[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041149
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI OCT 04 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
TROPICAL STORM KAREN IS CENTERED NEAR 25.2N 90.0W AT 04/1200 UTC
OR ABOUT 240 NM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER MOVING
NNW AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB.
MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT.
SCATTERED MODERATE CONVECTION IS FROM 23N-27N BETWEEN 85W-89W.
SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 11N48W TO 20N44W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN WEAK SURFACE TO 700 MB
TROUGHING WITH A 700 MB RELATIVE VORTICITY MAXIMUM NOTED ALONG
THE WAVE AXIS NEAR 16N. SCATTERED MODERATE CONVECTION IS WITHIN
120 NM EITHER SIDE OF A LINE FROM 10N50W TO 18N44W.

TROPICAL WAVE EXTENDS FROM 13N58W TO 20N55W MOVING W-NW AT 10-15
KT. THE WAVE CONTINUES TO SLOW IN SPEED AS SURFACE TO 700 MB
TROUGHING BROADENS BETWEEN 50W-60W. WITH SOUTHWESTERLY WIND
SHEAR ALOFT TO THE NW OF THE WAVE AXIS...NO SIGNIFICANT DEEP
CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N14W TO
09N23W TO 07N28W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N28W TO 05N37W TO 06N47W. ASIDE FROM CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES ACROSS THE EASTERN TROPICAL
ATLC...SCATTERED MODERATE CONVECTION IS FROM 04N-11N BETWEEN
08W-20W.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN FOR THE GULF THIS MORNING REMAINS TROPICAL
STORM KAREN WHICH IS FORECAST TO TRACK NNW TOWARD THE MOUTH OF
THE MISSISSIPPI RIVER BY LATE SATURDAY. KAREN REMAINS ON THE
NORTHERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION
CENTERED OVER THE YUCATAN PENINSULA NEAR 19N89W. WITH A
FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT IN THE VICINITY OF
THE CYCLONE AND AREAS TO THE EAST...PLENTY OF MIDDLE TO UPPER
LEVEL MOISTURE IS NOTED ON SATELLITE IMAGERY E OF 92W. ASIDE
FROM KAREN'S CORE CONVECTION OF SCATTERED SHOWERS AND TSTMS FROM
23N-27N BETWEEN 84W-89W WELL SHEARED TO THE EAST...ISOLATED
SHOWERS AND TSTMS ARE OCCURRING ELSEWHERE FROM 22N-29N BETWEEN
81W-90W. ACROSS THE WESTERN GULF W OF 92W...MOSTLY CLEAR SKIES
AND FAIR CONDITIONS PERSIST DUE TO A RELATIVELY DRY AND STABLE
ENVIRONMENT ALOFT FOCUSED IN THE VICINITY OF A WEAK UPPER LEVEL
LOW CENTERED NEAR 25N96W. LOOKING AHEAD...AS KAREN IS EXPECTED
TO MAKE LANDFALL DURING THE UPCOMING WEEKEND...A COLD FRONT IS
FORECAST TO EMERGE OFF THE TEXAS AND LOUISIANA COAST LATE
SATURDAY INTO SUNDAY USHERING IN NORTHERLY WINDS IN THE RANGE OF
15 TO 25 KT WITH SURFACE RIDGING EXPECTED TO BUILD IN ACROSS THE
WESTERN GULF THROUGH EARLY NEXT WEEK.

CARIBBEAN SEA...
MUCH OF THE WESTERN CARIBBEAN W OF 70W IS UNDER THE INFLUENCE OF
AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 19N89W PROVIDING THIS
AREA WITH NORTHEASTERLY TO EASTERLY FLOW ALOFT. WATER VAPOR
IMAGERY INDICATES THE AIRMASS REMAINS RELATIVELY DRY...HOWEVER
MIDDLE TO UPPER LEVEL CLOUDINESS...PARTIAL OUTFLOW MOISTURE FROM
TROPICAL STORM KAREN CENTERED IN THE GULF OF MEXICO...FANS OVER
THE AREA N OF 15N W OF 76W. A FEW ISOLATED SHOWERS AND TSTMS ARE
OCCURRING WITHIN THIS AREA PRIMARILY IN THE VICINITY OF THE
CAYMAN ISLANDS AND JAMAICA FROM 15N-21N BETWEEN 77W-83W. TO THE
SOUTH ACROSS THE SW CARIBBEAN...SCATTERED SHOWERS AND SCATTERED
STRONG TSTMS ARE OCCURRING S OF 13N...INCLUDING INLAND PORTIONS
OF NORTHERN COLOMBIA AND PANAMA. THIS PARTICULAR CONVECTION IS
LIKELY DUE TO LOW-LEVEL MOISTURE CONVERGENCE AND THE CLOSE
PROXIMITY OF THE MONSOON TROUGH AXIS ANALYZED ALONG 10N/11N. E
OF 70W...UPPER LEVEL FLOW REMAINS ANTICYCLONIC...HOWEVER IS
MOIST SOUTH-SOUTHWESTERLY FLOW ALOFT. WATER VAPOR IMAGERY ALSO
SHOWS THIS AIRMASS TO BE RELATIVELY DRY ALOFT WITH ONLY A FEW
PASSING MIDDLE TO UPPER LEVEL CLOUDS E OF 68W. AT THE SURFACE...
E-SE TRADES PERSIST WITH ISOLATED LOW-TOPPED SHOWERS EMBEDDED
WITHIN E OF 71W THIS MORNING.

HISPANIOLA...
CURRENTLY HISPANIOLA IS BENEATH THE BASE OF AN UPPER LEVEL LOW
CENTERED OVER THE SW NORTH ATLC NEAR 26N66W. SATELLITE IMAGERY
INDICATES LOW-LEVEL MOISTURE INCREASES TO THE NORTH OF 18N WITH
ENHANCEMENT OF ISOLATED SHOWERS DUE TO THE MARGINAL UPPER LEVEL
DYNAMICS ASSOCIATED WITH THE UPPER LEVEL LOW. A FEW ISOLATED
SHOWERS CONTINUE TO LINGER ACROSS THE ISLAND AND IN THE ADJACENT
COASTAL WATERS THIS MORNING WITH E-SE TRADES CONTINUING TO USHER
IN LOW-LEVEL MOISTURE AND A HIGHER PROBABILITY OF A PASSING
ISOLATED SHOWER FOR THE EARLY MORNING AND AFTERNOON HOURS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL RIDGE ANCHORED OVER THE NW CARIBBEAN SEA
CONTINUES TO PROVIDE DRY NORTHERLY FLOW ALOFT W OF 70W FOR
PORTIONS OF THE SW NORTH ATLC THIS MORNING. WHILE ONLY A FEW
UPPER LEVEL CLOUDS AND ISOLATED LOW-TOPPED SHOWERS ARE NOTED
OVER THIS AREA...AT THE SURFACE...WEAK RIDGING DOMINATES
ANCHORED BY A 1021 MB HIGH CENTERED OFF THE CAROLINA COAST NEAR
34N69W. TO THE EAST OF 70W OVER THE REMAINDER OF THE SW NORTH
ATLC...WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL LOW CENTERED
NEAR 26N66W THAT IS PROVIDING AMPLE LIFT OF LOW-LEVEL MOISTURE
TO INCREASE CLOUDINESS AND GENERATE WIDELY SCATTERED SHOWERS
FROM 18N-30N BETWEEN 61W-70W. ACROSS THE CENTRAL ATLC...AN UPPER
LEVEL TROUGH AXIS DIPS INTO THE DISCUSSION AREA NEAR 32N48W SW
TO 29N53W THAT SUPPORTS A DISSIPATING COLD FRONT ANALYZED FROM
35N44W TO 31N50W TO 29N59W AND A PRE-FRONTAL SURFACE TROUGH FROM
28N52W TO 31N46W. ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM
EITHER SIDE OF THE SURFACE TROUGH AXIS. TO THE EAST OF THESE
FEATURES...AND QUICKLY BECOMING EMBEDDED WITHIN THE FRONTAL
TROUGHING N OF 30N...THE REMNANT 1008 MB LOW OF JERRY IS
CENTERED NEAR 32N37W. WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS ARE OCCURRING PRIMARILY TO THE EAST OF THE LOW CENTER FROM
31N-35N BETWEEN 30W-36W. THE FRONTAL TROUGHING STRETCHES SOUTH-
SOUTHWEST AS A SURFACE TROUGH ALONG 30N37W TO 22N42W. SCATTERED
SHOWERS AND TSTMS ARE OCCURRING EAST OF THE AXIS FROM 22N-27N
BETWEEN 35W-40W. OTHERWISE THE REMAINDER OF THE EASTERN ATLC IS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1019 MB
HIGH CENTERED NEAR 25N32W AND A 1018 MB HIGH CENTERED NEAR
33N26W.

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

$$
HUFFMAN


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