[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132335
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED FEB 13 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF LIBERIA NEAR 6N10W
TO 3N14W WHERE IT TRANSITIONS INTO ITCZ AND CONTINUES ALONG
1N27W EQ37W 2S41W. SCATTERED MODERATE/STRONG CONVECTION IS FROM
3N-6N BETWEEN 9W-17W...FROM 1N-4N BETWEEN 20W-32W...AND FROM
1S-2N BETWEEN 32W-46W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT BISECTS THE GULF OF MEXICO CURRENTLY EXTENDING FROM
NE FLORIDA AT 31N81W TOWARDS THE SW GULF ALONG 26N88W 22N95W
20N97W 23N101W...AS OF 2100 UTC. A LINE OF SHOWERS/THUNDERSTORMS
IS ABOUT 150 NM AHEAD OF THE FRONT WHILE A SWATH OF WIDESPREAD
SHOWERS EXTENDS 90 NM TO 190 NM BEHIND...OR WEST OF THE FRONT.
NW WINDS UP TO ABOUT 15-20 KT ARE IMMEDIATELY BEHIND THE FRONT
ACROSS THE NORTHERN GULF...AND MAY REACH UP TO 30 KT BEHIND THE
AXIS IN THE SW GULF AS INDICATED BY AN EARLIER ASCAT PASS. SOME
OF THESE STRONGER WINDS ARE RESULTING FROM THE INCREASING
PRESSURE GRADIENT OVER THE WESTERN GULF AS HIGH PRESSURE BUILDS
BEHIND THE FRONT. ALOFT...AN ELONGATED UPPER TROUGH EXTENDING
FROM THE GREAT LAKES REGION TO WESTERN TEXAS SUPPORTS THE
FRONTAL BOUNDARY...WHILE AN UPPER LEVEL RIDGE COVERS THE AREA TO
THE SOUTH AND EAST. THIS PATTERN IS PROVIDING MAINLY
SOUTHWESTERLY FLOW ALOFT ACROSS THE GULF. DRY AIR CONTINUES TO
COVER THE SE GULF WHERE MOSTLY CLEAR SKIES ARE STILL OBSERVED.
THE FRONT IS EXPECTED TO CONTINUE MOVING SE ACROSS THE BASIN
THROUGH THE NEXT 24 HOURS. SHOWERS ARE LIKELY NEAR THE AXIS WITH
THUNDERSTORMS POSSIBLE. SURFACE RIDGING WILL CONTINUE TO BUILD
IN BEHIND THE FRONT.

CARIBBEAN SEA...
DRY AIR ALOFT COVERS THE CARIBBEAN AROUND A BROAD UPPER RIDGE
COVERING THE MAJORITY OF THE BASIN...AND AROUND AN UPPER LEVEL
TROUGH IN THE CENTRAL ATLC EXTENDING TO THE FAR NORTHEASTERN
CARIBBEAN. STRONG SUBSIDENCE IS ALSO NOTED IN WATER VAPOR
IMAGERY OVER THE EASTERN AND CENTRAL CARIBBEAN. THE DRY AIR AND
SUBSIDENCE ALOFT IS HELPING PROVIDE FAIR CONDITIONS ACROSS THE
BASIN WITH ONLY A FEW AREAS OF LOW LEVEL MOISTURE AND ISOLATED
SHOWERS. THESE AREAS OF LOW MOISTURE ARE MAINLY FROM 15N-17N
BETWEEN 69W-79W...AND FROM 15N-20N BETWEEN 82W-84W. MOSTLY 15-20
KT TRADEWIND FLOW DOMINATES WITH A SMALL AREA OF 25 KT WINDS
NEAR THE COAST OF COLOMBIA. EXPECT LITTLE CHANGE OVER THE NEXT
24 HOURS. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. BEYOND
THAT TIME...MOISTURE ASSOCIATED WITH THE COLD FRONT IN THE GULF
WILL LIKELY REACH THE FAR NW CARIBBEAN.

ATLANTIC OCEAN...
UPPER LEVEL RIDGING COVERS THE SW NORTH ATLC EXTENDING FROM THE
CARIBBEAN SUPPORTING SURFACE RIDGING AROUND A 1022 MB HIGH
CENTERED NEAR 28N50W. A FEW SHOWERS/THUNDERSTORMS AHEAD OF THE
COLD FRONT IN THE GULF ARE BEGINNING TO IMPACT THE FAR NW CORNER
OF THE DISCUSSION AREA. ACROSS THE CENTRAL ATLC...AN UPPER LEVEL
TROUGH IS APPROACHING THE AZORES ISLANDS ALONG 30W WITH AXIS
CONTINUING INTO THE CENTRAL TROPICAL ATLC AND TO THE FAR EASTERN
CARIBBEAN. THE UPPER TROUGH SUPPORTS A STATIONARY FRONT THAT
ENTERS THE DISCUSSION AREA NEAR 32N32W AND CONTINUES ALONG
25N42W 20N56W. POSSIBLE ISOLATED SHOWERS ARE ALONG THE AXIS. THE
FAR EASTERN ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1029
MB HIGH EAST OF THE AZORES NEAR 40N16W. THE RIDGE IS SUPPORTED
BY AN UPPER LEVEL RIDGE COVERING THE EASTERN ATLC ALONG 14W.

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

$$
WALTON





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