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000
AXNT20 KNHC 281158 AAA
TWDAT

TROPICAL WEATHER DISCUSSION...AMENDED
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI AUG 28 2015

AMENDED FOR UPDATED INFORMATION ON TROPICAL STORM ERIKA

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 1015 UTC.


...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 17.7N 68.5W AT 28/1200 UTC OR ABOUT 80 NM ESE OF SANTO DOMINGO DOMINICAN REPUBLIC AND ABOUT 335 NM SE OF GREAT INAGUA ISLAND...MOVING WNW AT 15 KT. ESTIMATED CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WINDS ARE 45 KT WITH GUSTS TO 55 KT. NUMEROUS MODERATE TO STRONG CONVECTION IS FROM 12N-18N BETWEEN 63W-68W. ERIKA IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 4 TO 8 INCHES WITH MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE ACROSS PORTIONS OF THE VIRGIN ISLANDS...PUERTO RICO...THE DOMINICAN REPUBLIC...TURKS AND CAICOS ISLANDS AND SOUTHERN BAHAMAS THROUGH SATURDAY. RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. PLEASE SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC AND THE HIGH SEAS FORECAST PRODUCT UNDER AWIPS/WMO HEADERS MIAHSFAT1/FZNT02 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS EXTENDING FROM 15N33W TO A 1012 LOW NEAR 10N34W TO 07N35W...MOVING W AT 15-20 KT OVER THE PAST 24 HOURS. MODERATE MOISTURE PREVAILS IN THE ENVIRONMENT OF THIS WAVE AS NOTED IN TPW IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 11N-14N BETWEEN 33W-37W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS EXTENDING FROM 21N47W TO 07N50W...MOVING W AT 15-20 KT OVER 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. HOWEVER...THE PRESENCE OF A SAHARAN DRY AIRMASS IN THE WAVE ENVIRONMENT IS CURRENTLY SUPPRESSING ANY CONVECTION.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS INTO THE TROPICAL ATLANTIC NEAR 17N17W TO A 1012 MB LOW NEAR 10N34W TO 10N38W. THE ITCZ BEGINS FROM THAT POINT TO 10N47W. ASIDE FROM THE CONVECTION RELATED TO THE TROPICAL WAVE ALONG 34W...SCATTERED MODERATE CONVECTION IS OBSERVED FROM 08N-14N BETWEEN 37W-48W.


...DISCUSSION...

GULF OF MEXICO...

A BROAD MID TO UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY TO THE S-SW ACROSS THE GULF TO A BASE OVER THE BAY OF CAMPECHE. THIS TROUGH SUPPORTS A STATIONARY FRONT THAT EXTENDS FROM NORTHERN FLORIDA NEAR 31N84W TO 23N87W TO 24N96W. SCATTERED MODERATE CONVECTION IS OBSERVED WITHIN 100 NM OF THE FRONTAL BOUNDARY. UPPER LEVEL DIFFLUENCE IS SUPPORTING ISOLATED CONVECTION ACROSS THE SOUTHERN GULF MAINLY S OF THE FRONT. SCATTEROMETER DATA DEPICTS A LIGHT TO GENTLE NORTHERLY FLOW ACROSS THE BASIN. OVER THE NEXT 24 HOURS...EXPECT FOR THE FRONTAL BOUNDARY TO DISSIPATE ACROSS THE SOUTHERN HALF OF THE GULF.

CARIBBEAN SEA...

THE MAIN FEATURE OF INTEREST IN THE BASIN IS TROPICAL STORM ERIKA CURRENTLY MOVING OVER THE NE CARIBBEAN. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. UPPER-LEVEL DIFFLUENCE GENERATED BY THE PROXIMITY OF THE UPPER-LEVEL TROUGH OVER THE GULF COMBINED WITH SUFFICIENT LOW LEVEL MOISTURE ARE SUPPORTING ISOLATED CONVECTION ACROSS THE WESTERN HALF OF CUBA AFFECTING THE NW CARIBBEAN AND THE STRAITS OF FLORIDA. FAIR WEATHER PREVAILS ACROSS THE REMAINDER OF THE BASIN. SCATTEROMETER DATA DEPICTS LIGHT TO GENTLE TRADES ACROSS THE W AND CENTRAL CARIBBEAN AND HIGHER WINDS SURROUNDING ERIKA MAINLY E OF 68W. OVER THE NEXT 24 HOURS...EXPECT FOR ERIKA TO CONTINUE MOVING ACROSS THE E CARIBBEAN THEN MOVE WNW ENTERING THE SW ATLANTIC.


...HISPANIOLA...

FAIR WEATHER PREVAILS ACROSS THE ISLAND AT THIS TIME. THE CENTER OF TROPICAL STORM ERIKA IS EXPECTED TO MOVE NEAR OR OVER DOMINICAN REPUBLIC OVER THE NEXT 06-12 HOURS. ERIKA IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 4 TO 8 INCHES WITH MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE ACROSS PORTIONS OF THE ISLAND THROUGH SATURDAY. RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.

ATLANTIC OCEAN...

UPPER-LEVEL DIVERGENCE ACROSS THE W ATLANTIC IS SUPPORTING ISOLATED CONVECTION ACROSS THE BAHAMAS MAINLY W OF 76W. TO THE SE...SCATTERED MODERATE CONVECTION ASSOCIATED WITH TROPICAL STORM ERIKA...DISCUSSED IN THE SPECIAL FEATURES SECTION ABOVE...IS S OF 21N BETWEEN 62W-66W. TWO TROPICAL WAVES ARE MOVING ACROSS THE E AND CENTRAL TROPICAL ATLANTIC. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. THE REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1020 MB HIGH NEAR 29N64W AND A 1021 MB HIGH NEAR 29N27W.

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

$$

ERA

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