[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 271745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 27 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
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM A 1014 MB LOW CENTERED NEAR 10N31W TO
19N29W MOVING W AT 10-15 KT. AS EXPECTED FROM YESTERDAY AT THIS
TIME...THE SOUTHERN VORTICITY MAXIMUM ALONG THE WAVE AXIS BECAME
THE DOMINATE FEATURE AND IS CURRENTLY A WEAK AND BROAD CYCLONIC
MONSOONAL GYRE WITH INFLUENCE FROM 08N-16N BETWEEN 23W-38W. AS
THE LOW-LEVEL ENERGY CONTINUES TO PROPAGATE WESTWARD AS A
WHOLE...UPPER LEVEL SOUTHWESTERLIES TO THE NORTHWEST OF THE WAVE
AXIS WILL SLOWLY FRACTURE ENERGY AWAY FROM THE WAVE TO THE NORTH
OVER THE NEXT 24 TO 48 HOURS. SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION IS WITHIN 120 NM EITHER SIDE OF A LINE FROM
13N31W TO 08N37W.

TROPICAL WAVE EXTENDS FROM 13N48W TO 23N44W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN A MAXIMUM OF TOTAL
PRECIPITABLE WATER EXTENDING NORTHWARD FROM THE MONSOON TROUGH
REGION FROM 11N-22N BETWEEN 39W-50W AND COINCIDES WITH A 700 MB
TROUGH AXIS WITH A RELATIVE VORTICITY MAXIMUM CENTERED IN THE
VICINITY OF 20N46W ALONG THE WAVE AXIS. THE WAVE LACKS ANY
SIGNIFICANT DEEP CONVECTION AT THIS TIME DUE TO THE PRESENCE OF
THE SAHARAN AIR LAYER ACROSS MUCH OF THE CENTRAL ATLC.

TROPICAL WAVE EXTENDS FROM 11N81W TO 20N83W MOVING W AT 10-15
KT. THE WAVE CONTINUES TO BE EMBEDDED WITHIN BROAD LOW-LEVEL
TROUGHING ACROSS THE WESTERN CARIBBEAN SEA. TOTAL PRECIPITABLE
WATER IMAGERY INDICATES THE WAVE LIES WITHIN A RELATIVELY MOIST
ENVIRONMENT W OF 80W WITH SCATTERED MODERATE CONVECTION FROM 11N-
18N BETWEEN 81W-85W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 12N17W TO 10N31W TO 12N46W TO A
1013 MB LOW NEAR 11N54W TO 09N56W. THE INTERTROPICAL CONVERGENCE
ZONE AXIS EXTENDS FROM 09N56W TO 11N64W AND THE MONSOON TROUGH
AXIS RESUMES NEAR 11N64W TO 11N70W TO 10N83W. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 06N-10N BETWEEN 14W-22W...AND WITHIN
60 NM OF THE 1013 MB LOW CENTER NEAR 11N54W. SCATTERED MODERATE
TO STRONG CONVECTION IS ALSO ENHANCED BY THE MONSOON TROUGH AXIS
OVER THE SW CARIBBEAN SEA FROM 08N-13N BETWEEN 74W-82W. THIS
CONVECTION IS LIKELY ENHANCED DUE TO AN UPPER LEVEL DIFFLUENT
ENVIRONMENT OVER THE WESTERN CARIBBEAN AT THIS TIME.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL LOW IS
CENTERED OVER THE STRAITS OF FLORIDA NEAR 23N81W THAT IS
PROVIDING THE SE GULF AND SOUTHERN FLORIDA PENINSULA WITH
SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS S OF 28N E OF 84W.
AS OF 27/1500 UTC A WEAK SURFACE TROUGH EXTENDS NORTHWEST OF
THIS CONVECTION PRECIPITATION FROM 25N85W TO 29N85W. AT THIS
TIME THE SURFACE TROUGH REMAINS FAIRLY BENIGN AS THE REMAINDER
OF THE GULF BASIN IS UNDER THE INFLUENCE OF NORTHERLY FLOW ALOFT
W OF 84W. THE NORTHERLY FLOW IS PROVIDING A STABLE ENVIRONMENT
AND SUPPORTING A BROAD SURFACE RIDGE EXTENDING FROM LOUISIANA
SOUTHWARD TO THE BAY OF CAMPECHE WITH OVERALL PARTLY CLOUDY
SKIES AND FAIR CONDITIONS THIS AFTERNOON. LOOKING AHEAD...WITH A
SURFACE RIDGE ANCHORED TO THE NORTH OVER THE SE CONUS...E-SE
WINDS ARE FORECAST TO PERSIST THROUGH LATE WEDNESDAY. DURING
THAT TIME...THE SURFACE RIDGING WILL SLOWLY SHIFT SOUTHWARD INTO
THE GULF BY LATE THURSDAY INTO FRIDAY AND REMAIN NEARLY
STATIONARY WITH A RIDGE AXIS ALONG 27N.

CARIBBEAN SEA...
THE BASE OF A MIDDLE TO UPPER LEVEL LOW CENTERED OVER THE
FLORIDA STRAITS NEAR 23N81W REMAINS OVER THE NW CARIBBEAN WITH
THE BASE OF THE TROUGH NEAR 17N84W. MIDDLE TO UPPER LEVEL
DIFFLUENCE ALONG WITH THE PRESENCE OF A TROPICAL WAVE ALONG 83W
IS PROVIDING FOR INCREASED ATMOSPHERIC LIFT AND GENERATING
SCATTERED SHOWERS AND TSTMS FROM 11N-18N BETWEEN 81W-85W...WITH
ISOLATED SHOWERS AND TSTMS ELSEWHERE S OF 21N W OF 80W. TO THE
SOUTHEAST OF THE TROPICAL WAVE...A LARGE COMPLEX OF SCATTERED
SHOWERS AND TSTMS IS OCCURRING IN THE VICINITY OF THE MONSOON
TROUGH FROM 08N-13N BETWEEN 74W-81W. THIS CONVECTION IS LIKELY
ENHANCED DUE TO A FAVORABLE UPPER LEVEL DIFFLUENT ENVIRONMENT S
OF 15N BETWEEN 72W-84W. FARTHER EAST...AN UPPER LEVEL
ANTICYCLONIC CIRCULATION IS CENTERED OVER THE EASTERN CARIBBEAN
NEAR 16N70W. WHILE WATER VAPOR IMAGERY INDICATES RELATIVELY
DRIER AIR ALOFT WITHIN A CORRIDOR FROM 20N60W TO OVER THE ABC
ISLANDS NEAR 12N69W...A SURFACE TROUGH IS ANALYZED TO THE NORTH
OF THIS CORRIDOR FROM 15N69W TO 21N68W. SCATTERED SHOWERS AND
ISOLATED TSTMS ARE OCCURRING FROM 14N-23N BETWEEN 65W-72W...
INCLUDING PUERTO RICO...THE MONA PASSAGE...AND PORTIONS OF
EASTERN HISPANIOLA. THE OTHER AREA OF SIGNIFICANT SCATTERED
SHOWERS AND TSTMS ARE OCCURRING OVER THE WINDWARD ISLANDS FROM
10N-15N BETWEEN 58W-63W. FINALLY...EASTERLY TRADES PERSIST
GENERALLY 20 KT OR LESS AND ARE FORECAST TO GRADUALLY INCREASE
BY EARLY THURSDAY AS THE OVERALL PRESSURE GRADIENT STRENGTHENS
BETWEEN LOWER PRESSURE ACROSS SOUTH AMERICA AND A SW NORTH ATLC
SURFACE RIDGE ALONG 26N/27N.

HISPANIOLA...
MOIST SOUTHWESTERLY FLOW ALOFT IS OVER HISPANIOLA THIS AFTERNOON
AND IS PROVIDING FOR AN OVERALL DIFFLUENT ATMOSPHERE FOR THE
ISLAND. MOVING WESTWARD BENEATH THIS FLOW IS SURFACE TROUGH
ANALYZED FROM 15N65W TO 22N68W. LOW-LEVEL MOISTURE IS FOCUSED ON
BOTH SIDES OF THE SURFACE TROUGH BETWEEN 65W-71W WHICH IS
ALREADY PROVIDING THE ISLAND WITH ISOLATED SHOWERS E OF 71W.
MOISTURE AND PRECIPITATION IS EXPECTED TO INCREASE AS THE SURFACE
TROUGH MOVES WEST OVER THE NEXT 24 TO 48 HOURS. PEAK DAYTIME
HEATING AND INSTABILITY WILL LIKELY GENERATE MORE INTENSE
SHOWERS AND TSTMS THIS AFTERNOON AND EVENING WITH ANY ACTIVITY
DIMINISHING BEYOND THE LATE EVENING HOURS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS INTO THE DISCUSSION
AREA NEAR 32N65W IN THE SW NORTH ATLC AND EXTENDS SOUTHWEST TO
28N74W AND INTO A MIDDLE TO UPPER LEVEL LOW CENTERED OVER THE
FLORIDA STRAITS NEAR 23N81W. THIS TROUGHING ALOFT SUPPORTS A
DISSIPATING STATIONARY FRONT ANALYZED FROM 31N62W TO 29NN70W TO
28N76W THEN CONTINUES SW AS A SURFACE TROUGH TO 24N80W. WATER
VAPOR IMAGERY INDICATES THAT THE UPPER LEVEL DYNAMICS ARE MORE
CONCENTRATED OVER THE FLORIDA STRAITS AND THIS IS WHERE
SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 23N-28N BETWEEN
77W-83W. TO THE NORTHEAST CLOSER TO THE STATIONARY FRONT...LOW-
LEVEL MOISTURE CONVERGENCE ALONG AND SOUTH OF THE BOUNDARY
CONTINUES TO PRODUCE ISOLATED SHOWERS AND TSTMS N OF 27N BETWEEN
58W-68W. TO THE SOUTHEAST...A SURFACE TROUGH EXTENDS FROM THE
NORTH-CENTRAL CARIBBEAN SEA NEAR 15N69W TO 22N68W WITH LOW-LEVEL
MOISTURE CONVERGENCE AND INSTABILITY GENERATING SCATTERED
SHOWERS AND TSTMS FROM 15N-23N BETWEEN 65W-70W. ASIDE FROM THE
TWO TROPICAL WAVES PROGRESSING WESTWARD...THE REMAINDER OF THE
CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE
RIDGE ANCHORED BY A 1031 MB HIGH CENTERED NORTH OF THE AZORES
NEAR 43N26W.

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

$$
HUFFMAN

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