[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN APR 17 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.

...THE ITCZ...

THE ITCZ AXIS IS ANALYZED SOUTH OF THE EQUATOR. NUMEROUS STRONG
CONVECTION IS FROM 4N TO INLAND OVER SW AFRICA E OF 5W TO JUST
ACROSS THE PRIME MERIDIAN. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE FROM 3N TO INLAND OVER SW AFRICA
BETWEEN 6W-9W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH CONTINUES TO MOVE INTO THE NW ATLC COVERING
THE NE GULF N OF 27N E OF 90W SUPPORTING A DISSIPATING FRONTAL
BOUNDARY THAT EXTENDS FROM THE W ATLC ACROSS S FLORIDA AT
17/2100 UTC BETWEEN FORT LAUDERDALE AND CAPE SABLE TO 24N87W.
THE REMAINDER OF THE GULF IS DOMINATED BY A BROAD UPPER RIDGE
ANCHORED IN THE E PACIFIC REGION. WEAK SURFACE RIDGE REMAINS
OVER THE NE GULF WITH A WEAK 1018 MB HIGH OFF THE FLORIDA COAST
NEAR PENSACOLA. THE GULF REMAINS UNDER MOSTLY CLEAR SKIES THIS
EVENING. THE EXCEPTION IS WITHIN 60 NM ALONG THE NW COAST OF
CUBA WHERE AFTERNOON SHOWERS/THUNDERSTORMS THAT DEVELOPED
INLAND ARE GIVING THE AREA ISOLATED SHOWERS THIS EVENING. HIGH
PRESSURE WILL CONTINUE TO DOMINATE MUCH OF THE GULF THROUGH FRI.
A TROUGH WILL DEVELOP OVER TEXAS AND NE MEXICO RESULTING IN
FRESH SE FLOW OVER MOST OF THE MID AND W PORTIONS THROUGH FRI.

CARIBBEAN SEA...
A BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC REGION COVERS THE
GULF OF MEXICO AND THE W CARIBBEAN N OF 16N W OF 70W. THE UPPER
TROUGH OVER THE CENTRAL ATLC DIPS S OVER THE FAR NE CARIBBEAN
FROM THE MONA PASSAGE TO THE LEEWARD ISLANDS N OF 16N. A SECOND
UPPER RIDGE COVERS THE S CARIBBEAN S OF 15N E OF 80W. TROPICAL
MOISTURE IS BEING DRAWN ACROSS THE S CARIBBEAN DUE TO THIS
UPPER FLOW GENERATING ISOLATED SHOWERS WITHIN 90 NM OF LINE FROM
12N76W TO ACROSS THE WINDWARD ISLANDS NEAR SAINT VINCENT. LIGHT
TO MODERATE TRADE WINDS PREVAIL ACROSS THE BASIN DUE TO THE
BROAD PRESSURE GRADIENT. THESE TRADE WINDS ARE BANKING LOW LEVEL
CLOUDS WITH SCATTERED SHOWERS OVER THE SE CARIBBEAN ALONG THE
MOUNTAINS OF W PANAMA AND COSTA RICA AND WITHIN 75 NM ALONG THE
COAST. THESE TRADE WINDS WILL CONTINUE OVER MOST OF THE
CARIBBEAN THROUGH NEXT WEEK.

ATLANTIC OCEAN...
A BROAD UPPER TROUGH IS MOVING OFF THE E CONUS INTO THE NW ATLC
SUPPORTING A COLD FRONT THAT ENTERS THE REGION AT 17/2100 UTC
NEAR 32N73W EXTENDING TO W GRAND BAHAMA ISLAND WHERE IT BEGINS
TO DISSIPATE ACROSS S FLORIDA INTO THE GULF OF MEXICO NEAR FORT
LAUDERDALE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN
30 NM OF THE FRONT MAINLY IN THE IMMEDIATE VICINITY OF S
FLORIDA. A SURFACE TROUGH IS TO THE E OF THE FRONT EXTENDING
FROM 27N77W ACROSS THE N BAHAMA ISLANDS INTO THE STRAITS OF
FLORIDA TO 24N80W. AN UPPER LEVEL TROUGH IS OVER THE CENTRAL
ATLC TO OVER THE FAR NE CARIBBEAN SUPPORTING A SURFACE TROUGH
THAT EXTENDS FROM 24N55W ALONG 19N58W TO 16N58W GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-26N BETWEEN
54W-58W. AN UPPER RIDGE AXIS IS OVER THE E/CENTRAL ATLC
EXTENDING FROM 21N46W TO BEYOND 32N50W GENERATING BROKEN/
OVERCAST MULTILAYERED CLOUDS WITH ISOLATED SHOWERS COVERING AN
AREA FROM 21N-32N BETWEEN 47W-55W. A DEEP LAYERED LOW IS OVER
THE E ATLC WITH THE UPPER LOW CENTERED NEAR 31N20W AND A 997 MB
SURFACE LOW NEAR 31N21W. A SURFACE TROUGH EXTENDS FROM THE
SURFACE LOW OVER THE WESTERN MOST CANARY ISLANDS ALONG 23N22W TO
20N33W. ISOLATED SHOWERS ARE N OF 31N BETWEEN 13W-23W. W ATLC
COLD FRONT WILL WEAKEN AS IT MOVES E AND DISSIPATE BY MON
EVENING. HIGH PRESSURE WILL THEN BEGIN TO BUILD OVER THE W AND
CENTRAL ATLC. THE SURFACE TROUGH CURRENTLY NE OF THE LEEWARD
ISLANDS WILL DRIFT WESTWARD THROUGH LATE WED. A TIGHT PRESSURE
GRADIENT INDUCED BETWEEN THIS TROUGH AND THE HIGH PRESSURE TO
THE N WILL MAINTAIN FRESH NE WINDS OVER THE W AND CENTRAL ATLC
THROUGH EARLY THU.

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

$$
PAW





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