[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI FEB 13 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1945 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG A LINE FROM 06N08W TO 04N14W TO 02N25W
CROSSING THE EQUATOR AT 33W AND INTO NE BRAZIL NEAR 04S40W.
SCATTERED MODERATE ISOLATED STRONG CONVECTION LIES WITHIN 90 NM
N AND 150 NM S OF THE ITCZ AXIS E OF 17W.

...DISCUSSION...

GULF OF MEXICO...
THE STATIONARY BOUNDARY FROM SOUTH OF NEW ORLEANS OVER THE NE
GULF OF MEXICO AND INTO FORT MYERS IS DISSIPATING THIS
AFTERNOON/EVENING.  SHOWERS AND ISOLATED THUNDERSTORMS CAN BE
FOUND NEAR THE NORTHERN END OF THE DISSIPATING BOUNDARY MAINLY
WITHIN 60 NM OF THE CENTRAL GULF COAST.  OVER THE REST OF THE
EASTERN GULF...LIGHT WINDS AND STABLE CONDITIONS SOUTH OF THE
DISSIPATING STATIONARY FRONT WILL PROMOTE THE DEVELOPMENT OF FOG
THROUGH SATURDAY.  THE SW GULF IS MOSTLY CLOUD FREE ON THE
WESTERN PERIPHERY OF A SFC RIDGE EXTENDS S OVER FLORIDA.
SOUTHERLY FLOW AHEAD OF THE TROUGH OVER THE SOUTHERN PLAINS
CURRENTLY DOMINATES THE WESTERN GULF OF MEXICO.  THE COLD FRONT
OVER THE SOUTHERN PLAINS WILL STRETCH EASTWARD...REACHING THE
NORTHERN GULF COAST BY SATURDAY MORNING AND MEANDERING THERE
OVERNIGHT UNTIL THE STEERING FLOW BECOMES MORE AMPLIFIED SUNDAY.
A SURFACE WAVE WILL DEVELOP OVER THE NORTHERN GULF OF MEXICO
MOVE EASTWARD INTO THE ATLC...SENDING THE ASSOCIATED COLD FRONT
SOUTHWARD THROUGH THE GULF SUN/MON.

CARIBBEAN SEA...
THE CARIBBEAN IS VOID OF DEEP CONVECTION WITH STRONG SUBSIDENCE
AND DRY AIR IN THE MID AND UPPER LEVELS COUPLED WITH CONFLUENT
FLOW ALOFT BETWEEN THE RIDGING OVER CENTRAL AMERICAN AND THE
SOUTHERN END OF THE TROUGH OVER THE WESTERN ATLC/EASTERN
CARIBBEAN.  TRADE WINDS HAVE DIMINISHED COMPARED TO
YESTERDAY...WITH EASTERLY WINDS GENERALLY IN THE 20 TO 25 KT
RANGE S OF 18N AND LESS THAN 20 KT ELSEWHERE ACCORDING TO THE
1440 UTC ASCAT PASS.  WEAK TO MODERATE TRADE WINDS SHOULD
CONTINUE OVER THE CARIBBEAN THROUGH THE WEEKEND...WITH ISOLATED
TRADE SHOWERS MOVING WESTWARD ACROSS THE REGION.

ATLANTIC OCEAN...
THE ASCAT PASSES FROM 1120 AND 1300 UTC SHOW TRADE WINDS IN THE
20 TO 25 KT RANGE ACROSS MUCH OF THE ATLC FROM 05N TO 20N W OF
30W.  WINDS ON THE WESTERN EDGE OF THIS SWATH SHOULD DIMINISH AS
THE DEEP LAYER TROUGH OVER THE WESTERN ATLC APPROACHES AND THE
SUBTROPICAL SURFACE HIGH...CURRENTLY 1022 MB NEAR 28N39N...
WEAKENS SLIGHTLY AND PUSHES EASTWARD TOWARD 30W.  THE SURFACE
COLD FRONT ASSOCIATED WITH THIS DEEP LAYER TROUGH LIES OVER
FORECAST WATERS FROM 31N58W TO 27N70W TO SOUTH OF PALM
BEACH...FL.  A COLDER AND MUCH DRIER AIRMASS HAS SETTLED INTO
THE W ATLC BEHIND THE FRONT. SCATTERED SHOWERS CAN BE FOUND
WITHIN 90 NM OF THE FRONT AND WINDS IN THE 25 TO 30 KT RANGE CAN
BE FOUND WITHIN 90 NM OF THE FRONT OVER FORECAST WATERS E OF 65W
ACCORDING TO THE 1436 AND 1256 UTC ASCAT PASSES.  THE FRONT IS
FORECAST TO DISSIPATE OVER WEST ATLC WATERS IN THE NEXT 24 HOURS
AS HIGH PRESSURE BUILDS BETWEEN FLORIDA AND BERMUDA.  AHEAD OF
THE FRONT...FAIR WEATHER COVERS THE CENTRAL AND EAST ATLC NEAR
THE AFOREMENTIONED HIGH PRESSURE CENTER.  UPPER LEVEL MOISTURE
IS BEING ADVECTED NORTHEASTWARD ACROSS THE ATLC S OF 20N BY FLOW
ON THE LEADING EDGE OF A WEAK UPPER TROUGH OVER THE EAST ATLC.
FARTHER SOUTH...DIFFLUENCE ASSOCIATED WITH AN UPPER LEVEL
ANTICYCLONE CENTERED NEAR 08N18W IS ENHANCING CONVECTION ALONG
THE ITCZ.  SCATTERED MODERATE ISOLATED STRONG CONVECTION LIES
WITHIN 90 NM N AND 150 NM S OF THE ITCZ AXIS E OF 17W.

$$
SCHAUER CLARK



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