[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 072344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
A 1010 MB SURFACE LOW IS EMBEDDED WITHIN THE MONSOON TROUGH
CENTERED NEAR 09N27W. THE LOW REMAINS THE FOCUS OF A RELATIVELY
BROAD MONSOONAL GYRE THAT COVERS THE EASTERN TROPICAL ATLC FROM
06N-14N BETWEEN 18W-33W AND FALLS BENEATH THE WESTERN PERIPHERY
OF AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 11N21W. THIS IS
PROVIDING AMPLE MIDDLE TO UPPER LEVEL DIFFLUENT IN THE VICINITY
OF THE LOW WITH SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION FROM 06N-13N BETWEEN 20W-30W.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 09N34W TO 19N34W MOVING W-NW AT 10-15
KT. THE WAVE CONTINUES TO PROPAGATE WESTWARD AWAY FROM THE
SPECIAL FEATURES LOW MENTIONED ABOVE WITH TOTAL PRECIPITABLE
WATER IMAGERY INDICATING THE POLEWARD EXTENSION OF MOISTURE FROM
A MAXIMUM NEAR 10N27W NW TO 17N35W N-NE TO 24N32W. WHILE FARTHER
NW FROM THE LOW EMBEDDED WITHIN THE MONSOON TROUGH...UPPER LEVEL
SOUTH-SOUTHWESTERLY SHEAR INCREASES AS A DRIER AIRMASS IS NOTED
W OF 35W AND AS A RESULT NO SIGNIFICANT DEEP CONVECTION IS NOTED
WITH THE WAVE AT THIS TIME.

TROPICAL WAVE EXTENDS FROM 11N64W TO 18N65W MOVING W AT 10-15
KT. THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP MOISTURE
COVERING THE EASTERN CARIBBEAN BETWEEN 58W-68W AS NOTED ON TOTAL
PRECIPITABLE WATER IMAGERY. THE WAVE IS ALSO LOCATED BENEATH THE
EASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONE CENTERED NEAR
15N64W. ISOLATED MODERATE CONVECTION IS FROM 13N-19N BETWEEN 58W-
67W AND IS LIKELY ENHANCED BY THE UPPER LEVEL DIFFLUENT
PROVIDING BY THE ANTICYCLONE ALOFT.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N15W
INTO THE 1010 MB SPECIAL FEATURES LOW NEAR 09N27W TO 08N33W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N34W TO
03N39W TO THE EQUATOR NEAR 48W. NO SIGNIFICANT CONVECTION IS
NOTED ON SATELLITE IMAGERY OUTSIDE OF THE CONVECTION ASSOCIATED
WITH THE SPECIAL FEATURES LOW.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE
WESTERN FLORIDA PANHANDLE NEAR 31N87W SW TO 24N95W THAT SUPPORTS
A 1007 MB LOW CENTERED NEAR THE FLORIDA BIG BEND NEAR 29N83W AND
THE ASSOCIATED COLD FRONT EXTENDING FROM THE LOW ALONG 26N85W TO
24N90W TO 22N94W TO THE MEXICO COAST NEAR 19N96W. THE FRONT
REMAINS RELATIVELY DRY N OF 25N...HOWEVER SCATTERED SHOWERS AND
ISOLATED TSTMS ARE OCCURRING MAINLY SOUTHEAST OF THE FRONT AND W
OF 87W...INCLUDING INLAND PORTIONS OF SOUTHERN MEXICO AND THE
YUCATAN PENINSULA THIS EVENING. FARTHER NORTH...MOST OF THE
CONVECTIVE ACTIVITY IS OCCURRING ACROSS THE EASTERN FLORIDA
PENINSULA AND INTO THE SW NORTH ATLC REGION. OTHERWISE...THE
REMAINDER OF THE NW AND NORTH-CENTRAL GULF IS UNDER THE
INFLUENCE OF NORTHERLY WINDS GENERALLY IN THE RANGE OF 10 TO 20
KT WITH CLEAR SKIES AS HIGH PRESSURE BUILDS IN ACROSS TEXAS AND
EASTERN MEXICO.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES GENERALLY NORTHWESTERLY UPPER
LEVEL FLOW W OF 74W ON THE WESTERN PERIPHERY OF AN UPPER LEVEL
TROUGH EXTENDING INTO THE CARIBBEAN FROM THE SW NORTH ATLC ALONG
28N72W TO A BASE NEAR 15N76W. IMAGERY INDICATES RELATIVELY DRY
AIR ALOFT AND THIS IS RESULTING IN MOSTLY CLEAR SKIES AND FAIR
CONDITIONS THIS EVENING. HOWEVER WITH PEAK DAYTIME HEATING AND
INSTABILITY...A FEW LINGERING SCATTERED SHOWERS AND ISOLATED
TSTMS ARE OCCURRING W OF A LINE FROM 21N87W TO 12N82W...
INCLUDING THE YUCATAN PENINSULA...HONDURAS...AND NICARAGUA.
FARTHER SOUTH...LOW-LEVEL MOISTURE CONVERGENCE AND THE CLOSE
PROXIMITY OF THE MONSOON TROUGH AXIS ALONG 10N IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 12N BETWEEN 71W-83W.
FINALLY...A TROPICAL WAVE IS ANALYZED ALONG 65W THAT IS
PROVIDING MUCH OF THE EASTERN CARIBBEAN E OF 68W WITH INCREASED
LOW-LEVEL MOISTURE AND PRECIPITATION. ALOFT...AN UPPER LEVEL
ANTICYCLONIC CIRCULATION IS CENTERED NEAR 14N64W AND THIS IS
LIKELY ENHANCING SCATTERED SHOWERS AND ISOLATED TSTMS IN THE
VICINITY OF THE TROPICAL WAVE AND ACROSS THE LESSER ANTILLES
THIS EVENING FROM 12N-19N BETWEEN 58W-68W.

HISPANIOLA...
CURRENTLY AFTERNOON AND EARLY EVENING SCATTERED SHOWERS AND
TSTMS ARE GRADUALLY DIMINISHING WITH THE LOSS OF PEAK DAYTIME
HEATING AND INSTABILITY. OTHERWISE...HISPANIOLA LIES EAST OF AN
UPPER LEVEL TROUGH AXIS THAT EXTENDS FROM THE SW NORTH ATLC NEAR
28N72W TO 15N76W AND THIS IS PROVIDING FOR AN OVERALL UPPER
LEVEL DIFFLUENT ENVIRONMENT. GIVEN THIS ENVIRONMENT AND THE
ANTICIPATED SLOW MOVEMENT OF THE TROUGHING THROUGH WEDNESDAY...
ISOLATED SHOWERS ARE FORECAST THROUGH THE OVERNIGHT HOURS WITH
INCREASED AREAL COVERAGE OF CONVECTION DURING THE AFTERNOON AND
EVENING HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE AXIS EXTENDS FROM THE EASTERN GULF OF
MEXICO OVER THE FLORIDA PENINSULA INTO THE SW NORTH ATLC NEAR
31N76W. THIS IS PROVIDING AN OVERALL UPPER LEVEL DIFFLUENT
ENVIRONMENT ACROSS THE SW NORTH ATLC AHEAD OF A COLD FRONT
CURRENTLY LOCATED ACROSS THE GULF OF MEXICO. SCATTERED SHOWERS
AND ISOLATED TSTMS ARE OCCURRING N OF 25N W OF 78W AS THE
REMNANT LOW OF KAREN AND THE ASSOCIATED FRONT BOUNDARY CONTINUES
TO MOVE EAST OVER THE NEXT 24 TO 36 HOURS. FARTHER EAST...A
MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR
IMAGERY NEAR 29N72W THAT SUPPORTS A 1013 MB LOW CENTERED NEAR
25N65W AND SURFACE TROUGHING EXTENDING NE FROM THE LOW TO 29N60W
AND SW FROM THE LOW TO 23N67W. LOW-LEVEL MOISTURE CONVERGENCE
ALONG WITH PLENTY OF MIDDLE TO UPPER LEVEL DIFFLUENCE IS
PROVIDING FOR A RATHER LARGE AREA OF SCATTERED SHOWERS AND
ISOLATED TSTMS FROM 20N-32N BETWEEN 52W-68W. SOME OF THIS
CONVECTIVE ACTIVITY STRETCHES SOUTHWARD ACROSS THE LESSER
ANTILLES FROM 12N-20N BETWEEN 58W-63W AND IS MORE LIKELY
ASSOCIATED WITH UPPER LEVEL RIDGING TO THE SOUTH OVER THE
EASTERN CARIBBEAN SEA. FINALLY...AN UPPER LEVEL SHORTWAVE TROUGH
IS LOCATED IN THE VICINITY OF 26N43W AND STRETCHES TROUGHING
INFLUENCE NORTHWARD TO AN UPPER LEVEL LOW CENTERED NEAR 43N41W.
WHILE NO SIGNIFICANT SURFACE FEATURES ARE ASSOCIATED WITH THE
SHORTWAVE TROUGH...THE MAIN DEEP LAYERED LOW TO THE NORTH
SUPPORTS A COLD FRONT ANALYZED FROM 36N40W TO 33N50W TO 34N58W
AND IS EXPECTED TO SKIRT THE NORTHERN FRINGE OF THE DISCUSSION
AREA. ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE
OF THE COLD FRONT.

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

$$
HUFFMAN


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