Tropical Weather Discussion
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000
AXNT20 KNHC 270517
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

TROPICAL STORM ERIKA IS CENTERED NEAR 16.7N 60.2W AT 27/0300 UTC
OR ABOUT 170 NM E OF ANTIGUA...MOVING W AT 15 KT. ESTIMATED
CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 40
KT WITH GUSTS TO 50 KT. NUMEROUS MODERATE TO ISOLATED STRONG
CONVECTION IS FROM 13N TO 17N BETWEEN 55W AND 59W. SCATTERED
MODERATE CONVECTION IS ELSEWHERE FROM 12N TO 19N BETWEEN 54W AND
60W. PLEASE SEE THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE CAME OFF THE WEST AFRICAN COAST EARLIER THIS
AFTERNOON...WITH AXIS EXTENDING FROM 17N21W TO 08N21W. MODERATE
MOISTURE IS ASSOCIATED WITH THIS WAVE AS INDICATED TPW IMAGERY.
LOW-LEVEL MOISTURE CONVERGENCE SUPPORTS ISOLATED CONVECTION FROM
08N-14N BETWEEN 21W-25W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS EXTENDING
FROM 21N39W TO 10N37W...MOVING W AT 15 KT DURING THE PAST 24
HOURS. A BROAD AREA OF MODERATE MOISTURE IS ASSOCIATED WITH THIS
WAVE AS INDICATED BY TPW IMAGERY. THE PRESENCE OF A SAHARAN
AIRMASS IS LIMITING SIGNIFICANT CONVECTION TO THE NORTHERN
PORTION OF THE WAVE N OF 19N BETWEEN 38W-40W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS W OF A TROPICAL WAVE FROM 09N23W
TO A 1014 MB LOW NEAR 09N28W TO 08N39W. ASIDE THE CONVECTION
ASSOCIATED WITH THE WAVE E OF THE CAPE VERDE ISLANDS...ISOLATED
SHOWERS ARE WITHIN 100 NM N OF THE AXIS.

...DISCUSSION...

GULF OF MEXICO...

A BROAD MID TO UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY S-
SW ACROSS THE GULF WITH BASE OVER THE YUCATAN PENINSULA. THIS
TROUGH SUPPORTS A STATIONARY FRONT THAT EXTENDS FROM A 1012 MB
LOW CENTERED OVER SOUTH CAROLINA ACROSS NORTHERN FLORIDA TO
29N83W TO 24N88W TO 24N94W. SCATTERED MODERATE CONVECTION IS
OBSERVED ALONG THE FRONT. TO THE W OF THE FRONT...A SURFACE
TROUGH EXTENDS ACROSS THE BAY OF CAMPECHE FROM 25N97W TO 20N95W.
SCATTERED MODERATE CONVECTION PREVAILS ACROSS THIS AREA MAINLY S
OF 22N BETWEEN 91W-97W. THE PROXIMITY OF THE FRONT AND UPPER
LEVEL DIFFLUENCE ARE SUPPORTING ISOLATED CONVECTION ACROSS THE
SE GULF MAINLY E OF 90W. SCATTEROMETER DATA DEPICTS A LIGHT TO
GENTLE NORTHERLY FLOW PREVAILING ACROSS THE BASIN. OVER THE NEXT
24 HOURS...EXPECT FOR THE STATIONARY FRONT TO WEAKEN AND BEGIN
TO DISSIPATE. A LOW PRESSURE CENTER IS FORECAST TO DEVELOP OVER
THE NE GULF.

CARIBBEAN SEA...

AN ELONGATED UPPER-LEVEL LOW EXTENDS FROM THE CENTRAL BAHAMAS S-
SW ACROSS THE CENTRAL CARIBBEAN. THIS FEATURE COMBINED WITH
SHALLOW MOISTURE ARE SUPPORTING ISOLATED CONVECTION ACROSS THE W
AND CENTRAL CARIBBEAN MAINLY W OF 70W. A SURFACE
TROUGH...REMNANT OF DANNY...PREVAILS ACROSS HAITI EXTENDING FROM
24N73W TO 17N74W. SCATTERED MODERATE CONVECTION IS OBSERVED
ALONG THIS BOUNDARY MAINLY BETWEEN 19N-21N. THE PROXIMITY OF
TROPICAL STORM ERIKA IS SUPPORTING ISOLATED CONVECTION ACROSS
THE E CARIBBEAN AFFECTING THE LESSER ANTILLES AND PUERTO RICO.
FOR MORE INFORMATION ABOUT ERIKA...PLEASE REFER TO THE SECTION
ABOVE. SCATTEROMETER DATA DEPICTS LIGHT TO GENTLE TRADES ACROSS
THE BASIN EXCEPT GENTLE TO MODERATE WINDS S OF 14N BETWEEN 72W-
77W. OVER THE NEXT 24 HOURS...EXPECT FOR ERIKA TO ENTER THE
EASTERN PORTION OF THE BASIN WITH CONVECTION.

...HISPANIOLA...

THE REMNANTS OF DANNY REMAIN ACROSS THE ISLAND IN THE FORM OF A
SURFACE TROUGH SUPPORTING SCATTERED SHOWERS AND TSTMS ACROSS
HAITI AND THE WINDWARD PASSAGE. OVER THE NEXT 24 HOURS...EXPECT
FOR THE TROUGH TO MOVE W AWAY FROM THE ISLAND AS TROPICAL STORM
ERIKA APPROACHES FROM THE E WITH CONVECTION.

ATLANTIC OCEAN...

THE MAIN FEATURE IN THE TROPICAL ATLANTIC IS TROPICAL STORM
ERIKA. FOR MORE DETAILS PLEASE REFER TO THE SECTION ABOVE. TWO
TROPICAL WAVES ARE MOVING ACROSS THE E AND CENTRAL ATLANTIC.
REFER TO THE TROPICAL WAVES SECTION ABOVE FOR DETAILS. A BROAD
MID TO UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY S-SW
ACROSS THE GULF TO A BASE OVER THE YUCATAN PENINSULA SUPPORTING
A STATIONARY FRONT THAT IS CURRENTLY EXTENDING FROM SOUTH
CAROLINA...ACROSS NORTHERN FLORIDA THEN INTO THE GULF OF MEXICO.
SCATTERED MODERATE CONVECTION PREVAILS S OF THE FRONT AFFECTING
THE FLORIDA PENINSULA AND THE W ATLANTIC MAINLY W OF 77W. TO THE
E...A SURFACE RIDGE EXTENDS ACROSS THE REMAINDER OF THE BASIN
ANCHORED BY A 1020 MB HIGH PRESSURE CENTERED NEAR 27N53W AND A
1022 MB HIGH NEAR 30N27W. OVER THE NEXT 24 OURS...EXPECT FOR
ERIKA TO ENTER THE E CARIBBEAN. CONVECTION WILL PREVAIL ACROSS
THE W ATLANTIC.

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

$$

ERA


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