[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 231141
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST SUN DEC 23 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC

...ITCZ...
ITCZ AXIS ALONG 7N12W 4N26W 4N40W 7N58W.  SCATTERED MODERATE
CONVECTION WITHIN 90 NM OF AXIS FROM 39W-48W.  ISOLATED
MODERATE CONVECTION WITHIN 150 NM N OF AXIS FROM 23W-33W.

...DISCUSSION...
GULF OF MEXICO...
STRONG COLD FRONT EXTEND FROM 30N89W TO 21N97W THEN NWD ALONG E
SLOPES OF SIERRA MADRE TO 23N100W.  FRONT SUPPORTED BY LARGE
AMPLITUDE LONGWAVE TROUGH ACROSS CENTRAL PLAINS PRODUCING VERY
WINTRY WEATHER ACROSS ITS PATH.  WELL DEFINED LINE OF CONVECTION
MARKS FRONTAL BOUNDARY.  N GALE FORCE WINDS EXPECTED W OF COLD
FRONT THROUGH THIS AFTERNOON.  BROKEN LOW LEVEL STRATIFIED
CLOUDINESS AND ISOLATED SHOWERS ASSOCIATED WITH DISSIPATED WARM
FRONT LINGERS AHEAD OF COLD FRONT.  E GULF APPEARS QUIET FOR
TIME BEING...BUT TRANQUILITY WILL NOT LAST AS COLD FRONT SHOULD
BRING STRONG NLY WINDS TONIGHT THROUGH MON.  HIGH PRES BUILDS
BEHIND FRONT AND MAINTAINS COOL DRY NE FLOW THROUGH REMAINDER OF
FORECAST PERIOD.

CARIBBEAN SEA...
MID TO UPPER RIDGE WELL ANCHORED OVER W CARIBBEAN WITH CREST
REACHING CENTRAL FLORIDA HAS FLOW ALOFT BECOMING ZONAL E OF 60W.
ABUNDANT MODERATE TO STRONG SUBSIDENCE ACROSS ENTIRE BASIN
MAINTAINS IT DRY AND STABLE CURTAILING VERTICAL DEVELOPMENT EVEN
WHEN SURFACE UPLIFT IS AVAILABLE LIKE WITH SURFACE TROUGH ALONG
72W OFF LAKE MARACAIBO.  ISOLATED DEEPER PRECIP IN SW CARIBBEAN
S OF 11N W OF 80W AS TRADES COLLIDE WITH MOUNTAIN RANGE IN
PANAMA AND COSTA RICA.

ATLANTIC OCEAN...
MAIN FEATURE IN W ATLC IS LOW PRES AT 28N69W...1011 MB...WITH
COLD FRONT EXTENDING FROM 29N66W TO 20N70W AND A TROUGH TO
23N74W TO 24N77W.  LOW PRES WELL SUPPORTED BY LONGWAVE TROUGH
RUNNING ALONG CENTRAL ATLC AND SHORTWAVE TROUGH NEAR 26N63W.
MODELS AGREE WITH SE MOVEMENT OF LOW PRES TO 25N60W IN 24 HRS
WITH VERY TIGHT GRADIENT OVER NRN SEMICIRCLE CAUSING GALE FORCE
WINDS WITHIN 300 NM N OF LOW PRES.  MOST DEEP CONVECTION...
SCATTERED TSTMS...REMAIN E OF CENTER UNDER DIFFLUENT ZONE ALOFT
ASSOCIATED WITH SHORTWAVE AND COLD FRONT.  LITTLE SIGNIFICANT
CONVECTION ASSOCIATED WITH SURFACE TROUGH.

TAIL END OF OLD FRONTAL BOUNDARY 31N40W 27N46W MOVING E
FORECAST TO BE OUT OF AREA WITHIN 24 HRS BY MODEL ENSEMBLE.
LITTLE SIGNIFICANT CLOUDINESS ALONG THIS WEAK BOUNDARY.

E ATLC UNDER UMBRELLA OF LARGE HIGH PRES RIDGE KEEPING LOW
PROFILE WITH STRONG ZONAL FLOW ALOFT DOMINATING WEATHER PATTERN.

$$
WALLY BARNES



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