[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 270605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 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 0000 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 0515 UTC.

...ITCZ...

ITCZ 7N12W 4N20W 4N25W 7N40W 8N48W 6N56W. SCATTERED MODERATE
TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS FROM THE EQUATOR
TO 4N BETWEEN 2W AND 6W. WIDELY SCATTERED TO SCATTERED
MODERATE/ISOLATED STRONG SHOWERS AND THUNDERSTORMS WITHIN
60 TO 90 NM ON EITHER SIDE OF 3N8W 4N20W 5N35W...AND THEN
FROM 1N TO 10N BETWEEN 35W AND 48W.

...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
27N90W 28N96W. SURFACE RIDGE FROM A CENTRAL LOUISIANA 1029 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 21N76W TO
THE WATERS JUST WEST OF JAMAICA NEAR 18.5N79W TO THE EASTERN
COAST OF NICARAGUA NEAR 12.5N83W. ISOLATED MODERATE SHOWERS HAVE
BEEN OCCURRING AT THE SOUTHERN END OF THE FRONT...WITHIN 15 NM
ON EITHER SIDE OF 16N81W 15N82W 13N83.5W. BROKEN LOW TO MIDDLE
LEVEL CLOUDS WEST AND NORTHWEST OF 20N73W 14N73W 12N79W 10N81W.
POSSIBLE SHOWERS IN CLOUD CLUSTERS FROM 15N TO 18N BETWEEN 60W
AND 70W...AND SOUTH OF 14N69W 13N65W 13N60W. WET WEATHER WILL
BE MOST LIKELY NEAR THE FRONTAL BOUNDARY...EXPECTED TO STALL
FROM NEAR JAMAICA TO NICARAGUA TOMORROW.

THE ATLANTIC OCEAN...
ANOTHER PESKY LOW HAS FORMED TODAY IN THE CENTRAL ATLC AROUND
23N46W ALONG A SINUOUS TROUGH FROM 14N47W 19N45W 26N47W 31N46W.
SCATTERED MODERATE TO ISOLATED STRONG SHOWERS AND THUNDERSTORMS
COVER THE WATERS FROM 10N TO 30N BETWEEN 30W AND 50W. THIS SYSTEM
REMAINS EXTRATROPICAL WITH A STRONG MID/UPPER LOW NEARLY
OVERHEAD...WITH A TROUGH TO 8N51W. THE MID/UPPER LOW NEAR 21N47W
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.  IN THE
EASTERN ATLANTIC...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 FROM A
REJUVENATED SUBTROPICAL RIDGE...1038 MB NEAR THE AZORES.
RIDGING CONTROLS THE AREA WITH THE WESTERN RIDGE AXIS ENTERING
THE AREA NEAR 31N55W SW TO 24N70W.

$$
MT

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