[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 081803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU NOV 08 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 56W S OF 13N MOVING W 10-15 KT. WHILE AT
FIRST GLANCE THERE DOES NOT APPEAR TO BE MUCH OF A WAVE IN THIS
VICINITY...A WAVE PASSAGE WAS EVIDENT VIA THE CAYENNE FRENCH
GUIANA RAOB DATA AROUND 1800 UTC YESTERDAY. A SMALL...LOW
AMPLITUDE MOISTURE SURGE WITH THIS WAVE IS ALSO NOTED IN THE
UW-CIMSS TPW PRODUCT. REGARDLESS...THE FEATURE IS NOT GENERATING
MUCH SHOWER ACTIVITY AT THE MOMENT AND IS POORLY DEFINED IN
SATELLITE IMAGERY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N12W 6N23W 7N36W 8N60W. THE AXIS IS
A LITTLE MORE ACTIVE TODAY WITH SCATTERED CLUSTERS OF MODERATE
CONVECTION NOTED WITHIN 180 NM S OF THE AXIS E OF 35W THROUGH
THE AFRICAN COAST. SIMILAR ACTIVITY IS WITHIN 180 NM N OF THE
AXIS BETWEEN 35W-47W. SOME OF THIS APPEARS TO BE ASSOCIATED WITH
A LOW AMPLITUDE TROPICAL WAVE IN THE VICINITY...BUT WILL HOLD
OFF ADDING TO THE MAP AT THIS POINT DUE TO THE RATHER LINEAR E-W
NATURE OF THE ITCZ. THIS MAY NEED TO BE REEVALUATED ON FUTURE
MAPS...AS MODEL GUIDANCE SUGGESTS THE ASSOCIATED SHOWER ACTIVITY
WILL AFFECT THE LESSER ANTILLES OVER THE WEEKEND.

DISCUSSION...

GULF OF MEXICO...
WINDS AND SEAS ARE MOSTLY RELAXING ACROSS THE GULF THIS
AFTERNOON IN WAKE OF THE FRONT THAT TRAVERSED THE AREA YESTERDAY
AND LAST NIGHT. WINDS ARE MOSTLY 15 KT OR BELOW...EXCEPT FOR A
BIT STRONGER NNE FLOW NEAR THE YUCATAN CHANNEL S OF 25N. A PIECE
OF YESTERDAYS FRONT STILL REMAINS OVER THE SW/W GULF...BETWEEN
THE NW YUCATAN PENINSULA AND BROWNSVILLE TEXAS. THIS LINGERING
QUASI-STATIONARY BOUNDARY IS CHARACTERIZED BY A LINE OF LOW TO
MID CLOUDS AND ISOLATED SHOWERS WITHIN 30 NM OF THE FRONT. LIGHT
ONSHORE SE WINDS HAVE DEVELOPED NEAR THE TEXAS AND WRN LOUISIANA
COAST AS HIGH PRES N OF THE AREA HAS MOVED E...THIS IS HELPING
TO SUPPORT THE BROKEN TO OVERCAST STRATUS NOTED NEAR THE NW GULF
COAST AND INLAND OVER ERN TEXAS. RECENT VIS IMAGERY SHOWS THESE
LOW CEILINGS THINNING A BIT THOUGH AS WE MOVE INTO THE AFTERNOON
HOURS. OTHERWISE FAIR WEATHER AND PLENTIFUL SUNSHINE IS
AFFECTING THE GULF. ALOFT...FAIRLY UNIFORM NW FLOW AND DRY AIR
IS OVER THE GULF...AIDING IN THE PLEASANT CONDITIONS.

CARIBBEAN SEA...
A COLD FRONT IS MOVING THROUGH THE NW CARIBBEAN...EXTENDING
BETWEEN WRN CUBA NEAR 22N80W AND THE YUCATAN NEAR 19N88W AS OF
08/1500 UTC. THE FRONT IS DIFFICULT TO FIND SOLELY WITH
WINDS...AS MODERATE TO FRESH NLY WINDS ARE BLOWING ON BOTH SIDES
OF THE BOUNDARY. HOWEVER...THE UW-CIMSS TPW PRODUCT HAS BEEN
EXTREMELY HELPFUL IN TRACKING THIS BOUNDARY. CONVENTIONAL
SATELLITE IMAGERY ALSO SHOWS A SMALL CONCENTRATION OF SHOWER
ACTIVITY ASSOCIATED WITH THE FRONT JUST OFFSHORE THE YUCATAN
PENINSULA AND BELIZE...WITHIN 60 NM OF 18N87W. A SEPARATE SFC
TROUGH IS BEING ANALYZED AHEAD OF THE FRONT...GENERALLY BETWEEN
SE JAMAICA TO JUST OFFSHORE THE COSTA RICA/PANAMA BORDER. THIS
IS GENERATING SCATTERED TSTMS JUST OFFSHORE NICARAGUA AND COSTA
RICA W OF 78W. A TYPICAL 1008 MB LOW IS OVER THE COLOMBIAN COAST
NEAR 10N76W...WHICH IS GENERATING ISOLATED TSTMS WITHIN 120 NM
OF THE COLOMBIAN COAST. ISOLATED TSTMS ARE ALSO AFFECTING THE
FAR NE CARIBBEAN NEAR PUERTO RICO AND VIRGIN ISLANDS...AS LIGHT
TO MODERATE TRADES OVER THE E CARIB CONVERGE WITH THE CYCLONIC
FLOW AROUND THE TROUGHING TO THE N IN THE ATLC.

ATLANTIC OCEAN...
A COLD FRONT ENTERS THE WRN ATLC AREA NEAR BERMUDA AND CONTINUES
SW THROUGH THE CENTRAL BAHAMAS. THE FRONT IS GENERATING ISOLATED
TSTMS WITHIN 60 NM OF THE BOUNDARY MOSTLY N OF 27N...AND ALSO
PARTLY RESPONSIBLE FOR THE FEW CELLS NOTED NEAR THE NW BAHAMAS.
MODERATE NLY WINDS ARE BEHIND THE FRONT...BUT HAVE GENERALLY
RELAXED SOME SINCE YESTERDAY AFTERNOON AND LAST NIGHT. THESE
WINDS EXPECTED TO RELAX FURTHER THROUGH FRI AS HIGH PRES BUILDS
OVER THE NE GULF. A LITTLE FURTHER E...A 1007 MB LOW IS NEAR
28N63W THAT HAS A TROUGH EXTENDING S TO HISPANIOLA...AND A
SEPARATE TROUGH EXTENDING ENE TO 31N57W. THE TROUGHING IS
GENERATING ISOLATED TSTMS S OF 25N TO THE COAST OF HISPANIOLA
BETWEEN 65W-71W...AND ALSO N OF 29N BETWEEN 54W-58W. A 1009 MB
SFC LOW IS NOW N OF THE AREA NEAR 34N29W...BUT AN ELONGATED
TRAILING TROUGH EXTENDS THROUGH THE AREA ALONG 32N25W 25N28W
20N42W 13N49W. THIS BOUNDARY IS NOT AS WELL DEFINED AS IT WAS IN
DAYS PAST WITH ONLY ISOLATED SHOWERS NEAR THE TROUGH...AND WILL
THUS LIKELY BE READJUSTED SOME AT 1800 UTC. THE REMAINDER OF THE
E ATLC IS DOMINATED BY FAIR WEATHER AND MODEST SFC
RIDGING...WITH THE UW-CIMSS SAL PRODUCT AND VISIBLE IMAGERY
SHOWING A FAIRLY DENSE AREA OF AFRICAN DUST AHEAD OF THE
AFOREMENTIONED ELONGATED SFC TROUGH.

$$
WILLIS




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