[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031810
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI OCT 03 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1545 UTC.

...TROPICAL WAVES...

A NEW TROPICAL WAVE HAS BEEN ANALYZED ALONG 18W BETWEEN 8N AND
17N MOVING W AROUND 10-15 KT.  SCATTERED MODERATE/ISOLATED
STRONG CONVECTION EXISTS WITHIN 120 NM OF THE WAVE AXIS.  THIS
WAS DIAGNOSED VIA SURFACE STATIONS IN WEST AFRICA...MODEL
ANALYSES...AND THE CIMSS WAVETRAK VORTICITY.

TROPICAL WAVE IS ALONG 46W BETWEEN 10N AND 18N MOVING W AROUND
10 KT.   WAVE CONTAINS ONLY ISOLATED SHOWERS WITHIN 120 NM OF
THE WAVE AXIS.  WAVE IS WELL-DEFINED VIA MODEL ANALYSES...CIMSS
WAVETRAK VORTICITY...AND TOTAL PRECIPITABLE WATER IMAGERY.

TROPICAL WAVE IS ALONG 58W BETWEEN 9N AND 18N MOVING W 10-15 KT.
NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS OCCURRING
WITHIN 120 NM ON EITHER SIDE OF THE WAVE AXIS SOUTH OF 16N.
WAVE IS WELL-DEFINED ON VISIBLE SATELLITE IMAGERY...CIMSS
WAVETRAK VORTICITY...AND TOTAL PRECIPITABLE WATER IMAGERY...BUT
NOT IN THE MODEL ANALYSES.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 13N17W 7N25W 5N32W 7N45W
11N61W.  SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN
120 NM N OF THE AXIS AND 240 NM S OF THE AXIS FROM THE WEST
AFRICAN COAST TO 32W.  NUMEROUS MODERATE/SCATTERED STRONG
CONVECTION WITHIN 120 NM ON EITHER SIDE OF THE AXIS FROM 53W
WESTWARD TO THE SOUTH AMERICAN COAST.

...DISCUSSION...

GULF OF MEXICO...
THE GULF OF MEXICO IS DOMINATED BY POST-FRONTAL...DRY STABLE
AIR.  WINDS ARE WEAK AND TURNING ANTICYCLONICALLY AT THE SURFACE
UNDER THE INFLUENCE OF A MODEST HIGH OVER THE SE UNITED STATES.
IN THE UPPER LEVELS...SUBSIDENT AND RELATIVELY ZONAL WEST TO
WEST- SOUTHWESTERLY MID TO UPPER FLOW EXISTS ACROSS THE GULF
WITH A WEAK MID-LEVEL VORT MAX JUST SOUTH OF LOUISIANA.


CARIBBEAN SEA...
A WEAK 1009 MB LOW IS LOCATED IN THE GULF OF HONDURAS.  A
SURFACE TROUGH EXTENDS FROM NEAR SOUTHERN CUBA...THROUGH THE
LOW...AND INTO HONDURAS/NICARAGUA.  NUMEROUS MODERATE/SCATTERED
STRONG CONVECTION EXISTS BETWEEN 80W AND 84W IN ASSOCIATION WITH
THE LOW/TROUGH.  ADDITIONAL CONVECTION IS OCCURRING NEAR THE
WINDWARD ISLANDS IN ASSOCIATION WITH THE AFOREMENTIONED TROPICAL
WAVE NEAR 58W.  WINDS ARE EASTERLY 10 TO 20 KT IN THE EASTERN
CARIBBEAN...SOUTHEASTERLY UP TO 20 KT IN THE WESTERN CARIBBEAN
EAST OF THE TROUGH AXIS...AND NORTHEASTERLY UP TO 20 KT WEST OF
THE TROUGH AXIS.  IN THE UPPER LEVELS...A HIGH PRESSURE IS
CENTERED OVER THE TROUGH AXIS IN THE WESTERN CARIBBEAN.  IN THE
EASTERN CARIBBEAN EASTERLY FLOW ALOFT DOMINATES UP THE INFLUENCE
OF A STRONG RIDGE IN THE WESTERN ATLANTIC.  HOWEVER...A
WELL-DEFINED CLOSED LOW CENTERED OVER THE WINDWARD ISLANDS IS
CAUSING UPPER LEVEL SOUTHWESTERLIES OVER THE LEEWARD ISLANDS.
THIS MAY BE FORCING THE ENHANCED CONVECTION IN ASSOCIATION WITH
THE EASTERLY WAVE AT 58W.

ATLANTIC OCEAN...
A COLD FRONT BEGINNING AT A WEAK 1013 MB LOW CENTERED AT 32N75W
EXTENDS SOUTHWESTWARD TO THE FLORIDA STRAITS.  SCATTERED SHOWERS
EXIST WITHIN 120 NM EAST OF THE FRONTAL BOUNDARY.  EARLIER...THE
FRONT HAD BEEN DIAGNOSED AS A STATIONARY FEATURE...BUT HAS BEEN
RECHRISTENED A COLD FRONT DUE TO ITS PROGRESSIVE NATURE TODAY.
FARTHER EAST...A SURFACE TROUGH IS OBSERVED ALONG 44W FROM 20N
TO 31N.  SCATTERED MODERATE CONVECTION EXISTS WITHIN 120 NM ON
EITHER SIDE OF THE TROUGH AXIS SOUTH OF 24N.  SCATTERED MODERATE
CONVECTION IS ALSO OCCURRING WITHIN 120 NM OF A LINE FROM 12N36W
TO 19N41W.  THIS APPEARS TO BE DUE TO THE BOUNDARY OF A MOIST
AIRMASS AND SAHARAN AIR LAYER COUPLED WITH UPPER LEVEL
SOUTHWESTERLIES.  IN THE UPPER LEVELS...A LARGE STRONG UPPER
RIDGE DOMINATES THE WESTERN ATLANTIC FROM 50 TO 72W.  WESTWARD
OF 72W...STRONG SOUTHWESTERLY WINDS EXIST BETWEEN UPPER RIDGE
AXIS AND THE STRONG LONG WAVE OVER THE EASTERN UNITED STATES.
EASTWARD OF 50W...A DEEP LOW IS OBSERVED NEAR 24N44W...WHICH IS
ASSOCIATED WITH THE EARLIER MENTIONED SURFACE TROUGH AT THE SAME
LONGITUDE.

$$
LANDSEA

WWWW
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