[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 162317
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 16 2012

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
2230 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH IS ALONG AFRICA ROUGHLY FROM 6N TO 8N WITH
NO PORTION OVER WATER. THE INTERTROPICAL CONVERGENCE AXIS
EXTENDS FROM THE COAST OF AFRICA AT SIERRA LEONE NEAR 8N13W TO
6N24W TO 3N40W TO THE COAST OF FRENCH GUIANA NEAR THE EQUATOR
AND 48W. SCATTERED MODERATE TO STRONG CONVECTION IS LOCATED
WITHIN 60-90 NM EITHER SIDE OF A LINE FROM 5N23W TO 7N32W TO
8N44W. SCATTERED MODERATE IS WITHIN AN AREA BOUNDED BY 2N38W TO
6N41W TO 3N44W TO 1N40W TO 2N38W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS POSITIONED
OFF OF THE PACIFIC COAST OF MEXICO NEAR 14N102W WITH AN UPPER
RIDGE EXTENDING NE ACROSS THE SE GULF TO THE U.S. MID-ATLANTIC
REGION. STRONG UPPER LEVEL WESTERLY WINDS OVER THE ENTIRE GULF.
SATELLITE DERIVED WINDS INDICATE THE STRONGEST WINDS N OF 28N
WITH SPEEDS AS HIGH AS 90-100 KNOTS.

A SURFACE COLD FRONT IS LOCATED OVER E TEXAS REACHING FROM
TEXARKANA TO THE TEXAS BIG BEND. SCATTERED SHOWERS AND
THUNDERSTORMS LOCATED ALONG MOST OF THE TEXAS COASTAL PLAINS
APPROACHING THE COASTAL WATERS AS THE FRONT CONTINUES EASTWARD.
THE FRONT WILL MOVE FAIRLY RAPIDLY ACROSS THE GULF REACHING FROM
SE LOUISIANA TO THE SW GULF MON...THEN WILL WEAKEN AS IT EXTENDS
FROM TAMPA FLORIDA TO THE E BAY OF CAMPECHE TUE...EXITING THE SE
GULF TUE NIGHT. LOOKING AHEAD...A STRONGER COLD FRONT WILL REACH
THE TEXAS COAST THU...MOVING ACROSS THE GULF BY THE END OF THE
WEEK INTO NEXT WEEKEND.

CARIBBEAN SEA...
MODERATE NORTHERLY WINDS ALOFT COVER MOST OF THE WESTERN HALF OF
THE CARIBBEAN AROUND THE UPPER RIDGE WHICH EXTENDS OVER THE SE
GULF OF MEXICO MENTIONED IN THE SECTION ABOVE. THE LATEST WATER
VAPOR SATELLITE IMAGERY SHOWS STRONG SUBSIDENCE AND VERY DRY AIR
OVER THE ENTIRE BASIN. THE SOUTHERN END OF A MIDDLE TO UPPER
LEVEL TROUGH EXTENDS FROM THE W CENTRAL ATLANTIC TO OVER PUERTO
RICO TO THE SW CARIBBEAN.

A WEAK AND ILL-DEFINED SURFACE TROUGH IS LOCATED ALONG 77W FROM
JAMAICA TO W OF THE COAST OF COLOMBIA. ISOLATED SHOWERS ARE
OCCURRING NEAR THE TROUGH AXIS. THIS TROUGH IS MOVING W-NW AT
10-15 KNOTS AND IT MAY DISSIPATE WITHIN THE NEXT 48 HOURS.

ATLANTIC OCEAN...
OVER THE WESTERN ATLANTIC...NORTHWESTERLY WINDS ALOFT HAVE
SPEEDS IN THE 45-60 KNOT RANGE. THESE WINDS ARE OCCURRING AROUND
THE PERIPHERY OF AN UPPER LEVEL RIDGE THAT EXTENDS TO THE U.S.
MID-ATLANTIC REGION FROM THE SE GULF OF MEXICO. THE REMAINDER OF
THE W CENTRAL ATLANTIC IS DOMINATED BY A MIDDLE TO UPPER LEVEL
TROUGH WITH THE AXIS EXTENDING THROUGH 32N55W TO PUERTO RICO.
THE TROUGH WILL MOVE ABOUT 20 KNOTS TO THE E OVER THE NEXT TWO
DAYS. MODERATE TO STRONG SOUTHWESTERLIES ALOFT ARE LOCATED UP TO
25 DEGREES E OF THIS UPPER TROUGH AXIS. BROAD RIDGING EXTENDS
ACROSS THE MAJORITY OF THE EASTERN ATLANTIC EXTENDING FROM AN
ANTICYCLONIC CIRCULATION OVER THE ITCZ NEAR 8N47W NE TOWARD
PORTUGAL.

AT THE SURFACE...A 1013 MB LOW IS CENTERED NEAR 21N51W AND IS
FORECAST TO DISSIPATE OVER THE NEXT 24 HOURS WHILE MOVING TO THE
NE. A TROUGH EXTENDS FROM 18N56W TO THE LOW TO THE NE THROUGH
32N42W AND BEYOND. SCATTERED MODERATE CONVECTION IS WITHIN
90-180 NM OF THE TROUGH AXIS N OF 26N. ANOTHER SURFACE TROUGH IS
E OF THE CARIBBEAN EXTENDING FROM 16N52W TO 12N53W TO 6N53W
MOVING W. ASSOCIATED SCATTERED MODERATE CONVECTION IS FROM 8N TO
12N. 1027 MB HIGH PRES IS LOCATED NEAR 33N20W WITH A RIDGE AXIS
EXTENDING SW ACROSS THE E ATLANTIC TO 18N44W.

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

$$
LEWITSKY




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