000
AXNT20 KNHC 121144
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT MON OCT 12 2009

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 17N42W TO 11N47W MOVING NW 10-15 KT. 
WAVE REMAINS TILTED WITH SMALL CYCLONIC CIRCULATIONS SPINNING 
OFF TO THE NE FROM THE N PORTION OF THE TROPICAL WAVE CAUGHT UP 
IN AN UPPER TROUGH. ALTHOUGH THE WAVE IS ALONG THE LEADING EDGE 
OF A MOISTURE MAXIMUM IN THE TOTAL PRECIPITABLE WATER IMAGERY... 
THERE ARE ONLY ISOLATED SHOWERS ALONG THE WAVE AXIS AND NO DEEP 
CONVECTION. HOWEVER...ONE OF THE SMALL CIRCULATIONS N OF THE 
WAVE AXIS IS GENERATING SCATTERED MODERATE/ISOLATED STRONG 
CONVECTION WITHIN A 60 NM RADIUS OF 19N38W. 

TROPICAL WAVE IS ALONG 81W S OF 18N MOVING W NEAR 15 KT. WAVE 
REMAINS EMBEDDED WITHIN A DEEP LAYER MOISTURE MAXIMUM IN THE 
TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS/ 
THUNDERSTORMS ARE S OF 12N TO OVER CENTRAL AMERICA BETWEEN 
COLOMBIA AND COSTA RICA. 

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N12W 6N21W 13N42W 10N64W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 9N-11N 
BETWEEN 30W-35W WITH CLUSTERS OF SIMILAR CONVECTION FROM 4N-10N 
BETWEEN 11W-23W. 

...DISCUSSION...

GULF OF MEXICO...
THE QUASI-STATIONARY FRONT REMAINS ACROSS THE GULF WITH PORTIONS 
OF IT BACKING N AS A WARM SECTORS RUNNING ACROSS NE FLORIDA 
ALONG THE N GULF COAST TO INLAND OVER MEXICO JUST S OF 
BROWNSVILLE TEXAS. THE FRONT CONTINUES TO WEAKEN WITH ISOLATED 
SHOWERS N OF 28N E OF 91W AND N OF 26N FROM 91W-96W. A BROAD 
UPPER RIDGE ANCHORED OVER THE E GULF NEAR 26N84W DOMINATES THE 
ENTIRE BASIN PROVIDING DIFFLUENCE ALOFT OVER THE W GULF TO 
GENERATE SCATTERED SHOWERS/THUNDERSTORMS WITHIN 90 NM OF LINE 
FROM 25N95W INTO THE BAY OF CAMPECHE TO THE COAST OF MEXICO NEAR 
19N94W. THE REMAINDER OF THE GULF IS EXPERIENCING GENERALLY FAIR 
WEATHER THIS MORNING WITH ISOLATED SHOWERS AND POSSIBLE ISOLATED 
THUNDERSTORMS OVER THE REMAINDER OF THE W GULF S OF 27N W OF 
90W. A SURFACE RIDGE IS BUILDING OVER THE E GULF ALONG 25N AND 
WILL CONTINUE TO BUILD W AS THE FRONTAL SYSTEM CONTINUES TO 
WEAKEN AND DRIFT NORTHWARD. 

CARIBBEAN SEA...
A SURFACE TROUGH...REMNANTS OF HENRI...EXTENDS FROM THE BAHAMA 
ISLANDS NEAR 23N75W ACROSS THE E CUBA TO NEAR 19N76W WHILE A 
SECOND SURFACE TROUGH...A REMNANT FRONTAL BOUNDARY...EXTENDS 
ACROSS THE VIRGIN ISLANDS NEAR 18N62W TO S OF THE MONA PASSAGE 
NEAR 17N67W. BROAD UPPER RIDGE THAT COVERS THE W AND CENTRAL 
ATLC IS GIVING MOST OF THE CARIBBEAN UPPER EASTERLY WINDS AND 
COUPLED WITH THE SURFACE TROUGHS ARE PRODUCING SCATTERED 
SHOWERS/ISOLATED THUNDERSTORMS OVER PORTIONS OF THE GREATER 
ANTILLES FROM 16N-19N FROM 61W-80W WITH ISOLATED SHOWERS/ 
THUNDERSTORMS S OF 20N BETWEEN 80W-87W. VERY DRY AIR AND 
SUBSIDENCE IS OVER THE E CARIBBEAN S OF 16N E OF 80W GIVING THE 
AREA CLEAR SKIES THIS MORNING. 

ATLANTIC OCEAN...
A QUASI-STATIONARY FRONT ENTERS THE REGION NEAR 32N69W 
CONTINUING ACROSS NE FLORIDA NEAR ST AUGUSTINE INTO THE GULF OF 
MEXICO. BROAD UPPER RIDGE DOMINATES THE ATLC W OF 40W ANCHORED 
NEAR 27N70W WHICH HAS STALLED THE EASTERLY MOVEMENT OF THE FRONT 
INTO THE REGION. A SURFACE HIGH RIDGE COVERS THE W ATLC INTO THE 
E GULF OF MEXICO N OF 22N W OF 55W ANCHORED BY A 1021 MB HIGH 
NEAR 30N70W. A SURFACE TROUGH...REMNANTS OF HENRI...IS IN THE 
FAR SW ATLC EXTENDING FROM THE BAHAMA ISLANDS NEAR 23N75W ACROSS 
THE E CUBA INTO THE CARIBBEAN. A SHARP UPPER TROUGH DIGS S INTO 
THE E ATLC NEAR 32N30W S TO 15N32W THEN EXTENDS W AS A SHEAR 
AXIS ALONG 15N45W OVER TRINIDAD AND THE N PORTION OF SOUTH 
AMERICA SUPPORTING A STATIONARY FRONTAL BOUNDARY THAT ENTERS THE 
REGION NEAR 32N27W EXTENDING ALONG 24N34W TO 18N48W CONTINUING 
AS A SURFACE TROUGH ALONG 18N61W ACROSS THE VIRGIN ISLANDS INTO 
THE NE CARIBBEAN TO NEAR 17N67W. SCATTERED SHOWERS/ISOLATED 
THUNDERSTORMS ARE WITHIN 200 NM E OF THE FRONT FROM 23N-29N AND 
IN THE NE CARIBBEAN. 
 
$$
WALLACE