Tropical Weather Discussion
Issued by NWS

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000
AXNT20 KNHC 202356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON APR 20 2015

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 TROPICAL ATLC
NEAR 12N16W ALONG 7N13W TO 5N15W WHERE THE ITCZ BEGINS AND
CONTINUES ALONG 1N19W 1N25W THEN S OF THE EQUATOR NEAR 27W.
CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE
FROM 3N TO S OF THE EQUATOR BETWEEN 21W-35W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE ANCHORED IN THE E PACIFIC EXTENDS ACROSS
MEXICO AND THE YUCATAN PENINSULA TO W CUBA COVERING THE GULF S
OF 27N AND INTO THE NW CARIBBEAN. A STRONG UPPER TROUGH COVERS
THE N GULF AND ALL OF THE E CONUS AND THE CENTRAL PLAINS
SUPPORTING A COLD FRONT THAT ENTERS THE GULF NEAR MOBILE BAY
ALABAMA AND EXTENDS ALONG 27N92W TO INLAND OVER MEXICO NEAR THE
RIO GRANDE. A SURFACE TROUGH PRECEDES THE FRONT EXTENDING FROM
CEDAR KEY FLORIDA ALONG 26N89W TO 25N97W. SCATTERED TO NUMEROUS
SHOWERS WITH EMBEDDED CLUSTERS OF NUMEROUS THUNDERSTORMS ARE
FROM 23N-26N BETWEEN 93W-97W AND FROM 23N-25N BETWEEN 85W-90W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 90 NM ALONG
THE FLORIDA COAST N OF FORT MYERS INTO THE BIG BEND AREA.
ISOLATED SHOWERS DOT THE REMAINDER OF THE GULF N OF 23N. A WEAK
SURFACE TROUGH IS IN THE SW GULF FROM 22N06W TO 19N94W. FRONT
WILL MOVE E THROUGH THE N GULF TONIGHT AND STALL ALONG 26N ON
TUE THEN DISSIPATE WED. PRE-FRONTAL TROF WILL DISSIPATE OVER THE
SE GULF TONIGHT. WEAK HIGH PRESSURE WILL BUILD IN THE WAKE OF
THE FRONT AND PREVAIL THROUGH THU.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE S GULF OF MEXICO COVERS THE NW
CARIBBEAN WHILE A SECOND UPPER RIDGE ANCHORED IN THE TROPICS
EXTEND ACROSS SOUTH AMERICA COVERING THE SE CARIBBEAN. THIS IS
INDUCING A WEAK UPPER TROUGH THAT EXTENDS FROM HISPANIOLA TO THE
COSTA RICA/NICARAGUA BORDER. SATELLITE WATER VAPOR IMAGERY SHOWS
STRONG SUBSIDENCE AND DRY STABLE AIR ACROSS THE CARIBBEAN IN THE
AREA DOMINATED BY THE UPPER TROUGH. AFTERNOON SHOWERS/ISOLATED
THUNDERSTORMS ARE ACROSS PUERTO RICO AND HISPANIOLA AND OVER A
SMALL PORTION OF JAMAICA AND CENTRAL CUBA. THIS IS LEAVING THE
REMAINDER OF THE CARIBBEAN UNDER CLEAR SKIES THIS EVENING. FRESH
TO LOCALLY STRONG TRADE WINDS WILL DEVELOP EACH NIGHT OFFSHORE
OF THE GULF OF HONDURAS AS WELL AS ALONG THE COAST OF COLOMBIA
THROUGH THU.

HISPANIOLA...
SCATTERED AFTERNOON SHOWERS/ISOLATED THUNDERSTORMS HAVE
DEVELOPED ACROSS THE ISLAND THIS EVENING. LOW LEVEL MOISTURE
COUPLED WITH THE EASTERLY TRADE WINDS WILL CONTINUE THE PATTERN
OF ISOLATED AFTERNOON SHOWERS WITH POSSIBLE THUNDERSTORMS
THROUGH THU.

ATLANTIC OCEAN...
A MESOSCALE 1011 MB LOW IS LOCATED OVER FLORIDA NEAR ORLANDO
WITH A SURFACE TROUGH EXTENDING S JUST E OF LAKE OKEECHOBEE TO
THE COAST OF FLORIDA BAY. AN UPPER RIDGE OVER THE W ATLC AND
INTO THE CENTRAL ATLC EXTENDS FROM PUERTO RICO NORTHWARD.
SCATTERED TO HEAVY SHOWERS WITH SCATTERED THUNDERSTORMS ARE N OF
LINE FROM FORT LAUDERDALE FLORIDA TO BEYOND 32N72W. AN UPPER
TROUGH IN THE N/CENTRAL ATLC IS SUPPORTING A COLD FRONT THAT
ENTERS THE AREA NEAR 32N41W AND EXTENDS ALONG 28N49W TO 28N59W
WHERE IT BECOMES STATIONARY ALONG 28N62W TO 31N66W. SCATTERED
SHOWERS ARE WITHIN 120 NM SE OF THE FRONT E OF 48W. A BROAD
SURFACE RIDGE COVERS THE ATLC ANCHORED BY 1026 MB HIGH OVER THE
AZORES AND A RIDGE AXIS ALONG 32N29W 26N38W TO A WEAKER 1020 MB
HIGH NEAR 24N49W. THE GULF OF MEXICO COLD FRONT WILL MOVE INTO
NW WATERS TONIGHT AND REACH FROM 31N74W TO CENTRAL FLORIDA LATE
TUE FROM BERMUDA TO THE NW BAHAMAS EARLY WED THEN STALL AND
DISSIPATE ALONG 25N E OF 75W ON THU.

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

$$
PAW



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