[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 182335
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU APR 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 13N16W THEN ALONG 8N18W TO 5N21W WHERE THE ITCZ BEGINS
AND CONTINUES ALONG 5N28W 3N37W TO S OF THE EQUATOR NEAR 43W.
SMALL CLUSTERS OF SCATTERED MODERATE CONVECTION ARE WITHIN 180
NM ALONG THE COAST OF SW AFRICA S OF 6N W OF 4W AND WITHIN 240
NM N OF THE ITCZ BETWEEN 33W-43W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE DOMINATES THE GULF WITH THE AXIS EXTENDING
ACROSS S MEXICO INTO THE GULF NEAR VERACRUZ ALONG 26N90W THEN N
TO OVER THE SE CONUS NEAR MOBILE ALABAMA. A LARGE UPPER TROUGH
IS MOVING FROM THE PLAIN STATES TOWARD THE MISSISSIPPI VALLEY
SUPPORTING A COLD FRONT THAT AT 18/2100 UTC EMERGED INTO THE
GULF ENTERING NEAR PORT ARTHUR TEXAS TO A 1005 MB LOW NEAR
28N96W CONTINUING TO INLAND OVER MEXICO AT THE TEXAS/MEXICO
BORDER. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE WITHIN 90/120 NM W OF THE FRONT. A WEAK SURFACE RIDGE
EXTENDS FROM THE W ATLC OVER THE N GULF COAST TO SE LOUISIANA.
SOUTHERLY SURFACE FLOW AND MOSTLY CLEAR SKIES COVER THE
REMAINDER OF THE GULF. THE COLD FRONT WILL EXTEND FROM MOBILE
BAY TO VERACRUZ MEXICO FRI WEAKEN AND STALL FROM SW FLORIDA TO
THE CENTRAL BAY OF CAMPECHE SAT THEN DISSIPATE SUN. GALE FORCE
WINDS AND RAPIDLY BUILDING SEAS ARE EXPECTED W OF THE FRONT IN
THE W AND SW GULF STARTING LATER TONIGHT THROUGH FRI NIGHT.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE FAR NW
CARIBBEAN. A SECOND UPPER RIDGE ANCHORED IN THE TROPICAL ATLC
COVERS MOST OF THE REMAINDER OF THE CARIBBEAN. BETWEEN THE TWO
UPPER RIDGES IS AN INDUCED UPPER TROUGH THAT EXTENDS FROM E CUBA
ACROSS THE CAYMAN ISLANDS TO OVER HONDURAS. THE TROPICAL ATLC
UPPER RIDGE IS ADVECTING UPPER LEVEL MOISTURE OVER THE S
CARIBBEAN WITH SCATTERED SHOWERS INLAND AND WITHIN 75 NM ALONG
THE COAST OF COLOMBIA AND VENEZUELA BETWEEN 67W-75W. ISOLATED
SHOWERS DOT THE N CARIBBEAN WITHIN 90/120 NM OF LINE FROM OVER
HISPANIOLA NEAR 19N70W TO 20N83W INCLUDING PORTIONS OF CUBA AND
JAMAICA. THIS IS LEAVING THE REMAINDER OF THE CARIBBEAN UNDER
MOSTLY CLEAR SKIES THIS EVENING. WEAK SURFACE RIDGE ACROSS THE W
AND CENTRAL ATLC WILL MAINTAIN MODERATE TO FRESH TRADE WINDS
ACROSS THE CARIBBEAN THROUGH FRI WITH FRESH TO STRONG WINDS IN
THE CENTRAL CARIBBEAN AND GULF OF HONDURAS. STRONG HIGH PRESSURE
IN THE NW ATLC WILL BUILD S ACROSS THE W ATLC TONIGHT AND FRI TO
STRENGTHEN WINDS FRI THROUGH SUN.

ATLANTIC OCEAN...
A BENIGN UPPER LEVEL PATTERN COVERS THE W ATLC THIS EVENING WHILE
A SURFACE RIDGE BUILDS S OVER THE W AND CENTRAL ATLC ANCHORED BY
A 1033 MB HIGH OFF THE CANADIAN MARITIMES. AN UPPER TROUGH IS IN
THE CENTRAL ATLC EXTENDING THROUGH 32N42W ALONG 26N50W TO 22N58W
SUPPORTING A COLD FRONT THAT EXTENDS THROUGH 32N39W TO 30N41W.
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN
75 NM E OF THE FRONT. THE REMAINDER OF THE ATLC IS UNDER THE
INFLUENCE OF WEAK SURFACE RIDGING. STRONG HIGH PRESSURE BUILDING
S FROM THE NW ATLC WILL PERSIST THROUGH FRI. A COLD FRONT WILL
ENTER THE W ATLC EARLY SAT MORNING STALLING LATE SAT/EARLY SUN
FROM 32N74W TO CENTRAL FLORIDA THEN DISSIPATING THE FIRST OF
NEXT WEEK.

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

$$
PAW

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