[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 15 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
2315 UTC.

...SPECIAL FEATURES...

A 1012 MB LOW LOCATED MIDWAY BETWEEN THE CAPE VERDE ISLANDS AND
THE LESSER ANTILLES IS CENTERED NEAR 12N43W ALONG A TROPICAL
WAVE THAT EXTENDS FROM 17N42W THROUGH THE LOW TO 08N42W...MOVING
NW N NEAR 10 KT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 13N TO 17N BETWEEN 39W AND 44W. ISOLATED MODERATE
CONVECTION IS FROM 07N TO 13N BETWEEN 40W AND 46W. SOME FURTHER
DEVELOPMENT OF THIS LOW IS POSSIBLE DURING THE NEXT DAY OR SO...
AFTER WHICH THE UPPER LEVEL WINDS ARE EXPECTED TO BECOME
UNFAVORABLE FOR DEVELOPMENT. THERE IS A MEDIUM CHANCE OF
TROPICAL FORMATION OVER THE NEXT 48 HOURS.

A 1011 MB BROAD LOW SSW OF THE CAPE VERDE ISLANDS IS CENTERED
NEAR 10N26W ALONG A TROPICAL WAVE THAT EXTENDS FROM 15N26W
THROUGH THE LOW TO 06N26W MOVING WNW NEAR 15 KT. ISOLATED
MODERATE CONVECTION IS FROM 07N TO 13N BETWEEN 24W AND 30W. THIS
ACTIVITY IS UNDER MID/UPPER LEVEL RIDGING AND CONTINUES TO SHOWS
SIGNS OF ORGANIZATION. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO
BE CONDUCIVE FOR FURTHER DEVELOPMENT OF THIS SYSTEM. THERE IS A
MEDIUM CHANCE OF TROPICAL FORMATION OVER THE NEXT 48 HOURS.

...TROPICAL WAVES...

A TROPICAL WAVE IS OVER THE WESTERN ATLC AND EASTERN CARIBBEAN
WITH AN AXIS THAT EXTENDS FROM 21N64W TO 11N65W...MOVING W AT
AROUND 10 KT. THIS WAVE IS WELL DEFINED IN 700 MB GFS
STREAMLINES WITH AN INVERTED TROUGH BETWEEN 60W AND 69W. SSMI
TPW INDICATES THAT AN AREA OF HIGH MOISTURE ACCOMPANIES THIS
WAVE. SCATTERED MODERATE CONVECTION IS FROM 14N TO 22N BETWEEN
62W AND 71W.

A TROPICAL WAVE OVER THE WESTERN CARIBBEAN HAS AN AXIS THAT
EXTENDS FROM 23N83W TO 13N84W...MOVING W AT AROUND 10 KT. A 700
MB TROUGH IS EVIDENT IN THE WAVE ENVIRONMENT BETWEEN 78W AND
86W. SSMI TPW INDICATES THAT THIS WAVE IS ASSOCIATED WITH
MODERATE MOISTURE. SCATTERED MODERATE CONVECTION IS FROM 20N TO
23N BETWEEN 79W AND 85W. ISOLATED THUNDERSTORMS ARE ELSEWHERE
WITHIN 50 NM OF THE WAVE AXIS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH AXIS EXTENDS FROM ACROSS WESTERN AFRICA TO
THE AFRICAN COAST AT 16N17W...AND CONTINUES SW THROUGH THE 1011
MB LOW AND TROPICAL WAVE NEAR 10N26W...TO 12N39W. THE ITCZ AXIS
BEGINS JUST W OF THE CENTRAL ATLC LOW AND TROPICAL WAVE NEAR
11N44W...AND CONTINUES TO 08N58W. OTHER THAN CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES AND LOWS...ISOLATED MODERATE
CONVECTION IS WITHIN 100 NM OF THE ITCZ AXIS.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER RIDGE IS CENTERED OVER THE SW GULF WITH A RIDGE AXIS
EXTENDING NE ACROSS THE FL PENINSULA. AN UPPER TROUGH EXTENDS
FROM THE TN VALLEY TO THE N CENTRAL GULF. A BROAD AREA OF UPPER
LEVEL DIFFLUENCE IS PRESENT UNDER THE UPPER RIDGE AND ITS AXIS
AND IS INTERACTING WITH A MOIST AIRMASS TO SUPPORT ENHANCED
CONVECTION WITH THREE SURFACE FEATURES AFFECTING THE GULF BASIN.
THE FIRST IS A 1013 MB LOW CENTERED NEAR 23N98W WITH A SURFACE
TROUGH EXTENDING ALONG THE MEXICO COAST FROM 25N97W THROUGH THE
LOW CENTER TO 21N98W. SCATTERED MODERATE CONVECTION IS WITHIN
250 NM OF THE LOW CENTER. THE SECOND FEATURE IS A DISSIPATING
STATIONARY FRONT THAT EXTENDS FROM CENTRAL FL TO 27N93W. THE
THIRD FEATURE IS A SURFACE TROUGH WHICH IS A NORTHERN EXTENSION
OF THE ENERGY ASSOCIATED WITH A TROPICAL WAVE OVER THE
CARIBBEAN...EXTENDS FROM 26N81W TO 23N83W. NUMEROUS SHOWERS AND
ISOLATED MODERATE CONVECTION IS FROM 23N TO 30N E OF 91W.
SURFACE HIGH PRESSURE CENTERED OVER THE EASTERN US SUPPORTS
MAINLY MODERATE NE TO SE SURFACE WINDS ACROSS THE GULF BASIN.
OVER THE NEXT 24 HOURS CONVECTION WILL REMAIN LIKELY OVER MUCH
OF THE GULF BASIN AS THE BROAD AREA OF UPPER LEVEL DIFFLUENCE
CONTINUES TO INTERACT WITH A MOIST AIRMASS.

CARIBBEAN SEA...
UPPER LEVEL RIDGING EXTENDS FROM THE SW GULF OVER THE NW
CARIBBEAN. UPPER LEVEL TROUGHING EXTENDS FROM THE S BAHAMAS TO
HISPANIOLA TO THE SW CARIBBEAN. ANOTHER UPPER LEVEL RIDGE IS
CENTERED JUST E OF THE CARIBBEAN WITH A RIDGE AXIS OVER THE
EASTERN CARIBBEAN. UPPER LEVEL DIFFLUENCE AND THE PRESENCE OF
THE WESTERN CARIBBEAN WAVE SUPPORTS CONVECTION OVER THE NW
CARIBBEAN. UPPER LEVEL DIFFLUENCE INTERACTING WITH THE EASTERN
CARIBBEAN TROPICAL WAVE SUPPORTS CONVECTION OVER THE NE
CARIBBEAN. PLEASE REFER TO THE TROPICAL WAVES SECTION FOR MORE
DETAILS. GENTLE TO MODERATE TRADE WINDS COVER THE MAJORITY OF
THE CARIBBEAN THIS EVENING...EXCEPT MODERATE TO FRESH TRADE
WINDS S OF 15N E OF 78W OVER THE CENTRAL CARIBBEAN. OVER THE
NEXT 24 HOURS CONVECTION WILL CONTINUE OVER THE NW CARIBBEAN AS
THE TROPICAL WAVE OVER THAT PORTION OF THE BASIN CONTINUES W.
CONVECTION OVER THE NE CARIBBEAN WILL SPREAD W TO THE N CENTRAL
CARIBBEAN WED AND THUR AS THAT WAVE SPREADS DEEP MOISTURE TO
THAT PORTION OF THE BASIN.

...HISPANIOLA...
ISOLATED THUNDERSTORMS ARE WEAKENING OVER HAITI THIS EVENING.
MOISTURE IS INCREASING FROM E TO W OVER THE DOMINICAN REPUBLIC
AHEAD OF A WESTWARD MOVING TROPICAL WAVE. THIS IS SUPPORTING
SHOWERS AND THUNDERSTORMS OVER THE EXTREME E PORTION OF
HISPANIOLA THIS EVENING. THIS ACTIVITY SHOULD SPREAD WESTWARD
OVERNIGHT. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE ACROSS
HISPANIOLA TONIGHT THROUGH WED AS THE TROPICAL WAVES PASSES OVER
THE ISLAND. THE HEAVY RAINFALL COULD RESULT IN FLOODING AND
MUDSLIDES IN THOSE AREAS PRONE TO SUCH CONDITIONS.

ATLANTIC OCEAN...
AN UPPER TROUGH OVER THE NW ATLC SUPPORTS A DISSIPATING
STATIONARY FRONT THAT EXTENDS FROM 31N72W TO 29N81W. ISOLATED
MODERATE CONVECTION IS WITHIN 150 NM OF EITHER SIDE OF THE
FRONTAL BOUNDARY. A TROPICAL WAVE EXTENDS FROM THE EASTERN
CARIBBEAN...TO PUERTO RICO...TO THE WESTERN ATLC NEAR 21N64W
SUPPORTING CONVECTION. PLEASE REFER TO THE TROPICAL WAVES
SECTION FOR MORE DETAILS. A SURFACE TROUGH EXTENDS FROM 29N60W
TO 24N60W. THIS TROUGH IS EMBEDDED IN AN AREA OF UPPER LEVEL
DIFFLUENCE WHICH SUPPORTS SCATTERED THUNDERSTORMS FROM 22N TO
29N BETWEEN 52W AND 64W. AN UPPER LOW TO THE EAST OF THIS TROUGH
IS CENTERED NEAR 25N43W SUPPORTS SCATTERED THUNDERSTORMS FROM
24N TO 29N BETWEEN 45W AND 50W. TWO TROPICAL WAVES WITH LOW
PRESSURE SYSTEMS ARE OVER THE CENTRAL AND EASTERN TROPICAL ATLC.
PLEASE REFER TO THE SPECIAL FEATURES SECTION FOR MORE DETAILS.
OVER THE NEXT 24 HOURS EXPECT SCATTERED THUNDERSTORMS W OF 60W.

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

$$
LATTO
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