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000
AXNT20 KNHC 290551
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0545 UTC.


...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 18.5N 72.9W AT 29/0300 UTC OR ABOUT 35 NM W OF PORT AU PRINCE HAITI AND ABOUT 126 NM SE OF THE EASTERN TIP OF CUBA MOVING W AT 17 KT. ESTIMATED CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. A CLUSTER OF MODERATE TO ISOLATED STRONG CONVECTION EXTENDS FROM 15N-21N BETWEEN 68W-74W. THE MAIN IMPACT OUTSIDE OF TROPICAL STORM FORCE WINDS WILL BE HEAVY RAINFALL ACROSS HISPANIOLA AND 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 19N15W TO 07N14W. LATEST VISIBLE SATELLITE IMAGERY SHOWS A HINT OF LOW-LEVEL CYCLONIC CIRCULATION TRYING TO DEVELOP ALONG THIS WAVE. SCATTERED MODERATE TO STRONG CONVECTION IS IN THE SOUTHERN PORTION OF THIS WAVE FROM 07N-11N BETWEEN 12W-18W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC ASSOCIATED WITH A 1014 MB LOW EMBEDDED IN THE MONSOON TROUGH NEAR 13N41W. THE WAVE AXIS EXTENDS FROM 17N39W TO 08N42W. 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 12N-17N BETWEEN 44W-47W WHILE ISOLATED MODERATE CONVECTION PREVAILS ACROSS THE WAVE AXIS FROM 13N-15N BETWEEN 39W-41W.

A TROPICAL WAVE IS WITHIN 285 NM E OF THE LESSER ANTILLES WITH AXIS EXTENDING FROM 20N51W TO 09N57W...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 EXTENDING FROM 10N-18N BETWEEN 54W-59W.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO 11N43W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THAT POINT TO 08N54W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION PREVAILS WITHIN 100 NM S OF THE MONSOON TROUGH AXIS.


...DISCUSSION...

GULF OF MEXICO...

A BROAD AND ELONGATED MID TO UPPER-LEVEL LOW IS CENTERED OVER THE NORTH-CENTRAL GULF NEAR 29N89W WITH ITS TROUGH EXTENDING SW INTO THE BAY OF CAMPECHE. THE TROUGHING SUPPORTS A DISSIPATING STATIONARY FRONT THAT MEANDERS FROM THE FLORIDA PANHANDLE NEAR 31N86W SW TO 26N86W TO 23N96W. UPPER-LEVEL DIFFLUENCE IS SUPPORTING ISOLATED MODERATE CONVECTION E OF THE NORTHERN PORTION OF THE FRONT AFFECTING THE E GULF E OF 88W. SCATTEROMETER DATA DEPICTS A LIGHT TO GENTLE EASTERLY FLOW PREVAILING ACROSS THE BASIN. OVER THE NEXT 24 HOURS...EXPECT FOR THE FRONT TO DISSIPATE. 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 ACROSS SOUTHERN 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. ISOLATED SHOWERS ARE ACROSS PUERTO RICO AND COASTAL WATERS DUE TO THE PROXIMITY OF ERIKA. 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 EXPECTED TO MOVING OVER HAITI AT THIS TIME. 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 TO THE WINDWARD PASSAGE SATURDAY MORNING BUT SHOWERS ARE EXPECTED TO CONTINUE THROUGH SUNDAY MORNING.

ATLANTIC OCEAN...

A MID TO UPPER-LEVEL DIFFLUENCE ACROSS THE SW ATLANTIC IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 27N W OF 72W...AFFECTING THE N BAHAMAS. SCATTERED HEAVY SHOWERS ARE OVER HISPANIOLA NORTHERN WATERS ASSOCIATED WITH TROPICAL STORM ERIKA THAT IS EXPECTED TO CONTINUE MOVE ACROSS THE ISLAND TONIGHT. THE REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A PAIR OF SURFACE HIGHS...A 1021 MB LOCATED NEAR 29N65W AND THE OTHER A 1020 MB CENTERED NEAR 26N32W.

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

$$

ERA

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