[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271812
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT 27 NOV 2004

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

BASED ON 1200 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 1745 UTC.

SPECIAL FEATURE...
A NON-TROPICAL AREA OF LOW PRESSURE IS CENTERED OVER THE CENTRAL
ATLANTIC OCEAN ABOUT 1175 MILES SOUTHWEST OF THE WESTERN AZORES.
UPPER LEVEL WINDS CURRENTLY APPEAR TO BE UNFAVORABLE FOR
SUBTROPICAL OR TROPICAL DEVELOPMENT. CONDITIONS COULD BECOME
MORE FAVORABLE HOWEVER FOR DEVELOPMENT DURING THE NEXT COUPLE
OF DAYS. DEEP LAYER CYCLONIC CIRCULATION CENTER NEAR 26N43W ON
WATER VAPOR IMAGERY. SURFACE 1002 MB GALE CENTER IS NEAR
27N44W...DRIFTING NORTHWESTWARD. THE HIGH SEAS FORECAST WITHIN
240 NM OF THE CENTER IN THE NORTHERN SEMICIRCLE IS FOR WIND FROM
30 TO 35 KT AND SEAS FROM 11 TO 16 FT. A DISSIPATING OCCLUSION IS
ALONG 27N44W 30N42W 28N39W. A DISSIPATING COLD FRONT GOES FROM
28N39W TO 23N39W 19N44W. A DEVELOPING COLD FRONT EXTENDS FROM
THE SURFACE LOW CENTER TO 25N42W CURVING TO 21N45W TO 24N52W.
A DEEP LAYER TROUGH HAS BEEN CARVED OUT IN THE ATMOSPHERE...FROM
26N53W TO 17N45W TO 10N50W TO THE COAST OF GUYANA NEAR 6N57W.


...ITCZ...

ITCZ 7N10W 7N30W 8N50W 8N63W...IN COLOMBIA FROM 7N76W TO 8N83W
SOUTH OF THE COSTA RICA/PANAMA BORDER. WIDELY SCATTERED MODERATE
TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM THE EQUATOR TO
11N BETWEEN 10W AND 40W. ISOLATED MODERATE SHOWERS FROM 5N TO 8N
BETWEEN 41W AND 56W.

...DISCUSSION...

THE GULF OF MEXICO...
A DEEP LAYER TROUGH RUNS FROM THE ARKANSAS/MISSISSIPPI BORDER
NEAR 34N TO THE MOUTH OF THE MISSISSIPPI RIVER TO COASTAL MEXICO
NEAR 23N98W. THIS TROUGH SUPPORTS A SURFACE FRONTAL BOUNDARY.
THE COLD FRONT RUNS FROM NORTHEAST TEXAS TO SOUTH TEXAS.
A SQUALL LINE IS JUST EAST OF THE FRONT. A WARM FRONT REACHES
THE NORTHEASTERN GULF WATERS. THE COLD FRONT WAS DEFINED AT
27/1500 UTC BY A ROPE CLOUD...A THIN CLOUD LINE IN THE NORTH-
WESTERN GULF WATERS...FROM SOUTHEASTERN LOUISIANA TO 27N94W
TO COASTAL MEXICO NEAR 23N98W. ANOTHER THIN LINE OF CLOUDS
SHOWS CONFLUENT FLOW ALONG 27N87W 26N90W 24N92W 22N93W. BROKEN
MULTILAYERED CLOUDS ARE NORTH OF 24N EAST OF 90W. SCATTERED
HIGH CLOUDS MOVING ON TOP OF SCATTERED LOW CLOUDS WEST OF 90W.

THE CARIBBEAN SEA...
DISSIPATING SURFACE STATIONARY FRONT 24N74W FROM THE BAHAMAS TO
NORTHWESTERN COASTAL CUBA TO 22N87W NEAR THE NORTHEASTERN TIP OF
THE YUCATAN PENINSULA. THE MIDDLE TO UPPER LEVEL WIND FLOW INTO
THE AREA FROM 10N TO 20N BETWEEN 50W AND 60W BECOMES DIFFLUENT...
WITH THE FLOW IN THE EASTERN PART OF THAT BLOCK CONTINUING
TOWARD THE DEEP LAYER TROUGH...AND THE FLOW IN THE WESTERN PART
OF THAT BLOCK BECOMING NORTHEASTERLY...HEADING TO THE CARIBBEAN
SEA. BROAD MIDDLE LEVEL ANTICYCLONIC FLOW AND MIDDLE TO UPPER
LEVEL DRY AIR EVERYWHERE ELSE...EXCEPT FOR SOME SHOWERS IN THE
EXTREME SOUTHEASTERN CORNER WITH THE ITCZ...SOME SHOWERS IN THE
SOUTHWESTERN CORNER WITH THE ITCZ...AND SHOWERS EAST OF NICARAGUA
WITH THE 16N78W 12N80W 8N81W SURFACE TROUGH. ISOLATED MODERATE
SHOWERS AND POSSIBLE THUNDERSTORMS FROM 12N TO 13N BETWEEN 61W
AND 62W NEAR GRENADA AND ST. VINCENT AND THE GRENADINES WITH THE
ITCZ. WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED STRONG
SHOWERS AND THUNDERSTORMS FROM 12N TO 15N BETWEEN 80W AND 82W
WITH THE SURFACE TROUGH. WIDELY SCATTERED TO SCATTERED
MODERATE/ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM PANAMA
AND COSTA RICA TO 12N BETWEEN 77W AND 85W WITH THE ITCZ.

THE ATLANTIC OCEAN...
THE MIDDLE TO UPPER LEVEL WIND FLOW IS WEST TO NORTHWEST FROM
FLORIDA INTO THE WESTERN ATLANTIC OCEAN IN THE SUBTROPICS...
SHIFTING TO NORTHWESTERLY WIND FLOW...DIVING TOWARD THE DEEP
LAYER 26N43W 17N45W 10N50W 6N57W TROUGH. THE WIND FLOW INTO THE
AREA FROM 10N TO 20N BETWEEN 50W AND 60W BECOMES DIFFLUENT...
WITH THE FLOW IN THE EASTERN PART OF THAT BLOCK CONTINUING
TOWARD THE DEEP LAYER TROUGH...AND THE FLOW IN THE WESTERN PART
OF THAT BLOCK BECOMING NORTHEASTERLY...HEADING TO THE CARIBBEAN
SEA. A NORTHWEST-TO-SOUTHEAST TILTED TROUGH RUNS FROM 33N58W TO
26N52W IN THE MIDDLE OF THIS OTHER FLOW REGIME. THIS TROUGH
SUPPORTS THE DISSIPATING SURFACE COLD FRONT FROM 32N59W TO
27N66W TO 24N74W. DISSIPATING SURFACE STATIONARY FRONT 24N74W
FROM THE BAHAMAS TO NORTHWESTERN COASTAL CUBA TO 22N87W NEAR
THE NORTHEASTERN TIP OF THE YUCATAN PENINSULA. BROAD UPPER LEVEL
ANTICYCLONIC FLOW IS EAST OF THE DEEP LAYER TROUGH TO AFRICA.
BROAD DEEP LAYER CYCLONIC FLOW FROM ANOTHER CYCLONIC CIRCULATION
CENTER AND WELL-ESTABLISHED FRONTAL BOUNDARY ARE NORTH OF 30N
BETWEEN EUROPE AND 30W.

$$
MT


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