[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 150611
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST WED 15 DEC 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 0000 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 0545 UTC.

...ITCZ...

ITCZ 6N10W 6N20W 7N30W 7N40W 8N50W 8N60W...AND FROM THE COLOMBIA
COAST FROM 3N77W TO 3N81W AND 6N85W. SCATTERED MODERATE TO
ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM 8N TO 10N BETWEEN
34W AND 35W.  WIDELY SCATTERED MODERATE TO ISOLATED STRONG
SHOWERS AND THUNDERSTORMS FROM 2N TO 10N BETWEEN 10W AND 30W...
AND ELSEWHERE FROM 8N TO 14N BETWEEN 30W AND 40W.

...DISCUSSION...

THE GULF OF MEXICO AND THE ATLANTIC OCEAN WEST OF 60W...
BIG PUSH OF COLD AIR...BEHIND A SURFACE COLD FRONT...HAS MOVED
THROUGH FLORIDA. THE FRONT GOES THROUGH 32N70W...TO THE NORTHERN
BAHAMAS...TO 24.5N80W AND THROUGH THE STRAITS OF FLORIDA...
BRUSHING THE NORTHWESTERN COAST OF CUBA...TO REACH THE COAST OF
THE NORTHERN YUCATAN PENINSULA...INTO THE SOUTHWESTERN GULF OF
MEXICO NEAR 20N94W...TO THE ISTHMUS OF TEHUANTEPEC NEAR 17N94W.
A STATIONARY FRONT...WHICH HAS BROKEN AWAY FROM THE COLD FRONT
IN THE OPEN AREA OF THE ISTHMUS OF TEHUANTEPEC...GOES FROM
16N96W TO 20N104W TO NORTHERN MEXICO NEAR 32N113W. THE PRESSURE
GRADIENT IS SO STRONG AT THIS MOMENT...FROM AN 1039 MB HIGH
PRESSURE CENTER IN EASTERN OKLAHOMA TO THE ISTHMUS OF
TEHUANTEPEC...THAT A GALE WARNING HAS BEEN ISSUED FOR THE GULF
OF MEXICO SOUTH OF 25N WEST OF 90W FOR NORTHERLY WIND FROM 30 TO
40 KT AND SEAS FROM 12 TO 18 FT. A STORM WARNING HAS BEEN ISSUED
FOR THE GULF OF TEHUANTEPEC ON THE PACIFIC OCEAN SIDE OF MEXICO
COAST FROM NORTH OF 14N BETWEEN 94W AND 96W...INCLUDING THE GULF
OF TEHUANTEPEC...NORTHERLY WIND FROM 45 TO 55 KT AND SEAS FROM
15 TO 18 FT...AND ELSEWHERE WITHIN 90 NM OF EITHER SIDE OF LINE
16N95W 14N95W 12N98W NORTHEASTERLY WIND FROM 30 TO 40 KT AND
SEAS FROM 10 TO 14 FT. UPPER LEVEL SOUTHWESTERLY WIND FLOW FROM
THE EASTERN PACIFIC OCEAN TO THE SOUTHWEST OF MEXICO IS MOVING
ACROSS THE SOUTHERN HALF OF MEXICO INTO THE WESTERN GULF OF
MEXICO...ON TOP OF THE SOUTHWESTERN END OF THE COLD FRONT.
SHOWERS ARE POSSIBLE SOUTH OF 25N WEST OF 90W. COLD AIR
STRATIFORM CLOUDS COVER THE GULF WATERS...EXCEPT FOR THE COASTAL
AREAS WITHIN 40 TO 60 NM OFFSHORE BETWEEN FLORIDA AND THE MIDDLE
TO SOUTH TEXAS COAST. BROKEN TO OVERCAST MULTILAYERED CLOUDS ARE
NORTHWEST OF 32N68W 27N74W 23N80W. COLD AIR STRATIFORM ARE MORE
EASILY RECOGNIZABLE NORTHWEST OF THE BAHAMAS. SURFACE TROUGH...
THE REMNANT BOUNDARY OF THE LAST COLD FRONT...IS MARKED BY A BAND
OF BROKEN LOW TO MIDDLE LEVEL CLOUDS WITHIN 30 NM ON EITHER SIDE
OF 32N62W 30N65W 25N70W 22N72W. ISOLATED MODERATE SHOWERS ARE
WITHIN 20 TO 30 NM ON EITHER SIDE OF 29N63W 27N65W 24N67W 21N69W
IN SURFACE CONFLUENT WIND FLOW IN FRONT OF THE TROUGH AND THE
END OF AN ATLANTIC SURFACE RIDGE. THE COLD FRONT SHOULD DEPART
THE GULF BY EARLY WEDNESDAY WITH GALE FORCE WINDS IN THE
SOUTHWESTERN GULF DUE TO THE 1039 MB OKLAHOMA HIGH CENTER...
BUILDING HIGH PRESSURE ALONG THE WESTERN GULF OF MEXICO COAST.
THE COLDEST NIGHT OF THE SEASON UP TO THIS MOMENT IS EXPECTED
TONIGHT/EARLY THIS MORNING FOR MANY OF THE GULF COAST STATES
WITH FREEZING TEMPERATURES INTO CENTRAL FLORIDA.  A SLOW
MODIFICATION OF THE COOL TEMPERATURES SHOULD OCCUR AS HIGH
PRESSURE MOVES EASTWARD OVER THE NEXT COUPLE OF DAYS...BRINGING
WINDS AROUND TO THE NORTHEAST WITH MORE OF A MARITIME WIND
EXPOSURE RATHER THAN COOL/DRY NORTHWESTERN CONTINENTAL FLOW.
THE NEXT REINFORCING PUSH OF COOLER AIR...ALBEIT WEAK..APPEARS
TO ENTER THE GULF ON FRIDAY.

THE CARIBBEAN SEA...
ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND THUNDERSTORMS
FROM 11N TO 16N BETWEEN 82W AND THE NICARAGUA/HONDURAS COASTS IN
SURFACE ONSHORE FLOW AND BROAD SURFACE LOW PRESSURE. UPPER LEVEL
SOUTHWESTERLY WIND FLOW IS SHEARING THE CLOUD TOPS IN THIS AREA.
SURFACE TROUGH FROM THE ATLANTIC OCEAN NEAR 23N67W TO 20N68W
16N70W 13N73W. ISOLATED MODERATE SHOWERS AND POSSIBLE
THUNDERSTORMS WITHIN 60 NM TO THE EAST AND 150 NM TO THE WEST
OF THE TROUGH. THIS TROUGH SHOULD WEAKEN DURING THE NEXT COUPLE
OF DAYS BUT STILL REMAIN A FOCUSING MECHANISM FOR SHOWERS IN THE
CENTRAL CARIBBEAN. INSTABILITY ALONG WITH HIGH MOISTURE VALUES
LOOK LIKELY TO SPAWN HIGHER-THAN-AVERAGE SHOWER CLUSTERS UNTIL
LATER IN THE WEEK IN THE LEEWARD ISLANDS. MIDDLE TO UPPER LEVEL
DRY AIR ELSEWHERE...IN BROAD UPPER LEVEL ANTICYCLONIC FLOW.

THE ATLANTIC OCEAN...
ISOLATED MODERATE SHOWERS AND POSSIBLE THUNDERSTORMS ARE
OCCURRING FROM 11N TO 23N BETWEEN 52W AND 62W...IN AN AREA
OF AN UPPER LEVEL DIFFLUENT WIND FLOW PATTERN. UPPER LEVEL
WESTERLY WIND IS BLOWING FROM 16N TO 25N BETWEEN 50W AND 60W.
THE UPPER LEVEL WIND FLOW BECOMES SOUTHERLY TO THE NORTH OF 26N
AND NORTHWESTERLY TO WESTERLY FROM 10N TO 20N BETWEEN 40W AND
60W. THE WESTERN ATLANTIC COLD FRONT GOES THROUGH
32N70W...CROSSING OVER THE NORTHERN BAHAMAS...TO 24.5N80W IN
THE STRAITS OF FLORIDA. ONE AREA OF MIDDLE TO UPPER LEVEL
CYCLONIC FLOW COVERS THE WATERS FROM 17N TO 33N BETWEEN 40W AND
50W...AND THE SECOND ONE IS RIGHT UP AGAINST THE AFRICA COAST
FROM 19N TO 35N BETWEEN THE PRIME MERIDIAN AND 27W. WELL-
DEFINED UPPER LEVEL ANTICYCLONIC FLOW IS ON TOP OF THE MORE
WESTERN AREA OF CYCLONIC FLOW. UPPER LEVEL WESTERLY AND
SOUTHWESTERLY WIND FLOW IN THE TROPICS. A MIDDLE TO UPPER LEVEL
TROUGH RUNS FROM A CYCLONIC CENTER NEAR 21N44W TO 13N44W AND
8N43W. A SURFACE RIDGE RUNS FROM THE 1030 MB HIGH PRESSURE CENTER
NEAR 36N39W TO 33N49W 31N55W 28N61W 25N64W. A SURFACE 1004 MB
GALE LOW PRESSURE CENTER IS PART OF THE WHOLE DEEP LAYER EASTERN
ATLANTIC CYCLONIC SYSTEM...NEAR 27N20W. ISOLATED TO WIDELY
SCATTERED MODERATE SHOWERS AND THUNDERSTORMS IN CLUSTERS FROM
25N TO 30N BETWEEN 10W AND 18W.

$$
MT


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