[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232353
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT APR 23 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 05N08W 03N20W CROSSING THE EQUATOR
NEAR 33W/34W THEN INTO NE BRAZIL NEAR 02S43W. SCATTERED MODERATE
TO STRONG CONVECTION IS FROM THE EQUATOR TO 06N BETWEEN 10W-17W.
ISOLATED MODERATE CONVECTION IS ALONG THE EQUATOR BETWEEN
31W-38W.

...DISCUSSION...

GULF OF MEXICO...
A WEAK SHEARING UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM
MISSISSIPPI INTO THE NW GULF TO NEAR 25N94W. WATER VAPOR IMAGERY
INDICATES MODERATE SUBSIDENCE MAINTAINING GENERALLY FAIR WEATHER
AND MOSTLY CLEAR SKIES. AT THE SURFACE...SOUTHEAST TO SOUTH
WINDS CONTINUE ACROSS THE BASIN IN THE RANGE OF 10 TO 15
KT...AND 20 KT ALONG THE TEXAS COAST AS A SURFACE RIDGE AXIS
EXTENDS FROM THE W ATLC REGION NEAR 30N80W ACROSS THE NORTHERN
FLORIDA PENINSULA TO THE NW GULF NEAR 27N95W. THE RIDGE IS
FORECAST TO REMAIN IN PLACE THROUGH LATE TUESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE AXIS EXTENDS FROM AN UPPER LEVEL
ANTICYCLONE OVER THE TROPICAL NORTH ATLC NEAR 09N42W THROUGH
10N55W THEN ALONG THE NORTHERN COAST OF VENEZUELA TO THE WEST
CENTRAL CARIBBEAN NEAR 12N78W. ON THE NORTHERN PERIPHERY OF THIS
UPPER LEVEL RIDGE...MODERATE TO STRONG UPPER LEVEL SOUTHWESTERLY
FLOW CONTINUES TO ADVECT MIDDLE TO UPPER LEVEL MOISTURE FROM
NORTHERN SOUTH AMERICA ACROSS THE E HALF OF THE CARIBBEAN SEA.
AT THE SURFACE...THE EASTERLY TRADES E OF 70W APPEAR TO BE
DISRUPTED BY THE PRESENCE OF THE SURFACE LOW ABOUT 300 NM N OF
PUERTO RICO WITH NE WINDS GENERALLY 10 KT OR LESS. THIS WAS
CONFIRMED BY A 1406 UTC ASCAT PASS IN THE REGION. FURTHER W
MODERATE EAST-NORTHEASTERLY TRADES RESUME AND ARE GENERALLY IN
THE 15 TO 20 KT RANGE WITH HIGHEST WINDS JUST S OF THE DOMINICAN
REPUBLIC AND OVER THE NW CARIBBEAN SOUTH OF CUBA TO 19N. A FEW
AREAS OF ISOLATED SHOWERS ARE OCCURRING DUE TO LOW-LEVEL SPEED
CONVERGENCE S OF 13N BETWEEN 62W-72W. ANOTHER AREA OF ISOLATED
SHOWERS IS LOCATED WEST OF 80W FROM 16N-20N AND SW OF HISPANIOLA
FROM 16N-18N BETWEEN 72W-75W.

ATLANTIC OCEAN...
MUCH OF THE SW NORTH ATLC W OF 65W IS UNDER THE INFLUENCE OF AN
UPPER LEVEL RIDGE WITH AXIS EXTENDING FROM 31N76W TO 24N70W.
THIS UPPER LEVEL FEATURE SUPPORTS A SURFACE RIDGE WHICH EXTENDS
IN A NORTHEAST TO SOUTHWEST ORIENTATION THROUGH 32N74W TO NE
FLORIDA NEAR JACKSONVILLE. MOSTLY FAIR CONDITIONS AND FRESH NE
WINDS DOMINATE THE AREA. FARTHER EAST...A 1013 MB LOW CENTERED
NEAR 24N66W WITH A WELL DEFINED CIRCULATION PER VISIBLE
SATELLITE IMAGERY CONTINUES TO MOVE W AT 10-12 KT. DATA FROM
NOAA BUOY 41043 STILL INDICATES A CLOSED LOW AT THE SURFACE.
THE LOW IS EMBEDDED WITHIN A BROAD AREA OF STRONG UPPER LEVEL
SUBSIDENCE TO THE NW OF A TROUGH AND SHEAR AXIS WHICH EXTENDS
FROM 32N50W THROUGH 26N60W TO 24N66W. THE STRONG SUBSIDENCE
ALOFT HAS INHIBITED ANY DEEP CONVECTION ASSOCIATED WITH THE LOW
WITH ONLY ISOLATED TO LOCALLY SCATTERED SHOWERS LOCATED WITHIN
150 NM OF THE CENTER OF THE LOW BUT MAINLY IN THE EAST AND
SOUTHEAST QUADRANTS. THE LOW IS FORECAST TO WEAKEN TO A SURFACE
TROUGH WITHIN THE NEXT 24 HOURS AS IT PUSHES TOWARD THE BAHAMAS.

A FAIRLY EXTENSIVE AREA OF WIDELY SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS IS LOCATED SE OF THE AFOREMENTIONED UPPER TROUGH
BENEATH AN AREA OF UPPER LEVEL DIFFLUENCE FROM 22N-30N BETWEEN
45W-57W. ELSEWHERE AT THE SURFACE A TROUGH WAS LOCATED JUST NE
OF THE LEEWARD ISLANDS EXTENDING FROM 18N59W SE TO NEAR
BARBADOS. THE REMAINDER OF THE EASTERN ATLC E OF 45W IS UNDER
THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1029 MB HIGH
CENTERED SOUTH OF THE AZORES NEAR 37N28W.

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

$$
COBB





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