[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071707
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU NOV 07 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1645 UTC.

...SPECIAL FEATURES...
A GALE WARNING GOES INTO EFFECT FOR THE SW GULF OF MEXICO AT
07/1800 UTC. THIS GALE IS ASSOCIATED WITH THE COLD FRONT
CURRENTLY ANALYZED ACROSS THE NORTH-CENTRAL AND WESTERN GULF. SEE
THE HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02
KNHC FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO
12N22W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
04N26W TO 04N33W TO 07N41W. A SURFACE TROUGH IS ANALYZED AT THE
WESTERN EXTENT OF THE AXIS FROM 05N44W TO 12N42W. SCATTERED
MODERATE CONVECTION IS FROM 01N-12N BETWEEN 25W-44W. ISOLATED
MODERATE CONVECTION IS FROM 03N-07N BETWEEN 08W-17W...AND FROM
08N-13N BETWEEN 44W-53W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES A BROAD LONGWAVE TROUGH OVER THE
GREAT LAKES AND OHIO RIVER VALLEY WITH A TROUGH AXIS EXTENDING S-
SW TO OVER THE LOWER MISSISSIPPI RIVER VALLEY TO A BASE OVER THE
NW GULF WATERS. THIS TROUGHING SUPPORTS A COLD FRONT ANALYZED
FROM MOBILE BAY NEAR 31N88W SW TO THE MEXICO COAST NEAR 25N97W.
WITH MOST OF THE UPPER LEVEL DYNAMICS REMAINING N OF 36N...THE
FRONT LACKS ANY SIGNIFICANT DEEP CONVECTION...HOWEVER OVERCAST
SKIES AND A FEW AREAS OF ISOLATED SHOWERS ARE NOTED ON SATELLITE
IMAGERY WITHIN 75 NM EITHER SIDE OF THE FRONT. THE MOST
IMPORTANT IMPACT ASSOCIATED WITH THE FRONT IS THE SPECIAL
FEATURE HIGHLIGHTING A DEVELOPING GALE SITUATION ACROSS A
PORTION OF THE WESTERN GULF WATERS BEGINNING THIS AFTERNOON AND
REMAINING VALID THROUGH EARLY FRIDAY. A PAIR OF SURFACE TROUGHS
ARE ANALYZED IN ADVANCE OF THE COLD FRONT...ONE ANALYZED ACROSS
THE CENTRAL GULF WATERS FROM 30N88W TO 24N92W AND THE OTHER
SURFACE TROUGH EXTENDING SOUTHWARD FROM THE COLD FRONT NEAR
25N96W TO 20N95W. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM
EITHER SIDE OF THE EASTERN-MOST BOUNDARY...WHILE ISOLATED
SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM WEST OF THE WESTERN-
MOST BOUNDARY. FINALLY...A BROAD UPPER LEVEL ANTICYCLONE IS
CENTERED OVER THE NW CARIBBEAN SEA NEAR 21N84W THAT IS PROVIDING
SOUTH-SOUTHWESTERLY FLOW ALOFT ACROSS THE MAJORITY OF THE GULF E
OF 94W. MARGINAL UPPER LEVEL DIFFLUENCE AND THE CLOSE PROXIMITY
OF A SURFACE TROUGH AXIS ANALYZED ACROSS THE NW CARIBBEAN SEA
AND NE YUCATAN PENINSULA IS PROVIDING FOR WIDELY SCATTERED
SHOWERS AND ISOLATED TSTMS S OF 25N BETWEEN 83W-88W. BY EARLY
FRIDAY...WITH FRONTAL PASSAGE HAVING OCCURRING OVER MUCH OF THE
GULF...NORTHEAST WINDS WILL DOMINATE GENERALLY IN THE RANGE OF
20 TO 30 KT AND GRADUALLY DECREASE THROUGH THE DURATION OF THE
UPCOMING WEEKEND.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE NW
CARIBBEAN NEAR 21N84W THAT IS PROVIDING AN OVERALL DIFFLUENT
ENVIRONMENT ALOFT FOR THE NW CARIBBEAN AND PORTIONS OF CENTRAL
AMERICA THIS AFTERNOON. WHILE THE DIFFLUENCE SUPPORTS ONGOING
CONVECTION...A SURFACE TROUGH IS ANALYZED FROM 15N83W TO 22N87W
AND IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND ISOLATED TSTMS
OCCURRING N OF 16N W OF 81W...INCLUDING THE GULF OF HONDURAS.
FURTHERMORE...A LINE OF ISOLATED SHOWERS AND TSTMS IS NOTED
WITHIN 60 NM EITHER SIDE OF A LINE FROM 11N84W TO 16N84W MOVING
INLAND ACROSS EASTERN HONDURAS AND NICARAGUA THIS AFTERNOON. THE
REMAINDER OF THE CENTRAL AND EASTERN CARIBBEAN IS UNDER THE
INFLUENCE OF RELATIVELY DRIER NORTH-NORTHEASTERLY FLOW ALOFT ON
THE EASTERN PERIPHERY OF THE UPPER LEVEL ANTICYCLONE. THE
OVERALL STABILITY IS RESULTING IN MOSTLY FAIR CONDITIONS AND
MOSTLY CLEAR SKIES E OF 80W...WITH THE ONLY EXCEPTION BEING AN
AREA OF ISOLATED SHOWERS AND TSTMS S OF 13N BETWEEN 75W-80W.
TRADES ARE EXPECTED TO PERSIST GENERALLY IN THE RANGE OF 10 TO
20 KT THROUGH LATE SATURDAY WHEN THE PRESSURE GRADIENT ACROSS
THE BASIN WILL BEGIN TO GRADUALLY STRENGTHEN DUE TO STRONG HIGH
PRESSURE BUILDING TO THE NORTH ACROSS THE SW NORTH ATLC. TRADES
ARE FORECAST FRESH TO STRONG THROUGH THE FRONT PORTION OF NEXT
WEEK.

HISPANIOLA...
CURRENTLY CONDITIONS ACROSS THE ISLAND ARE RELATIVELY TRANQUIL
DUE TO DRY NE WINDS ALOFT AND STRONG SUBSIDENCE IN PLACE. WHILE
NO SIGNIFICANT DEEP CONVECTION IS ANTICIPATED THROUGH THE
AFTERNOON AND EVENING HOURS...A FEW ISOLATED SHOWERS ARE
POSSIBLE AS WEAK LOW-LEVEL MOISTURE CONVERGENCE AND OROGRAPHIC
LIFT WILL INCREASE CLOUDINESS AND THE PROBABILITY OF
PRECIPITATION.

ATLANTIC OCEAN...
AN UPPER LEVEL ANTICYCLONE ANCHORED OVER THE NW CARIBBEAN SEA
EXTENDS AN UPPER LEVEL RIDGE AXIS NE TO BEYOND 32N70W. MUCH OF
THE SW NORTH ATLC IS UNDER THE INFLUENCE OF THIS RIDGING WITH A
NARROW STREAM OF MOISTURE NOTED ON WATER VAPOR IMAGERY EXTENDING
FROM THE NW CARIBBEAN SEA THROUGH THE SE GULF OF MEXICO AND INTO
FAR WESTERN PORTIONS OF THE SW NORTH ATLC. A WEAKNESS WITHIN THE
RIDGE ALOFT REFLECTS TO THE SURFACE AS A SURFACE TROUGH ANALYZED
FROM THE CENTRAL BAHAMAS NEAR 25N77W TO 30N79W AND INTO A 1014
MB LOW CENTERED ALONG THE NORTH CAROLINA COAST NEAR 35N77W. MOST
OF THE MOISTURE MANIFESTS ITSELF AS CLOUDINESS W OF 76W...
HOWEVER A FEW ISOLATED SHOWERS ARE OCCURRING N OF 26N W OF 75W
TO THE FLORIDA PENINSULA COASTLINE. THE REMAINDER OF THE SW
NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE AXIS
EXTENDING FROM BEYOND 32N65W SW TO 27N74W. FARTHER EAST...A
MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 31N53W WITH A TROUGH
AXIS EXTENDING S-SW TO A BASE NEAR 17N58W. THE UPPER LEVEL
TROUGH SUPPORTS A 1014 MB LOW CENTERED NEAR 31N47W AND
ASSOCIATED WARM FRONT EXTENDING E-NE TO BEYOND 32N46W. A
STATIONARY FRONT EXTENDS SW FROM THE LOW CENTER TO 29N53W AND
BECOMES A SHEAR LINE TO 27N63W. MAXIMUM MIDDLE TO UPPER LEVEL
DIFFLUENCE IS OCCURRING EAST OF THE UPPER LEVEL TROUGH AXIS AND
INDUCES TROUGHING AS THE SURFACE EXTENDING TO THE SW OF THE LOW
CENTER. A PAIR OF SURFACE TROUGHS ARE NOTED IN THE VICINITY OF A
LINE FROM 30N48W TO 17N60W AND ARE PROVIDING FOCUS FOR SCATTERED
SHOWERS AND TSTMS OCCURRING WITHIN 240 NM EITHER SIDE OF A LINE
FROM 32N44W TO 18N58W. OTHERWISE...THE REMAINDER OF THE EASTERN
ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A
1025 MB HIGH CENTERED NEAR 30N27W AND A 1026 MB HIGH CENTERED
NEAR 32N19W.

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

$$
HUFFMAN


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