[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 170553
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU SEP 17 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 DEPRESSION NINE IS CENTERED NEAR 15.8N 45.1W AT 17/0300
UTC OR ABOUT 935 NM E OF THE LESSER ANTILLES AND ABOUT 1215 NM W
OF THE CAPE VERDE ISLANDS MOVING NW AT 6 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND SPEED IS 25
KT WITH GUSTS TO 35 KT. SCATTERED MODERATE/STRONG CONVECTION IS
WITHIN 120 NM OF LINE FROM 14N45W TO 18N40W. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.

A 1010 MB LOW SW OF THE CAPE VERDE ISLANDS IS CENTERED NEAR
11N31W ALONG A TROPICAL WAVE THAT EXTENDS FROM THE LOW TO 17N
MOVING W NEAR 10 KT OVER THE PAST 24 HOURS. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 5N-14N
BETWEEN 30W-38W. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
CONDUCIVE FOR A TROPICAL DEPRESSION TO DEVELOP DURING THE NEXT
DAY OR TWO. THERE IS A HIGH CHANCE OF TROPICAL FORMATION OVER
THE NEXT 48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE IN THE CARIBBEAN EXTENDS FROM 19N74W ALONG 14N76W
TO 10N77W MOVING W-SW 20-25 KT OVER THE PAST 24 HOURS. SSMI TPW
INDICATES THE WAVE IS EMBEDDED WITHIN SURGE OF DEEP MOISTURE.
ACTIVITY IN THE VICINITY OF THE WAVE IS ASSOCIATED WITH UPPER
TROUGH AND ONLY BEING ENHANCED BY THE WAVE.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 15N17W ALONG 15N93W THROUGH THE 1010 MB LOW IN THE
SPECIAL FEATURES NEAR 11N31W TO 13N38W. THE ITCZ BEGINS SW OF
T.D. NINE NEAR 10N49W AND CONTINUES ALONG 9N55W TO SOUTH AMERICA
NEAR 7N61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
WITHIN 45/60 NM OF 9N16W AND WITHIN 45 NM OF LINE FROM 11N20W TO
13N22W. THE REMAINDER OF THE CONVECTION IS ASSOCIATED WITH
T.D. NINE AND THE LOW/TROPICAL WAVE IN THE SPECIAL FEATURES.

...DISCUSSION...

GULF OF MEXICO...
A NARROW UPPER TROUGH EXTENDS ACROSS ALABAMA INTO THE GULF NEAR
PENSACOLA FLORIDA TO MERIDA MEXICO ON THE YUCATAN PENINSULA.
STRONG SUBSIDENCE AND DRY STABLE AIR WITH CLEAR SKIES ARE N OF
23N W OF 87W. A SURFACE TROUGH IS OVER THE E GULF EXTENDING AT
17/0300 UTC FROM 29N84W THROUGH A WEAK 1013 MB LOW NEAR 25N86W
TO CANCUN MEXICO. SCATTERED TO NUMEROUS SHOWERS/ISOLATED
THUNDERSTORMS ARE E OF THE SURFACE TROUGH TO OVER S FLORIDA...W
CUBA...AND THROUGH THE STRAITS OF FLORIDA WITH SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90 NM W OF THE SURFACE
TROUGH N OF 27N. A SECOND SECOND SURFACE TROUGH IS FROM 22N89W
TO OVER THE W COAST OF THE YUCATAN PENINSULA GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND AND ALONG THE
IMMEDIATE COAST S OF 20N. SURFACE TROUGH/LOW WILL MEANDER OVER
THE E GULF THROUGH THU THEN GRADUALLY SHIFT E OF THE AREA THIS
WEEKEND. WEAK HIGH PRES WILL MOVE INTO THE N CENTRAL GULF OVER
THE WEEKEND.

CARIBBEAN SEA...
AN UPPER RIDGE EXTENDS FROM THE NE YUCATAN PENINSULA ACROSS CUBA
NEAR 23N81W INTO THE W ATLC COVERING THE NW CARIBBEAN N OF 15N W
OF 78W. AN UPPER TROUGH EXTENDS THROUGH THE WINDWARD PASSAGE TO
NEAR 13N79W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE E OF
THE UPPER TROUGH WITHIN 75 NM OF LINE FROM E CUBA NEAR 20N77W
ACROSS JAMAICA TO 13N82W AND W OF THE UPPER TROUGH WITHIN 90 NM
OF LINE FROM 15N72W ACROSS THE DOMINICAN REPUBLIC TO BEYOND
20N69W. THIS IS LEAVING THE FAR E AND FAR W CARIBBEAN WITH CLEAR
SKIES TONIGHT. THE CARIBBEAN TROPICAL WAVE WILL REACH THE W
CARIBBEAN THU AND OVER CENTRAL AMERICA FRI. A WEAKENED SURFACE
RIDGE OVER THE W ATLC WILL DIMINISH WINDS IN THE CENTRAL
CARIBBEAN THU THROUGH SAT.

...HISPANIOLA...
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ACROSS THE
DOMINICAN REPUBLIC WITH ISOLATED SHOWERS POSSIBLE OVER HAITI ALL
ASSOCIATED WITH THE UPPER TROUGH THAT EXTENDS THROUGH THE
WINDWARD PASSAGE AND ENHANCED BY THE CARIBBEAN TROPICAL WAVE.
THE UPPER TROUGH WILL SHIFT EASTWARD THU EXTENDING FROM THE
CENTRAL ATLC ACROSS HISPANIOLA FRI THEN WILL SHIFT S ON SAT.
MOISTURE AND SHOWER/THUNDERSTORM ACTIVITY WILL PERSIST THROUGH
SAT.

ATLANTIC OCEAN...
AN UPPER RIDGE EXTENDS FROM THE NW CARIBBEAN ACROSS W CUBA NEAR
23N81W ALONG 26N78W TO BEYOND 32N73W. THE SURFACE TROUGH/LOW IN
THE E GULF OF MEXICO IS GENERATING SCATTERED TO NUMEROUS
SHOWERS/ISOLATED THUNDERSTORMS ACROSS FLORIDA INTO THE W ATLC N
OF 24N W OF 75W. AN UPPER TROUGH EXTENDS FROM 25N67W THROUGH THE
WINDWARD PASSAGE INTO THE CENTRAL CARIBBEAN GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS WITHIN 90/120 NM OF LINE FROM
23N68W TO ACROSS HISPANIOLA NEAR 20N69W. AN UPPER TROUGH IN THE
CENTRAL ATLC NEAR 50W IS SUPPORTING A SURFACE TROUGH THAT
EXTENDS FROM 29N48W TO 23N52W GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 90 NM ON BOTH SIDES OF THE SURFACE
TROUGH. A SURFACE RIDGE COVERS THE W ATLC N OF 26N W OF 60W
ANCHORED BY A 1015 MB HIGH OVER VIRGINIA. A WEAK SURFACE RIDGE
DOMINATES THE E ATLC E OF 40W ANCHORED BY A 1019 MB HIGH NEAR
28N31W. THE CARIBBEAN TROPICAL WAVE WILL REACH THE STRAITS OF
FLORIDA BY FRI. WEAK HIGH PRESSURE OVER THE NW ATLC WILL SHIFT E
AS A TROUGH DEVELOPS OFF THE FLORIDA E COAST THU BECOMING
ORIENTED FROM 32N78W TO S FLORIDA FRI THROUGH SAT.

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

$$
PAW
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