[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON SEP 09 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...
TROPICAL STORM HUMBERTO IS CENTERED NEAR 13.7N 25.3W AT 09/2100
UTC OR 80 NM SW OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING W
AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM
SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SCATTERED
MODERATE AND SCATTERED STRONG CONVECTION IS FROM 11N-15N BETWEEN
24W-29W WITH WIDELY SCATTERED MODERATE CONVECTION ELSEWHERE FROM
08N-18N BETWEEN 17W-33W. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.

THE REMNANT 1009 MB LOW OF GABRIELLE IS CENTERED NEAR 26N66W
MOVING N-NE AT 10-15 KT. A SURFACE TROUGH AXIS EXTENDS N-NE TO
BEYOND 32N64W AND SW FROM THE LOW CENTER TO THE TURKS AND CAICOS
ISLANDS NEAR 22N71W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING
PRIMARILY EAST OF THE SURFACE TROUGHING FROM 23N-33N BETWEEN 61W-
67W. CONVECTIVE TRENDS NEAR THE LOW CENTER WILL CONTINUE TO BE
MONITORED OVER THE NEXT FEW DAYS AS THIS SYSTEM HAS A MEDIUM
CHANCE OF BECOMING A TROPICAL CYCLONE OVER THE NEXT 48 HOURS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 17N42W TO 25N43W MOVING W AT 10-15
KT. A 1012 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 18N AND
THIS REMAINS THE FOCUS FOR ISOLATED MODERATE CONVECTION
OCCURRING WITHIN 120 NM OF THE LOW CENTER IN THE NW QUADRANT.
GLOBAL MODELS SUGGEST THE WAVE WILL CONTINUE TO DRIFT WESTWARD
DURING THE NEXT FEW DAYS WEAKENING SOMEWHAT AS IT APPROACHES W
OF 50W AS A MID-LATITUDE UPPER LEVEL TROUGH DIGS SOUTHWARD AND
BEGINS TO PROVIDE AN INCREASED SHEAR ENVIRONMENT ACROSS THE
CENTRAL TROPICAL ATLC.

TROPICAL WAVE EXTENDS FROM 16N92W TO 22N90W MOVING W AT 10-15
KT. THE WAVE COINCIDES WITH BROAD AND WEAK SURFACE TO 700 MB
TROUGHING OVER THE NW CARIBBEAN SEA...YUCATAN PENINSULA...AND SW
GULF OF MEXICO. SCATTERED MODERATE CONVECTION IS FROM 16N-23N
BETWEEN 90W-94W...AND IT IS LIKELY ENHANCED BY BROAD UPPER LEVEL
DIFFLUENCE AS AN UPPER LEVEL RIDGE AXIS EXTENDS FROM OVER THE NW
CARIBBEAN NEAR 18N80W TO OVER SOUTHERN MEXICO NEAR 17N95W.

...ITCZ/MONSOON TROUGH...
NONE.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE SW NORTH ATLC
NEAR 30N76W TO OVER THE CENTRAL FLORIDA PENINSULA NEAR 27N82W
AND OVER THE NE GULF WATERS TO 27N88W. THIS UPPER LEVEL PATTERN
IS RESULTING IN MOST OF THE GULF E OF 92W UNDER THE INFLUENCE OF
WEST-NORTHWESTERLY FLOW ALOFT. OVER WESTERN PORTIONS OF THE
BASIN STRETCHING INLAND OVER WEST TEXAS...ANOTHER UPPER LEVEL
TROUGH EXTENDS FROM AN UPPER LEVEL LOW CENTERED NEAR 32N101W SE
TO 24N95W. THIS TROUGHING SUPPORTS A SURFACE TROUGH ANALYZED
FROM 20N95W TO 26N97W WITH SCATTERED SHOWERS AND TSTMS OCCURRING
OVER A LARGE PORTION OF THE WESTERN GULF W OF 89W. A TROPICAL
WAVE ALONG 91W IS ALSO GENERATING SCATTERED SHOWERS AND STRONG
TSTMS W OF 90W. GENERALLY E-SE WINDS IN THE RANGE OF 10-20 KT
WILL PERSIST THROUGH THE OVERNIGHT HOURS INTO TUESDAY AS SURFACE
RIDGING REMAINS ANCHORED OVER THE SE CONUS. EASTERLY WINDS WILL
GRADUALLY INCREASE INTO WEDNESDAY AS THE PRESSURE GRADIENT
BETWEEN THE RIDGE AND LOWER PRESSURE OVER SOUTHERN MEXICO
STRENGTHENS. LOOKING AHEAD...MODEL COMPARISONS SUGGEST THIS AREA
OF LOW PRESSURE TO DEVELOP OVER THE SW GULF OF MEXICO LATE
WEDNESDAY THROUGH FRIDAY WITH GRADIENT WINDS INCREASING W OF 90W
IN THE RANGE OF 15 TO 25 KT.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 17N84W
AND EXTENDS INFLUENCE OVER MUCH OF THE CARIBBEAN W OF 70W
PROVIDING FOR AN OVERALL DIFFLUENT ENVIRONMENT THIS EVENING.
NORTH OF THE RIDGE...THE DIFFLUENT ENVIRONMENT CONTINUES AS A
LIFTING MECHANISM GENERATING SCATTERED SHOWERS AND TSTMS N OF
16N BETWEEN 70W-90W. SOUTH OF THE RIDGE...CONDITIONS REMAIN
GENERALLY FAIR WITH ONLY SCATTERED SHOWERS AND ISOLATED TSTMS
OCCURRING PRIMARILY S OF 11N AND OVER INTERIOR PORTIONS OF
NICARAGUA...COSTA RICA...AND PANAMA. THE ONGOING CONVECTION IS
LIKELY ENHANCED BY THE PRESENCE OF THE MONSOON TROUGH AXIS
ANALYZED FROM NORTHERN COLOMBIA TO THE COSTA RICA AND NICARAGUA
BORDER. FINALLY...AN UPPER LEVEL LOW IS CENTERED EAST OF THE
LESSER ANTILLES NEAR 14N59W THAT IS EXPECTED TO IMPACT THE
EASTERN CARIBBEAN WITH A WEAK SURFACE TROUGH ANALYZED CURRENTLY
ALONG 58W OVER THE NEXT FEW DAYS AS IT DRIFTS WESTWARD. WATER
VAPOR IMAGERY INDICATES THIS UPPER LEVEL LOW CONTAINS MOSTLY DRY
AIR...HOWEVER A FEW ISOLATED LOW-TOPPED SHOWERS ARE POSSIBLE AS
THE FEATURE MOVES WEST OVER THE NEXT 36 TO 48 HOURS.

HISPANIOLA...
CURRENTLY AN UPPER LEVEL RIDGE AXIS EXTENDS EASTWARD FROM THE NW
CARIBBEAN OVER THE ISLAND TO 19N69W. THIS IS PROVIDING AN
OVERALL DIFFLUENT ENVIRONMENT OVER THE REGION AND HELPING TO
SUPPORT ONGOING LATE AFTERNOON AND EVENING CONVECTION OCCURRING
ACROSS NORTH-CENTRAL PORTIONS OF HISPANIOLA. THIS UPPER LEVEL
RIDGING WILL EVENTUALLY BE REPLACED BY AN UPPER LEVEL LOW...
CURRENTLY EAST OF THE LESSER ANTILLES...BY LATE WEDNESDAY INTO
THURSDAY AND MOST LIKELY USHER IN A DRIER AIRMASS ALOFT.
HOWEVER...GIVEN PEAK DAYTIME HEATING AND INSTABILITIES...THE
CHANCE FOR AFTERNOON AND EVENING SHOWERS AND TSTMS WILL PERSIST
OVER THE NEXT FEW DAYS AS E-SE TRADES CONTINUE.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE SW NORTH ATLC
NEAR 30N76W. WHILE THE UPPER LEVEL FEATURE DOES NOT SUPPORT ANY
SURFACE FRONTAL BOUNDARY...MIDDLE TO UPPER LEVEL DYNAMICS ARE
SUPPORTING ENHANCED CLOUDINESS AND WIDELY SCATTERED SHOWERS AND
ISOLATED TSTMS OCCURRING FROM 23N-32N BETWEEN 70W-79W...
INCLUDING THE NW AND CENTRAL BAHAMAS THIS EVENING. TO THE SOUTH
OF THE INFLUENCE OF THE UPPER LEVEL TROUGHING...PEAK DAYTIME
CONVECTION IS OCCURRING OVER INTERIOR PORTIONS OF CUBA DUE TO AN
OVERALL DIFFLUENT ENVIRONMENT ALOFT AND MAXIMUM INSTABILITY.
FARTHER EAST...THE REMNANT 1009 MB LOW OF GABRIELLE IS CENTERED
NEAR 26N66W WITH A SURFACE TROUGH AXIS EXTENDING N-NE TO BEYOND
32N64W AND SW FROM THE LOW CENTER TO THE TURKS AND CAICOS
ISLANDS NEAR 22N71W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING
PRIMARILY EAST OF THE SURFACE TROUGHING FROM 23N-33N BETWEEN 61W-
67W. EAST OF THIS CONVECTION...A SURFACE RIDGE ANCHORED BY A
1034 MB HIGH CENTERED N OF THE AZORES NEAR 41N30W DOMINATES THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC.

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

$$
HUFFMAN


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