[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 232340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 23 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 LORENZO IS CENTERED NEAR 29.3N 48.7W AT 23/2100
UTC OR ABOUT 850 NM E OF BERMUDA MOVING E AT 4 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND
SPEED IS 40 KT WITH GUSTS TO 50 KT. ISOLATED MODERATE CONVECTION
IS FROM 27N-28N BETWEEN 46W-49W. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE
DETAILS.

GALE FORCE WINDS ARE OCCURRING IN THE SW GULF OF MEXICO IN
ASSOCIATION WITH A COLD FRONT ANALYZED FROM THE SOUTHERN FLORIDA
PENINSULA SOUTHWEST TO THE EASTERN BAY OF CAMPECHE NEAR 21N91W.
A RECENT ASCAT PASS AROUND 23/1536 UTC INDICATED NORTHERLY WINDS
IN THE RANGE OF 30 TO 35 KT IN THE VICINITY OF 19N96W WITH SEAS
BEGINNING A GRADUAL SUBSIDING TREND FROM A MAXIMUM OF 13 FT.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 06N27W TO 14N24W MOVING W AT 10-15
KT. THE WAVE COINCIDES WITH BROAD LOW-LEVEL TROUGHING ACROSS THE
EASTERN ATLC AND A RELATIVE MAXIMUM IN TOTAL PRECIPITABLE WATER
AS NOTED ON IMAGERY FROM 04N-12N BETWEEN 19W-30W. WIDELY
SCATTERED MODERATE CONVECTION SPANS MOSTLY THE SAME AREA FROM
03N-12N BETWEEN 20W-29W.

TROPICAL WAVE EXTENDS FROM 09N55W TO 17N57W MOVING W AT 10-15
KT. WATER VAPOR IMAGERY INDICATES VERY DRY AIR AND STRONG
SUBSIDENCE ON THE WESTERN PERIPHERY OF AN UPPER LEVEL LOW
CENTERED NEAR 16N48W THAT IS INHIBITING ANY SIGNIFICANT DEEP
CONVECTION WITH THE WAVE AT THIS TIME. LOW-LEVEL MOISTURE
HOWEVER CONTINUES TO MOVE WEST WITH ISOLATED SHOWERS POSSIBLE
WITHIN 180 NM EITHER SIDE OF THE AXIS.

TROPICAL WAVE EXTENDS FROM 11N83W TO 17N83W MOVING W AT 10 KT.
LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE WAVE AXIS
ALONG WITH AMPLE MIDDLE TO UPPER LEVEL DIFFLUENCE OVER CENTRAL
AMERICA IS GENERATING SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION FROM 10N-16N BETWEEN 82W-87W...INCLUDING PORTIONS OF
COSTA RICA...NICARAGUA...AND HONDURAS THIS EVENING. LOCALLY
HEAVY RAINFALL THIS EVENING MAY LEAD TO LOCALIZED FLOODING AND
MUDSLIDES ACROSS THESE AREAS.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN
COAST NEAR 12N16W TO 10N25W THEN RESUMES NEAR 07N29W TO 07N37W
TO 05N43W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL
WAVE ALONG 26W...ISOLATED MODERATE CONVECTION IS FROM 03N-09N
BETWEEN 29W-36W...AND FROM 05N-11N BETWEEN 36W-49W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LONGWAVE TROUGH IS ACROSS THE EASTERN CONUS
PROVIDING SOUTHWESTERLY FLOW ALOFT FOR MUCH OF THE GULF THIS
EVENING. THE TROUGHING SUPPORTS A PAIR OF COLD FRONTS ANALYZED
ACROSS THE BASIN WHICH CONTINUE TO FILTER IN A COOLER AND DRIER
AIRMASS IN THEIR WAKE. THE PRIMARY COLD FRONT EXTENDS FROM THE
SW NORTH ATLC ACROSS THE SOUTHERN FLORIDA PENINSULA AND INTO THE
SE GULF NEAR 26N82W THEN WSW TO 23N90W THEN SW TO THE MEXICO
COAST NEAR 19N93W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING
WITHIN 120 NM EITHER SIDE OF THE FRONT E OF 87W. W OF 87W...
SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 180 NM EITHER
SIDE OF THE FRONT...INCLUDING CONVECTION ACROSS THE YUCATAN
PENINSULA. A SECONDARY COLD FRONT IS ANALYZED FROM NEAR THE
FLORIDA BIG BEND REGION NEAR 28N84W SW TO 22N97W. WHILE THE
SECONDARY FRONT IS RELATIVELY DRIER THAN THE PRIMARY FRONT...
ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE
FRONT. THIS REINFORCING FRONT CONTINUES TO BECOME DIFFUSE AND IS
EXPECTED TO DISSIPATE FULLY OVER THE NEXT 3 TO 6 HOURS. TO THE
NORTHWEST OF THIS SECONDARY BOUNDARY...A 1022 MB HIGH IS
CENTERED ACROSS SOUTHERN TEXAS NEAR 29N99W WITH THE RIDGING
EXPECTED TO CONTINUE BUILDING IN ACROSS NORTHERN PORTIONS OF THE
BASIN THROUGH LATE THURSDAY.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS CENTERED OVER THE WINDWARD PASSAGE NEAR
20N74W THAT IS PROVIDING A SMALL AREA OF DRY AIR ALOFT OVER THE
NW CARIBBEAN THIS EVENING. SATELLITE IMAGERY INDICATES A SMALL
AREA OF RELATIVELY CLEAR SKIES...HOWEVER SCATTERED SHOWERS AND
TSTMS ARE OCCURRING ACROSS CUBA...JAMAICA...AND THE ADJACENT
COASTAL WATERS. ALSO TO THE SOUTH...A TROPICAL WAVE IS ANALYZED
ALONG 84W THAT IS GENERATING SCATTERED SHOWERS AND TSTMS FROM
10N-16N BETWEEN 82W-87W...INCLUDING INLAND PORTIONS OF CENTRAL
AMERICA. IN ADDITION...THE MONSOON TROUGH AXIS EXTENDS ALONG 10N
BETWEEN NORTHERN COLOMBIA AND NORTHERN COSTA RICA ENHANCING
CONVECTION S OF 12N. FARTHER EAST...SOUTH-SOUTHWESTERLY FLOW
EAST OF THE UPPER LEVEL LOW AND ASSOCIATED TROUGH AXIS IS
PROMOTING AN UPPER LEVEL DIFFLUENT ENVIRONMENT OVER THE CENTRAL
AND EASTERN CARIBBEAN. ISOLATED SHOWERS AND TSTMS ARE OCCURRING
FROM 12N-19N BETWEEN 70W-78W IN ASSOCIATION WITH THE UPPER LEVEL
LOW WITH ANOTHER AREA OF ISOLATED SHOWERS AND TSTMS OCCURRING
ACROSS THE EASTERN CARIBBEAN IN THE VICINITY OF A SURFACE TROUGH
ANALYZED FROM 13N67W TO 17N65W. AS THE UPPER LEVEL LOW GRADUALLY
LIFTS NORTHWARD AND WEAKENS THROUGH LATE FRIDAY...CONTINUED
ADVECTION OF MOISTURE E OF 75W WILL PROVIDING THE EASTERN
CARIBBEAN WITH THE POTENTIAL FOR SHOWERS AND TSTMS UNTIL THE
WEEKEND.

HISPANIOLA...
CURRENTLY SOUTHWESTERLY MIDDLE TO UPPER LEVEL FLOW IS OVER
HISPANIOLA DUE TO AN UPPER LEVEL LOW CENTERED OVER THE WINDWARD
PASSAGE NEAR 20N74W. WITH MOISTURE AND LIFTING DYNAMICS IN PLACE
ACROSS THE ISLAND THIS EVENING...CONTINUED ISOLATED SHOWERS ARE
EXPECTED THROUGH THE OVERNIGHT HOURS INTO THURSDAY. ANOTHER AREA
OF LOW-LEVEL MOISTURE ASSOCIATED WITH A SURFACE TROUGH ANALYZED
ACROSS THE EASTERN CARIBBEAN WILL DRIFT CLOSER BY EARLY THURSDAY
ADDING TO THE POTENTIAL FOR AFTERNOON AND EVENING CONVECTION AS
THE UPPER LEVEL LOW LIFTS NORTHWARD AND DISSIPATES BY THE
WEEKEND.

ATLANTIC OCEAN...
AN UPPER LEVEL LONGWAVE TROUGH IS OVER THE EASTERN CONUS THIS
EVENING THAT SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION
AREA NEAR 32N72W. THE COLD FRONT STRETCHES SW TO THE SOUTHERN
FLORIDA PENINSULA NEAR 27N80W AND CONTINUES TO GENERATE WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 240 NM EAST OF THE
FRONT AND WITHIN 90 NM WEST OF THE FRONT. FARTHER EAST...A
MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION DOMINATES THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC CENTERED NEAR 29N54W.
ASIDE FROM TROPICAL STORM LORENZO EMBEDDED WITHIN THE MID-LEVEL
RIDGING...AT THE SURFACE A RIDGE REMAINS ANCHORED BY A 1018 MB
HIGH CENTERED NEAR 27N40W. THE RIDGE AXIS EXTENDS SW FROM THE
HIGH TO NORTH OF HISPANIOLA NEAR 22N70W AND DUE EAST FROM THE
HIGH TO THE CANARY ISLANDS NEAR 28N16W. FINALLY...THE EXTREME
NORTHEASTERN FRINGE OF THE DISCUSSION AREA IS INFLUENCED BY A
COLD FRONT ANALYZED FROM 32N30W TO 31N38W TO 32N44W. ISOLATED
SHOWERS AND TSTMS ARE OCCURRING WITHIN 180 NM SOUTH OF THE
BOUNDARY.

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

$$
HUFFMAN

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