[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271029
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON 27 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 0600 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 0945 UTC.

...ITCZ...

ITCZ 6N10W 5N20W 5N30W 6N40W 6N50W 6N57W. SCATTERED MODERATE TO
STRONG SHOWERS AND THUNDERSTORMS FROM THE EQUATOR TO 2N BETWEEN
5W AND 6W. WIDELY SCATTERED TO SCATTERED MODERATE/ISOLATED
STRONG SHOWERS AND THUNDERSTORMS WITHIN 60 TO 90 NM ON EITHER
SIDE OF 2N8W 4N20W 4N30W 5N36W 6N40W. ISOLATED MODERATE SHOWERS
FROM EQUATOR TO 10N BETWEEN 40W AND 50W.

...DISCUSSION...

THE GULF OF MEXICO...
AN EASTERN PACIFIC OCEAN RIDGE IS BUILDING EASTWARD...REACHING
WESTERN INTERIOR MEXICO. UPPER LEVEL WESTERLY FLOW PREVAILS
ACROSS THE OPEN GULF WATERS...WEST-SOUTHWEST OF THE DEEP LAYER
TROUGH WHICH IS SUPPORTING THE NOW-WESTERN ATLANTIC SURFACE COLD
FRONT. UPPER LEVEL SOUTHWESTERLY FLOW GOES FROM THE ISTHMUS OF
TEHUANTEPEC TO THE YUCATAN PENINSULA...THROUGH THE STRAITS OF
FLORIDA AND INTO THE WESTERN ATLANTIC OCEAN...ALONG THE EASTERN
SIDE OF THE DEEP LAYER TROUGH. DRY AIR EVERYWHERE ACROSS THE
GULF ALSO. BROKEN TO OVERCAST STRATIFORM CLOUDS SOUTH OF 26N83W
28N90W 28N95W. SURFACE RIDGE FROM A SOUTHWESTERN LOUISIANA
1032 MB HIGH PRESSURE CENTER TOWARD THE SOUTHWESTERN CORNER OF
THE AREA.

THE CARIBBEAN SEA...
BROAD MIDDLE TO UPPER LEVEL DRY AIR IN THE AREA. BROAD MIDDLE
LEVEL ANTICYCLONIC FLOW ALSO. SURFACE COLD FRONT RUNS FROM THE
WESTERN ATLANTIC OCEAN THROUGH SOUTHEASTERN CUBA NEAR 20N74W
TO THE EASTERN TIP OF JAMAICA TO THE EASTERN COAST OF NICARAGUA
NEAR 12N84W. ISOLATED MODERATE SHOWERS HAVE BEEN OCCURRING AT
THE SOUTHERN END OF THE FRONT...WITHIN 15 NM ON EITHER SIDE OF
15N80W 12N83W. BROKEN LOW TO MIDDLE LEVEL CLOUDS WEST AND
NORTHWEST OF 20N73W 13N74W 11N82W. POSSIBLE SHOWERS IN CLOUD
CLUSTERS FROM 15N TO 18N BETWEEN 60W AND 70W...AND SOUTH OF 14N
EAST OF 70W. WET WEATHER WILL BE MOST LIKELY NEAR THE FRONTAL
BOUNDARY...EXPECTED TO STALL FROM NEAR JAMAICA TO NICARAGUA
TOMORROW.

THE ATLANTIC OCEAN...
SURFACE 1011 MB LOW PRESSURE CENTER NEAR 23N46W. SURFACE TROUGH
FROM 29N47W TO THE LOW CENTER TO 20N46W 16N46W 13N50W. SCATTERED
STRONG SHOWERS AND THUNDERSTORMS FROM 16N TO 19N BETWEEN 39W AND
42W. THIS SYSTEM REMAINS EXTRATROPICAL WITH A STRONG MID/UPPER
LOW NEARLY OVERHEAD...WITH A TROUGH TO 8N51W. THE MIDDLE TO
UPPER LEVEL CYCLONIC CIRCULATION CENTER NEAR 21N46W DOMINATES
THE REGION WITH DRY AIR IN THE TROPICS WEST OF 50W.  UPPER
RIDGING IS ALONG 30W WITH CIRRUS DEBRIS CLOUDS WEST OF THE
RIDGE DIMINISHING ON THE DOWNWIND SUBSIDENCE-LACED SIDE. BROKEN
TO OVERCAST LOW AND MIDDLE LEVEL CLOUDS ARE IN THE SUBTROPICAL
ATLANTIC EAST OF THE LOW PRESSURE SYSTEM. THE CLOUDS ARE BEING
FORCED INTO THE AREA BY THE SURFACE FLOW AROUND THE 1038 MB
SURFACE HIGH PRESSURE NEAR THE AZORES. UPPER LEVEL RIDGE IN
BETWEEN THE WESTERN ATLANTIC DEEP LAYER TROUGH AND THE CYCLONIC
FLOW AROUND THE 21N47W DEEP LAYER CYCLONIC CENTER...THROUGH
33N60W TO 24N65W 20N66W.

$$
MT

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