[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 150605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED APR 15 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 0000 UTC SURFACE ANALYSIS AND GOES0-12 SATELLITE
IMAGERY THROUGH 0315 UTC...AND METEOSAT-9 IMAGERY THROUGH
0515 UTC.

...THE ITCZ...
FROM 5N8W AT THE SOUTHERN COAST OF LIBERIA...CROSSING THE
EQUATOR ALONG 15W...TO 2S23W...CROSSING THE EQUATOR ALONG
30W TO 1N34W...AND GOING INTO NORTHEASTERN BRAZIL NEAR 3S44W.
A SURFACE TROUGH WAS ANALYZED ALONG 13W AT 15/0000 UTC.
I STUDIED ALL THE AVAILABLE METEOSAT-9 VISIBLE SATELLITE FROM
14/0930 UTC UNTIL 14/1645 UTC AND I SEE ONLY A SMALL AMOUNT
OF CYCLONIC TURNING AT AN UNKNOWN LEVEL IN THE ATMOSPHERE NEAR
2N17W AT THE END OF THAT CYCLE OF IMAGES. I SEE A SOLID FIELD OF
LOW CLOUDS IN THAT CYCLE OF VISIBLE IMAGES MOVING FROM THE AREA
TO THE SOUTH OF THE EQUATOR TOWARD THE ITCZ...WITHOUT CYCLONIC
TURNING. I AM INCLINED NOT TO BELIEVE THAT A SURFACE TROUGH
EXISTS NOW OR EXISTED AT THE TIME THAT IT WAS ADDED TO THE MAP
AND WHERE IT WAS PUT ON THE MAP ANALYSIS YESTERDAY. THAT IS NOT
TO SAY THAT A SURFACE TROUGH MAY NOT FORM AT SOME TIME IN THE
FUTURE IN THE ITCZ. SOME FORM OF CYCLONIC TURNING IS EVIDENT IN
THE LATEST METEOSAT-9 INFRARED IMAGERY...BUT AT WHICH LEVEL OF
THE ATMOSPHERE IS NOT FOR CERTAIN. POSSIBLE PRECIPITATION IS
SURROUNDED BY BROKEN TO OVERCAST MULTILAYERED CONVECTIVE DEBRIS
CLOUDS ARE TO THE SOUTH OF 7N BETWEEN 10W AND 20W. ISOLATED AND
DISORGANIZED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE TO
THE SOUTH OF 3N BETWEEN 25W AND 50W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL RIDGE IS ALONG 102W IN MEXICO. THE FLOW ON THE
EASTERN SIDE OF THE RIDGE MOVES ACROSS THE OPEN WATERS OF THE
GULF OF MEXICO RIGHT INTO THE DEEP LAYER TROUGH THAT IS
SUPPORTING THE CURRENT EASTERN GULF OF MEXICO COLD FRONT. THE
FRONT EXTENDS FROM NORTHERN FLORIDA TO THE SOUTH CENTRAL GULF OF
MEXICO JUST TO THE NORTH OF THE YUCATAN PENINSULA. ISOLATED
MODERATE TO STRONG SHOWERS AND THUNDERSTORMS ARE FROM 24N TO 25N
BETWEEN 81W AND 85W...AND IN THE ATLANTIC OCEAN FROM 26N TO 28N
BETWEEN 75W AND 78W. A SEPARATE AREA OF UPPER LEVEL ANTICYCLONIC
FLOW MOVES FROM THE EASTERN PACIFIC OCEAN ACROSS SOUTHERN MEXICO
AND THE SOUTHWESTERN CORNER OF THE GULF OF MEXICO TO THE YUCATAN
PENINSULA.

THE CARIBBEAN SEA...
A NORTH-TO-SOUTH SURFACE TROUGH IS IN THE YUCATAN PENINSULA
ALONG 88W/89W. SHOWERS AND POSSIBLE THUNDERSTORMS ARE BETWEEN
88W AND 89W FROM BELIZE TO 20N AND THE CLOUD TOPS ARE BEING
SHEARED BY THE UPPER LEVEL WESTERLY WIND FLOW. A LOT OF MIDDLE
LEVEL TO UPPER LEVEL WESTERLY WIND FLOW IS MOVING ACROSS THE
AREA. UPPER LEVEL SOUTHWESTERLY WIND FLOW MOVES ACROSS COSTA
RICA AND PANAMA INTO THE SOUTHWESTERN CORNER OF THE CARIBBEAN
SEA TOWARD THE CENTRAL WATERS OF THE AREA. A SHORTWAVE MIDDLE
LEVEL TO UPPER LEVEL TROUGH ALONG 56W/57W IN THE ATLANTIC OCEAN
IS IMPARTING CYCLONIC FLOW INTO THE AREA FROM PUERTO RICO
EASTWARD.

THE ATLANTIC OCEAN...
LARGE-SCALE UPPER LEVEL ANTICYCLONIC FLOW COVERS THE AREA TO THE
NORTH OF 20N BETWEEN 39W AND 80W. A SHORTWAVE MIDDLE LEVEL TO
UPPER LEVEL TROUGH ALONG 56W/57W FROM 10N TO 20N IS IMPARTING
CYCLONIC FLOW INTO THE CARIBBEAN SEA FROM PUERTO RICO EASTWARD.
THIS CYCLONIC FLOW REACHES AT LEAST 15N40W BEFORE IT BECOMES
LESS APPARENT. BROAD LARGE-SCALE UPPER LEVEL ANTICYCLONIC FLOW
IS TO THE SOUTH OF 11N60W 17N40W 25N30W BEYOND 28N20W. THE
SOUTHERN BOUNDARY OF AN EASTERN ATLANTIC OCEAN DEEP LAYER TROUGH
REACHES MOROCCO ALONG 30N TO THE EAST OF 20W. THE COLD FRONT
FROM 24 HOURS AGO HAS DISSIPATED.

$$
MT



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