of circulation.  The winds in the southwestern part of the circulation were mostly below tropical storm force.

Tropical Storm Cristobal will move through an environment favorable for intensification during the next 24 hours.  Cristobal will move over water where the Sea Surface Temperature is near 27°C.  It will continue to move under the western side of the upper level ridge.  The ridge will produce southerly winds which will blow toward the top of the circulation.  Those winds will cause some vertical wind shear, which will inhibit intensification.  However, the ridge will continue to create upper level divergence which will support intensification.  Tropical Cyclone Cristobal will strengthen on Saturday.

Tropical Storm Cristobal will move around the western end of a subtropical high pressure system over the western Atlantic Ocean.  The high will steer Cristobal toward the north during the next 24 to 36 hours.  On its anticipated track Tropical Storm Cristobal will approach the coast of Louisiana on Sunday afternoon.

The circulation around Tropical Storm Cristobal is large and winds to tropical storm force will reach the coast around the northern Gulf of Mexico several hours before the center makes landfall.  Cristobal will bring gusty winds to the portion of the coast from Northwest Florida to Southeast Louisiana on Sunday.  Those winds will blow water toward the coast and they will cause a storm surge of 1 to 4 feet (0.3 to 1.3 meters) in many locations.  The water could rise by 3 to 6 feet (1 to 2 meters) in some locations.  Tropical Storm Cristobal will also drop heavy rain over parts of Northwest Florida, Southwest Alabama, Southern Mississippi and Southeast Louisiana.  Flood Watches have been issued for some of those areas.