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AXNT20 KNHC 291104
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 29 2015

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1045 UTC.


...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 19.1N 75.1W AT 29/0900 UTC OR ABOUT 65 NM S OF GUANTANAMO CUBA MOVING W AT 17 KT. ESTIMATED CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. AN AREA OF MODERATE TO ISOLATED STRONG CONVECTION EXTENDS FROM 15N-22N BETWEEN 68W-75W. THE MAIN IMPACT OUTSIDE OF TROPICAL STORM FORCE WINDS WILL BE HEAVY RAINFALL ACROSS W HISPANIOLA AND E CUBA AS WELL AS THE ADJACENT COASTAL WATERS RESULTING IN FLASH FLOODING AND DANGEROUS MUD SLIDES. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

A TROPICAL WAVE IS BEGINNING TO EXIT THE AFRICAN COAST. ITS AXIS EXTENDS FROM 19N16W TO A 1008 MB LOW NEAR 10N16W TO 07N15W. SCATTERED MODERATE TO STRONG CONVECTION PREVAILS IN THE VICINITY OF THE LOW CENTER FROM 06N-12N BETWEEN 12W-20W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC ASSOCIATED WITH A 1013 MB LOW EMBEDDED IN THE MONSOON TROUGH NEAR 10N44W. THE WAVE AXIS EXTENDS FROM 17N42W TO 08N45W. THESE FEATURES ARE MOVING W AT ABOUT 15-20 KT OVER THE LAST 24 HOURS. MODERATE MOISTURE IS ASSOCIATED WITH THIS WAVE FROM THE SURFACE TO 700 MB AS INDICATED BY CIRA LAYER PRECIPITABLE WATER IMAGERY. UPPER-LEVEL DIFFLUENCE W OF THE LOW SUPPORTS ISOLATED MODERATE CONVECTION FROM 11N-17N BETWEEN 45W-48W WHILE ISOLATED MODERATE CONVECTION PREVAILS E OF THE WAVE AXIS FROM 14N-16N BETWEEN 39W-42W.

A TROPICAL WAVE IS WITHIN 220 NM E OF THE LESSER ANTILLES WITH AXIS EXTENDING FROM 20N52W TO 09N58W...MOVING W AT 15 KT DURING THE PAST 24 HOURS. MODERATE MOISTURE FROM THE SURFACE TO NEARLY 700 MB IS ASSOCIATED WITH THIS WAVE AS INDICATED BY CIRA LAYER PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION PREVAILS ACROSS THE WESTERN PORTION OF THE WAVE FROM 14N-18N BETWEEN 55W-60W.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 11N15W TO 09N22W TO 12N36W TO 10N44W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THAT POINT TO 12N56W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION PREVAILS WITHIN 300 NM S OF THE MONSOON TROUGH AXIS AND FROM 07N-12N BETWEEN 46W-51W.


...DISCUSSION...

GULF OF MEXICO...

A BROAD AND ELONGATED MID TO UPPER-LEVEL LOW IS CENTERED OVER THE NORTH-CENTRAL GULF NEAR 30N89W EXTENDS ITS TROUGH SW INTO THE BAY OF CAMPECHE. THE TROUGHING SUPPORTS A SURFACE TROUGH FROM THE FLORIDA PANHANDLE NEAR 30N84W TO 25N88W. UPPER-LEVEL DIFFLUENCE IS SUPPORTING ISOLATED MODERATE CONVECTION ACROSS THE E GULF MAINLY E OF 87W. A SURFACE TROUGH IS OVER BAY OF CAMPECHE EXTENDING FROM 23N97W TO 19N94W. ISOLATED MODERATE CONVECTION PREVAILS S OF 21N AND W OF 94W. SCATTEROMETER DATA DEPICTS A LIGHT TO GENTLE EASTERLY FLOW PREVAILING ACROSS THE BASIN. OVER THE NEXT 24 HOURS...TROPICAL STORM ERIKA IS EXPECTED TO APPROACH THE SE GULF AFFECTING THE FLORIDA PENINSULA...STRAITS AND KEYS. FOR MORE DETAILS ABOUT ERIKA...PLEASE REFER TO THE SECTION ABOVE.

CARIBBEAN SEA...

TROPICAL STORM ERIKA IS THE MAIN FEATURE OF INTEREST IN THE CARIBBEAN...CURRENTLY MOVING W OF HISPANIOLA. PLEASE REFER TO THE SECTION ABOVE FOR DETAILS. ISOLATED CONVECTION IS OBSERVED ACROSS THE NW CARIBBEAN SUPPORTED BY UPPER-LEVEL DIFFLUENCE MAINLY N OF 20N AND W OF 79W. THE REMAINDER OF THE BASIN REMAIN RELATIVELY QUIET WITH MOSTLY DRY AIR NOTED ON WATER VAPOR IMAGERY ALOFT DUE TO AN UPPER-LEVEL RIDGE ANCHORED NEAR 17N83W COVERING THE W AND CENTRAL BASIN. SCATTEROMETER DATA DEPICTS MODERATE TO OCCASIONAL FRESH E-NE TRADES ACROSS PORTIONS OF THE W AND CENTRAL CARIBBEAN DUE TO ERIKA WHILE GENTLE TO MODERATE TRADES PREVAIL OVER THE REMAINDER OF THE BASIN. OVER THE NEXT 24 HOURS...EXPECT FOR ERIKA TO MOVE NW INTO THE ATLANTIC WITH CONVECTION.


...HISPANIOLA...

THE CENTER OF TROPICAL STORM ERIKA IS MOVING OVER THE WINDWARD PASSAGE. THE MAIN IMPACT FROM ERIKA ASIDE FROM TROPICAL STORM FORCE WINDS IS HEAVY RAINFALL WITH THE POTENTIAL OF LIFE- THREATENING FLASH FLOODS AND MUD SLIDES. THE CENTER OF THE STORM IS FORECAST TO MOVE ACROSS CUBA THEN INTO THE SE GULF OF MEXICO.

ATLANTIC OCEAN...

MID TO UPPER-LEVEL DIFFLUENCE ACROSS THE SW ATLANTIC IS SUPPORTING ISOLATED SHOWERS AND TSTMS N OF 25N W OF 73W...AFFECTING THE NORTHERN BAHAMAS. SCATTERED MODERATE CONVECTION PREVAILS OVER HAITI AND ADJACENT WATERS S OF 22N BETWEEN 69W-75W ASSOCIATED WITH TROPICAL STORM ERIKA. THE REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A PAIR OF 1021 MB SURFACE HIGHS...THE FIRST LOCATED NEAR 30N67W AND THE OTHER CENTERED NEAR 26N37W. AN UPPER-LEVEL TROUGH IS SUPPORTING SCATTERED MODERATE CONVECTION ACROSS THE NE ATLANTIC MAINLY N OF 29N BETWEEN 29W-34W. THIS ACTIVITY IS EXPECTED TO MOVE SE OVER THE NEXT 24 HOURS.

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

$$

ERA

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