[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232359
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SAT FEB 23 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
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM A 1006 MB LOW OVER GUINEA-BISSAU
IN AFRICA NEAR 12N15W TO 6N18W. THE ITCZ BEGINS AT 6N18W AND
CONTINUES ALONG 1N30W EQ36W 2S47W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS FROM 3N-5N BETWEEN 17W-24W...FROM 1N-4N
BETWEEN 27W-31W...AND FROM 2S-2N BETWEEN 33W-39W. SCATTERED
MODERATE CONVECTION IS ALSO NORTH OF THE AXIS FROM 2N-7N BETWEEN
42W-50W.

...DISCUSSION...

GULF OF MEXICO...
THE NORTHWEST HALF OF THE GULF OF MEXICO CONTINUES TO BE
IMPACTED BY A FRONTAL BOUNDARY. AS OF 2100 UTC...A STATIONARY
FRONT EXTENDS FROM THE FLORIDA PANHANDLE NEAR 31N85W TO 27N94W
20N96W. A PRE-FRONTAL TROUGH IS EAST OF THE FRONT IN THE NE GULF
ALONG 31N83W TO 29N87W. RADAR IMAGERY AND LIGHTNING DATA
INDICATE HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE BETWEEN
THE SURFACE TROUGH AND FRONT CONTINUING 80 NM NW OF THE FRONT.
SCATTERED SHOWERS ARE WITHIN 50 NM EITHER SIDE OF THE FRONTAL
BOUNDARY ELSEWHERE NORTH OF 25N. POSSIBLE ISOLATED SHOWERS ARE
SOUTH OF 25 NORTH NEAR THE FRONT AXIS. THE FRONT IS SUPPORTED BY
A SHORTWAVE UPPER TROUGH OVER ARKANSAS...WHICH IS EMBEDDED
WITHIN A LARGER SCALE UPPER TROUGH/LOW OVER THE GREAT LAKES
REGION. THE REMAINDER OF THE BASIN IS COVERED BY A BROAD UPPER
TROUGH WITH AXIS ALONG 74W. DRY AIR ALOFT COVERS THE AREA SE OF
THE FRONT...WHICH IS HELPING PROVIDE FAIR CONDITIONS AND WEAK
SURFACE RIDGING. SOUTHERLY WINDS OF 10-15 KT ARE PRESENT ACROSS
THIS AREA WITH SLIGHTLY STRONGER NORTHERLY FLOW WEST OF THE
FRONT. THE FRONT WILL REMAIN RELATIVELY STATIONARY FOR THE NEXT
6-12 HOURS BEFORE DRIFTING EAST WHILE THE PORTION IN THE SW GULF
LIFTS NORTH AS A WARM FRONT AHEAD OF THE NEXT STRONG FRONTAL
SYSTEM EXPECTED TO ENTER THE GULF ON MONDAY.

CARIBBEAN SEA...
FAIR CONDITIONS SPREAD ACROSS THE CARIBBEAN DUE TO DRY AIR ALOFT
COVERING THE BASIN AROUND A BROAD UPPER LEVEL RIDGE ALONG 74W.
WATER VAPOR IMAGERY ALSO INDICATES STRONG SUBSIDENCE IS ACROSS
THE CENTRAL CARIBBEAN. MOSTLY CLEAR SKIES ARE PRESENT WITH A FEW
LOW LEVEL CLOUDS AND POSSIBLE ISOLATED SHOWERS EMBEDDED WITHIN
THE TRADEWIND FLOW OF 15-20 KT. SHOWERS ARE MOST LIKELY NORTH OF
VENEZUELA IN THE SOUTHERN WINDWARD ISLANDS. DUE TO A STRONG
PRESSURE GRADIENT BETWEEN A HIGH PRESSURE CENTER TO THE NORTH
AND LOW PRESSURE OVER COLOMBIA...GALE FORCE WINDS ARE PRESENT
JUST OFF THE NORTHERN COAST OF COLOMBIA. THE WINDS ARE EXPECTED
TO DIMINISH BELOW GALE FORCE WITHIN THE NEXT 12-24 HOURS. LITTLE
CHANGE IS EXPECTED ELSEWHERE OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE DOMINATES THE WEST ATLC WITH AXIS ALONG
74W. IT SUPPORTS A SURFACE RIDGE ANCHORED BY A PAIR OF 1022 MB
HIGHS NEAR 30N66W AND 33N64W. A DEEP LAYERED TROUGH IN THE
CENTRAL ATLC ALONG 42W SUPPORTS A STORM-FORCE SURFACE LOW CENTER
WELL NORTH OF THE DISCUSSION AREA NEAR 41N44W. AN ASSOCIATED
COLD FRONT ENTERS THE AREA NEAR 32N38W CONTINUING ALONG 25N44W
21N55W. GALE FORCE WINDS ARE BOTH EAST AND WEST OF THE FRONT
NORTH OF 28N. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE UP TO
250 NM EAST OF THE FRONT NORTH OF 26N. THE REMAINDER OF THE EAST
ATLC IS COVERED BY SURFACE RIDGING AROUND A 1026 MB HIGH NEAR
38N18W. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE ALONG
23W. THE GALE FORCE WINDS ARE EXPECTED TO DROP BELOW GALE FORCE
WITHIN THE NEXT 12 HOURS.

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

$$
WALTON





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