[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071148
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 07 2008

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

HANNA LOSES TROPICAL CHARACTERISTICS AS IT MOVES THROUGH NEW
ENGLAND. AT 07/0900 UTC...ITS CENTER IS NEAR 42.6N 70.0W OR OR
ABOUT 50 NM...100 KM...NORTH OF CHATHAM MASSACHUSETTS AND ABOUT
305 NM...560 KM...WEST-SOUTHWEST OF HALIFAX NOVA SCOTIA MOVING
NE AT 31 KT. THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 24
HOURS. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 55 KT. PLEASE SEE
LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. HANNA IS EXPECTED TO
PRODUCE ADDITIONAL RAINFALL ACCUMULATIONS OF 1 TO 2 INCHES
ACROSS CENTRAL TO SOUTHERN MAINE EARLY SUNDAY MORNING...WITH THE
RAINFALL ENDING ACROSS MAINE BY AROUND SUNRISE. THE LAST
ADVISORY WAS ISSUED BY THE NATIONAL HURRICANE CENTER ON THIS
SYSTEM AT 07/0900 UTC.

HURRICANE IKE IS CENTERED NEAR 21.0N 72.8W AT 07/1200 UTC OR
JUST EAST OF GREAT INAGUA ISLAND MOVING JUST SOUTH OF DUE WEST
AT 12 KT. A WEST TO WEST-SOUTHWEST MOTION IS EXPECTED TO
CONTINUE TODAY WITH A TURN TOWARD THE W-NW EXPECTED ON MONDAY.
ON THIS TRACK...THE CORE OF THE HURRICANE WILL MOVE THROUGH THE
SOUTHEASTERN BAHAMAS THIS MORNING AND MOVE NEAR OR OVER EASTERN
CUBA TONIGHT...AND NEAR OR OVER CENTRAL CUBA LATE MONDAY.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 949 MB. MAXIMUM SUSTAINED
WIND SPEED IS 115 KT WITH GUSTS TO 140 KT. PLEASE SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24 KNHC
FOR MORE DETAILS. IKE IS AN EXTREMELY DANGEROUS CATEGORY FOUR
HURRICANE ON THE SAFFIR-SIMPSON SCALE HEADING FOR GREAT INAGUA
ISLAND IN THE SOUTHEASTERN BAHAMAS.  RAINFALL AMOUNTS OF 4 TO 8
INCHES WITH ISOLATED MAXIMUM AMOUNTS OF 12 INCHES ARE EXPECTED
OVER THE TURKS AND CAICOS ISLANDS AND THE SOUTHEASTERN BAHAMAS.
HISPANIOLA AND EASTERN CUBA COULD SEE 6 TO 12 INCHES OF RAIN
WITH ISOLATED MAXIMUM AMOUNTS OF UP TO 20 INCHES POSSIBLE.
THESE RAINS WILL LIKELY CAUSE LIFE-THREATENING FLASH FLOODS AND
MUDSLIDES OVER MOUNTAINOUS TERRAIN.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 33W/34W S OF 15N MOVING W 10-15 KT.
ISOLATED MODERATE CONVECTION IS NEAR THE SOUTHERN END OF THE
WAVE AXIS FROM 6N-8N. SCATTERED SHOWERS ARE AHEAD OF THE WAVE
LINE NEAR 11N36W.

A TROPICAL WAVE IS ALONG 59W SOUTH 17N MOVING W 10-15 KT. THE
WAVE IS CROSSING THE ISLAND OF BARBADOS...WHICH IS REPORTING
HEAVY TSTMS AND SUSTAINED WINDS OF 25 KT FROM THE SE. A CLUSTER
OF MODERATE TO ISOLATED STRONG CONVECTION IS OVER THAT ISLAND.
SFC DATA AND AN EARLIER ASCAT PASS...BOTH SHOWED VERY WELL THE
WIND SHIFT ASSOCIATED WITH THE WAVE. THE WAVE SHOWS UP ON THE
THE TPW PRODUCT FROM CIMSS WHERE A BULGE OF MOISTURE MAXIMUM IS
NOTED. 850 MB SATELLITE DERIVED VORTICITY ALSO SUPPORTS THE
POSITION OF THE WAVE AXIS.

...THE ITCZ...

THE ITCZ AXIS IS ALONG 13N17W 8N23W 8N31W 10N40W 11N58W.
BESIDES THE CONVECTION MENTIONED IN THE TROPICAL WAVE SECTION...
A CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-7N
BETWEEN 27W-29W. SCATTERED MODERATE CONVECTION IS NEAR 11N22W
AND 5N31W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0900 UTC...A WEAKENING STATIONARY FRONT EXTENDS FROM THE W
FLORIDA PANHANDLE TO THE DEEP SOUTH TEXAS. THE FRONT IS SLIGHTLY
MOVING N PARTICULARLY ON THE WESTERN PART. SCATTRED SHOWERS AND
ISOLATED TSTMS ARE ALONG THE FRONTAL BOUNDARY. A SURFACE TROUGH
REMAINS OVER THE BAY OF CAMPECHE ALONG 93W/94W S OF 23N.
CONVECTION ASSOCIATED WITH THIS TROUGH HAS INCREASED OVERNIGHT
AND NOW SATELLITE IMAGERY SHOWS A LARGE AREA OF MODERATE TO
STRONG CONVECTION OVER THE BAY OF CAMPECHE AND SE MEXICO NEAR
VERACRUZ WHICH IS REPORTING LIGHT TO MODERATE. NE WINDS OF 15-20
KT ARE NOTED WHILE WINDS HAS VEERED TO THE E BEHIND THE FRONTAL
SYSTEM. A SFC RIDGE FROM THE ATLC DOMINATES THE EASTERN PORTION
OF THE GULF AND THE STATE OF FLORIDA WITH A 1016 MB HIGH LOCATED
NEAR 28N85W. IN THE UPPER LEVELS...A MID/UPPER LEVEL RIDGE
COVERS MOST OF THE AREA WITH A LONGWAVE TROUGH OVER THE CENTRAL
U.S. CLIPPING THE FAR N CENTRAL GULF. THIS UPPER-LEVEL TROUGH IS
SUPPORTING THE AFOREMENTIONED FRONTAL BOUNDARY. LOOKING
AHEAD...MAJOR HURRICANE IKE CURRENTLY EAST OF GREAT INAGUA
ISLANDS IN THE SE BAHAMAS IS FORECAST TO ENTER THE SE GULF TUE
THEN TRACKS NW TO N CENTRAL GULF THU. ONCE IKE MOVES INTO THE SE
GULF...CONDITIONS APPEAR FAVORABLE FOR STRENGTHENING.

CARIBBEAN SEA...
ALL THE ATTENTION REMAINS FOCUSED ON THE EXTREMELY DANGEROUS
HURRICANE IKE THAT IS FORECAST TO MOVE OVER OR NEAR EASTERN CUBA
TONIGHT AND EARLY MONDAY. OUTER RAINBANDS ASSOCIATED WITH IKE
ARE AFFECTING WESTERN PUERTO RICO AND HISPANIOLA. THE SAN JUAN
DOPPLER RADAR DEPICTS A BAND OF SHOWERS WITH EMBEDDED TSTMS OVER
THE MONA PASSAGE AND THE SW PORTION OF PUERTO RICO UNDER A SE
WIND FLOW. THE FIRST RAINBAND ASSOCIATED WITH IKE IS REACHING
THE EASTERNMOST TIP OF CUBA. SEE SPECIAL FEATURES FOR DETAILS
ABOUT IKE. THE REMAINDER OF THE BASIN IS PRETTY QUIET EARLY THIS
MORNING WITH LOW TOPPED SHOWERS AND HIGH CLOUDS FROM THE OUTFLOW
OF IKE. ALOFT...UPPER-LEVEL ELY FLOW DOMINATES THE CENTRAL AND
WESTERN CARIBBEAN WHILE AN UPPER-LEVEL TROUGH FROM THE CENTRAL
ATLC ENTERS THE E CARIBBEAN BETWEEN GUADALOUPE AND MARTINIQUE.

ATLANTIC OCEAN...
MAJOR HURRICANE IKE IS THE MAIN CONCERN FOR THE NEXT FEW DAYS
OVER THE SW ATLC INCLUDING THE BAHAMAS...SEE SPECIAL FEATURES
ABOVE. IN THE TROPICS...A 1010 MB SFC LOW...REMNANTS OF
JOSEPHINE...IS CENTERED NEAR 17N39W. A SWIRL OF MAINLY LOW
CLOUDS DEFINES THE LOW CENTER WHILE CONVECTION HAS SIGNIFICANTLY
INCREASED IN THE NW QUADRANT OVER THE PAST FEW HOURS. A LARGE
CLUSTER OF MODERATE TO STRONG CONVECTION COVERS THE AREA FROM
FROM 17N-21N BETWEEN 40W-43W. UPPER-LEVEL WINDS ARE CURRENTLY
UNFAVORABLE FOR RE-DEVELOPMENT TO OCCUR. A 1026 MB HIGH LOCATED
NEAR 37N54W EXTENDS A RIDGE SWWD INTO THE E PORTION OF THE GULF
OF MEXICO...AND ALSO ENVELOPS THE N PORTION OF THE FORECAST
AREA. A MID-UPPER LEVEL RIDGE OVER THE CENTRAL AND W ATLC INTO
THE FLORIDA PENINSULA AND THE EASTERN GULF IS STEERING IKE WWD.
AN UPPER-LEVEL LOW OVER THE CENTRAL ATLC NEAR 20N54W HAS A
TROUGH EXTENDING SW INTO THE E CARIBBEAN TO ANOTHER UPPER-LEVEL
LOW LOCATED NEAR 13N66W. THE E ATLC IS UNDER THE INFLUENCE OF
RIDGE ANCHORED ON A HIGH SITUATED NEAR 20N32W. A JET-STREAM
BRANCH IS PRODUCING ABUNDANT CLOUDINESS WITH POSSIBLE SHOWERS
OVER THE CANARY ISLANDS.

$$
GR


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