[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251748
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT 25 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ...

ITCZ AXIS ALONG 7N12W 4N25W 3S42W. THE ITCZ IS ACTIVE WITH
SCATTERED MODERATE TO STRONG CONVECTION LOCATED WITHIN 60 NM
EITHER SIDE OF A 4N13W 2N26W LINE...FROM 1N TO 6N BETWEEN 26W
AND 31W...AND WITHIN 60 NM EITHER SIDE OF A 2N31W 1S39W
LINE.

...DISCUSSION...

GULF OF MEXICO/FLORIDA/FAR W ATLANTIC...
MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED OVER THE NW
GULF OF MEXICO NEAR 28N94.5W...MOVING ENE 15 TO 20 KT. A TROUGH
AXIS EXTENDS SW FROM THE CIRCULATION INTO CENTRAL MEXICO NEAR
22N102W. A STRONG...FAIRLY NARROW...SOUTHWESTERLY JET IS LOCATED
FROM NEAR THE BASE OF TROUGH NEAR 19N105W TO 26N87W. 300 MB
SATELLITE DERIVED WINDS ARE IN THE 90-110 KT RANGE ALONG THE JET
AXIS. THE FLOW ALOFT THEN DIVERGES OVER THE EASTERN GULF AND
FLORIDA INCLUDING THE FLORIDA PANHANDLE. THIS DIVERGENT
SOUTHWESTERLY FLOW IS AIDING CONVECTIVE ACTIVITY OVER THIS AREA.
AT THE SURFACE A COLD FRONT IS LOCATED THROUGH 31N73W TO NEAR
27N76W AND THEN CONTINUES AS A STATIONARY FRONT TO 24N79.5W.
CONTINUING WESTWARD A WARM FRONT CUTS ACROSS THE STRAITS OF
FLORIDA TO A 1006 MB SURFACE LOW NEAR 25N89.5W. A COLD FRONT
EXTENDS FROM THE LOW TO 16N93.5W. EXTENSIVE CLOUDINESS COVERS
THE WHOLE GULF EXCEPT S OF THE WARM FRONT WITH SLEET/FREEZING
RAIN CURRENTLY BEING REPORTED ALONG THE LOUISIANA COAST. SKIES
HAVE CLEARED OVER E TEXAS WITH LATEST VISIBLE IMAGERY CLEARLY
INDICATING SNOW EXTENDING INLAND FROM THE COAST ABOUT 70 NM FROM
NEAR GALVESTON TO ABOUT 160 NM FROM THE LOWER TEXAS COAST.
HISTORIC SNOWFALL AMOUNTS INCLUDE A FOOT IN VICTORIA AND AN INCH
AND A HALF IN BROWNSVILLE.

CARIBBEAN/ATLANTIC BETWEEN 60W AND 75W...
FURTHER DOWNSTREAM A BROAD RIDGE PATTERN ALOFT HAS ITS AXIS
EXTENDING FROM CENTRAL NICARAGUA ACROSS EASTERN CUBA TO BEYOND
32N70W. WATER VAPOR IMAGES INDICATE STRONG SUBSIDENCE OVER THE
ENTIRE CARIBBEAN. GENERALLY FAIR WEATHER ACROSS THE AREA EXCEPT
FOR A VERY NARROW...PRE-FRONTAL ROPE CLOUD FEATURE...ORIENTED
NORTH-SOUTH EXTENDING THROUGH THE WESTERN YUCATAN CHANNEL TO
16.5N88W.

REMAINDER ATLANTIC...
MIDDLE/UPPER LEVEL TROUGH OVER THE CENTRAL ATLANTIC HAS ITS AXIS
EXTENDING THROUGH 32N50W TO 22N55W TO 10N63W. TWO CYCLONIC
CIRCULATIONS ARE LOCATED WITHIN THE TROUGH. ONE IS LOCATED AT
31N51W AND DRIFTING SW. THE OTHER IS LOCATED NEAR 22N51W. A 1014
MB LOW IS ASSOCIATED WITH THE NORTHERN CIRCULATION AND IS
CENTERED NEAR 31N44W. A TROUGH EXTENDS S FROM THE LOW TO 22N46W.
THIS FEATURE IS MARKED BY A SWIRL OF LOW CLOUDS EXCEPT FOR
LAYERED CLOUDS AND FEW TSTMS OVER THE NE QUADRANT. A SURFACE
TROUGH IS ASSOCIATION WITH THE OTHER CYCLONIC CIRCULATION AND IS
LOCATED FROM 20N53W TO 12N54W. SHOWERS AND TSTMS EXTEND E FROM
THE TROUGH TO 38W FROM 10N TO 24N. A WELL-DEFINED RIDGE IS
LOCATED OVER THE E CENTRAL AND E ATLANTIC WITH ITS AXIS ALONG
32W FROM NEAR 5N TO 30N. ANTICYCLONIC FLOW IS LOCATED ABOUT 10
DEGREES EITHER SIDE OF THE RIDGE AXIS.

$$
CAB


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