Caribbean-On-Line's Caribbean Hurricane Blog



Tropical Storm Henri

Henri devolves into a depression

Published on October 8, 2009 4:42 AM | Comments

Henri is weakening:

TROPICAL DEPRESSION HENRI DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009 500 AM AST THU OCT 08 2009

ALTHOUGH A FEW SHOWERS AND THUNDERSTORMS HAVE REDEVELOPED NEAR THE
ESTIMATED CENTER OF CIRCULATION...THE CONVECTION IS POORLY
ORGANIZED AND PROBABLY TRANSIENT. HENRI HAS A VERY SMALL
CIRCULATION THAT CONTINUES TO BE IN AN ENVIRONMENT OF STRONG
SOUTHWESTERLY SHEAR...DIAGNOSED AT AROUND 20 KT BY THE SHIPS MODEL.
THEREFORE...THE TROPICAL CYCLONE IS EXPECTED TO DISSIPATE WITHIN
12 TO 24 HOURS IF NOT SOONER. THE SHEAR IS ASSOCIATED WITH AN
UPPER-LEVEL TROUGH OR SHEAR AXIS SITUATED JUST TO THE NORTHWEST OF
THE TROPICAL CYCLONE...AND THE GLOBAL MODELS INDICATE THAT THE
UPPER TROUGH WILL WEAKEN WITHIN THE NEXT DAY OR SO. THEREAFTER...
HENRI OR ITS REMNANT LOW IS EXPECTED TO MOVE INTO AN AREA OF
UPPER-LEVEL NORTHEASTERLY TO NORTHERLY FLOW ASSOCIATED WITH A LARGE
200 MB ANTICYCLONE CENTERED JUST EAST OF FLORIDA. ALTHOUGH THE
SHEAR OVER HENRI OR ITS REMNANT DISTURBANCE WILL PROBABLY LESSEN
SOMEWHAT IN A DAY OR TWO...SUBSIDENCE ASSOCIATED WITH THE
AFOREMENTIONED ANTICYCLONE SHOULD PRODUCE A LARGE-SCALE DYNAMICAL
ENVIRONMENT THAT IS NOT VERY CONDUCIVE FOR RESTRENGTHENING.

SATELLITE FIXES INDICATE THAT THE MOTION CONTINUES AT AROUND 285/13.
HENRI OR ITS REMNANT LOW SHOULD GRADUALLY TURN TOWARD THE WEST OR
EVEN A LITTLE SOUTH OF WEST DURING THE NEXT 48 HOURS AS IT BECOMES
INFLUENCED BY A STRONG MID-LEVEL ANTICYCLONE OVER THE EXTREME
WESTERN ATLANTIC. THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE
PREVIOUS ONE AND IS NEAR THE SOUTHERN SIDE OF THE MODEL GUIDANCE
ENVELOPE.



New Atlantic storm Henri expected to fizzle out

Published on October 7, 2009 3:51 PM | Comments

From Reuters:

MIAMI (Reuters) - Tropical Storm Henri formed in the Atlantic Ocean, east of the Caribbean's Leeward Islands, on Tuesday, but was expected to dissipate within two days, the U.S. National Hurricane Center said.

The eighth tropical storm of the 2009 Atlantic hurricane season had sustained winds of 40 miles per hour (65 km per hour) and was located about 600 miles east of the northern Leewards at 5 p.m. EDT (2100 GMT), the hurricane center said.

The system was moving to the west-northwest at 18 mph on a path that would keep it well north of the Caribbean islands in the near future, the center added.

Henri was moving through an area with high wind shear, forecasters said. Wind shear is a difference in wind speeds at different altitudes that can tear apart nascent cyclones.

"The cyclone is expected to weaken to a depression over the next 24 hours and most of the global model fields show Henri dissipating by 48 hours," the hurricane center said in a statement.

Computer models disagreed on the future for the remnants of the cyclone. Several took it to the southwest in the direction of Puerto Rico and Hispaniola, the island shared by Haiti and the Dominican Republic. One had it headed out into the open Atlantic.



Tropical Storm Henri

Published on October 7, 2009 12:19 PM | Comments

We haven't been paying much attention to Henri because it doesn't seem like it will affect the Caribbean. But the path is fairly close now and the remnants of it may come through the Bahamas and/or the T&C.

TROPICAL STORM HENRI DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102009 1100 AM AST WED OCT 07 2009

SATELLITE IMAGES SHOW THAT THE CENTER OF HENRI HAS BECOME EXPOSED AGAIN TO THE WEST OF A MASS OF DEEP CONVECTION. IN ADDITION...THE LOW-CLOUD CIRCULATION CENTER LOOKS A LITTLE LESS WELL-DEFINED THAN YESTERDAY. DVORAK CLASSIFICATIONS HAVE DECREASED SOMEWHAT...AND THE INITIAL WIND SPEED HAS BEEN REDUCED TO 40 KT FOR THE ADVISORY. FURTHER WEAKENING IS LIKELY DUE TO SOUTHWESTERLY SHEAR FOR THE NEXT DAY OR SO. AFTER THAT TIME...MOST OF GLOBAL MODELS INDICATE THAT HENRI WILL ENCOUNTER A SHARP UPPER-LEVEL SHEAR AXIS...AND THEN COME UNDER THE INFLUENCE OF STRONG...CONVERGENT...NORTHEASTERLY UPPER FLOW. THESE ENVIRONMENTAL CONDITIONS ARE RATHER HOSTILE...AND THE OFFICIAL FORECAST CONTINUES THE TREND OF THE PREVIOUS FORECAST PACKAGES BY SHOWING THE CYCLONE DISSIPATING WITHIN A COUPLE OF DAYS.

THE BEST ESTIMATE OF INITIAL MOTION IS 290/13...A LITTLE FASTER THAN BEFORE. SUBTROPICAL RIDGING OVER THE WESTERN ATLANTIC OCEAN SHOULD FAVOR A WEST OR WEST-NORTHWEST MOTION OF HENRI OVER THE NEXT 24-36 HOURS. THIS RIDGE IS EXPECTED BECOME STRONGER AFTER THAT TIME...WHICH SHOULD CAUSE A WESTWARD TURN OF THE TROPICAL CYCLONE OR ITS REMNANT. MOST OF THE MODEL GUIDANCE IS IN AGREEMENT ON THE TRACK...AND THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ADVISORY...AND ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE.