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000
AXNT20 KNHC 210520
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE APR 21 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC.


...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLANTIC NEAR 11N15W TO 05N13W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 01N25W THEN S OF THE EQUATOR NEAR 37W. SCATTERED MODERATE CONVECTION IS FROM 03N TO S OF THE EQUATOR BETWEEN 17W- 38W.


...DISCUSSION...

GULF OF MEXICO...

A BROAD UPPER-LEVEL RIDGE ANCHORED IN THE EPAC EXTENDS E REACHING THE WESTERN HALF OF THE GULF. AN UPPER-LEVEL TROUGH COVERS THE E CONUS SUPPORTING A FRONTAL SYSTEM THAT PREVAILS ACROSS THE NORTHERN GULF. IT BEGINS AS A STATIONARY FRONT FROM 25N98W TO 26N92W THEN IT TRANSITIONS INTO A COLD FRONT THROUGH 30N87W. ISOLATED CONVECTION IS OBSERVED IN THE VICINITY OF THE FRONTS MAINLY N OF 28N. A SURFACE TROUGH IS AHEAD OF THE COLD FRONT FROM 25N90W TO 27N83W. ISOLATED CONVECTION IS ALONG THIS BOUNDARY. LIGHT TO GENTLE NE FLOW PREVAILS ACROSS THE BASIN W OF 90W WHILE A GENTLE NW FLOW IS OBSERVED IN SCATTEROMETER DATA AND CURRENT OBSERVATIONS E OF 90W AND N OF THE COLD FRONT. EXPECT OVER THE NEXT 24-48 HOURS FOR THE STATIONARY FRONT TO WEAKEN ACROSS THE NW GULF. THE COLD FRONT WILL CONTINUE MOVING SE ENHANCING CONVECTION. THE SURFACE TROUGH ACROSS THE SE GULF WILL DISSIPATE. A WEAK HIGH PRESSURE WILL BUILD IN THE WAKE OF THE COLD FRONT.

CARIBBEAN SEA...

THE UPPER-LEVEL RIDGE THAT EXTENDS FROM THE EPAC INTO THE GULF ALSO REACHES THE W CARIBBEAN. TO THE E OF THIS...AN UPPER-LEVEL TROUGH EXTENDS ITS AXIS FROM HISPANIOLA TO 10N83W. SATELLITE WATER VAPOR IMAGERY SHOWS STRONG SUBSIDENCE AND DRY STABLE AIR ACROSS THE CARIBBEAN IN THE AREA DOMINATED BY THE UPPER-LEVEL TROUGH. DESPITE THIS...LOW-LEVEL MOISTURE IS ALSO PRESENT ACROSS THE BASIN GENERATING ISOLATED CONVECTION. LIGHT TO GENTLE TRADES PREVAIL ACROSS THE BASIN EXCEPT N OF COLOMBIA FROM 12N-16N BETWEEN 69W-76W WHERE GENTLE TO MODERATE FLOW IS OBSERVED IN SCATTEROMETER DATA. THERE IS ALSO A SMALL AREA N OF HONDURAS MAINLY S OF 17N WHERE A MODERATE FLOW IS DEPICTED. EXPECT A SIMILAR WEATHER PATTERN OVER THE NEXT 24-48 HOURS.

HISPANIOLA...

CLEAR SKIES AND FAIR WEATHER PREVAILS ACROSS THE AREA OVERNIGHT. LOW-LEVEL MOISTURE COUPLED WITH THE EASTERLY TRADE WINDS WILL CONTINUE TO GENERATE ISOLATED CONVECTION ACROSS THE ISLAND MAINLY IN THE AFTERNOON OVER THE NEXT IN 24 HOURS.

ATLANTIC OCEAN...

A 1012 MB SURFACE LOW IS CENTERED OVER THE W ATLANTIC NEAR 30N78W. A SURFACE TROUGH EXTENDS FROM THE LOW TO 27N81W. A SQUALL LINE IS E OF THE LOW AND TROUGH EXTENDING FROM 30N77W TO 26N79W. SCATTERED MODERATE CONVECTION IS N OF 26N BETWEEN 71W- 77W. A FRONTAL SYSTEM CONTINUES ACROSS THE CENTRAL ATLANTIC...BEGINNING AS A STATIONARY FRONT FROM 28N57W TO 29N45W THEN TRANSITIONING INTO A COLD FRONT TO 31N40W. ISOLATED CONVECTION PREVAILS ALONG THE COLD FRONT MAINLY N OF 30N. A PAIR OF SURFACE HIGH PRESSURES CENTERED NEAR 24N48W AND 38N24W EXTEND ACROSS THE REMAINDER OF THE BASIN WITH FAIR WEATHER. EXPECT OVER THE NEXT 24-48 HOURS FOR A COLD FRONT TO REACH THE W ATLANTIC WITH CONVECTION. THE FRONTAL SYSTEM OVER THE CENTRAL ATLANTIC WILL WEAKEN.

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

$$

ERA

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