[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041934 CCA
TWDAT

TROPICAL WEATHER DISCUSSION...CORRECTION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 04 2014

CORRECTED FOR ISSUE TIME

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
1745 UTC.

...SPECIAL FEATURES...
HURRICANE ARTHUR IS CENTERED NEAR 38.5N 72.4W AT 04/1800 UTC OR
ABOUT 110 NM ESE OF ATLANTIC CITY NEW JERSEY MOVING NE AT 23 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 977 MB. MAXIMUM SUSTAINED
WINDS ARE NOW DOWN TO 80 KT WITH GUSTS TO 100 KT. THE EYE OF
ARTHUR IS SWEEPING RAPIDLY NORTHEASTWARD WELL OFF THE MID
ATLANTIC COAST. STRONG CONVECTION IS LOCATED WITHIN A 120 NM
RADIUS FROM THE STORM CENTER IN THE NORTHERN SEMICIRCLE AND 90
NM IN THE S SEMICIRCLE. ALTHOUGH THE CENTER OF ARTHUR IS WELL
SOUTH OF THE AREA...STEADY HEAVY RAINS ARE RAPIDLY OVERSPREADING
LONG ISLAND AND NEW ENGLAND. SEE LATEST INTERMEDIATE PUBLIC
ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT1/WTNT31 KNHC AND THE
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT1/WTNT21
KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE OFF THE AFRICAN COAST EXTENDS FROM 20N22W TO
09N24W AND IS MOVING W AT 20 KT. A STRONG SAHARAN AIR LAYER
SIGNAL IS NOTED ON METEOSAT-9 IMAGERY TO THE WEST AND NORTH OF
THE WAVE. NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THE WAVE.

A TROPICAL WAVE EXTENDING FROM 20N50W TO 15N51W TO 10N49W IS
MOVING W AT 15-20 KT AND IS EASILY IDENTIFIABLE ON RECENT
VISIBLE SATELLITE IMAGERY. THERE IS NO SIGNIFICANT DEEP
CONVECTION OCCURRING AT THIS TIME WITH THE WAVE DUE TO THE
WAVE BEING EMBEDDED WITHIN A STRONG SAHARAN AIR LAYER.

A TROPICAL WAVE EXTENDS FROM 19N72W TO 12N74W AND IS MOVING W AT
15-20 KT. THE WAVE HAS FRACTURED WITH THE A SURFACE TROUGH N OF
THE GREATER ANTILLES FROM 24N69W TO 20N72W. THE WAVE IS
CURRENTLY MOVING BENEATH A BROAD ELONGATED UPPER LEVEL LOW
CENTERED NEAR HISPANIOLA. DUE TO THE RELATIVELY UNFAVORABLE
ENVIRONMENT OF UPPER LEVEL WIND SHEAR IMPACTING THE WAVE...NO
SIGNIFICANT CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME.

A TROPICAL WAVE EXTENDS FROM 21N90W TO 10N92W AND IS MOVING W-NW
AT 15 KT. RIDGING ALOFT IS IN THE VICINITY OF THE WAVE.
SCATTERED STRONG CONVECTION IS LOCATED WITHIN 90 NM OF THE GULF
OF TEHUANTEPEC IN THE E PACIFIC.

A TROPICAL WAVE EXTENDS FROM 22N100W TO 11N99W AND IS MOVING W
AT 10-15 KT. THE WAVE IS MOVING OVER THE HIGH TERRAIN OF MEXICO
AND WILL ONLY BE DISCERNIBLE IN THE EAST PACIFIC. THUS THE WAVE
WILL NO LONGER BE CARRIED OVER MEXICO ON THE 1800 UTC ANALYSIS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO
09N35W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
09N35W TO THE COATS OF SOUTH AMERICA NEAR 05N52W. SCATTERED
MODERATE ISOLATED STRONG CONVECTION IS LOCATED S OF THE MONSOON
TROUGH WITHIN 75-90 NM EITHER SIDE OF A LINE FROM 07N15W TO
07N26W.

...DISCUSSION...

GULF OF MEXICO...
A WEAKENING MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS
POSITIONED OVER THE NW GULF NEAR 27.5N94.5W AND IS NEARLY
STATIONARY. BROAD RIDGING ALOFT COVERS MOST OF THE SOUTHERN HALF
OF THE GULF. OVER THE NE GULF SATELLITE DERIVED WINDS INDICATE
SOUTHWESTERLY WINDS WITH SPEEDS IN THE 15 TO 20 KT RANGE. AT THE
SURFACE A TROUGH EXTENDS FROM FLORIDA BIG BEND TO 27N89W. A
STATIONARY FRONT IS LOCATED ACROSS THE FLORIDA PANHANDLE INTO SE
LOUISIANA. SCATTERED SHOWERS AND TSTMS ARE LOCATED OVER THE
WESTERN TWO-THIRDS OF THE BAY OF CAMPECHE...AND WITHIN 45 NM
EITHER SIDE OF THE SURFACE TROUGH NOTED ABOVE.

CARIBBEAN SEA...

UPPER LEVEL ANTICYCLONIC FLOW PREVAILS OVER THE CARIBBEAN W OF
80W AND E OF 65W...WITH A FAIRLY AMPLIFIED MID-TO UPPER LEVEL
TROUGH IN BETWEEN. THE TROUGH EXTENDS FROM A CYCLONIC
CIRCULATION LOCATED OVER HAITI TO A BASE NEAR 12N77W. RESULTING
SOUTHERLY WINDS ALOFT ARE LOCATED OVER THE EASTERN THIRD OF THE
CARIBBEAN. AT THE SURFACE MODERATE EASTERLY TRADE WIND FLOW WAS
NOTED IN GENERALLY FAIR SKIES. SCATTERED TSTMS WERE ERUPTING
OVER OROGRAPHICALLY FAVORED AREAS IN HISPANIOLA...CUBA AND
CENTRAL AMERICA.

...HISPANIOLA...
SCATTERED TSTMS WERE DEVELOPING OVER THE INTERIOR OF HAITI AND
THE DOMINICAN REPUBLIC. THE 1200 UTC SOUNDING FROM SANTO DOMINGO
INDICATED A MORE MOIST ATMOSPHERE THAN THE PREVIOUS SEVERAL DAYS
WITH PRECIPITABLE WATER VALUES OF 1.83 INCHES...CLOSER TO NORMAL
VALUES. GIVEN THE EARLY DEVELOPMENT OF TSTMS...THE POTENTIAL IS
FOR MORE COVERAGE OF THUNDERSTORMS LATER THIS AFTERNOON THAN
NOTED PREVIOUSLY. ADDITIONALLY THE PRESENCE OF THE UPPER LOW IN
THE AREA IS PROVIDING ENOUGH INSTABILITY WITH LIFTED INDICES OF -
6C AND CAPE VALUES OF 2968 J/KG NOTED IN THE SOUNDING AS WELL.

ATLANTIC OCEAN...
UPPER LEVEL RIDGING NOTED OVER THE WESTERN ATLANTIC W OF 75W. A
MID-TO UPPER LEVEL TROUGH AXIS EXTENDS THROUGH 32N58W TO
HISPANIOLA WITH CYCLONIC FLOW LOCATED UP TO 10 TO 15 DEGREES
EITHER SIDE OF THE AXIS. THE TROUGH AND CYCLONIC CIRCULATION
WERE MOVING W AND IMPINGING UPON THE RIDGE. FURTHER E...BROAD
UPPER LEVEL RIDGING COVERED THE CENTRAL ATLANTIC FROM 10N TO 30N
BETWEEN 38W AND 62W. WATER VAPOR IMAGERY INDICATES STRONG
SUBSIDENCE ASSOCIATED WITH THIS FEATURE. MOVING DOWNSTREAM A
WELL-DEFINED MIDDLE/UPPER LEVEL CYCLONIC CIRCULATION IS CENTERED
NEAR 30N30W AND IS MOVING S AT 10 KT. LIGHT TO MODERATE EASTERLY
WINDS ALOFT COVER THE DEEP TROPICS. AT THE SURFACE A TROUGH IS
LOCATED THROUGH 31N55W TO 25N62W. SCATTERED LOW TOPPED SHOWERS
ARE LOCATED ABOUT 60 NM EITHER SIDE OF THE TROUGH.

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

$$
COBB


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