[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 291751
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT DEC 29 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN 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 1645 UTC.

...THE ITCZ/THE MONSOON TROUGH...

ITCZ AXIS EXTENDS FROM WEST AFRICA AT THE COAST OF SIERRA LEONE
TO 02N25W TO 04N38W TO 02N50W IN NE BRAZIL.  SCATTERED MODERATE
CONVECTION FROM 02N-06N BETWEEN 20W-40W.  ISOLATED MODERATE
ELSEWHERE WITHIN 120 NM NORTH AND 90 NM SOUTH OF AXIS.

...DISCUSSION...

GULF OF MEXICO...
COLD FRONT EXTENDS FROM N FLORIDA BIG BEND TO 23N90W TO 19N92W
IN THE BAY OF CAMPECHE.  SCATTERED STRONG CONVECTION NOTED ON
SATELLITE IMAGERY N OF 25N E OF FRONT.  ISOLATED SHOWERS ALONG
TEXAS COAST AND N OF 28N W OF 90W.  STRONG SOUTHWESTERLY WINDS
AHEAD OF FRONT SHIFT NORTHWEST TO NORTH BEHIND BOUNDARY.  STRONG
UPPER LEVEL SUPPORT IN THE WAY OF 170 KT JETSTREAM SHIFT MORE TO
THE NORTH WEAKENING FRONT ONCE IT MOVES EAST OF FLORIDA
PENINSULA.  BROAD UPPER LEVEL RIDGE COVER ENTIRE GULF BEHIND
FRONT WITH COLD...DRY AND STABLE AIR MASS BRINGING A TOUCH OF
WINTER WEATHER TO THE LOWER LATITUDES.  RIDGE SHIFT EAST AND
ALLOWS NEXT FRONTAL SYSTEM TO MOVE INTO NORTHWEST GULF EARLY
TUE.

THE CARIBBEAN SEA...
FAIR...DRY AND STABLE CONDITIONS RULE ACROSS THE BASIN WITH
FRESH EAST TO NORTHEAST TRADES OBSERVED E OF 80W AS BROAD
SURFACE RIDGE SPREADS THROUGH ENTIRE SOUTHWEST NORTH ATLC.
GENTLE TO MODERATE BREEZE NOTED W OF 80W IN ADVANCE OF COLD
FRONT APPROACHING YUCATAN PASSAGE.  NOT MUCH CONVECTION EXPECTED
INTO NORTHWEST CARIBBEAN FROM FRONTAL BOUNDARY SUN AS MOST
SUPPORTING ENERGY EXPECTED TO SHIFT NORTH AWAY FROM SOUTHERN
PART OF FRONT.  SCATTERED CONVECTION COULD DEVELOP OVER PANAMA
AND COSTA RICA DUE TO LOW PRESSURE CENTER FORMING IN EASTERN
PACIFIC JUST S OF PANAMA.

THE ATLANTIC OCEAN...
VERY BROAD MID TO UPPER LEVEL RIDGE COVERS SOUTHWEST NORTH ATLC
SUPPORTING WEAK SURFACE HIGH PRESSURE CENTER 1024 MB AT 30N52W.
WEAK LOW PRESSURE CENTER 1017 MB JUST SE OF ANTICYCLONE AT
24N42W HAS ATTENDANT TROUGH MEANDERS FROM 18N42W TO 18N47W
BRINGING SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 90
NM ON ITS EAST SEMICIRCLE...LITTLE CONVECTION ELSEWHERE IN
CENTRAL ATLC.  LOW EXPECTED TO DISSIPATE EARLY SUN WHILE TROUGH
WEAKENS AND MOVES NORTHEAST.

APPROACHING COLD FRONT FROM GULF OF MEXICO PROMPTS SCATTERED
MODERATE TO STRONG CONVECTION OFF FLORIDA EAST COAST WITH MAIN
CLUSTER MOSTLY NORTH OF 27N EAST OF 72W.  FRONT HAS ALSO BROUGHT
STRONG SOUTHWESTERLIES WITHIN 180 NM EAST OF BOUNDARY WHICH WILL
SHIFT NORTHWEST ONCE FRONT MOVES EAST OF FLORIDA COAST.  FARTHER
EAST...UPPER LEVEL CYCLONE AT 24N39W SUPPORTS ABOVE MENTIONED
SURFACE LOW PRESSURE AT 24N42W WITH ITS ATTENDANT SURFACE
TROUGH.  CYCLONE EXPECTED TO WEAKEN AND BE FORCED EAST BY
WESTERN ATLC RIDGE MOVING EAST DISSIPATING SURFACE LOW PRESSURE.

REMAINDER OF EASTERN ATLC UNDER BROAD RIDGE AROUND HEALTHY 1032
MB HIGH PRESSURE CENTER OVER AZORES ISLANDS.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALLY BARNES




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