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000
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

$$ NR

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