[Tropical] Tropical Weather Discussion

[EMWIN Server]

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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