[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED SEP 11 2013

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...
HURRICANE HUMBERTO IS CENTERED NEAR 18.0N 29.0W AT 11/2100 UTC
OR ABOUT 225 NM WNW OF THE CAPE VERDE ISLANDS MOVING N AT 10 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 986 MB. MAXIMUM SUSTAINED
WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SCATTERED MODERATE
CONVECTION IS FROM 11N-23N BETWEEN 23W-33W. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.

TROPICAL STORM GABRIELLE IS CENTERED NEAR 32.8N 66.4W AT 11/2100
UTC OR ABOUT 85 NM WNW OF BERMUDA AND ABOUT 540 NM SSE OF
NANTUCKET MASSACHUSETTS MOVING WNW AT 4 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1009 MB. MAXIMUM SUSTAINED WIND SPEED IS 35
KT WITH GUSTS TO 45 KT. SCATTERED MODERATE CONVECTION IS FROM
32N-34N BETWEEN 63W-66W. ISOLATED MODERATE CONVECTION IS WITHIN
45 NM EITHER SIDE OF A LINE FROM 31N64W TO 28N69W. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22
KNHC FOR MORE DETAILS.

A BROAD AREA OF LOW PRESSURE IS ACROSS THE NW CARIBBEAN AND
YUCATAN PENINSULA THIS EVENING FOCUSED IN THE VICINITY OF A
SURFACE TROUGH ANALYZED FROM 16N89W TO 22N88W. GLOBAL MODEL DATA
ALSO INDICATES THIS REGION FALLS BENEATH A STRONG 700 MB TROUGH
AND RELATIVE VORTICITY MAXIMUM OVER THE YUCATAN PENINSULA NEAR
19N90W. GIVEN THE LOW TO MIDDLE LEVEL LIFT ASSOCIATED WITH THE
CYCLONIC MOTION AND AN OVERALL DIFFLUENT ENVIRONMENT ALOFT...
SCATTERED MODERATE CONVECTION CONTINUES TO BE SUSTAINED BUT
REMAIN GENERALLY DISORGANIZED AT THIS TIME OVER A LARGE PORTION
OF THE WESTERN CARIBBEAN SEA...CUBA...THE SE GULF OF MEXICO...
AND THE YUCATAN PENINSULA FROM 16N-24N BETWEEN 79W-91W. ASIDE
FROM POSSIBLE TROPICAL CYCLONE DEVELOPMENT OVER THE NEXT 48
HOURS...PLENTY OF HEAVY RAINFALL AND POTENTIAL LOCALIZED
FLOODING IS EXPECTED OVER WESTERN CUBA...BELIZE...AND PORTIONS
OF THE YUCATAN PENINSULA AS THIS SYSTEM MOVES WNW.

...TROPICAL WAVES...
NONE.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 12N35W TO 09N49W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N49W TO
06N56W. SCATTERED MODERATE CONVECTION IS FROM 06N-12N BETWEEN
11W-18W. ISOLATED MODERATE CONVECTION IS FROM 07N-09N BETWEEN
43W-50W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL LOW IS CENTERED
OVER EAST TEXAS NEAR 31N95W AND EXTENDS A NARROW UPPER LEVEL
TROUGH AXIS SOUTHWARD TO A BASE OVER THE SW GULF NEAR 21N94W.
THIS TROUGHING SUPPORTS A SURFACE TROUGH ANALYZED FROM EAST-
CENTRAL MEXICO NEAR 23N99W SE TO 19N94W AND ALONG WITH MID-LEVEL
LIFTING DYNAMICS IS GENERATING SCATTERED SHOWERS AND TSTMS S OF
26N W OF 93W THIS EVENING. EAST OF THE UPPER LEVEL TROUGHING...
DIFFLUENCE ALOFT IS MAXIMIZED AND THIS ENVIRONMENT SPREADS
EASTWARD ACROSS THE YUCATAN PENINSULA INTO THE PORTIONS OF THE
NW CARIBBEAN SEA. A SURFACE TROUGH IS ANALYZED ACROSS THE
YUCATAN PENINSULA FROM 16N89W TO 22N88W AND IS FORECAST TO MOVE
INTO THE SW GULF THURSDAY. SLOW DEVELOPMENT OF THIS SYSTEM IS
EXPECTED WITH E-SE WINDS FORECAST TO INCREASE ACROSS THE WESTERN
GULF WATERS LATE SATURDAY INTO SUNDAY GENERALLY S OF 26N W OF
90W. ELSEWHERE...A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER
THE NORTHERN FLORIDA PENINSULA NEAR 29N81W CONTINUING TO SLOWLY
DRIFT WESTWARD. THE UPPER LEVEL TROUGHING SUPPORTS A SURFACE
TROUGH ANALYZED FROM ACROSS THE SW NORTH ATLC WATERS AND THE
SOUTHERN FLORIDA PENINSULA INTO THE SE GULF WATERS NEAR 25N84W.
THIS AREA MARKS THE NORTHERN FRINGE OF CONVECTION OCCURRING WITH
THE ACTIVE WEATHER ACROSS THE NW CARIBBEAN SEA AND YUCATAN
PENINSULA THIS EVENING. HOWEVER...LOW-LEVEL MOISTURE CONVERGENCE
IN THE VICINITY OF THE SURFACE TROUGH AND MIDDLE TO UPPER LEVEL
DYNAMICS ASSOCIATED WITH THE UPPER LEVEL LOW ARE GENERATING
SCATTERED SHOWERS AND TSTMS FROM 24N-27N BETWEEN 80W-84W...AND
IN THE VICINITY OF THE FLORIDA BIG BEND REGION FROM 29N-31N
BETWEEN 82W-85W.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE NW
CARIBBEAN NEAR 18N86W AND IS PROVIDING MUCH OF THE WESTERN
CARIBBEAN AND CENTRAL AMERICA WITH AN UPPER LEVEL DIFFLUENT
ENVIRONMENT. THIS ENVIRONMENT IS SUPPORTIVE OF SCATTERED SHOWERS
AND TSTMS PRIMARILY OCCURRING W OF 78W THIS EVENING. MUCH OF
THIS CONVECTION REMAINS DISORGANIZED HOWEVER THE MOST INTENSE
ACTIVITY IS NOTED OVER THE NW CARIBBEAN WATERS EAST OF A SURFACE
TROUGH ANALYZED ACROSS THE YUCATAN PENINSULA. THE REMAINDER OF
THE BASIN IS UNDER THE INFLUENCE OF AN UPPER LEVEL LOW CENTERED
SOUTH OF HISPANIOLA NEAR 16N70W. WATER VAPOR IMAGERY INDICATES
DRY AIR ALOFT BETWEEN 72W-78W PROVIDING OVERALL FAIR CONDITIONS
THIS EVENING. HOWEVER E OF 72W...MOISTURE CONTINUES TO ADVECT
AROUND THE UPPER LEVEL LOW WITH WIDELY SCATTERED SHOWERS
OCCURRING FROM 10N-18N BETWEEN 61W-72W. THE CHANCE FOR
PRECIPITATION IS EXPECTED TO CONTINUE THROUGH THE NEXT FEW DAYS
AS A SURFACE TROUGH ANALYZED NE OF THE LEEWARD ISLANDS CONTINUES
TO MOVE W-SW AND IS FORECAST BRING WIDELY SCATTERED SHOWERS TO
THE LEEWARD ISLANDS ON THURSDAY.

HISPANIOLA...
AN UPPER LEVEL LOW IS CENTERED SOUTH OF THE ISLAND NEAR 18N86W
AND CONTINUES TO ADVECT MOISTURE OVER MUCH OF THE EASTERN
CARIBBEAN AND WESTERN PORTIONS OF THE ISLAND THIS EVENING.
ISOLATED SHOWERS ARE LIKELY OCCURRING AND ARE EXPECTED TO
CONTINUE AS THE UPPER LEVEL LOW DRIFTS WESTWARD OVER THE NEXT
FEW DAYS. IN ADDITION...A SURFACE TROUGH IS ANALYZED NE OF THE
LEEWARD ISLANDS WILL IS EXPECTED TO CONTINUE MOVING WESTWARD
OVER THE NEXT FEW DAYS. WIDELY SCATTERED SHOWERS ASSOCIATED WITH
THIS TROUGHING WILL LIKELY IMPACT HISPANIOLA LATE THURSDAY INTO
FRIDAY.

ATLANTIC OCEAN...
THE PRIMARY CONCERNS FOR THE BASIN ARE TROPICAL STORM GABRIELLE
IN THE SW NORTH ATLC AND HURRICANE HUMBERTO IN THE EASTERN ATLC.
SEE SPECIAL FEATURES ABOVE. A MIDDLE TO UPPER LEVEL LOW IS
CENTERED OVER THE NORTHERN FLORIDA PENINSULA NEAR 29N81W THAT
SUPPORTS A SURFACE TROUGH EXTENDING FROM 29N72W WSW TO THE
SOUTHERN FLORIDA PENINSULA NEAR 26N80W. SCATTERED SHOWERS AND
ISOLATED TSTMS ARE OCCURRING N OF 22N W OF 74W IN ASSOCIATED
WITH THE SURFACE BOUNDARY AND UPPER LEVEL LOW. FARTHER
SOUTHEAST...ANOTHER SURFACE TROUGH IS ANALYZED FROM 17N57W TO
19N61W TO 23N63W TO THE NE OF THE LEEWARD ISLANDS AND REMAINS
THE FOCUS FOR WIDELY SCATTERED SHOWERS OCCURRING WITHIN 120 NM
EITHER SIDE OF THE BOUNDARY. SOMEWHAT DETACHED FROM THE SURFACE
TROUGH IS A 1010 MB LOW CENTERED NEAR 17N52W. OVER THE PAST 6
HOURS CONVECTION FLARED UP NEAR THE LOW CENTER...WITH ONLY A FEW
ISOLATED SHOWERS AND TSTMS OCCURRING IN THE VICINITY OF 16N51W
AT THIS TIME. OTHERWISE...THE REMAINDER OF THE EASTERN ATLC N OF
HUMBERTO AND E OF 50W...IS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED BY A 1031 MB HIGH CENTERED WELL NORTH OF THE
AZORES NEAR 44N26W.

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

$$
HUFFMAN

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