[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI AUG 28 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 17.9N 71.2W AT 28/2100 UTC
OR ABOUT 84 NM WSW OF SANTO DOMINGO DOMINICAN REPUBLIC AND ABOUT
224 NM SSE OF GREAT INAGUA ISLAND MOVING W AT 18 KT. ESTIMATED
CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 45
KT WITH GUSTS TO 55 KT. TWO CLUSTERS OF MODERATE TO ISOLATED
STRONG CONVECTION ARE ASSOCIATED WITH ERIKA...ONE FROM 17N TO
20N BETWEEN 69W AND 72W...THE SECOND FROM 15N TO 18N BETWEEN 68W
AND 71W. SCATTERED MODERATE CONVECTION AND TSTMS ARE FROM 14N TO
20N BETWEEN 66W AND 72W. 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 OVER THE CENTRAL ATLANTIC ASSOCIATED WITH A
1012 MB LOW EMBEDDED IN THE MONSOON TROUGH NEAR 12N38W. THE WAVE
AXIS AT 700 MB FORMERLY E OF THE LOW MERGED WITH IT LAST
NIGHT...RESULTING IN A WESTWARD TRANSLATION MOVEMENT OF 20-25 KT
WITHIN 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
SUPPORT SCATTERED MODERATE CONVECTION FROM 08N TO 14N BETWEEN
43W AND 47W. ISOLATED SHOWERS ARE ELSEWHERE FROM 07N TO 17N
BETWEEN 32W AND 48W.

A TROPICAL WAVE IS WITHIN 440 NM E OF THE LESSER ANTILLES WITH
AXIS NEAR 53W...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. A SLIGHT MIDDLE LEVEL DIFFLUENT
ENVIRONMENT AHEAD OF THE WAVE AXIS SUPPORT ISOLATED SHOWERS AND
TSTMS FROM 11N TO 15N BETWEEN 54W AND 58W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
11N15W TO 12N30W TO 11N41W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 11N41W TO 10N51W. ASIDE FROM CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION IS FROM 05N-11N E OF 30W.

...DISCUSSION...

GULF OF MEXICO...

A BROAD AND ELONGATED MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER
THE NORTH-CENTRAL GULF NEAR 29N89W THAT STRETCHES TROUGHING
ALOFT FROM OVER THE SE CONUS SW TO A BROAD BASE OVER THE S-SW
GULF. WHILE NORTHERLY FLOW EMBEDDED IN DRY AIR ALOFT... AND
STABLE CONDITIONS ARE NOTED OVER THE W GULF WATERS N OF 21N W OF
88W...THE TROUGHING SUPPORTS A DISSIPATING STATIONARY FRONT
MEANDERING FROM THE FLORIDA PANHANDLE NEAR 30N84W SW TO 25N86W
TO 23N95W. LOW-LEVEL MOISTURE CONVERGENCE ALONG AND SOUTH OF THE
WEAK FRONT...ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE EAST OF
THE TROUGH AXIS IS GENERATING SCATTERED SHOWERS AND TSTMS E OF A
LINE FROM 30N87W SW TO 25N90W TO 18N95W. THE FRONT IS EXPECTED
TO DISSIPATE FULLY BY SATURDAY WITH GENERALLY GENTLE TO MODERATE
E-SE BREEZE CONDITIONS PREVAILING. CERTAINLY WITH THE APPROACH
OF TROPICAL STORM ERIKA BY SUNDAY... INTERESTS LOCATED IN THE
EASTERN GULF WATERS AND FLORIDA STRAITS...KEYS...AND PENINSULA
SHOULD MONITOR THE PROGRESS OF ERIKA.

CARIBBEAN SEA...

TROPICAL STORM ERIKA IS THE MAIN FEATURE OF INTEREST IN THE
CARIBBEAN AS ITS CURRENT TRACK TAKES THE CYCLONE ACROSS
HISPANIOLA TONIGHT AND OVER CUBA SATURDAY TO SUNDAY. 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.
OTHERWISE...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 12N83W COVERING THE CENTRAL AND
WESTERN BASIN. OTHERWISE...SCATTERED SHOWERS AND TSTMS ARE ALONG
THE SOUTHERN COAST OF CUBA AND ADJACENT WATERS. ISOLATED SHOWERS
ARE ACROSS PUERTO RICO AND COASTAL WATERS. ACROSS PORTIONS OF
THE CENTRAL CARIBBEAN AND THE WESTERN CARIBBEAN...MODERATE TO
OCCASIONAL FRESH E-NE TRADES PREVAIL AND WITH THE PASSAGE OF
ERIKA TO THE NORTH THROUGH THE WEEKEND...AS SURFACE RIDGING
FOLLOWS IN ERIKA'S WAKE...TRADES ARE FORECAST TO INCREASE ACROSS
THE CENTRAL CARIBBEAN INTO THE FRESH TO STRONG BREEZE RANGE AND
PERSIST THROUGH SUNDAY...THEN DECREASE SLIGHTLY INTO MONDAY.

...HISPANIOLA...

THE CENTER OF TROPICAL STORM ERIKA IS EXPECTED TO MOVE OVER
HISPANIOLA TONIGHT. 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...

MIDDLE TO UPPER-LEVEL DIFFLUENCE ACROSS THE SW NORTH ATLC IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 24N W OF
76W...INCLUDING THE NW BAHAMAS. TO THE E...ISOLATED SHOWERS AND
TSTMS ARE FROM 25N TO 27N BETWEEN 70W AND 75W. SCATTERED HEAVY
SHOWERS ARE OVER HISPANIOLA NORTHERN WATERS ASSOCIATED WITH
TROPICAL STORM ERIKA THAT IS EXPECTED TO MOVE ACROSS THE ISLAND
TONIGHT. THE REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE
RIDGE ANCHORED BY A PAIR OF 1021 MB HIGHS CENTERED NEAR 28N64W
AND NEAR 26N32W.

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

$$
NR
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