[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 130006 AAA
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...SPECIAL FEATURES...
THE CENTER OF HURRICANE FLORENCE AT 12/2100 UTC WAS NEAR 39.3N
59.3W. THIS POSITION IS ALSO ABOUT 520 NM/965 KM SOUTHWEST OF
CAPE RACE NEWFOUNDLAND. FLORENCE IS MOVING NORTHEAST AT
17 KT. SOME INCREASE IN FORWARD SPEED IS EXPECTED DURING THE
NEXT 24 HOURS. THE CENTER OF FLORENCE IS EXPECTED TO PASS JUST
SOUTHEAST OF NEWFOUNDLAND DURING THE NEXT DAY OR SO. THE
ESTIMATED MINIMUM CENTRAL PRESSURE IS 980 MB. THE MAXIMUM
SUSTAINED WIND SPEEDS ARE 65 KT WITH GUSTS TO 80 KT. LITTLE
CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 24 HOURS AS
FLORENCE TRANSITIONS INTO A LARGE AND POWERFUL EXTRATROPICAL
CYCLONE. PLEASE READ THE LAST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC OR THE PUBLIC ADVISORY
UNDER MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. RESIDENTS IN
EXTREME EASTERN CANADA SHOULD CONSULT BULLETINS ISSUED BY
ENVIRONMENT CANADA FOR STORM INFORMATION SPECIFIC TO YOUR
AREA...INCLUDING POSSIBLE WATCHES AND WARNINGS. THE ONLY
CONVECTION REMAINING NEAR THE CENTER IS A BAND OF SHOWERS AND
THUNDERSTORMS LOCATED ABOUT 100 NM NORTHWEST OF THE
CENTER.

THE CENTER OF TROPICAL STORM GORDON AT 12/2100 UTC WAS NEAR
23.7N 58.4W. THIS POSITION ALSO IS ABOUT 440 NM/815 KM
NORTH-NORTHEAST OF THE LEEWARD ISLANDS. GORDON IS MOVING NORTH
AT 6 KT AND THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB. THE
MAXIMUM SUSTAINED WIND SPEEDS ARE 55 KT WITH GUSTS TO 65 KT.
ADDITIONAL  STRENGTHENING IS FORECAST AND GORDON COULD BECOME A
HURRICANE TONIGHT OR ON WEDNESDAY. PLEASE READ THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
AND THE PUBLIC ADVISORY MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION EXISTS FROM
22N-26N BETWEEN 56W-60W. ANOTHER REGION OF NUMEROUS
SHOWERS/TSTMS IS NOTED FURTHER E OF THE CENTER FROM 20N-26N
BETWEEN 51W-56W...SPREADING E WITH UPPER LEVEL WESTERLY FLOW.

THE CENTER OF TROPICAL DEPRESSION EIGHT AT 12/2100 UTC
WAS NEAR 12.0N 23.9W. THIS POSITION ALSO IS ABOUT 170 NM/295 KM
SOUTH SOUTHERNMOST CAPE VERDE ISLANDS. T.D. EIGHT IS MOVING WEST
AT 13 KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. THE
MAXIMUM SUSTAINED WINDS ARE 30 KT WITH GUSTS TO 40 KT.
STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS...AND THE
DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT OR EARLY
WEDNESDAY.PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC AND THE PUBLIC ADVISORY
MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS. SATELLITE IMAGES SHOW
THAT THE DEPRESSION IS GRADUALLY BECOMING MORE ORGANIZED WITH
FAIRLY PROMINENT BANDING FEATURES OVER THE WESTERN AND SOUTHERN
PORTIONS OF THE CIRCULATION.  HOWEVER THE CENTER IS STILL RATHER
BROAD AND ELONGATED...AND THE AREA OF CONVECTION TO THE WEST OF
THE CENTER IS MOVING WESTWARD AND BECOMING MORE SEPARATED FROM
THE CENTER OF THE CYCLONE.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 37W/38W SOUTH OF 17N
MOVING WEST NEAR 10 KT. THIS WAVE HAS BEEN FAIRLY
STRAIGHTFORWARD TO TRACK THE LAST FEW DAYS WITH A CLEAR SIGNAL
ON A METEOSAT8 HOVMOLLER DIAGRAM...BUT IS NOT THE CASE ANYMORE.
ONE CAN DETECT A BIT OF LOW/MID CLOUD TURNING CURRENTLY
APPROACHING 40W FROM 5N-10N THAT IS PROPAGATING WWARD.
ASSOCIATED SCATTERED MODERATE CONVECTION LIES FROM 5N-8N BETWEEN
39W-43W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 48W SOUTH OF 16N MOVING
WEST 10 TO 15 KT. THIS WAVE IS LOW AMPLITUDE WITH MINIMAL DEEP
CONVECTION. ISOLATED MODERATE CONVECTION FROM 4N-7N BETWEEN
46W-50W.

A NEW TROPICAL WAVE OR REPOSITION OF THE WAVE NEAR 48W WILL
LIKELY BE ADDED TO THE 13/0000 UTC MAP JUST E OF THE WINDWARD
ISLANDS ALONG 57W. A CLASSIC WAVE PATTERN IS SEEN IN THIS REGION
S OF 19N. ISOLATED SHOWERS/TSTMS DOT THE AREA FROM 11N-16N
BETWEEN 54W-60W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 65W SOUTH OF 16N MOVING
WEST NEAR 15 KT. THERE IS A HINT OF LOW/MID CYCLONIC TURNING
NEAR THE WAVE AXIS ALONG WITH NUMEROUS SHOWERS/TSTMS OVER S
AMERICA MOVING W...THOUGH OVERALL THE SIGNAL IS VAGUE.

...THE ITCZ...
ITCZ IS CENTERED ALONG 9N25W 8N35W 7N39W 7N46W 8N50W 10N62W.
ASIDE FROM THE CONVECTION NEAR THE TROPICAL WAVES AND T.D.
EIGHT...A CLUSTER OF SCATTERED MODERATE CONVECTION IS SEEN FROM
7N-11N BETWEEN 55W-58W. SEVERAL SIMILAR CLUSTERS OVER NRN S
AMERICA ALSO LIKELY ENHANCED BY THE ITCZ.

...DISCUSSION...

THE GULF OF MEXICO...
A MID TO UPPER LEVEL ANTICYCLONE IS SPINNING NEAR COASTAL NE
MEXICO...THAT HAS RIDGING EXTENDING E TO NEAR 86W MORE OR LESS
ALONG 27N. ANOTHER SMALLER MID/UPPER HIGH IS OVER THE FAR SE
GULF. UPPER DIFFLUENT AIR BETWEEN THIS FEATURES AND THE WRLY
FLOW OVER THE SRN UNITED STATES IS HELPING TO SUPPORT THE
SCATTERED MODERATE CONVECTION IN THE NW GULF FROM 25N-30N
BETWEEN 93W-98W...AS WELL AS IN THE NE GULF FROM 25N-30N BETWEEN
83W-88W. A MID TO UPPER LOW IS MOVING SLOWLY W THROUGH THE BAY
OF CAMPECHE CENTERED NEAR 20N94W...THAT HAS ISOLATED
SHOWERS/TSTMS MOVING AROUND ITS PERIPHERY. A CLUSTER OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER THE YUCATAN
SEEMS MORE ASSOCIATED WITH AFTERNOON HEATING...AND IS MOVING
INTO THE EXTREME ERN BAY OF CAMPECHE. AT THE SURFACE...FAIRLY
LIGHT SE FLOW DOMINATES MUCH OF THE GULF ON THE S/SW PORTION OF
THE HIGH BUILDING OVER NEW ENGLAND. THE EXCEPTION IS LIGHT W/SW
FLOW IN THE NW GULF AHEAD OF A STATIONARY FRONTAL BOUNDARY.

THE CARIBBEAN SEA...
OVERALL THE CARIBBEAN REMAINS FAIRLY QUIET THIS EVENING WITH
ABUNDANT DRY AIR. AFTERNOON AND EVENING SHOWERS/TSTMS OVER
CUBA...JAMAICA...AND HISPANIOLA ARE DRIFTING SOUTH INTO THE FAR
NRN PORTION OF THE CARIBBEAN...WITH MID/UPPER LEVEL NRLY FLOW
BETWEEN UPPER ANTICYCLONES OVER THE FAR NW CARIBBEAN AND SE
GULF...AND UPPER TROUGHING EXTENDING THROUGH THE CTRL AND ERN
CARIBBEAN BETWEEN 61W-75W. 10-20 KT TRADES PERSIST THIS EVENING
AND WILL CONTINUE THROUGH TOMORROW...EXCEPT LIGHTER FAR NW
CARIB.

THE ATLANTIC OCEAN...
ABUNDANT DRY MID TO UPPER LEVEL AIR OVER THE SW NORTH ATLC IS
SEEN IN WV IMAGERY THIS EVENING...AND IS BEING ADVECTED SW/S
BETWEEN AN UPPER ANTICYCLONE EXTENDING E FROM THE SE GULF...AND
THE UPPER TROUGH EXTENDING NE THROUGH THE LEEWARD ISLANDS TO
NEAR 25N BETWEEN 61W-72W. A LARGE FETCH OF N/NE WINDS PERSISTS
OFF THE MID ATLC AND NE US COAST BETWEEN FLORENCE AND THE 1026MB
HIGH BUILDING INTO NEW ENGLAND. ASSOCIATED MODERATE TO STRONG NE
SWELL WILL CONTINUE TO PRODUCE DANGEROUS SURF CONDITIONS AT
BEACHES EXPOSED TO NE SWELL OVER THE NEXT COUPLE OF
DAYS...BEFORE SUBSIDING THROUGH THE WEEKEND. SEE STATEMENTS FROM
LOCAL WEATHER SERVICE OFFICES FOR MORE DETAILS. GORDON CONTINUES
TO STRENGTHEN AS DESCRIBED ABOVE. SE OF GORDON LIES AN UPPER
ANTICYCLONE CENTERED NEAR 18N54W....AND NE OF GORDON IS AN UPPER
LOW NEAR 30N44W. ISOLATED SHOWERS/TSTMS ARE SPINNING
CYCLONICALLY AROUND THIS UPPER LOW WITHIN 150NM OF ANY SIDE OF
THE CENTER. A MID TO UPPER HIGH IS OVER THE ERN ATLC OFF THE
COAST OF AFRICA NEAR 25N28W. THIS REGION IS ALSO DOMINATED BY
THE SRN PORTION OF A 1025MB SFC HIGH CENTERED ESE OF THE AZORES
NEAR 36N37W.

$$
WILLIS




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