000
AXNT20 KNHC 181800
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU JUN 18 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS MOVING THROUGH THE ISTHMUS OF TEHUANTEPEC TO THE 
SOUTH OF 20N. A WEAK MIDDLE LEVEL INVERTED TROUGH IS ALONG 100W/101W 
FROM 16N TO 23N. A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION
CENTER IS NEAR 24N85W...APPEARING TO BE MOVING SOUTHWESTWARD. DRY 
AIR IN SUBSIDENCE ON THE WATER VAPOR IMAGERY COVERS THE GULF OF 
MEXICO TO THE WEST OF THE CYCLONIC CENTER. SHOWERS AND THUNDERSTORMS
ARE ALONG THE MEXICO COAST AND IN THE COASTAL PLAINS IN THE GULF OF 
MEXICO FROM 18N TO 21N BETWEEN 96W AND 97W...IN THE CENTER OF THE 
ISTHMUS OF TEHUANTEPEC...AND IN THE WESTERN PART OF THE GULF OF 
TEHUANTEPEC.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 43W/44W TO THE SOUTH OF 8N
MOVING WEST 10 TO 15 KT. THIS WAVE IS BEING FOLLOWED ON THE BASIS OF 
AN AREA OF CONCENTRATED MOISTURE ON THE MIMIC-TOTAL TPW FIELD...AND
IN VISIBLE SATELLITE IMAGERY. ANY NEARBY PRECIPITATION IS ALREADY
EMBEDDED IN THE ITCZ.

...THE ITCZ...

FROM AFRICA NEAR 8N12W TO 7N20W TO 5N30W TO 3N40W...PASSING THROUGH 
50W AT THE EQUATOR INTO NORTHEASTERN BRAZIL NEAR 1S52W. ISOLATED TO 
WIDELY SCATTERED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE 
FROM 5N TO 11N BETWEEN 10W AND 20W...FROM 5N TO 8N BETWEEN 20W AND 
30W...AND FROM 4N TO 7N BETWEEN 33W AND 45W.

...DISCUSSION...

ACROSS INTERIOR MEXICO AND IN THE GULF OF MEXICO...
A TROPICAL WAVE IS MOVING THROUGH THE ISTHMUS OF TEHUANTEPEC TO
THE SOUTH OF 20N. A WEAK MIDDLE LEVEL INVERTED TROUGH IS ALONG
100W/101W FROM 16N TO 23N. A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC 
CIRCULATION CENTER IS NEAR 24N85W...APPEARING TO BE MOVING
SOUTHWESTWARD. DRY AIR IN SUBSIDENCE ON THE WATER VAPOR IMAGERY
COVERS THE GULF OF MEXICO TO THE WEST OF THE CYCLONIC CENTER.
SHOWERS AND THUNDERSTORMS ARE ALONG THE MEXICO COAST AND IN THE
COASTAL PLAINS IN THE GULF OF MEXICO FROM 18N TO 21N BETWEEN 96W
AND 97W...IN THE CENTER OF THE ISTHMUS OF TEHUANTEPEC...
AND IN THE WESTERN PART OF THE GULF OF TEHUANTEPEC.
 
THE CARIBBEAN SEA...
A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH THE AREA OF THE 
SOUTHERN BAHAMAS AND THE WINDWARD PASSAGE...INTO THE SOUTH CENTRAL 
CARIBBEAN SEA...TO THE COAST OF COLOMBIA NEAR THE GUAJIRA PENINSULA.
SHOWERS AND THUNDERSTORMS ARE IN THE AREA TO THE SOUTH OF 11N 
BETWEEN 77W AND 84W. SOME OF THIS PRECIPITATION REACHES THE GULF OF 
URABA AND COLOMBIA...AND SOME OF IT REACHES SOUTHEASTERN NICARAGUA
AND NORTHEASTERN COSTA RICA.

THE ATLANTIC OCEAN...
A DEEP LAYER CENTRAL ATLANTIC OCEAN TROUGH IS SUPPORTING THE CURRENT 
COLD FRONT THAT PASSES THROUGH 32N54W TO 30N60W TO 29N66W TO 30N70W.
A WARM FRONT CONTINUES FROM 30N70W TO A 1012 MB LOW PRESSURE CENTER 
NEAR 31N75W. A STATIONARY FRONT CONTINUES FROM THE LOW CENTER TO
31N77W AND BEYOND 32N78W. A TROUGH EXTENDS FROM THE LOW CENTER TO
THE GRAND BAHAMA ISLAND. A MIDDLE LEVEL TO UPPER LEVEL INVERTED
TROUGH IS ALONG THE LINE FROM 30N73W TO THE STRAITS OF FLORIDA...
TO THE 24N85W CYCLONIC CENTER IN THE GULF OF MEXICO. ISOLATED 
MODERATE SHOWERS ARE WITHIN 180 NM TO THE SOUTHEAST OF THE TROUGH.
SHOWERS AND THUNDERSTORMS ARE FROM 22N TO 27N BETWEEN 76W AND 79W
IN THE BAHAMAS. ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS
ARE TO THE NORTH OF 30N TO THE WEST OF 49W. ISOLATED MODERATE 
SHOWERS ARE FROM 30N TO 32N BETWEEN 37W AND 38W IN A TROUGH THAT 
PASSES THROUGH 32N38W TO 24N35W. A CYCLONIC CIRCULATION CENTER ON 
WATER VAPOR IMAGERY IS NEAR 31N20W. THE CORRESPONDING 1016 MB LOW 
PRESSURE CENTER IS NEAR 30N19W. THIS LOW CENTER IS FORECAST TO MOVE
TO THE NORTHWEST DURING THE NEXT 24 HOURS AND AWAY FROM THE CANARY 
ISLANDS. SHOWERS ARE POSSIBLE FROM 31N TO 32N BETWEEN 17W AND 19W.

$$
MT