[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 122331
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT SEP 12 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
2330 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE OVER THE EASTERN ATLANTIC HAS AN AXIS THAT
EXTENDS FROM 16N26W TO 09N29W...MOVING W AT 05-10 KT. SSMI TPW
SHOWS HIGH MOISTURE IN THE VICINITY OF THIS WAVE. A TILTED 700
MB TROUGH EXTENDS FROM W OF THE CAPE VERDE ISLANDS TO NEAR
09N31W WHICH INCLUDES THE ENVIRONMENT OF THE WAVE. SCATTERED
MODERATE CONVECTION IS S OF 12N BETWEEN 22W-31W.

A TROPICAL WAVE IS OVER THE CENTRAL ATLANTIC WITH AXIS THAT
EXTENDS FROM 16N49W TO 09N51W...MOVING W AT 15-20 KT. A BROAD
700 MB TROUGH IS EVIDENT BETWEEN 42W AND 55W. HIGH MOISTURE IS
EVIDENT IN TPW IMAGERY IN THE ENVIRONMENT OF THIS WAVE.
SCATTERED MODERATE CONVECTION IS FROM 10N-15N BETWEEN 47W-55W.

A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS THAT
EXTENDS FROM 19N70W TO 12N70W...MOVING W AT AROUND 15 KT. THIS
POSITION WAS CALCULATED AFTER ANALYZING THE LATEST SCATTEROMETER
DATA AND SURFACE OBSERVATIONS. A SHARP 700 MB TROUGH IS EVIDENT
BETWEEN 65W-73W. TPW IMAGERY DEPICTS MODERATE MOISTURE
SURROUNDING THIS WAVE. SCATTERED MODERATE CONVECTION PREVAILS E
OF THE WAVE AXIS AFFECTING PUERTO RICO...THE MONA PASSAGE AND
PORTIONS OF DOMINICAN REPUBLIC AS WELL AS THEIR ADJACENT NE
CARIBBEAN WATERS N OF 16N AND E OF 70W. THIS CONVECTION IS BEEN
ENHANCED BY AN UPPER-LEVEL TROUGH LOCATED OVER HISPANIOLA AND
EXTENDS ACROSS THE NE CARIBBEAN.

A TROPICAL WAVE IS OVER CENTRAL AMERICA AND E PACIFIC WITH AXIS
THAT EXTENDS FROM 14N84W TO 07N85W...MOVING W AT 15-20 KT. A
SUBTLE 700 MB TROUGH IS EVIDENT BETWEEN 80W-89W. NUMEROUS
SHOWERS AND THUNDERSTORMS ARE OBSERVED ACROSS
NICARAGUA...HONDURAS AND THE SW CARIBBEAN WATERS S OF 16N AND W
OF 80W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N17W TO
09N33W TO 11N49W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 10N51W TO 10N60W. ASIDE FROM THE CONVECTION
GENERATED BY THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION
IS FROM 07N-12N BETWEEN 31W-43W. ISOLATED CONVECTION IS WITHIN
200 NM N OF THE ITCZ AXIS.

...DISCUSSION...

GULF OF MEXICO...

A BROAD UPPER-LEVEL TROUGH EXTENDS FROM THE OHIO VALLEY SW TO
THE NW AND N CENTRAL GULF SUPPORTING A COLD FRONT THAT EXTENDS
ACROSS THE NORTHERN GULF WATERS FROM 27N97W TO 28N90W TO 30N86W.
A LARGE PRE-FRONTAL SURFACE TROUGH EXTENDS ACROSS THE CENTRAL
GULF FROM 22N96W TO 29N83W. NUMEROUS MODERATE CONVECTION
PREVAILS ACROSS MOST OF THE BASIN N OF 19N. SCATTEROMETER DATA
DEPICTS GENTLE TO MODERATE N TO NE WINDS N OF THE COLD FRONT
WHILE MODERATE TO FRESH WINDS ARE PREVAILING BETWEEN THE FRONT
AND THE TROUGH FROM 25N-27N BETWEEN 89W-92W. GENTLE SW TO SE
WINDS ARE S OF THE TROUGH. OVER THE NEXT 24 HOURS...EXPECT FOR
THE COLD FRONT AND TROUGH WILL MOVE OVER THE CENTRAL AND
SOUTHERN GULF WITH CONVECTION AFFECTING THE WHOLE BASIN.

CARIBBEAN SEA...

AN UPPER-LEVEL TROUGH OVER HISPANIOLA AND THE EASTERN CARIBBEAN
IS INTERACTING WITH A TROPICAL WAVE TO PRODUCE SCATTERED
MODERATE CONVECTION OVER THE NE CARIBBEAN...INCLUDING PUERTO
RICO AND DOMINICAN REPUBLIC. SCATTERED MODERATE CONVECTION IS
OBSERVED OVER THE SW CARIBBEAN ARE ASSOCIATED WITH ANOTHER
TROPICAL WAVE. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR
MORE DETAILS. GENTLE TO MODERATE TRADE WINDS COVER THE MAJORITY
OF THE CARIBBEAN...EXCEPT FOR A SMALL AREA OF MODERATE TO FRESH
TRADE WINDS N OF 16N WITHIN 150 NM OF THE AXIS OF THE TROPICAL
WAVE OVER THE CENTRAL CARIBBEAN. OVER THE NEXT 24 HOURS...EXPECT
GUSTY WINDS AND CONVECTION TO SPREAD W ACROSS PUERTO
RICO...HISPANIOLA...AND CARIBBEAN WATERS AS THE TROPICAL WAVE
CONTINUES MOVING W.

...HISPANIOLA...

MOISTURE WILL CONTINUE ON THE INCREASE AS A TROPICAL WAVE
CONTINUES MOVING W AND INTERACTS WITH AN UPPER-LEVEL TROUGH
GENERATING SCATTERED MODERATE CONVECTION AFFECTING THE ISLAND.
THIS ACTIVITY IS EXPECTED TO CONTINUE OVER THE NEXT 24 HOURS
WITH THE RISK OF HEAVY RAINFALL...FLASH FLOODING...AND MUD
SLIDES.

ATLANTIC OCEAN...

AN UPPER-LEVEL TROUGH OVER THE OHIO VALLEY IS PRODUCING SW FLOW
ALOFT OVER THE SW N ATLC W OF 75W. ASCENT ASSOCIATED WITH THIS
FLOW ALOFT SUPPORTS SCATTERED MODERATE CONVECTION N OF 27N W OF
74W. TO THE E...AN UPPER-LEVEL LOW CENTERED NEAR 28N56W IS
REFLECTED AT THE SURFACE AS A TROUGH THAT EXTENDS FROM 31N53W TO
27N53W. ISOLATED CONVECTION IS OBSERVED ALONG THIS BOUNDARY. A
1016 MB SURFACE LOW CENTERED NEAR 28N42W HAS A SURFACE TROUGH
THAT EXTENDS FROM THE LOW CENTER TO 30N40W. ISOLATED CONVECTION
IS FROM 28N-32N BETWEEN 40W-44W. THE REMAINDER OF THE BASIN IS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED N OF OUR AREA.
TWO TROPICAL WAVES ARE OVER THE TROPICAL ATLANTIC. PLEASE REFER
TO THE TROPICAL WAVES SECTION FOR MORE DETAILS. OVER THE NEXT 24
HOURS...CONVECTION WILL INCREASE E OF FL AS THE UPPER-LEVEL
TROUGH OVER THE OHIO VALLEY MOVES E AND A COLD FRONT APPROACHES
THE W ATLANTIC.

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

$$

ERA
This weather bulletin was brought to you by:
www.nashvilleweather.net