[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282349
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 28 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...
TROPICAL DEPRESSION ELEVEN IS CENTERED NEAR 27.5N 70.2W AT
28/2100 UTC OR ABOUT 405 NM SW OF BERMUDA MOVING W AT 5 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM SUSTAINED
WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SCATTERED MODERATE
CONVECTION IS FROM 22N-27N BETWEEN 66W-71W. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC
FOR MORE DETAILS.

STRONG SOUTHERLY INFLOW INTO CONVECTIVE UPDRAFTS ASSOCIATED WITH
A 1007 MB LOW CENTERED NEAR 26N86W IS GENERATING A SWATH OF NEAR
GALE TO GALE FORCE WINDS ACROSS THE SE GULF OF MEXICO. AS
DEPICTED ON AN EARLIER ASCAT PASS AROUND 28/1548 UTC...THE CORE
OF THE STRONG WIND FIELD WAS NOTED IN THE VICINITY OF 25N85W AND
HAS GENERALLY COINCIDED WITH STRONG MIDDLE TO UPPER LEVEL
DIFFLUENCE AND PERSISTENT CONVECTION THROUGH THE EVENING HOURS.
CURRENTLY ACTIVE CONVECTION...NUMEROUS SHOWERS AND SCATTERED
TSTMS...ARE OCCURRING ACROSS THE EASTERN GULF FROM THE FLORIDA
STRAITS TO THE TAMPA BAY REGION.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 12N19W TO 16N18W MOVING W AT 5 KT.
THE WAVE COINCIDES WITH SUBTLE AND LOW-AMPLITUDE 700 MB
TROUGHING ALOFT BETWEEN 15W-21W AS WELL AS A LOW TO MID-LEVEL
MONSOONAL GYRE FOCUSED ON A 1008 MB LOW CENTERED AT THE SOUTHERN
EXTENT OF THE WAVE AXIS ALONG THE MONSOON TROUGH NEAR 12N19W.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 11N-15N BETWEEN 15W-
21W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
10N23W TO 12N32W TO 09N42W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 09N42W TO 06N56W. ISOLATED MODERATE CONVECTION
IS FROM 07N-13W BETWEEN 21W-38W.

...DISCUSSION...

GULF OF MEXICO...
SOUTHWESTERLY FLOW ALOFT IS NOTED OVER MUCH OF THE GULF THIS
EVENING BETWEEN A RELATIVELY BROAD MIDDLE TO UPPER LEVEL LOW
CENTERED OVER COASTAL TEXAS NEAR 29N95W AND AN UPPER LEVEL RIDGE
ANCHORED OVER THE THE SW NORTH ATLC WATERS NEAR 26N79W. THE
UPPER LEVEL LOW SUPPORTS A 1007 MB LOW CENTERED NEAR 28N94W WITH
A ISOLATED SHOWERS AND TSTMS OCCURRING WITHIN THE NORTHERN
QUADRANT OF THE LOW AND ACROSS INLAND PORTIONS OF SE TEXAS.
FARTHER EAST...WITHIN THE AREA OF MAXIMUM MIDDLE TO UPPER LEVEL
DIFFLUENCE NUMEROUS SHOWERS AND SCATTERED TSTMS ARE OCCURRING
MOSTLY EAST OF A SURFACE TROUGH ANALYZED FROM 29N87W INTO A 1007
MB LOW CENTERED NEAR 26N86W TO 23N87W. THE STRONGEST CONVECTION
PERSISTS ACROSS THE SE GULF AND A SMALLER AREA IN THE VICINITY
OF THE FLORIDA PANHANDLE. THE UPPER LEVEL LOW AND ASSOCIATED
NEARLY COLLOCATED SURFACE LOW IS EXPECTED TO BE SLOW TO MOVE THE
NEXT FEW DAYS WHILE THE EASTERN GULF LOW ACCELERATES NORTHWARD
TO THE FLORIDA BIG BEND REGION WITHIN THE NEXT 24 TO 36 HOURS.
ASIDE FROM POTENTIAL TROPICAL CYCLONE DEVELOPMENT...THE MAIN
IMPACT WILL CONTINUE TO BE CONVECTIVE PRECIPITATION...HEAVY AT
TIMES...AND POTENTIAL FLOODING ACROSS FLORIDA.

CARIBBEAN SEA...
NORTH-NORTHEASTERLY FLOW PREVAILS OVER MUCH OF THE WESTERN
CARIBBEAN W OF 75W THAT IS PROVIDING OVERALL STABLE CONDITIONS
AND FAIR WEATHER THIS EVENING. HOWEVER...ONE EXCEPTION LIES
ACROSS THE NW CARIBBEAN WHERE MIDDLE TO UPPER LEVEL DIFFLUENCE
IS MAXIMIZED AND LOW-LEVEL MOISTURE CONVERGENCE AND INSTABILITY
IS PRODUCING ISOLATED SHOWERS AND TSTMS W OF 83W...INCLUDING
PORTIONS OF WESTERN CUBA AND CENTRAL AMERICA. FARTHER EAST...
MOSTLY CLEAR SKIES PREVAIL WITH THE EXCEPTION OF A FEW ISOLATED
SHOWERS AND TSTMS ACROSS HISPANIOLA AND THE ADJACENT COASTAL
WATERS. WATER VAPOR IMAGERY INDICATES RELATIVELY STRONG DRY AIR
ALOFT IN ASSOCIATION WITH A BROAD AND ELONGATED UPPER LEVEL LOW
CENTERED NEAR 16N63W. OTHERWISE...MAINLY FRESH TO OCCASIONAL
STRONG TRADES PERSIST WITH THE STRONGEST WINDS NOTED ACROSS
SOUTH-CENTRAL PORTIONS.

...HISPANIOLA...
CURRENTLY LINGERING LATE AFTERNOON AND EARLY EVENING ISOLATED
SHOWERS CONTINUE TO GRADUALLY DIMINISH WITH MOSTLY FAIR SKIES
EXPECTED FOR THE OVERNIGHT HOURS INTO EARLY MONDAY.
NORTHEASTERLY FLOW ALOFT PREVAILS OVER THE ISLAND.

ATLANTIC OCEAN...
ASIDE FROM TROPICAL DEPRESSION ELEVEN...THE REMAINDER OF THE SW
NORTH ATLC IS UNDER THE INFLUENCE OF MOSTLY NORTH-NORTHEASTERLY
FLOW ALOFT ON THE EASTERN PERIPHERY OF AN UPPER LEVEL RIDGE
ANCHORED OVER THE OFFSHORE WATERS OF THE FLORIDA PENINSULA NEAR
27N79W. OUTSIDE OF THE INFLUENCE OF THE TROPICAL DEPRESSION...
MOSTLY FAIR SKIES ARE NOTED WITH ONLY A FEW ISOLATED SHOWERS AND
TSTMS INITIATING OFF THE FLORIDA COAST N OF 26N W OF 79W.
FARTHER EAST...AN COLD FRONT ENTERS THE NORTH-CENTRAL DISCUSSION
WATERS NEAR 32N31W AND EXTENDS SW TO 28N42W BECOMING STATIONARY
WESTWARD TO 27N58W THEN W-NW TO BEYOND 32N69W. ISOLATED SHOWERS
AND TSTMS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF BOUNDARY.
ANOTHER IMPACT ASSOCIATED WITH THE FRONT IS AN INCREASED
PRESSURE GRADIENT AND RESULTING STRONG WINDS NORTH OF THE FRONT
AS DEPICTED BY EARLIER MORNING ASCAT PASSES. WINDS RANGE FROM 25
TO 30 KT. TO THE SOUTH OF THE FRONT ACROSS THE CENTRAL ATLC...
THE REMNANT LOW OF IDA IS CENTERED NEAR 23N52W AND CONTINUES TO
GENERATE SCATTERED SHOWERS AND ISOLATED TSTMS FROM 20N-25N
BETWEEN 49W-54W.

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

$$
HUFFMAN
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