[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 092339
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 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...
A 1010 MB LOW IS CENTERED NEAR 10N27W AND REMAINS EMBEDDED
WITHIN THE MONSOON TROUGH. THE LOW IS THE FOCAL POINT OF A
BROADER MONSOONAL GYRE WITH INFLUENCE FROM 08N-14N BETWEEN 23W-
37W. THE GYRE CONTINUES TO LIE BENEATH THE WESTERN PERIPHERY OF
AN UPPER LEVEL ANTICYCLONIC CIRCULATION PROVIDING AMPLE UPPER
LEVEL DIFFLUENCE FOR WIDELY SCATTERED MODERATE CONVECTION FROM
11N-14N BETWEEN 28W-33W...AND ISOLATED MODERATE CONVECTION
ELSEWHERE FROM 08N-14N BETWEEN 23W-35W.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 11N35W TO 19N36W MOVING W AT 10-15
KT. THE WAVE HAS MOVED ACROSS THE NORTHERN PERIPHERY OF THE
MONSOONAL GYRE MENTIONED IN THE SPECIAL FEATURES SECTION IN THE
PAST 24 HOURS AND RESIDUAL ENERGY IN THE VICINITY OF THE WAVE
AXIS IS UNDER THE INFLUENCE OF DRIER AIR TO THE WEST AND
INCREASED SOUTHWESTERLY SHEAR. GIVEN THE HOSTILE ENVIRONMENT FOR
THE WAVE...NO SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT
THIS TIME.

TROPICAL WAVE EXTENDS FROM 14N45W TO 21N46W MOVING W AT 5-10 KT.
THE WAVE REMAINS WITHIN WEAK SURFACE TO 700 MB TROUGHING BETWEEN
42W-52W AND IT IS LIKELY A PORTION OF THE ENERGY ASSOCIATED WITH
THE WAVE IS STRETCHING NORTHWARD INTO A MID-LEVEL MID-LATITUDE
TROUGH TO THE NORTH WHILE AT THE SAME TIME INTERACTING WITH AN
UPPER LEVEL LOW CENTERED NEAR 20N46W. ISOLATED MODERATE
CONVECTION IS FROM 17N-23N BETWEEN 41W-47W.

TROPICAL WAVE EXTENDS FROM 11N76W TO 18N74W MOVING W AT 10-15
KT. THE WAVE LIES WITHIN BROAD SURFACE TO 700 MB TROUGHING OVER
THE CENTRAL AND WESTERN CARIBBEAN SEA AND FALLS BENEATH AN UPPER
LEVEL TROUGH AXIS EXTENDING FROM 19N71W TO 12N77W. AS THE WAVE
HAS CONTINUED TO MOVE WESTWARD OVER THE PAST 24 HOURS...MOST OF
THE MOISTURE ADVECTION OCCURRING DUE TO THE UPPER LEVEL TROUGH
REMAINS TO THE EAST WHILE ONLY ISOLATED MODERATE CONVECTION IS
OCCURRING FROM 15N-19N BETWEEN 73W-77W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO
11N27W TO 09N34W TO 09N39W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 09N39W TO 09N50W. ASIDE FROM THE CONVECTION
ASSOCIATED WITH THE SPECIAL FEATURES LOW...ISOLATED MODERATE
CONVECTION IS FROM 02N-05N BETWEEN 11W-20W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER THE SE CONUS NEAR
31N84W SOUTH-SOUTHWESTWARD TO A BASE NEAR 22N87W. THE TROUGHING
SUPPORTS A STATIONARY FRONT ANALYZED FROM THE UPPER FLORIDA KEYS
NEAR 25N80W TO WESTERN CUBA NEAR 22N84W ACROSS THE YUCATAN
CHANNEL AND NORTHERN COAST OF THE YUCATAN PENINSULA TO 20N92W
AND INTO A WEAK 1013 MB LOW CENTERED NEAR 18N94W. WATER VAPOR
IMAGERY INDICATES MOST OF THE TROUGH ITSELF AND AREAS TO THE
NORTH AND WEST REMAIN DRY AND STABLE WHILE THE AREA IN THE
VICINITY OF THE FRONT AND S OF 21N ARE EXPERIENCING INCREASED
CLOUDINESS AND ISOLATED SHOWERS AND TSTMS WITHIN 90 NM EITHER
SIDE OF THE FRONT AND S OF 21N BETWEEN 90W-95W...INCLUDING
INLAND PORTIONS OF THE YUCATAN PENINSULA. OTHERWISE...A SURFACE
RIDGE AXIS EXTENDS FROM A 1022 MB HIGH CENTERED OVER EASTERN
TENNESSEE NEAR 36N86W SW TO THE EAST-CENTRAL MEXICO COAST NEAR
22N98W. AS HIGH PRESSURE HAS BUILT IN ACROSS MUCH OF THE
NORTHERN AND WESTERN GULF...MOSTLY CLEAR SKIES AND FAIR
CONDITIONS ARE NOTED ON SATELLITE IMAGERY THIS EVENING. LIGHT
NORTHEAST TO EASTERLY WINDS ARE EXPECTED IN THE RANGE OF 5 TO 15
KT THROUGH LATE THURSDAY AS THE FRONT SLOWLY DRIFTS EASTWARD
INTO THE SW NORTH ATLC AND NW CARIBBEAN SEA REGIONS.

CARIBBEAN SEA...
A NARROW UPPER LEVEL RIDGE AXIS EXTENDS OVER THE NW CARIBBEAN
BETWEEN TWO UPPER LEVEL TROUGHS ONE NOTED ON WATER VAPOR IMAGERY
OVER THE EASTERN GULF OF MEXICO AND THE OTHER EXTENDING FROM
OVER HISPANIOLA NEAR 19N71W TO 11N78W. UPPER LEVEL DIFFLUENT
FLOW IS PRIMARILY OVER THE NW CARIBBEAN SOUTH OF A SURFACE
STATIONARY FRONT ANALYZED FROM WESTERN CUBA TO THE NORTHERN
YUCATAN PENINSULA COAST. LOW-LEVEL MOISTURE CONVERGENCE SOUTH OF
THE BOUNDARY ALONG WITH THE UPPER LEVEL DYNAMICS IS GENERATING
SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS N OF 15N W OF A
LINE FROM 22N81W TO 16N84W. THE FRONT IS FORECAST TO GRADUALLY
DRIFT SOUTHEASTWARD AND BECOME DIFFUSE OVER THE NEXT 24 TO 36
HOURS. FARTHER EAST...IN THE VICINITY OF THE EASTERN-MOST UPPER
LEVEL TROUGH...A TROPICAL WAVE IS ALONG 75W. WHILE MOST OF THE
UPPER LEVEL DIFFLUENCE IS LOCATED TO THE EAST OF THE TROPICAL
WAVE AND UPPER LEVEL TROUGH AXIS...LOW-LEVEL CONVERGENCE
ASSOCIATED WITH THE TROPICAL WAVE IS GENERATING ISOLATED SHOWERS
AND TSTMS WITHIN 120 NM EITHER SIDE OF A LINE FROM 18N74W TO
13N82W. THE LOW-LEVEL CONVERGENCE CONTINUES ACROSS THE SW
CARIBBEAN AS THE MONSOON TROUGH AXIS REMAINS ANALYZED FROM
NORTHERN COLOMBIA ACROSS PANAMA TO SOUTHERN COSTA RICA WITH
SCATTERED SHOWERS AND WIDELY SCATTERED STRONG TSTMS S OF 12N
BETWEEN 69W-86W. CURRENTLY THE STRONGEST CONVECTION IS PARALLEL
TO THE EAST PACIFIC COAST OF PANAMA AND COSTA RICA. FINALLY...A
MARGINALLY DIFFLUENT UPPER LEVEL ENVIRONMENT IS NOTED ACROSS THE
EASTERN CARIBBEAN WITH WIDELY SCATTERED SHOWERS AND ISOLATED
TSTMS OCCURRING E OF A LINE FROM SOUTHWESTERN HISPANIOLA NEAR
18N73W TO 12N65W. LOW-LEVEL MOISTURE CONTINUES TO ADVECT FROM
THE TROPICAL ATLC INTO THE EASTERN CARIBBEAN AND RE-DIRECT
NORTHWARD ON THE SOUTHERN PERIPHERY OF AN UPPER LEVEL
ANTICYCLONE CENTERED IN THE SW NORTH ATLC NEAR 22N62W.

HISPANIOLA...
CURRENTLY MIDDLE TO LOW-LEVEL MOISTURE...PEAK HEATING...AND
INSTABILITY ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS
ACROSS HISPANIOLA BETWEEN A TROPICAL WAVE TO THE SOUTHWEST ALONG
75W AND THE DIFFLUENT EASTERN PERIPHERY OF AN UPPER LEVEL TROUGH
AXIS EXTENDING FROM OVER THE ISLAND NEAR 19N71W TO 11N78W. THIS
MOISTURE STRETCHES EASTWARD TO 59W AND IS EXPECTED TO REMAIN IN
PLACE OVER THE NEXT FEW DAYS WITH MAXIMUM AREAL COVERAGE OF
CONVECTIVE ACTIVITY OCCURRING DURING THE AFTERNOON AND EVENING
HOURS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR
IMAGERY CENTERED OVER THE MID-ATLC STATES NEAR 36N78W. THE
TROUGH SUPPORTS A 1008 MB LOW CENTERED NEAR 34N76W WITH A COLD
FRONT EXTENDING S-SW TO 31N77W WHICH CONTINUES SOUTHWESTWARD AS
A STATIONARY FRONT TO THE UPPER FLORIDA KEYS NEAR 25N80W. ASIDE
FROM THE LOW AND FRONTAL BOUNDARY...MUCH OF THE SW NORTH ATLC
FALLS UNDER A VERY WEAK SURFACE PRESSURE GRADIENT WITH LOWER
PRESSURE GENERALLY BETWEEN 60W-80W. WIDELY SCATTERED SHOWERS AND
ISOLATED TSTMS ARE OCCURRING WITHIN 300 NM EAST OF THE
FRONT...BUT ARE ALSO OCCURRING FROM 18N-27N BETWEEN 58W-72W IN
ASSOCIATION WITH AN UPPER LEVEL LOW CENTERED NEAR 26N67W.
EVENTUALLY BY EARLY SATURDAY MOST OF THE SURFACE TROUGHING
SHIFTS NORTH OF THE DISCUSSION AREA WITH HIGH PRESSURE RIDGING
BUILDING IN FROM BOTH THE EAST ACROSS THE CENTRAL ATLC AND THE
WEST FROM THE NE GULF OF MEXICO. UNTIL THEN...CONDITIONS ARE
EXPECTED TO REMAIN RATHER DISORGANIZED AND UNSETTLED WITH
SHOWERS AND TSTM ACTIVITY. FARTHER EAST...A SURFACE RIDGE
INFLUENCES THE CENTRAL ATLC N OF 23N BETWEEN 40W-60W ANCHORED BY
A 1023 MB HIGH CENTERED NEAR 35N54W. THE SURFACE RIDGING
STRETCHES ACROSS THE EASTERN ATLC...HOWEVER IS SLIGHTLY WEAKER
DUE TO A DISSIPATING COLD FRONT EXTENDING FROM 32N29W SW TO
28N41W AND SUPPORTED ALOFT BY A DEEP LAYERED LOW CENTERED NW OF
THE AZORES NEAR 44N37W. NO SIGNIFICANT PRECIPITATION IS
OCCURRING ALONG THE FRONT AT THIS TIME.


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

$$
HUFFMAN

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