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Atlantic Tropical Discussion

Active Tropical Systems Basin Outlooks Satellite
Atlantic Basin Tropical Discussion
 
121 
AXNT20 KNHC 190004
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL 
705 PM EST THU DEC 18 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 THE AFRICAN COAST NEAR 08N13W AND 
CONTINUES OVER THE EASTERN ATLANTIC TO NEAR 07N15W WHERE THE 
ITCZ BEGINS AND CONTINUES ALONG 04N32W TO THE NORTHERN COAST OF 
BRAZIL NEAR 03N51W. ISOLATED MODERATE CONVECTION IS FROM 02N-07N 
E OF 16W AND FROM 01N-06N W OF 40W. SCATTERED MODERATE 
CONVECTION IS FROM 01N-07N BETWEEN 20W AND 40W. 
 
...DISCUSSION...

GULF OF MEXICO... 

MIDDLE- TO UPPER-LEVEL SW TO W FLOW MOVES ACROSS THE BASIN AND 
CONTINUES TO ADVECT MOISTURE FROM THE ITCZ IN THE EPAC TO THE 
NORTHERN GULF WATERS. A 1014 MB SURFACE LOW IS OVER SOUTHERN 
TEXAS FROM WHICH A STATIONARY FRONT EXTENDS ALONG 29N95W SE TO 
27N91W TO 25N86W. LOW-LEVEL MOISTURE CONVERGENCE ASSOCIATED WITH 
THE LOW ALONG WITH MOISTURE ALOFT SUPPORT SCATTERED MODERATE 
CONVECTION AND ISOLATED TSTMS N OF 26N W OF 90W. A BROAD SURFACE 
RIDGE COVERING THE CENTRAL AND EASTERN U.S. BEING ANCHORED BY A 
1028 MB HIGH OVER CENTRAL ILLINOIS EXTENDS SE INTO THE NE GULF 
WATERS. RETURN FLOW OF 5-15 KT ASSOCIATED WITH THE RIDGE 
CONTINUES TO ADVECT DRY COOL AIR ACROSS THE REMAINDER 
BASIN...WHICH ALONG DRY AIR SUBSIDENCE FROM ALOFT PROMOTE FAIR 
WEATHER AND CLEAR SKIES. OVER THE NEXT 48 HOURS...THE LOW OVER 
SOUTHERN TEXAS WILL TRACK E-NE ALONG THE NORTHERN GULF COASTLINE 
WITH AN ASSOCIATED COLD FRONT TO EXTEND FROM SOUTHERN 
MISSISSIPPI SW TO EASTERN-CENTRAL MEXICO COASTAL WATERS.

CARIBBEAN SEA...   

THE FOCUS ON THE CARIBBEAN REMAINS TO BE A SURFACE TROUGH OVER 
THE WESTERN BASIN EXTENDING FROM 20N84W TO 15N83W TO 11N82W. A 
PLUME OF HIGH LOW-LEVEL MOISTURE EXTENDS FROM THE NW BASIN NEAR 
20N85W SE TO 13N67W...WHICH CONVERGES ALONG THE NORTHERN TROUGH 
TO ENHANCE SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS FROM 
15N-21N BETWEEN 80W-86W. ANOTHER PLUME OF MOISTURE IS ENTERING 
THE EASTERN CARIBBEAN BEING ADVECTED FROM AN AREA OF LOW 
PRESSURE IN THE CENTRAL ATLC. THIS MOISTURE IS ENHANCING 
SCATTERED SHOWERS ACROSS THE NE CARIBBEAN...INCLUDING PUERTO 
RICO AND COASTAL WATERS. FAIR WEATHER PREVAILS ELSEWHERE ACROSS 
THE BASIN BEING SUPPORTED BY DRY AIR SUBSIDENCE FROM ALOFT. 
OTHERWISE...TRADES OF 15 KT DOMINATE ACROSS THE BASIN. THE 
SURFACE TROUGH IS FORECAST TO DISSIPATE BY FRIDAY 
MORNING...HOWEVER LINGERING MOISTURE ASSOCIATED WITH IT MAY 
ENHANCE ISOLATED SHOWERS OVER THE NW BASIN THROUGH LATE SATURDAY.
                             
HISPANIOLA...                   

BOTH TOTAL PRECIPITABLE WATER AND WATER VAPOR IMAGERY SHOW DRY 
AIR ACROSS THE ISLAND WHICH HAVE STABILIZED THE ENVIRONMENT AND 
IS PROMOTING FAIR WEATHER CONDITIONS. FAIR WEATHER IS FORECAST 
TO CONTINUE THROUGH FRIDAY MORNING...THEN A MOIST AIRMASS MOVES 
ACROSS THE ISLAND TO ENHANCE SHOWERS THROUGH SATURDAY AFTERNOON.

ATLANTIC OCEAN...   

A CYCLONIC CIRCULATION ALOFT OVER THE NW ATLC CONTINUES TO 
SUPPORT A LOW PRESSURE SYSTEM FROM WHICH A COLD FRONT EXTENDS 
AND ENTER THE AREA OF DISCUSSION ALONG 30N62W SW TO 28N67W TO 
26N74W. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM EITHER 
SIDE OF THE FRONT. SE OF THE FRONT...A 1019 MB HIGH IS NEAR 
26N64W WHICH IS FORECAST TO REMAIN STATIONARY WITHIN THE NEXT 24 
HOURS. OVER THE CENTRAL ATLC...A MIDDLE-LEVEL CYCLONE SUPPORTS A 
SURFACE LOW OF 1014 MB NEAR 24N46W FROM WHICH A COLD FRONT 
EXTENDS ALONG 22N45W TO 20N47W. A STATIONARY FRONT EXTENDS FROM 
THE LOW NORTHWARD ALONG 28N44W TO 32N42W TO 42N30W. SCATTERED 
MODERATE CONVECTION AND ISOLATED TSTMS ARE N OF 21N BETWEEN 36W-
47W. OTHERWISE...SURFACE RIDGING PREVAILS OVER THE EASTERN 
BASIN. OVER THE NEXT 48 HOURS THE LOW OVER THE CENTRAL ATLANTIC 
WILL MOVE NW WHILE THE FRONTS ASSOCIATED WITH THE LOW DISSIPATE. 
CONVECTION WILL CONTINUE IN THE VICINITY OF THE LOW. A COLD 
FRONT WILL EXIT THE SE CONUS AND WILL ENTER THE SW N ATLC.
 
FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

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NR