[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201801
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU AUG 20 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...

THE CENTER OF HURRICANE DANNY AT 20/1500 UTC WAS NEAR 12.5N
44.8W...OR 950 NM TO THE EAST OF THE LESSER ANTILLES...MOVING
WESTWARD...OR 295 DEGREES...AT 10 KNOTS. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 992 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 65 KNOTS WITH GUSTS TO 80 KNOTS. CLUSTERS OF MODERATE TO
STRONG CONVECTION ARE WITHIN 80 NM OF THE CENTER OF THE
HURRICANE. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE OVER THE EASTERN ATLC HAS AN AXIS THAT EXTENDS
FROM 21N26W TO 07N27W...MOVING W AT AROUND 10 KT OVER THE PAST
24 HOURS. DEEP MOISTURE EXTENDS AS FAR N AS 16N ALONG THE WAVE
AXIS WITH A POLEWARD SURGE IN MOISTURE ASSOCIATED WITH THE WAVE.
A 700 MB TROUGH IS NOTED BETWEEN 26W AND 35W. ISOLATED MODERATE
CONVECTION IS FROM 07N TO 17N BETWEEN 24W AND 28W.

A TROPICAL WAVE EXTENDS FROM THE VIRGIN ISLANDS TO S AMERICA AND
OVER THE EASTERN CARIBBEAN WITH AN AXIS FROM 19N65W TO
09N67W...MOVING W AT AROUND 20 KT. A SUBTLE 700 MB TROUGH IS
INDICATED IN MODEL FIELDS BETWEEN 63W AND 70W. SSMI TPW
INDICATES A MODEST INCREASE IN LOW LEVEL MOISTURE ASSOCIATED
WITH THE WAVE. THE PRESENCE OF STRONG SHEAR AND DRY AIR IN THE
MIDDLE TO UPPER LEVELS IS PREVENTING DEEP CONVECTION ALONG THE
WAVE. HOWEVER...A SUFFICIENT INCREASE IN MOISTURE S OF 12N
BEHIND THE WAVE IS SUPPORTING CLUSTERS OF MODERATE TO STRONG
CONVECTION FROM 09N TO 12N BETWEEN 57W AND 65W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH PASSES THROUGH COASTAL SECTIONS OF AFRICA
NEAR 14N16W...THROUGH A TROPICAL WAVE NEAR 10N27W...TO 11N39W.
NO ITCZ IS PRESENT AT THIS TIME DUE TO THE CIRCULATION
ASSOCIATED WITH DANNY TO THE WEST OF THE MONSOON TROUGH.
SCATTERED MODERATE CONVECTION IS FROM 07N TO 15N BETWEEN 15W AND
24W.

...DISCUSSION...

THE GULF OF MEXICO...

A BROAD MID TO UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE NE
GULF WHILE AN UPPER TROUGH IS OVER THE CENTRAL US WITH AN AXIS
EXTENDING ACROSS TX. THE UPPER TROUGH SUPPORTS A COLD FRONT
INLAND OVER TX AND LA. PRE-FRONTAL CONVERGENCE AND ASCENT
ASSOCIATED WITH THE UPPER TROUGH SUPPORTS CLUSTERS OF
THUNDERSTORMS WITHIN 50 NM OF THE COAST OF MEXICO N OF 25N...AND
THE ENTIRE TX COAST. UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THE
UPPER RIDGE SUPPORTS SCATTERED THUNDERSTORMS FROM 29N TO 31N
BETWEEN 82W AND 80W. GENERALLY S TO SE WINDS OF 10 TO 15 KT
COVER THE GULF WITH FLOW AROUND THE PERIPHERY OF THE ATLC
SUBTROPICAL SURFACE RIDGE. LIGHTER WINDS ARE NOTED OVER THE NE
GULF. OVER THE NEXT 24 HOURS CONVECTION WILL CONTINUE TO BE
LIKELY OVER THE WESTERN GULF ASSOCIATED WITH THE UPPER TROUGH.

...THE CARIBBEAN SEA...

AN UPPER LEVEL LOW IS CENTERED OVER BELIZE NEAR 18N89W. AN UPPER
LEVEL ANTICYCLONE IS CENTERED OVER S AMERICA WITH WESTERLY FLOW
ALOFT COVERING THE CENTRAL AND EASTERN CARIBBEAN. DIFFLUENT FLOW
BETWEEN THE UPPER LOW AND ANTICYCLONE SUPPORTS SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS FROM 10N TO 19N BETWEEN 80W AND 86W.
DRIER AIR AND SHEAR ARE INHIBITING CONVECTION OVER THE CENTRAL
CARIBBEAN. A TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN. PLEASE
REFER TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. MODERATE
TO FRESH TRADE WINDS ARE OVER THE CENTRAL CARIBBEAN S OF 16N.
GENTLE TO MODERATE TRADE WINDS COVER THE REMAINDER OF THE
CARIBBEAN. OVER THE NEXT 24 HOURS EXPECT AN INCREASE IN
CONVECTION OVER THE SW CARIBBEAN.

...HISPANIOLA...

MARGINAL LOW TO MID LEVEL MOISTURE OVER HAITI IS SUPPORTING
ISOLATED AFTERNOON AND EVENING THUNDERSTORMS TODAY. A TROPICAL
WAVE WILL MOVE ACROSS THE ISLAND TONIGHT WHICH MAY BRING
SCATTERED SHOWERS TO THE ISLAND. ISOLATED THUNDERSTORMS WILL BE
POSSIBLE ACROSS THE ISLAND ON FRIDAY AFTERNOON.

THE ATLANTIC OCEAN...

HURRICANE DANNY IS OVER THE CENTRAL TROPICAL ATLC. PLEASE SEE
THE SPECIAL FEATURES SECTION FOR MORE DETAILS. A UPPER TROUGH
OVER THE NW ATLC SUPPORTS A 1012 MB LOW NEAR 31N68W. THE
COMBINATION OF LOW LEVEL CONVERGENCE WITH THE LOW AND ASCENT
ASSOCIATED WITH THE UPPER TROUGH SUPPORTS SCATTERED MODERATE
CONVECTION FROM 26N TO 31N BETWEEN 55W AND 72W. A TROPICAL WAVE
IS OVER THE EASTERN TROPICAL ATLC. PLEASE REFER TO THE TROPICAL
WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS EXPECT
ONGOING CONVECTION BETWEEN 60W AND 70W N OF 25 N ASSOCIATED WITH
THE 1012 MB LOW OVER THE WESTERN ATLC.

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

$$
LATTO
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