[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN 02 JAN 2005

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 IS CENTERED ALONG 5N1W 6N20W 7N36W 5.5N55W.  ISOLATED
MODERATE WITHIN 75 NM OF AXIS BETWEEN 35W-45W.  ISOLATED
WEAK/MODERATE S OF 11N W OF 52W.  CLUSTERS OF MODERATE
CONVECTION ARE NEAR 1N22W 6.5N20W AND 5N11W.

...DISCUSSION...

GULF OF MEXICO AND W ATLC...
STRONG HIGH PRES RIDGING CONTINUES TO PRODUCE WINDY CONDITIONS
OVER THE W ATLC AND GULF OF MEXICO WATERS...GENERALLY S OF
27-28N E OF 90W.  A QUIKSCAT PASS STILL INDICATES NE/E 20-25 KT
WINDS EXTENDING ACROSS THE BAHAMAS INTO THE E GULF.   EARLIER S
TEXAS SHOWERS HAVE MOVED WELL INLAND BUT A FEW ISOLATED ONES
COULD OCCUR IN PATCHY LOW/MID CLOUD CLUSTERS.  UPPER LEVEL
RIDGING IS OVER THE AREA WITH SUBSIDENCE/DRY AIR INCREASING FROM
N TO S.  A WEAK SHORTWAVE JUST E OF FLORIDA IS RESPONSIBLE A FEW
HIGH LEVEL CLOUDS OVER THE W ATLC WATERS AHEAD OF THIS FEATURE.
OTHERWISE SCATTERED LOW/MIDDLE CLOUDS WITH ISOLATED SHOWERS
COVER THE AREA.  ONLY SUBTLE CHANGES LOOK LIKELY THIS WEEK WITH
FRONTS STALLING N OF THE REGION AND GENERALLY WEAKENING ELY FLOW
SHIFTING TO SE ALONG THE TEXAS COAST.

CARIBBEAN...
SURFACE HIGH OVER THE EASTERN US IS ALSO RESPONSIBLE FOR THE
ENHANCED PRES GRADIENT OVER CARIBBEAN WATERS WHERE WINDS OF
20-25 KT ENVELOP MOST OF THE REGION.  CLUSTERS OF STRATOCUMULUS
CLOUDS WITH SOME SHOWERS ARE WITHIN 90 NM OF 15N72W AND WITHIN
60 NM OF 12.5N74W TO THE NICARAGUA/COSTA RICA BORDER.
PERSISTENT UPPER TROUGHING REMAINS FROM SE CUBA THRU JAMAICA
THEN INTO COSTA RICA.  DRY ALOFT IS ANCHORED W OF 65W WHILE
BROAD SW FLOW EMERGING FROM S AMERICA IS INCREASING UPPER LEVEL
MOISTURE ACROSS THE LESSER ANTILLES TOWARDS THE CNTRL ATLC.
WINDS/SEAS SHOULD DIMINISH A BIT AS HIGH PRESSURE WEAKENS DURING
THE WEEK WHILE INCREASED MOISTURE SHOULD ENHANCE RAIN CHANCES IN
THE WINDWARD ISLANDS.

CENTRAL AND EAST ATLC...
DEEPENING 1009 MB LOW IS OVER THE CNTRL ATLC NEAR 30N50W...
DRIFTING SE...WITH A COLD FRONT EXTENDING FROM 32N48W TO 26N46W
THEN 20N50W BEFORE DISSIPATING TO 17N56W.  LOW IS OCCLUDING WITH
AN OCCLUDED FRONT ALONG 30N52 TO 32N48W AND GALE-FORCE WINDS ON
THE N SIDE OF THE LOW.  UPPER SYSTEM APPEARS VERTICALLY STACKED
WITH THE COMMA SHAPE BECOMING BETTER-DEFINED.  ISOLATED MODERATE
CONVECTION IS WITHIN 60 NM OF LOW WHILE WIDELY SCATTERED
WEAK/MODERATE CONVECTION IS WITHIN 90 NM AHEAD OF THE COLD FRONT
N OF 22N.  AMPLIFIED RIDGE IS OVER THE TROPICAL ATLC WITH AXIS
ALONG 38W COVERING THE AREA W TO THE LESSER ANTILLES AND E TO
THE CAPE VERDES.  DRY AIR IS BENEATH THE RIDGE S OF 15N WITH
ENHANCED SHOWERS IN THE ITCZ AXIS SE OF TRINIDAD.  STRONG JET IN
EXCESS OF 120 KT IS ON THE N SIDE OF THE RIDGE SPREADING HIGH
CLOUDS ALONG 18N-21N OVER ATLC WATERS E OF 55W THRU THE CAPE
VERDES.  FARTHER E... WEAKENING UPPER LOW ELONGATES ALONG AXIS
21N22W 28N37W WITH PERHAPS SOME REFLECTION AT THE SURFACE AS A
WEAK TROF TRAVERSES 31W BETWEEN 18N AND 26N.  ELSEWHERE
STRONG NE TRADES ARE IN THE NE ATLC E OF THE SURFACE TROUGH
THANKS TO A 1042 MB HIGH SEVERAL HUNDRED MILES W OF PORTUGAL.

FARTHER S...AN AMPLIFIED UPPER RIDGE EXTENDS OFF
THE BRAZILIAN COAST ALONG EQ40W 10N45W WHICH IS SPREADING HIGH
CLOUDS FROM THE WINDWARD ISLANDS NE THEN EWD ACROSS THE ATLC TO
THE CAPE VERDE ISLANDS. A BROAD SFC TROF IS LOCATED NW OF THE
CAPE VERDES ALONG 19N30W 28N28W AND IS PRODUCING LIGHT SHOWERS
FROM 20N-25N BETWEEN 28W-31W. AN ELONGATED UPPER LOW IS CENTERED
SW OF THE CANARY ISLANDS NEAR 26N28W WITH ITS AXIS EXTENDING SE
TO THE MOROCCAN COAST BUT IT IS PRODUCING NO SIGNIFICANT
WEATHER. THE ITCZ IS RELATIVELY INACTIVE BUT A FEW SHOWERS/TSTMS
ARE LOCATED ALONG THE AXIS BETWEEN 23W-41W DUE TO A SMALL AREA
OF UPPER LEVEL DIFFLUENCE W OF A TROF ALONG 25W/26W.

$$
BLAKE


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