[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191745
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST THU DEC 19 2013

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 04N13W TO
04N24W TO 06N34W TO THE EQUATOR NEAR 49W. WHILE NO SIGNIFICANT
CONVECTION IS NOTED ALONG THE ITCZ AXIS...A SURFACE TROUGH
ANALYZED FROM 07N34W TO 16N31W REMAINS EMBEDDED WITHIN THE ITCZ
AXIS AND IS LARGELY A SURFACE REFLECTION OF A VIGOROUS MIDDLE TO
UPPER LEVEL LOW CENTERED NEAR 19N35W. LOW-LEVEL MOISTURE
CONVERGENCE ALONG THE SURFACE TROUGH IN TANDEM WITH MAXIMUM
MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING A LARGE AREA OF
CLOUDINESS AND ISOLATED MODERATE CONVECTION FROM 08N-24N BETWEEN
20W-35W.

...DISCUSSION...

GULF OF MEXICO...
WEAK UPPER LEVEL RIDGING IS NOTED ALOFT OVER THE GULF THIS
AFTERNOON THAT IS FURTHER SUPPORTING THE SURFACE RIDGE CURRENTLY
ANALYZED ACROSS THE BASIN. A 1028 MB HIGH IS CENTERED OFF THE
COAST OF THE CAROLINAS NEAR 34N78W THAT EXTENDS A RIDGE AXIS SW
TO 25N90W TO A 1022 MB HIGH CENTERED INLAND ACROSS EAST-CENTRAL
MEXICO NEAR 20N98W. SOUTH-SOUTHEAST WINDS PREVAIL ACROSS MOST OF
THE BASIN IN THE RANGE OF 10 TO 20 KT WITH THE POSSIBILITY OF 15
TO 25 KT OVER FAR NORTHWESTERN PORTIONS N OF 24N W OF 95W.
OTHERWISE...GENERALLY CLEAR SKIES DOMINATE WITH ONLY A FEW
ISOLATED SHOWERS ADVECTING NORTHWARD ACROSS THE NW GULF THIS
AFTERNOON. THE SOUTHERLY RETURN FLOW IS FORECAST TO INCREASE BY
EARLY SATURDAY AS A COMPLEX AREA OF LOW PRESSURE DEVELOPS ACROSS
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI RIVER VALLEY. THE NEXT
COLD FRONT IS EXPECTED TO EMERGE OFF THE TEXAS AND LOUISIANA
COASTS EARLY SUNDAY.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES A BROAD MIDDLE TO UPPER LEVEL
RIDGE OVER THE CARIBBEAN WITH THE AIRMASS REMAINING RELATIVELY
MORE MOIST ALOFT W OF 72W. OVERALL STABILITY FILTERS DOWN TO THE
SURFACE WHERE ONLY A FEW PASSING ISOLATED LOW-TOPPED SHOWERS ARE
NOTED ON SATELLITE IMAGERY OCCURRING ACROSS THE SE CARIBBEAN...
IN THE VICINITY OF THE MONA PASSAGE...AND ALONG THE CENTRAL
AMERICA COASTLINE. SLIGHTLY DEEPER CONVECTION IS OCCURRING S OF
11N IN THE SW CARIBBEAN DUE TO THE CLOSE PROXIMITY OF THE
MONSOON TROUGH AXIS. OTHERWISE...TRADES ARE EXPECTED TO PERSIST
IN THE RANGE OF 15 TO 25 KT THROUGH EARLY SATURDAY AND GRADUALLY
INCREASE OVER THE WEEKEND DUE TO A STRENGTHENED PRESSURE
GRADIENT BETWEEN HIGH PRESSURE ACROSS THE SW NORTH ATLC AND
LOWER PRESSURE ACROSS NORTHERN SOUTH AMERICA.

...HISPANIOLA...
CURRENTLY RELATIVELY DRY AIR AND STABLE CONDITIONS ALOFT PREVAIL
WITH SATELLITE IMAGERY INDICATING ONLY LOWER LEVEL CLOUDINESS
AND POSSIBLE ISOLATED SHOWERS OCCURRING TO THE WEST OF THE
ISLAND. THE OVERALL STABILITY WILL LIKELY LIMIT ANY SIGNIFICANT
CONVECTION...HOWEVER AN ISOLATED SHOWER CANNOT BE RULED OUT
DURING THE LATE AFTERNOON AND EARLY EVENING HOURS WITH PEAK
DAYTIME HEATING AND INSTABILITY OCCURRING NEAR THE SURFACE.
LOOKING AHEAD...A MOSTLY NORMAL PATTERN OF WINTER TIME TRADES IS
EXPECTED TO CONTINUE ACROSS THE ISLAND WITH WINDS INCREASING
SLIGHTLY INTO FRIDAY DUE TO A STRENGTHENING PRESSURE GRADIENT
ACROSS THE REGION. THE STRONG TRADES WILL PERSIST DURING THE
UPCOMING WEEKEND.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH AXIS EXTENDS OVER THE WESTERN
NORTH ATLC AND SUPPORTS A COLD FRONT INTO THE DISCUSSION AREA
NEAR 32N57W SW TO THE NW BAHAMAS NEAR 25N78W. AN OLDER REMNANT
FRONTAL BOUNDARY...NOW ANALYZED AS A SURFACE TROUGH IS NOTED SE
OF THE COLD FRONT FROM 30N58W SW TO THE CENTRAL BAHAMAS NEAR
23N76W. MOST OF THE LOWER LEVEL MOISTURE IS ASSOCIATED WITH THE
SURFACE TROUGH WITH ISOLATED SHOWERS OCCURRING WITHIN 120 NM
EITHER SIDE OF THE BOUNDARY. OTHERWISE...THE REMAINDER OF THE SW
NORTH ATLC NW OF THE COLD FRONT IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1028 MB HIGH CENTERED OFF THE
CAROLINA COAST NEAR 34N78W. THE REMAINDER OF THE CENTRAL AND
EASTERN ATLC IS ALSO UNDER THE INFLUENCE OF A BROAD SURFACE
RIDGE ANCHORED BY A 1036 MB HIGH CENTERED IN THE VICINITY OF THE
AZORES NEAR 38N26W.

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

$$
HUFFMAN


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