[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUL 21 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 09N12W TO 17N18W MOVING W AT 10-15
KT. THIS WAVE IS BEGINNING TO EMERGE OFF THE COAST OF WEST
AFRICA AND EXHIBITS FAVORABLE MID-LEVEL VORTICITY ENERGY IN THE
VICINITY OF 12N15W ALONG THE WAVE AXIS. GLOBAL MODELS INDICATE
THE WAVE COINCIDES WITH A WEAK 700 MB TROUGH ALONG 16W THAT IS
FORECAST TO MOVE WESTWARD ON THE SOUTHERN PERIPHERY OF CENTRAL
ATLC RIDGING DURING THE WEEK AHEAD. SCATTERED MODERATE
CONVECTION IS FROM 06N-12N BETWEEN 13W-17W.

TROPICAL WAVE EXTENDS FROM 12N55W TO 23N53W MOVING W AT 15-20
KT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THE WAVE LIES
WITHIN A POLEWARD EXTENDING MAXIMUM FROM 06N-24N BETWEEN 49W-
59W...HOWEVER THE PRESENCE OF THE SAHARAN AIR LAYER IS PROVIDING
FOR AN OVERALL STABLE ENVIRONMENT FOR THE WAVE RESULTING IN A
LACK OF DEEP CONVECTION AT THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR
12N17W TO 10N25W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 10N25W TO 07N33W TO 04N38W TO 03N47W TO 06N57W.
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 07N-
13N BETWEEN 18W-29W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR
IMAGERY PROGRESSING E-NE OVER MISSISSIPPI THIS AFTERNOON WITH A
TROUGH AXIS EXTENDS SOUTHWEST OVER PORTIONS OF THE NW GULF TO
27N94W. WHILE THE PRIMARY SURFACE FEATURE REMAINS A SURFACE
RIDGE ANCHORED OVER THE SW NORTH ATLC...THE MIDDLE TO UPPER
LEVEL DYNAMICS ARE GENERATING SCATTERED SHOWERS AND TSTMS N OF
27N BETWEEN 89W-97W...INCLUDING INLAND SOUTHERN LOUISIANA AND
IMMEDIATELY ALONG THE TEXAS GULF COAST. OTHERWISE...THE
REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF THE PREVIOUSLY
MENTIONED SURFACE RIDGE WITH AXIS EXTENDING FROM A 1023 MB HIGH
CENTERED NEAR 29N66W IN THE SW NORTH ATLC TO EAST-CENTRAL MEXICO
NEAR 21N97W. ANOTHER MID-LEVEL SHORTWAVE TROUGH IS NOTED OFF THE
COAST OF THE NORTHERN FLORIDA PENINSULA AND IS PROVIDING FOR
SCATTERED SHOWERS AND TSTMS PRIMARILY IN THE SW NORTH ATLC
REGION...HOWEVER A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING
ACROSS THE FLORIDA PENINSULA AND ADJACENT COASTAL EASTERN GULF
WATERS S OF 27N E OF 84W. THE SURFACE RIDGE AXIS IS FORECAST TO
REMAIN ALONG 26N/27N THROUGH WEDNESDAY.

CARIBBEAN SEA...
CONDITIONS ACROSS THE NW CARIBBEAN REMAIN TRANQUIL THIS
AFTERNOON AS WATER VAPOR IMAGERY INDICATES DRY AIR AND A FAIRLY
STABLE ATMOSPHERE ALOFT. VERY FEW CLOUDS ARE NOTED ON SATELLITE
IMAGERY AS EAST WINDS PERSIST. A MIDDLE TO UPPER LEVEL DIFFLUENT
ATMOSPHERE IS HOWEVER CENTERED OVER THE SW CARIBBEAN WHICH IS
GENERATING SCATTERED SHOWERS AND TSTMS...SOME STRONG...S OF 13N
BETWEEN 77W-86W...INCLUDING PANAMA...COSTA RICA...AND SOUTHERN
NICARAGUA. THIS AREA OF CONVECTION IS LIKELY ENHANCED AS WELL BY
THE CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS EXTENDING ALONG
09N. FINALLY...OVER THE EASTERN AND CENTRAL PORTIONS OF THE
CARIBBEAN...THE WESTERN PERIPHERY OF AN UPPER LEVEL RIDGE IS
PROVIDING FOR SOUTHWESTERLY FLOW ALOFT E OF 76W. HIGH-LEVEL
CLOUDINESS IS NOTED ON SATELLITE IMAGERY...WITH ONLY A FEW AREAS
OF ISOLATED SHOWERS OCCURRING ACROSS THE LESSER ANTILLES AND
AREAS E OF 73W. THE PRIMARY IMPACT THIS AFTERNOON REMAINS
MODERATE TO FRESH TRADES WHICH ARE EXPECTED TO PERSIST THROUGH
MUCH OF THE WEEK AHEAD.

HISPANIOLA...
CURRENTLY CONDITIONS ACROSS THE ISLAND REMAIN FAIRLY TRANQUIL AS
A RIDGE ANCHORED BY A 1023 MB HIGH TO THE NORTH NEAR 29N66W
CONTINUES TO PROVIDE OVERALL STABLE CONDITIONS THIS AFTERNOON. A
FEW PASSING ISOLATED SHOWERS ARE POSSIBLE THROUGH THE LATE
EVENING HOURS...HOWEVER NO SIGNIFICANT DEEP CONVECTION IS
EXPECTED TO IMPACT HISPANIOLA FOR THE NEXT 36 TO 48 HOURS. A
FAST MOVING TROPICAL WAVE ANALYZED ALONG 55W IS EXPECTED TO PASS
THROUGH LATE MONDAY INTO TUESDAY...WITH ONLY ISOLATED SHOWERS
EXPECTED AT THIS TIME DUE TO THE PRESENCE OF A FAIRLY STRONG
SAHARAN AIR LAYER WHICH PROVIDES A STABLE ENVIRONMENT AND
INHIBITS DEEP CONVECTION.

ATLANTIC OCEAN...
NORTH-NORTHEASTERLY FLOW ALOFT DOMINATES ACROSS THE SW NORTH
ATLC BETWEEN AN UPPER LEVEL LOW CENTERED NEAR 28N70W AND AN
UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE EASTERN
GULF OF MEXICO NEAR 27N85W. AN EMBEDDED SHORTWAVE TROUGH OVER
THIS REGION IN THE VICINITY OF 30N77W IS GENERATING SCATTERED
SHOWERS AND TSTMS FROM 25N TO BEYOND 32N BETWEEN 72W-81W.
OTHERWISE THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED
SOUTH OF BERMUDA NEAR 29N66W. ASIDE FROM THE TROPICAL WAVE ALONG
55W...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS ALSO
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB
HIGH CENTERED NEAR 29N41W. THE SURFACE RIDGE IS LARGELY THE
RESULT OF A STRONG MID-LEVEL RIDGE CENTERED NEAR 29N52W
PROVIDING FOR OVERALL STABLE CONDITIONS.

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

$$
HUFFMAN


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