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AXNT20 KNHC 200003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST FRI DEC 19 2014

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 2345 UTC.


...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH CROSSES THROUGH NORTHERN LIBERIA AND CONTINUES OVER THE EASTERN ATLANTIC TO NEAR 07N12W WHERE THE ITCZ BEGINS AND CONTINUES ALONG 05N26W TO 04N37W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 02N-07N E OF 35W.


...DISCUSSION...

GULF OF MEXICO...

MIDDLE- TO UPPER-LEVEL SW TO W FLOW CONTINUES TO MOVE ACROSS THE BASIN AND ADVECTS MOISTURE FROM THE ITCZ IN THE EPAC TO A GREAT PORTION OF GULF WATERS. A 1013 MB SURFACE LOW IS OVER SE TEXAS COASTAL WATERS NEAR 28N94W FROM WHICH A COLD FRONT EXTENDS SW TO SOUTHERN TEXAS NEAR 26N97W THEN CONTINUING OVER NORTHERN MEXICO. A STATIONARY FRONT EXTENDS EASTWARD FROM THE LOW ALONG 28N90W TO 28N85W. LOW-LEVEL MOISTURE CONVERGENCE ASSOCIATED WITH THE LOW AND ALONG THE STATIONARY FRONT ENHANCE ISOLATED SHOWERS N OF 26N E OF 94W AND FOG ELSEWHERE W OF THE LOW. A BROAD SURFACE RIDGE COVERING THE EASTERN U.S. BEING ANCHORED BY A 1028 MB HIGH OVER CENTRAL ILLINOIS IS PROVIDING RETURN FLOW OF 5-20 KT ACROSS THE BASIN AND ADVECT DRY COOL AIR TO SOUTHERN PORTIONS OF THE GULF WATERS. DRY AIR SUBSIDENCE FROM ALOFT OVER THE SOUTHERN GULF PROMOTES FAIR WEATHER AND MOSTLY CLEAR SKIES. HOWEVER...HIGH MOISTURE ASSOCIATED WITH AN AREA OF LOW PRESSURE OVER THE NW CARIBBEAN MOVING NW IS SUPPORTING CLOUDINESS AND ISOLATED SHOWERS ACROSS THE YUCATAN CHANNEL. OVER THE NEXT 24 HOURS...THE LOW WILL TRACK E-NE ALONG THE NORTHERN GULF COASTLINE WITH THE ASSOCIATED COLD FRONT EXTENDING SW TO EASTERN-CENTRAL MEXICO COASTAL WATERS. BY SUNDAY MORNING THE COLD FRONT IS FORECAST TO TRANSITION INTO A STATIONARY FRONT. A LOW WILL REFORM OVER THE NE BASIN BY SUNDAY MORNING WITH THE EASTERN PART OF THE FRONT BECOMING A WARM FRONT. SHOWERS ARE EXPECTED TO CONTINUE ACROSS THE NORTHERN GULF WATERS THROUGH THIS PERIOD.

CARIBBEAN SEA...

THE FOCUS ON THE CARIBBEAN IS A SURFACE 1011 MB LOW E OF BELIZE NEAR 18N87W WITH ASSOCIATED TROUGH EXTENDING ALONG 21N85W TO THE LOW TO 16N87W. DEEP LAYER MOISTURE IN THE FAR WESTERN BASIN ENHANCES SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS N OF 16N W OF 80W. A MOIST AIRMASS CONTINUES TO MOVES ACROSS THE FAR EASTERN CARIBBEAN BEING ADVECTED FROM AN AREA OF LOW PRESSURE IN THE CENTRAL ATLC. THIS MOISTURE MAY ENHANCE ISOLATED SHOWERS ACROSS THIS REGION OF THE BASIN...INCLUDING PUERTO RICO. FAIR WEATHER PREVAILS ELSEWHERE ACROSS THE BASIN BEING SUPPORTED BY DRY AIR SUBSIDENCE FROM ALOFT. OTHERWISE...TRADES OF 15 KT DOMINATE ACROSS THE BASIN...INCREASING TO 20 KT ALONG THE COAST OF COLOMBIA. THE LOW IS FORECAST TO MOVE NW INTO THE YUCATAN PENINSULA BY SATURDAY AFTERNOON BUT LINGERING MOISTURE ASSOCIATED WITH IT MAY CONTINUE TO ENHANCE SHOWERS OVER THE NW BASIN THROUGH EARLY SUNDAY.

HISPANIOLA...

A SHALLOW MOIST AIRMASS IS MOVING ACROSS THE ISLAND SUPPORTING CLOUDINESS AND POSSIBLE ISOLATED SHOWERS. NO DEEP CONVECTION IS EXPECTED DUE TO STRONG DRY AIR SUBSIDENCE FROM ALOFT. FAIR WEATHER IS FORECAST TO RESUME BY SATURDAY AFTERNOON.

ATLANTIC OCEAN...

A BROAD MIDDLE-LEVEL TROUGH OVER THE W ATLC CONTINUES TO SUPPORT A SURFACE PRE-FRONTAL TROUGH ALONG 33N53W SW TO 28N60W TO 26N69W. SCATTERED SHOWERS ARE N OF 26N BETWEEN 55W-75W.

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