Tropical Weather Discussion
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000
AXNT20 KNHC 271752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ERIKA AS OF 27/1500 UTC WAS CENTERED NEAR 16.4N
63.3W OR ABOUT 110 NM W OF GUADELOUPE...MOVING W AT 14 KT.
ESTIMATED CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WINDS
ARE 45 KT WITH GUSTS TO 55 KT. CLUSTERS OF MODERATE TO STRONG
CONVECTION ARE FROM 12N TO 20N BETWEEN 58W AND 66W. 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 EXTENDING FROM
17N25W TO 09N25W...MOVING W AT ABOUT 15 KT OVER THE PAST 24 HRS.
SSMI TPW INDICATES MODERATE MOISTURE S OF 15N IN THE ENVIRONMENT
OF THE WAVE. ISOLATED MODERATE CONVECTION IS FROM 08N TO 11N
BETWEEN 21W AND 27W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS EXTENDING
FROM 21N43W TO 11N44W...MOVING W AT 15 TO 20 KT DURING THE PAST
24 HOURS. A BROAD AREA OF MODERATE MOISTURE IS ASSOCIATED WITH
THIS WAVE AS INDICATED BY TPW SSMI IMAGERY. SAHARAN DUST IS ALSO
EVIDENT ALONG THE WAVE. NO DEEP CONVECTION IS NOTED WITH THIS
WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS INTO THE TROPICAL ATLANTIC NEAR
16N16W TO 12N24W THEN CONTINUES W OF A TROPICAL WAVE NEAR 11N27W
TO A 1012 MB LOW NEAR 10N32W. THE ITCZ BEGINS NEAR THIS LOW AND
CONTINUES TO 10N43W. OTHER THAN THE CONVECTION ASSOCIATED WITH
THE WAVE NEAR THE CAPE VERDE ISLANDS...ISOLATED MODERATE
CONVECTION IS FROM 06N TO 14N BETWEEN 28W AND 41W.

...DISCUSSION...

GULF OF MEXICO...

A MID TO UPPER LEVEL TROUGH EXTENDS FROM THE EASTERN US SW
ACROSS THE GULF OF MEXICO WITH A BASE NEAR 20N. THIS TROUGH
SUPPORTS A STATIONARY FRONT THAT EXTENDS FROM N FL NEAR 30N83W
TO 25N86W TO 23N94W. A PRE-FRONTAL SURFACE TROUGH EXTENDS ACROSS
S FL TO 24N83W. SCATTERED MODERATE CONVECTIO0N IS FROM 25N TO
29N BETWEEN THE FRONT AND THE FL PENINSULA. SCATTERED MODERATE
CONVECTION IS ALSO OVER THE SW GULF FROM 18N TO 24N BETWEEN 88W
AND 97W AND IS BEING SUPPORTED BY A COMBINATION OF THE
STATIONARY FRONT AND A DIURNAL SURFACE TROUGH THAT EXTENDS FROM
22N96W TO 18N94W. DRY AIR AND SUBSIDENCE COVERS THE GULF NW OF
THE STATIONARY FRONT. 10 TO 15 KT N TO NE WINDS COVER THE GULF N
OF THE FRONT AND OVER THE SW GULF. SW WINDS OF 5 TO 10 KT COVER
THE SE GULF. THE MID TO UPPER TROUGH WILL REMAIN IN TACT ACROSS
THE BASIN THROUGH FRIDAY WHICH WILL SUPPORT CONVECTION OVER THE
SOUTHERN AND EASTERN GULF THROUGH THAT TIME.

CARIBBEAN SEA...

THE BASE OF THE MID TO UPPER LEVEL TROUGH OVER THE GULF RESIDES
ALONG 20N. THIS SUPPORTS ISOLATED THUNDERSTORMS OVER THE NW
CARIBBEAN N OF 17N W OF 83W. UPPER LEVEL DIFFLUENCE AND DEEP
MOISTURE SUPPORTS ISOLATED MODERATE CONVECTION S OF 12N E OF 78W
OVER THE SW CARIBBEAN. TROPICAL STORM ERIKA IS OVER THE EASTERN
CARIBBEAN. PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE
DETAILS. ASIDE FROM THE WINDS ASSOCIATED WITH ERIKA...GENTLE TO
MODERATE TRADE WINDS COVER THE CARIBBEAN BASIN. OVER THE NEXT 24
HOURS CONVECTION WILL CONTINUE OVER THE SW CARIBBEAN. CONVECTION
AND WINDS ASSOCIATED WITH ERIKA WILL SPREAD W TO NW OVER THE NE
CARIBBEAN.

...HISPANIOLA...
GENERALLY FAIR CONDITIONS ARE EXPECTED OVER THE WESTERN PORTIONS
OF THE ISLAND TODAY. SHOWERS ARE INCREASING THIS AFTERNOON OVER
THE EASTERN PORTION OF THE ISLAND WELL IN ADVANCE OF TROPICAL
STORM ERIKA. ERIKA IS FORECAST TO MOVE ACROSS PORTIONS OF
HISPANIOLA ON FRIDAY. HEAVY RAINFALL WITH FLASH FLOODING AND
MUDSLIDES WILL BECOME POSSIBLE FRIDAY THROUGH FRIDAY NIGHT.

ATLANTIC OCEAN...

A MID TO UPPER LEVEL TROUGH OVER THE EASTERN US AND GULF OF
MEXICO SUPPORTS A PRE-FRONTAL SURFACE TROUGH THAT EXTENDS FROM
21N76W TO THE FL STRAITS NEAR 25N81W. SCATTERED MODERATE
CONVECTION AND THUNDERSTORMS ARE FROM 25N TO 31N BETWEEN 72W AND
THE FL PENINSULA. ANOTHER SURFACE TROUGH...FORMERLY THE REMNANTS
OF DANNY...EXTENDS FROM 23N75W TO 19N74W. ISOLATED MODERATE
CONVECTION IS N OF 22N WITHIN 30 NM OF THE TROUGH AXIS.
CONVECTION ASSOCIATED WITH TROPICAL STORM ERIKA OVER THE EASTERN
CARIBBEAN EXTENDS OVER THE CENTRAL ATLC. PLEASE SEE THE SPECIAL
FEATURES SECTION FOR MORE DETAILS. SURFACE RIDGING OVER THE
CENTRAL AND EASTERN ATLC IS ANCHORED BY A PAIR OF SURFACE HIGHS
NEAR 28N61W AND 31N25W. THIS RIDGING SUPPORTS GENERALLY FAIR
WEATHER OVER THE SUBTROPICAL N ATLC E OF 67W. TWO TROPICAL WAVES
ARE OVER THE TROPICAL ATLC. PLEASE REFER TO THE TROPICAL WAVES
SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS EXPECT
CONVECTION TO CONTINUE OVER THE W ATLC OVER THE BAHAMAS AND
NEARBY WATERS DUE TO THE PRESENCE OF THE UPPER TROUGH TO THE
WEST OF THE AREA.

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

$$

LATTO



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