[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041055
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 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.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 10N36W TO 19N38W MOVING W AT 15 KT.
THE WAVE REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS WITH
MID-LATITUDE MID-LEVEL TROUGHING NOTED TO THE NW OF THE WAVE IN
THE VICINITY OF 21N46W. WHILE NEITHER FEATURE EXHIBITS A STRONG
SIGNAL ON SATELLITE IMAGERY AND IN GLOBAL MODEL DATA...ENERGY
ASSOCIATED WITH EACH ARE FORECAST TO MERGE WITHIN THE NEXT 12 TO
24 HOURS ACROSS THE CENTRAL ATLC AND CONTINUE A WESTWARD
MOVEMENT TOWARD THE LESSER ANTILLES REACHING 60W BY MONDAY. THE
WAVE IS SURROUNDED BY A LARGE AREA OF SUSPENDED SAHARAN DUST AT
THIS TIME WITH NO CONVECTION OCCURRING IN THE VICINITY OF THE
WAVE.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
16N17W TO 14N24W TO 09N35W TO 09N43W TO 07N50W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N50W TO
06N54W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 150 NM
EITHER SIDE OF A LINE FROM 09N14W TO 13N25W TO 06N37W TO 07N47W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED
OVER NORTH TEXAS NEAR 32N98W AND IS PROVIDING THE GULF WITH
NORTHEAST TO EASTERLY FLOW ALOFT. WATER VAPOR IMAGERY INDICATES
IT REMAINS MODERATELY DRY AND STABLE WITH UPPER LEVEL CONVECTIVE
DEBRIS CLOUDINESS COVERING THE CENTRAL GULF FROM 23N-27N THIS
MORNING. OTHERWISE...THE GULF IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED OVER THE
EASTERN GULF NEAR 26N83W. A FEW ISOLATED SHOWERS AND TSTMS ARE
OCCURRING FROM 24N-26N BETWEEN 81W-83W AND S OF 21N OVER THE SW
GULF. LOOKING AHEAD...RIDGING WILL DOMINATE OVER THE BASIN
THROUGH WEDNESDAY WITH SOUTHERLY WINDS PREVAILING W OF 90W IN
THE RANGE OF 10-20 KT.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
WESTERN CARIBBEAN NEAR 13N81W THAT IS ADVECTING MOISTURE
NORTHWARD ON THE WESTERN PERHIPHERY OF THE RIDGING ACROSS
PORTIONS OF CENTRAL AMERICA. THIS IS RESULTING IN GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS S OF 18N W OF 82W. FARTHER
SOUTH ACROSS SOUTHERN NICARAGUA...COSTA RICA...AND PANAMA...
SCATTERED SHOWERS AND TSTMS ARE OCCURRING DUE TO MAXIMUM UPPER
LEVEL DIFFLUENCE AND ALSO THE PRESENCE OF THE MONSOON TROUGH
AXIS ANALYZED ALONG 09N FROM NORTHERN COLOMBIA TO SOUTHERN COSTA
RICA AND INTO THE EAST PACIFIC REGION. ON THE EASTERN PERIPHERY
OF THE UPPER LEVEL ANTICYCLONE...A DRIER NORTHWESTERLY FLOW
PREVAILS BETWEEN 70W-80W WITH MOSTLY CLEAR SKIES AND FAIR
CONDITIONS. FINALLY...OVER THE EASTERN CARIBBEAN AN UPPER LEVEL
LOW IS CENTERED NORTH OF PUERTO RICO NEAR 23N66W PROVIDING
TROUGHING E OF 70W. WATER VAPOR IMAGERY INDICATES THE TROUGHING
EXHIBITS RELATIVELY DRY AIR ALOFT AND THIS IS RESULTING IN ONLY
A FEW ISOLATED LOW-TOPPED SHOWERS OCCURRING FROM 16N-18N BETWEEN
69W-73W...AND E OF 66W...INCLUDING THE LESSER ANTILLES.
OTHERWISE...THE SAHARAN AIR LAYER CONTINUES TO PROVIDE A LARGE
INFLUENCE TO THE OVERALL STABILITY OF THE BASIN E OF 80W.

HISPANIOLA...
CURRENTLY A FEW ISOLATED SHOWERS ARE OCCURRING ALONG THE
SOUTHERN COAST OF THE ISLAND AND INTO THE ADJACENT COASTAL
CARIBBEAN SEA WATERS. THESE SHOWERS ARE EXPECTED TO CONTINUE
DRIFTING WESTWARD OVER THE NEXT FEW HOURS. SATELLITE IMAGERY
INDICATES THAT THE SAHARAN AIR LAYER WILL PROVIDE AN OVERALL
STABLE ATMOSPHERE OVER THE NEXT FEW DAYS. HAZY SKIES ARE
EXPECTED DURING THE NEXT 24 TO 48 HOURS.

ATLANTIC OCEAN...
NORTHERLY UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY
BETWEEN 70W-82W AND A NARROW MID-LEVEL TROUGH IS IN THE VICINITY
OF 28N77W ACROSS THE SW NORTH ATLC. THIS TROUGH SUPPORTS A 1011
MB LOW CENTERED NEAR 34N75W AND A SURFACE TROUGH EXTENDING FROM
THE LOW TO 31N76W. GENERALLY AN OVERALL WEAKNESS IN THE SURFACE
RIDGING EXTENDING FROM THE CENTRAL ATLC TO THE GULF OF MEXICO...
MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE IN THE REGION IS
GENERATING OVERCAST CLOUDINESS WITH ISOLATED SHOWERS AND TSTMS
WITHIN 150 NM EITHER SIDE OF A LINE FROM 33N74W TO 25N80W. THIS
AREA OF TROUGHING...ALONG WITH THE LOW PRESSURE CENTER IS
EXPECTED TO MOVE NORTHEAST AND WELL NORTH OF THE DISCUSSION AREA
OVER THE NEXT 12 TO 24 HOURS. OTHERWISE THE REMAINDER OF THE SW
NORTH ATLC...CENTRAL ATLC...AND EASTERN ATLC ARE UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED
NEAR 30N57W AND A 1027 MB HIGH CENTERED S OF THE AZORES NEAR
34N30W. EMBEDDED WITHIN THE SOUTHERN PERIPHERY OF THE RIDGE...
MID-LATITUDE MID-LEVEL ENERGY IS LOCATED IN THE VICINITY OF
21N46W. WHILE NO SIGNIFICANT CONVECTION IS OCCURRING WITH THIS
FEATURE...IT IS FORECAST TO MERGE WITH ENERGY ASSOCIATED WITH
THE TROPICAL WAVE ALONG 37W OVER THE NEXT 24 HOURS. FINALLY...
SAHARAN DUST COVERS MUCH OF THE TROPICAL ATLC AND IS PROVIDING
OVERALL STABLE CONDITIONS THIS MORNING.

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

$$
HUFFMAN


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