[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281108
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST TUE NOV 28 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1100 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 7N26W 6N35W 4N45W 3N52W. THE
ITCZ IS RATHER QUIET WITH ONLY ISOLATED MODERATE CONVECTION
WITHIN 180 NM S OF THE AXIS E OF 19W AND BETWEEN 37W-45W.
ISOLATED MODERATE IS WITHIN 180 NM N OF THE AXIS BETWEEN 27W-36W.

...DISCUSSION...
THE GULF OF MEXICO...
THE WEATHER ACROSS THE GULF HAS CHANGED LITTLE OVER THE PAST FEW
DAYS AS SFC HIGH PRES CONTINUES TO DOMINATE THE AREA. BREEZY
15-20 KT ELY WINDS IN THE ERN AND CNTRL GULF IS ADVECTING
PATCHES OF LOW-LEVEL CLOUDS AND EMBEDDED ISOLATED TO SCATTERED
SHOWERS ACROSS CENTRAL AND SOUTH FLORIDA ON THE BREEZE. SOME OF
THIS LOW-LEVEL MOISTURE IS BEING DRIVEN ACROSS THE GULF AND
TOWARDS THE SE TEXAS COAST BY S TO SELY RETURN FLOW AROUND THE
1028 MB SFC HIGH CENTERED JUST OFFSHORE OF THE MID-ATLANTIC
STATES. IN THE UPPER LEVELS...A STRONG RIDGE IS CENTERED IN THE
CENTRAL GULF NEAR 24N88W WITH RIDGING EXTENDING ACROSS THE FL
PANHANDLE AND THE SOUTHEAST. WIDESPREAD STRONG SUBSIDENCE EXISTS
EVERYWHERE ABOVE THE GULF. THIS STRONG CAP IS PREVENTING THE
LOW-LAYER MOISTURE TO ACQUIRE MUCH DEPTH. GFS SHOWS THE SFC AND
UPPER RIDGE SLIDING E IN RESPONSE TO A DIGGING UPPER TROUGH
CURRENTLY OVER THE ROCKIES. THIS WILL ALLOW TEMPS TO REMAIN
SLIGHTLY ABOVE NORMAL VALUES OVER THE NEXT COUPLE DAYS BEFORE A
STRONG COLD FRONT MOVES OFF THE TX COAST LATE THU. GALE FORCE
CONDITIONS AND A MUCH COLDER/DRIER AIRMASS WILL BE IN STORE FOR
THE WRN GULF LATE THIS WEEK AND THIS WEEKEND. LESS OF AN AIRMASS
CHANGE IS ANTICIPATED IN THE E GULF AS MUCH OF THE MODEL
GUIDANCE STALLS THE FRONT OVER N FLORIDA.

THE CARIBBEAN SEA...
A WELL-DEFINED HIGHLY ELONGATED UPPER LEVEL TROUGH STRETCHES
ACROSS HISPANIOLA AND JAMAICA TO NEAR 17N80W. THE TAIL END OF AN
ASSOCIATED COLD FRONT IS DISSIPATING FROM 20N62W TO THE MONA
PASSAGE. MULTILAYER CLOUDINESS AND SCATTERED SHOWERS ASSOCIATED
WITH THE TROUGH/FRONT IS MAINLY CONTAINED N OF 18N BETWEEN
64W-72W WHICH INCLUDES PORTIONS OF HISPANIOLA...PUERTO RICO AND
THE VIRGIN ISLANDS AS INDICATED ON SAN JUAN'S 88-D. A VERY BROAD
FLATTENING UPPER LEVEL RIDGE LIES S AND E OF THE TROUGH CENTERED
OVER VENEZUELA. S-SWLY UPPER LEVEL FLOW ON THE W SIDE OF THE
BROAD RIDGE AXIS IS DRAWING SOME MOISTURE FROM THE ITCZ AND
UPPER DIFFLUENCE IS PROVIDING ENOUGH INSTABILITY TO SPARK
SCATTERED SHOWERS AND TSTMS S OF 14N BETWEEN 76W-84W. THE
REMAINDER OF THE CARIB IS QUIET WITH VERY DRY AIR/STRONG
SUBSIDENCE...DUE TO UPPER CONFLUENT FLOW...ABOVE THE NW CARIB
AND MODERATELY DRY AIR ALOFT ELSEWHERE. THIS DRY AIR IS
SUPPRESSING ANY DEEP CLOUDINESS IN THE AREAS NOT OUTLINED.
TRADES ARE MODERATE AND WILL LIKELY REMAIN THAT WAY OVER THE
NEXT DAY OR SO. LATER THIS WEEK...THESE WINDS WILL LIKELY
INCREASE AS THE FRONTAL BOUNDARY PULLS NE AND STRONG HIGH PRES
DEVELOPS TO THE N TIGHTENING THE PRES GRAD.

THE ATLANTIC OCEAN...
THE WRN ATLC IS DOMINATED BY VERY DRY AIR ALOFT...PRODUCED BY
UPPER LEVEL CONFLUENCE BETWEEN A WELL-DEFINED UPPER TROUGH ALONG
32N55W 25N65W TO HISPANIOLA AND AN UPPER HIGH IN THE GULF.
PATCHES OF LOW-LEVEL MOISTURE UNDERNEATH THE STRONG MID-LEVEL
CAP ARE BEING DRIVEN TOWARDS THE BAHAMAS/FLORIDA BY MODERATE
NELY FLOW. THE ONLY LOW PRES FEATURE IN THE DISCUSSION AREA IS
IN THE CNTRL ATLC WHERE A COLD FRONT EXTENDS FROM AN OCCLUDED
1003 MB LOW NEAR 33N48W ALONG 24N55W 21N59W THEN DISSIPATING TO
THE MONA PASSAGE. SWLY UPPER LEVEL FLOW...ON THE E SIDE OF THE
MID/UPPER LEVEL TROUGH AXIS...AND LOW-LEVEL LIFT NEAR THE SFC
BOUNDARY IS PRODUCING MULTILAYERED CLOUDS WITH EMBEDDED
SCATTERED SHOWERS WITHIN 400 NM E AND 180 NM W OF THE FRONT N OF
28N AND WITHIN 240 NM EITHER SIDE OF THE FRONT S OF 28N. MODELS
SHOW THE SFC LOW QUICKLY RACING TO THE NE WHICH SHOULD HELP TO
SLOWLY THIN THE MOISTURE PLUME IN THIS AREA OVER THE NEXT DAY OR
TWO. AN ELONGATED LOW AMPLITUDE MID/UPPER RIDGE LIES E OF THE
TROUGH AND COVERS THE AREA BETWEEN 25W-50W N OF 20N. SLIGHT
TROUGHING...REMNANTS OF AN UPPER LOW...EXISTS SW OF THE RIDGE
BETWEEN 40W-55W. DEEP MOISTURE IS VERY LIMITED IN THE
SUBTROPICAL E ATLC AND MUCH OF TROPICAL ATLC WATERS INCLUDING
THE ITCZ...WHICH LOOKS PARTICULARLY QUIET THIS MORNING. PLENTY
OF DRY STABLE AIR ALOFT IS LOCATED E OF 20W S OF 20N ENHANCED BY
UPPER LEVEL CONFLUENT FLOW W OF AN UPPER TROUGH OVER AFRICA. AT
THE SFC...WEAK TO MODERATE HIGH PRES RIDGING IS THE RULE ACROSS
THE ERN AND WRN SUBTROPICAL ATLC SUPPORTED BY A 1027 MB HIGH
NEAR THE AZORES AND A 1028 MB HIGH OFFSHORE OF THE MID-ATLANTIC
U.S. A PRONOUNCED WEAKNESS IN THIS RIDGING LIES IN THE CNTRL
ATLC DUE TO THE SFC LOW AND FRONTAL BOUNDARY MENTIONED.

$$
CANGIALOSI






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