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AXNT20 KNHC 280004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2345 UTC.


...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 16.6N 64.0W AT 27/2100 UTC OR ABOUT 151 NM W OF GUADELOUPE...MOVING W-NW AT 13 KT. ESTIMATED CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WINDS ARE 40 KT WITH GUSTS TO 50 KT. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION IS FROM 14N TO 18N BETWEEN 61W AND 65W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 11N TO 19N BETWEEN 60W AND 65W. PLEASE SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.


...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE E ATLANTIC WITH AXIS APPROXIMATELY ALONG 27W...MOVING W AT ABOUT 20 KT OVER THE PAST 24 HRS. MODERATE MOISTURE IS ASSOCIATED WITH THIS WAVE FROM THE SURFACE TO 850 MB AS INDICATED BY CIRA LAYER PRECIPITABLE WATER IMAGERY. HOWEVER...THE PRESENCE OF SAHARAN DRY AIR AND DUST IN THE WAVE ENVIRONMENT SUPPRESS THE DEVELOPMENT OF CONVECTION. AHEAD OF THE TROPICAL WAVE...A 1012 MB LOW IS EMBEDDED IN THE MONSOON TROUGH NEAR 10N32W. MODERATE TO HIGH MOISTURE FROM THE SURFACE TO NEAR 700 MB AND MIDDLE LEVEL DIFFLUENCE SUPPORT SCATTERED MODERATE CONVECTION FROM 07N TO 13N BETWEEN 34W AND 38W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS NEAR 46W
...MOVING W AT 15-20 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. HOWEVER...THE PRESENCE OF SAHARAN DRY AIR AND DUST IN THE WAVE ENVIRONMENT SUPPRESS THE DEVELOPMENT OF CONVECTION.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS INTO THE TROPICAL ATLANTIC NEAR 14N17W TO 13N28W TO A 1012 MB LOW NEAR 10N32W TO 07N36W. THE ITCZ BEGINS NEAR 07N36W AND CONTINUES TO 08N45W. A 1012 MB LOW IS EMBEDDED IN THE MONSOON TROUGH NEAR 10N32W. MODERATE TO HIGH MOISTURE FROM THE SURFACE TO NEAR 700 MB AND MIDDLE LEVEL DIFFLUENCE SUPPORT SCATTERED MODERATE CONVECTION FROM 07N TO 13N BETWEEN 34W AND 38W.


...DISCUSSION...

GULF OF MEXICO...

A BROAD MIDDLE TO UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY S-SW ACROSS THE GULF TO A BASE OVER THE GULF OF CAMPECHE. THIS TROUGH SUPPORTS A STATIONARY FRONT THAT EXTENDS FROM NORTHERN FLORIDA TO A 1012 MB LOW NEAR 28N85W TO 23N88W TO 24N95W. THE UPPER TROUGH ALSO SUPPORT A SURFACE TROUGH S OF THE FRONT TAIL FROM 23N96W TO 19N94W. MOISTURE ADVECTION FROM THE CARIBBEAN IS CONVERGING WITH MOISTURE ASSOCIATED WITH THE FRONT GENERATING INSTABILITY THAT ALONG WITH A DIVERGENT ENVIRONMENT ALOFT SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS OVER THE SW GULF S OF 24N. SIMILAR CONVECTION IS OVER THE SE GULF WATERS AHEAD OF THE FRONT...S OF 27N E OF 87W. DRY AIR SUBSIDENCE AND ADVECTION FROM SOUTHERN U.S. SUPPORT FAIR WEATHER N AND W OF THE FRONT. NORTHERLY WIND FLOW OF OF LESS THAN 15 KT COVERS THE BASIN. THE LOW PRESSURE CENTER IS FORECAST TO DISSIPATE BY FRIDAY MORNING...THE STATIONARY FRONT EXPECTED TO DISSIPATE BY SATURDAY MORNING LEAVING A TROUGH OF LOW PRESSURE IN THE NE GULF.

CARIBBEAN SEA...

THE MAIN FEATURE OF INTEREST IN THE BASIN IS TROPICAL STORM ERIKA OVER THE EASTERN CARIBBEAN. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A COMBINATION OF UPPER DIFFLUENCE GENERATED BY THE TROUGH IN THE GULF AND AN UPPER HIGH S OF CUBA AND AN UPPER LOW FARTHER E OVER CENTRAL CUBA IS CAUSING AN UNSTABLE ENVIRONMENT THAT ALONG WITH MODERATE LOW LEVEL MOISTURE IN THE NW CARIBBEAN SUPPORT HEAVY SHOWERS AND TSTMS ACROSS CUBA. ISOLATED SHOWERS AND TSTMS ARE OVER THE NW BASIN W OF JAMAICA. THE CENTER OF ERIKA WILL MOVE NEAR THE VIRGIN ISLANDS THIS EVENING...MORE NEAR OR OVER PUERTO RICO TONIGHT...AND NEAR OR OVER THE DOMINICAN REPUBLIC ON FRIDAY. ERIKA IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 4 TO 8 INCHES WITH MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE ACROSS PORTIONS OF THE LEEWARD ISLANDS...VIRGIN ISLANDS...PUERTO RICO TONIGHT...THE DOMINICAN REPUBLIC...TURKS AND CAICOS ISLANDS AND SOUTHERN BAHAMAS THROUGH SATURDAY. RAINS COULD CAUSE LIFE- THREATENING FLASH FLOODS AND MUD SLIDES. TROPICAL STORM FORCE WINDS WITHIN 90 NM E SEMICIRCLE AND 0 NM W SEMICIRCLE OF ERIKA. SEAS 12 FT OR GREATER WITHIN 180 NM NE QUADRANT WITH SEAS TO 16 FT. ELSEWHERE WITHIN 270 NM NE SEMICIRCLE WINDS 20 TO 33 KT. SEAS 8 TO 12 FT. EASTERLIES OF 10-15 KT DOMINATE ELSEWHERE ACROSS THE BASIN.


...HISPANIOLA...

CURRENTLY CLOUDY SKIES WITH POSSIBLE ISOLATED SHOWERS OVER EASTERN HISPANIOLA AS TROPICAL STORM ERIKA CONTINUE TO MOVE W-NW OVER EASTERN CARIBBEAN WATERS. THE CENTER OF ERIKA WILL MOVE NEAR OR OVER THE DOMINICAN REPUBLIC ON FRIDAY. 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 AHEAD OF A STATIONARY FRONT EXTENDING ACROSS NORTHERN FLORIDA INTO THE GULF OF MEXICO ALONG WITH LOW LEVEL MOISTURE CONVERGENCE OVER THE FAR SW N ATLC SUPPORT SCATTERED HEAVY SHOWERS AND TSTMS N OF 22N W OF 70W. SCATTERED MODERATE CONVECTION ASSOCIATED WITH ERIKA...DISCUSSED IN THE SPECIAL FEATURES...IS S OF 19N BETWEEN 60W AND 65W. THERE ARE TWO TROPICAL WAVES...ONE OVER THE CENTRAL BASIN AND OTHER W OF THE CAPE VERDE ISLANDS NONE GENERATING CONVECTION AT THE TIME. SEE THE TROPICAL WAVES SECTION. A LOW PRESSURE CENTER IS BETWEEN THE WAVES GENERATING SCATTERED MODERATE CONVECTION FROM 07N TO 13N BETWEEN 34W AND 38W. OTHERWISE...SURFACE RIDGING AND FAIR WEATHER DOMINATE ELSEWHERE.

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

$$ NR

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