[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211733
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SAT DEC 21 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
1700 UTC.

...SPECIAL FEATURES...
GALE FORCE WINDS CONTINUE ACROSS A SMALL PORTION OF THE SW
CARIBBEAN SEA...NORTH OF THE COAST OF COLOMBIA...DUE TO STRONG
PRESSURE GRADIENT INDUCED BETWEEN A STRONG WEST ATLANTIC RIDGE
CENTERED ON A 1033 MB HIGH NE OF BERMUDA NEAR 35N54W...AND A
BROAD AREA OF LOW PRES NEAR 1008 MB ACROSS NORTHERN COLOMBIA.
OVERNIGHT AND MORNING ASCAT PASSES HAVE SHOWN MINIMAL GALES
OCCURRING WITHIN 100 NM OF THE COAST OF COLOMBIA...EMBEDDED IN A
BROADER AREA OF 25-30 KT TRADEWINDS OCCURRING SOUTH OF 14N OFF
THE COAST OF COLOMBIA. GALE FORCE WINDS IN THE AREA ARE EXPECTED
TO PERSIST UNTIL SUN MORNING.

A STRONG COLD FRONT IS MOVING ACROSS W TEXAS THIS MORNING...AND
IS FORECAST TO MOVE INTO THE NW GULF OF MEXICO COASTAL WATERS
THIS EVENING AND REACH FROM NEAR THE MOUTH OF THE MISSISSIPPI
RIVER TO TAMPICO MEXICO SUNDAY AFTERNOON AND THEN REACH FROM THE
FLORIDA PANHANDLE TO CENTRAL BAY OF CAMPECHE LATE MONDAY. STRONG
HIGH PRES AND COLD AIR WILL BEGIN TO BUILD S AND SE BEHIND THE
FRONT LATE SUN AND MONDAY...WITH STRONG NORTHERLY WINDS ACROSS
NW AND W PORTIONS EXPECTED TO INCREASE TO GALE FORCE ACROSS SW
PORTIONS BY MONDAY MORNING.

SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS
MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS ON BOTH OF THESE GALE
EVENTS.

...ITCZ/MONSOON TROUGH...
THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM THE AFRICAN
COAST NEAR 6N10W TO 4.5N27W TO THE COAST OF SOUTH AMERICA NEAR
3.5N52W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS
OCCURRING WITHIN 60 NM EITHER SIDE OF ITCZ BETWEEN 17W AND
24W.

...DISCUSSION...

GULF OF MEXICO...
A STRONG WEST ATLANTIC RIDGE CONTINUES TODAY...EXTENDING FROM A
1033 MB HIGH CENTERED NE OF BERMUDA...WEST SOUTHWESTWARD ACROSS
THE NORTHERN GULF. A COLD FRONTAL SYSTEM AND AN ASSOCIATED
DEEPENING LOW PRESSURE SYSTEM MOVING ACROSS WEST TEXAS THIS
MORNING AND COMBINING WITH THE ATLANTIC RIDGE TO PRODUCE FRESH
TO STRONG S TO SE WINDS ACROSS THE MAJORITY OF THE BASIN.
MOISTURE EMBEDDED IN THIS SOUTHERLY FLOW IS CONVERGING ACROSS
NORTHWEST PORTIONS AND COOLER WATERS TO PRODUCE BROKEN TO
OVERCAST LOW AND MIDDLE CLOUDS. NUMEROUS OIL RIGS AND COASTAL
OBS ACROSS COASTAL TEXAS AND SW LOUISIANA WERE REPORTING
VISIBILITIES 2 TO 4 NM IN FOG AND DRIZZLE.  ADDITIONAL PATCHES
OF LOW CLOUDS WERE NOTED OVER THE NE GULF NEAR THE FLORIDA BIG
BEND. OTHERWISE MOSTLY CLEAR SKIES PREVAIL. IN THE UPPER
LEVELS...RIDGE AXIS EXTENDS FROM AN ANTICYCLONE OVER COLOMBIA
NORTHWARD ALONG 80W. SOUTHWESTERLY FLOW ON THE BACKSIDE OF THE
RIDGE AND WELL E OF A SHARP UPPER LEVEL TROUGH OVER EASTERN NEW
MEXICO AND WEST TEXAS IS PROVIDING FAVORABLE DYNAMICS ALOFT FOR
VERY INCREASING CONVECTION ACROSS EASTERN TEXAS...AHEAD OF THE
FRONT. THE COLD FRONT IS FORECAST TO MOVE OFF THE TEXAS COAST
LATE THIS AFTERNOON--EARLY EVENING WITH A MODEST WIND SHIFT...
WITH A REINFORCING STRONG NORTHERLY SURGE SLATED TO MOVE OFF
LATE SUN ACCOMPANIED BY GALES ACROSS SW PORTIONS
MONDAY MORNING.

CARIBBEAN SEA...
AS MENTIONED ABOVE...THE STRONG ATLANTIC RIDGE AND RESULTANT
PRESSURE GRADIENT IS PRODUCING FRESH TO STRONG TRADEWINDS ACROSS
THE BASIN EAST OF 80W...WHILE MODERATE SOUTHEASTERLY FLOW IS
OPENING UP ACROSS NW PORTIONS...AND FLOWING INTO THE GULF OF
MEXICO. DRY AND STABLE CONDITIONS ALOFT GENERALLY PREVAIL ACROSS
THE BASIN...WITH MODEST LLVL MOISTURE CONVERGING ACROSS CENTRAL
PORTIONS RESULTING IN ISOLATED TO SCATTERED FAST MOVING SHOWERS
WITH LITTLE VERTICAL EXTENT. SIMILAR SHOWERS WERE NOTED ACROSS
THE GULF OF HONDURAS...BELIZE... HONDURAS...AND NICARAGUA.
STABLE AND BREEZY CONDITIONS ARE EXPECTED TO PERSIST THROUGH THE
WEEKEND.


...HISPANIOLA...
SCATTERED LOW TOPPED SHOWERS ARE ACROSS THE MONA PASSAGE AND
ATLANTIC COASTAL WATERS OF PUERTO RICO AND MOVING RAPIDLY INTO E
PORTIONS OF THE DOMINICAN REPUBLIC THIS MORNING...EMBEDDED IN
MODERATE TO FRESH TRADEWIND FLOW. GENERALLY STABLE CONDITIONS
ARE EXPECTED THROUGH THE WEEKEND AS STRONG UPPER LEVELS
SUBSIDENCE PREVAILS. THE STRONG SUBSIDENCE IS REFLECTED IN VERY
DRY AIR ABOVE 700 MB IN THE 12Z SAN JUAN RAOB.

ATLANTIC OCEAN...
THE STRONG ATLANTIC RIDGE CENTERED ON A 1033 MB HIGH NEAR 35N54W
IS PRODUCING FRESH TO STRONG ENE TRADEWINDS BETWEEN 45W AND
70W...AND CONTINUES WWD THROUGH THE SOUTHEAST BAHAMAS.
OTHERWISE...FAIR WEATHER PREVAILS OVER THE BAHAMAS AND WESTERN
ATLANTIC IN LIGHT TO MODERATE SOUTHEAST WINDS. A SURFACE TROUGH
CENTERED OVER THE CENTRAL TROPICAL ATLANTIC EXTENDS FROM 26N46W
TO 10N45W. SCATTERED LOW TOPPED SHOWERS ARE WITHIN 120 NM EITHER
SIDE OF THE TROUGH AXIS...EXCEPT FROM 23N TO 27N WHERE SCATTERED
MODERATE TSTORMS ARE OCCURRING DUE TO THE INTERACTION OF THE
ENHANCED LLVL WINDS AND A STATIONARY UPPER TROUGH. ANOTHER
SURFACE TROUGH WAS NOTED FROM 31N34W TO 22N37W WITH SIMILAR
SHOWER ACTIVITY NOTED. A LARGE MID TO UPPER LEVEL LOW IS
CENTERED OVER THE E ATLANTIC NEAR 25N28W AND HAS BEGUN TO SHIFT
NE AND LIFT OUT. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WERE OCCURRING E OF THE LOW...FROM 23N-32N BETWEEN 20W-31W. THE
WESTERN MOST TROUGH IS FORECAST TO SHIFT GRADUALLY W DURING THE
NEXT FEW DAYS AND REACH 60W BY LATE MONDAY...WHILE THE RIDGE
SHIFTS SLIGHTLY E. THIS WILL RESULT IN WINDS GRADUALLY
DIMINISHING W AND NW OF THE TROUGH...AND REMAIN FRESH TO STRONG
N AND E OF THE TROUGH.

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

$$
STRIPLING


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