[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 27 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 2315 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO COASTAL LIBERIA
NEAR 5N9W TO 4N16W. THE ITCZ BEGINS FROM 4N16W AND CONTINUES
ALONG 3N29W 1S40W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 4N-6N BETWEEN 14W-17W. SCATTERED MODERATE/STRONG
CONVECTION IS FROM 1N-5N BETWEEN 30W-36W...AND FROM 3N-6N
BETWEEN 38W-43W.

...DISCUSSION...

GULF OF MEXICO...
MAINLY ZONAL WESTERLY FLOW ALOFT COVERS THE GULF OF MEXICO
AROUND A BROAD UPPER RIDGE COVERING THE CARIBBEAN AND THE SW
NORTH ATLC. THE UPPER RIDGE SUPPORTS A WEAK SURFACE RIDGE ACROSS
THE EASTERN GULF...WHICH IS HELPING PROVIDE FAIR WEATHER EAST OF
90W. AN APPROACHING UPPER TROUGH CURRENTLY OVER THE WESTERN
CONUS IS BEGINNING TO SUPPORT A FORMING FRONTAL SYSTEM ALONG THE
TEXAS COAST. AS OF 2100 UTC...A 1009 MB SURFACE LOW IS ON THE
TEXAS COAST NEAR 27N98W WITH A STATIONARY FRONT EXTENDING
THROUGH THE LOW CENTER HUGGING THE COASTLINE OF TEXAS. THE FRONT
WILL REMAIN STATIONARY FOR ABOUT 24 HOURS BEFORE MOVING INTO THE
GULF AS A COLD FRONT. ISOLATED SHOWERS ARE CURRENTLY NEAR THE
TEXAS COAST AND A FEW AREAS INLAND. WHILE WINDS ARE LIGHT ACROSS
THE EASTERN GULF...THEY INCREASE TO 20-25 KT OVER THE WESTERN
GULF AHEAD OF THE FRONT. THE SURFACE RIDGE IS EXPECTED TO SHIFT
EAST ALLOWING THE FRONTAL BOUNDARY ON THE TEXAS COAST TO MOVE
INTO THE GULF OF MEXICO OVER THE WEEKEND. SURFACE RIDGING WILL
RE-ESTABLISH OVER THE BASIN BY SUNDAY AND INTO THE FIRST PART OF
NEXT WEEK.

CARIBBEAN SEA...
AS OF 2100 UTC...THE COLD FRONT IN THE WEST ATLC CONTINUES INTO
THE NW CARIBBEAN AS A STATIONARY FRONT. THE AXIS CURRENTLY
EXTENDS FROM CENTRAL CUBA NEAR 22N80W TO HONDURAS AT 16N88W.
ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 150 NM EITHER
SIDE OF THE AXIS. TRADEWIND FLOW OF 15-20 KT DOMINATES THE
REMAINDER OF THE CARIBBEAN ALONG WITH MOSTLY CLEAR SKIES DUE TO
DRY AIR ALOFT AROUND A BROAD UPPER LEVEL RIDGE COVERING THE
BASIN. THE FRONT IS EXPECTED TO DISSIPATE WITH MOISTURE
REMAINING IN THE NW CARIBBEAN AND DRIFTING NW INTO THE SE GULF
OF MEXICO.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH OVER THE NW ATLC SUPPORTS A COLD FRONT THAT
ENTERS THE DISCUSSION AREA NEAR 32N68W TO THE CENTRAL BAHAMAS
NEAR 24N76W CONTINUING TO THE NW CARIBBEAN. POSSIBLE ISOLATED
SHOWERS ARE ALONG THE FRONT AXIS. DUE TO DRY AIR ALOFT ON EITHER
SIDE OF THE FRONT...FAIR CONDITIONS ARE NOTED ELSEWHERE ACROSS
THE WESTERN ATLC. A BROAD UPPER LEVEL RIDGE COVERING THE
CARIBBEAN EXTENDS INTO THE CENTRAL ATLC ALONG 54W SUPPORTING A
WEAK SURFACE RIDGE AROUND A 1021 MB HIGH NEAR 28N55W. FARTHER
EAST...A NEARLY CUT-OFF UPPER LEVEL LOW/TROUGH ALONG 41W
SUPPORTS A WEAK 1015 MB SURFACE LOW NEAR 28N42W. A SURFACE
TROUGH EXTENDS NORTHWARD FROM THE LOW TO 33N38W. A SECOND
SURFACE TROUGH WRAPS AROUND THE LOW CENTER CONTINUING TO THE SW
ALONG 18N43W 8N52W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE
NEAR THE LOW CENTER AND ALONG THE SURFACE TROUGH TO THE NORTH.
SIMILAR ACTIVITY IS ALSO TO THE EAST NORTH OF 24N BETWEEN
34W-39W. THE REMAINDER OF THE EASTERN ATLC IS DOMINATED BY
SURFACE RIDGING EXTENDING FROM A HIGH CENTER OVER PORTUGAL. THE
RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 18W.

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

$$
WALTON





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