[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151158
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED SEP 15 2010

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...

TROPICAL STORM KARL IS CENTERED NEAR 18.6N 87.6W AT 15/1200 UTC
OR ABOUT 90 NM E OF CHETUMAL MEXICO MOVING W-NW AT 11 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB. MAXIMUM SUSTAINED
WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SEE LATEST NHC
INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT3/WTNT33 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. NUMEROUS STRONG
CONVECTION IS WITHIN 30/45 NM OF THE CENTER IN THE ALL QUADRANTS
WITH SCATTERED MODERATE/STRONG CONVECTION COVERING THE REMAINDER
OF THE AREA FROM 17N-19N W OF 85W TO INLAND OVER THE YUCATAN AND
SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 45 NM OF
LINE FROM 21N84W TO INLAND OVER THE YUCATAN NEAR 20N87W. KARL
COULD INTENSIFY BEFORE LANDFALL BUT FORTUNATELY TIME IS SHORT
BEFORE THE CENTER SHOULD CROSS THE COAST.

HURRICANE IGOR IS CENTERED NEAR 19.5N 54.5W AT 15/0900 UTC OR
ABOUT 495 NM E OF THE NORTHERN LEEWARD ISLANDS AND ABOUT 950 NM
KM SE OF BERMUDA MOVING W-NW AT 9 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 935 MB. MAXIMUM SUSTAINED WIND SPEED IS 125 KT WITH
GUSTS TO 155 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.
SCATTERED STRONG CONVECTION IS WITHIN 15O NM FROM THE CENTER IN
THE SE QUADRANT WITH SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERING THE REMAINDER OF THE AREA FROM 16N-23N
BETWEEN 50W-57W. ALTHOUGH IGOR HAS WEAKEN SLIGHTLY IT IS STILL A
LARGE CATEGORY FOUR HURRICANE.

HURRICANE JULIA IS CENTERED NEAR 17.3N 31.8W AT 15/0900 UTC OR
ABOUT 455 NM W OF THE CAPE VERDE ISLANDS MOVING NW AT 9 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 950 MB. MAXIMUM SUSTAINED
WIND SPEED IS 115 KT WITH GUSTS TO 140 KT. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
FOR MORE DETAILS. SCATTERED STRONG CONVECTION IS WITHIN 60 NM
FROM THE CENTER IN THE SW QUADRANT WITH SCATTERED MODERATE/
ISOLATED STRONG CONVECTION COVERING THE REMAINDER OF THE AREA
FROM 14N-21N BETWEEN 30W-34W. ALTHOUGH JULIA IS A RELATIVE
SMALLER HURRICANE THAN IGOR IT IS NOW ALSO A CATEGORY FOUR
HURRICANE.

...ITCZ...

THE ITCZ/MONSOONAL TROUGH REMAINS ACROSS THE ATLC BASIN BEING
DISTORTED SOMEWHAT BY HURRICANES IGOR AND JULIA. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN 90/120 NM N OF THE AXIS
FROM 16-19 AND FROM 21W-24W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 4N-9N E OF 34W TO INLAND OVER SW AFRICA AND
WITHIN 120/150 NM OF LINE FROM 6N37W TO 12N42W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER LEVEL RIDGE COVERS THE GULF N OF 25N TO OVER THE
SE U.S. EXTENDING E TO OVER THE FLORIDA PENINSULA ANCHORED OFF
THE SE LOUISIANA COAST NEAR 29N89W. SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 60/75 NM OF 28N FROM
83W-88W. THE BROAD UPPER RIDGE ASSOCIATED WITH T.S. KARL COVERS
THE SE GULF S OF 25N E OF 90W PROVIDING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS OVER THE AREA. SIMILAR ACTIVITY IS BEING
GENERATED BY THE SOUTHERLY FLOW ALOFT AND THE CONVERGING
NORTHERLY SURFACE FLOW S OF 23N BETWEEN 90W-94W. A WEAK UPPER
INVERTED TROUGH IS ALONG THE COAST OF MEXICO FROM VERACRUZ TO
TUXPAN IN THE W BAY OF CAMPECHE GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 60 NM OF THE COAST S OF
24N W OF 94W. OTHERWISE...MOSTLY DRY STABLE AIR ALOFT DOMINATES
THE REMAINDER OF THE GULF THIS MORNING WITH MOSTLY CLEAR SKIES.

CARIBBEAN SEA...
THE PRIMARY FOCUS FOR THE CARIBBEAN THIS MORNING IS TROPICAL
STORM KARL. HEAVY RAIN HAS ALREADY MOVED ONSHORE AS KARL
APPROACHES THE COAST...SEE SPECIAL FEATURES ABOVE. THE UPPER
LEVELS OF THE CARIBBEAN ARE DOMINATED BY A BROAD UPPER RIDGE
THAT IS ASSOCIATED WITH T.S. KARL EXTENDING AN AXIS SE FROM
20N80W TO 16N69W PROVIDING DIFFLUENCE ALOFT TO GENERATE CLUSTERS
OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS W OF 74W TO OVER THE
GREATER ANTILLES AND CENTRAL AMERICA. A WEAKENING UPPER TROUGH
REMAINS OVER THE E CARIBBEAN EXTENDING FROM THE LEEWARD/VIRGIN
ISLANDS NEAR 17N63W TO 13N66W COVERING THE REMAINDER OF THE E
CARIBBEAN WITH DRY STABLE AIR E OF THE HURRICANE IGOR. SCATTERED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 60/75 NM
OF A LINE FROM 13N67W TO 15N74W.

ATLANTIC OCEAN...
HURRICANES IGOR AND JULIA ARE THE PRIMARY FOCUS FOR THE ATLC
AGAIN THIS MORNING. THE UPPER RIDGE ASSOCIATED WITH T.S. KARL IS
PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 25N TO OVER CUBA W OF 75W INTO THE
FLORIDA STRAITS. A WEAK SURFACE RIDGE COVERS THE REMAINDER OF
THE W ATLC WITH A 1020 MB HIGH NEAR 32N77W. A WEAKENING UPPER
TROUGH EXTENDS FROM 22N62W ACROSS THE LEEWARD/VIRGIN ISLANDS
INTO THE E CARIBBEAN NEAR 17N63W PROVIDING DRY STABLE AIR E OF
HURRICANE IGOR. THE UPPER RIDGE ASSOCIATED WITH IGOR IS A LARGE
NEARLY UNIFORMED IN AREA WHILE THE UPPER RIDGE ASSOCIATED WITH
JULIA IS NARROW AND ELONGATED N-NE TO S-SW AND AN UPPER TROUGH
BETWEEN. STRONG SUBSIDENCE/DRY STABLE AIR AND THUS MOSTLY CLEAR
SKIES DOMINATE THE REMAINDER OF THE W AND CENTRAL ATLC BETWEEN
IGOR AND JULIA.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW






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