[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 300004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON AUG 29 2011

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
2345 UTC.

...SPECIAL FEATURE...

T.D. TWELVE IS CENTERED NEAR 10.2N 28.4W AS OF 29/2100 UTC...OR
ABOUT 360 NM SW OF THE SOUTHERNMOST CAPE VERDE ISLANDS MOVING W
AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE
THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADER
MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS MOSTLY W OF
THE CENTER FROM 8N-14N BETWEEN 29W-35W. ENVIRONMENTAL CONDITIONS
ARE CONDUCIVE FOR GRADUAL INTENSIFICATION OF THIS SYSTEM OVER
THE NEXT COUPLE OF DAYS.

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

THE MONSOON TROUGH IS ANALYZED ACROSS AFRICA AND BARELY ENTERS
THE E TROPICAL ATLC THROUGH THE COAST OF MAURITANIA NEAR 19N16W
TO 18N18W. THE BROAD CYCLONIC WIND FIELD ASSOCIATED TO T.D.
TWELVE HAS DISRUPTED THE OCEANIC MONSOON TROUGH...ONLY ALLOWING
A SMALL PORTION OF ITCZ TO REDEVELOPED FROM 10N45W TO 10N58W.
ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE ITCZ AXIS
BETWEEN 50W AND 56W.  THE MONSOON TROUGH FROM THE NORTHEAST
PACIFIC CURRENTLY EXTENDS ACROSS CENTRAL AMERICA AND ENTERS THE
CARIBBEAN NEAR 11N83W TO THE COAST OF COLUMBIA AT 09N76W.
MODERATE CONVECTION IS OCCURRING WITHIN 120 NM OF THE TROUGH
AXIS.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A DISSIPATING STATIONARY FRONT IS DRAPED ACROSS
THE NORTH CENTRAL GULF OF MEXICO.  WINDS ARE LIGHT AND VARIABLE
OVER THE CENTRAL AND WESTERN PORTIONS OF THE GULF THIS
EVENING...WHILE THE EASTERN GULF SHOWS SW WINDS OF 10-15 KT ON
THE EQUATORWARD SIDE OF THE FRONT.  OVER THE YUCATAN OF MEXICO
AND EXTENDING NORTHWARD JUST SLIGHTLY INTO THE SOUTHERN GULF OF
MEXICO IS A SURFACE TROUGH.  SCATTERED MODERATE CONVECTION IS
OCCURRING OVER THE STRAITS OF FLORIDA...SOUTHERN FLORIDA...AND
THE YUCATAN OF MEXICO.  THE TOTAL PRECIPITABLE WATER IMAGERY
INDICATES SUBSTANTIAL MOISTURE IN THE SOUTHERN TWO-THIRDS OF THE
GULF...LIKELY ENHANCING THE AFOREMENTIONED CONVECTION.  THE
COMBINATION OF SURFACE RIDGING BECOMING MORE ESTABLISHED
NORTHEAST OF FLORIDA AND PERSISTENCE OF THE TROUGH OVER
YUCATAN...SHOULD LEAD TOWARD EASTERLY SURFACE WINDS PREVAILING
DURING THE NEXT DAY OR TWO ALONG WITH INCREASED CHANCES FOR
PRECIPITATION NEAR THE TROUGH.  IN THE UPPER LEVELS...A SHARP
NE-SW TROUGH IS LOCATED OVER THE GULF IN ASSOCIATION WITH THE
FRONTAL BOUNDARY.  SOUTH OF THE TROUGH AXIS...SOME UPPER LEVEL
MOISTURE IS BEING ADVECTED NORTHEASTWARD ACROSS THE GULF AND THE
FLORIDA PENINSULA.

CARIBBEAN SEA...
EASTERLY TRADEWINDS OF 15-20 KT IN THE EASTERN AND CENTRAL
CARIBBEAN CONVERGING WITH WEAKER TRADES IN THE WESTERN CARIBBEAN
ARE CONTRIBUTING TOWARD A WIDESPREAD AREA OF MODERATE CONVECTION
IN THE CENTRAL AND WESTERN CARIBBEAN.  WHILE THERE DOES NOT
APPEAR TO BE A COHERENT SURFACE FEATURE ASSOCIATED WITH THIS
CONVECTION...AN UPPER LOW CENTERED OVER HISPANIOLA MAY ALSO BE
ENHANCING THE CONVECTIVE ACTIVITY.  DURING THE NEXT DAY OR
TWO...THE CONVERGENCE LINE...AND THUS THE CONVECTION...MAY SHIFT
WESTWARD AND BECOME ASSOCIATED MORE WITH THE AFOREMENTIONED
TROUGH OVER THE YUCATAN.  THUS GENERALLY DRIER CONDITIONS OVER
THE EASTERN AND CENTRAL CARIBBEAN AND A HIGHER CHANCE OF
PRECIPITATION OVER THE WESTERN CARIBBEAN DURING THE NEXT COUPLE
DAYS.

ATLANTIC OCEAN...
THE MAIN FEATURE OF INTEREST IS T.D. TWELVE IN THE EASTERN
ATLANTIC.  SEE EARLIER DISCUSSION OF THIS SYSTEM.  ELSEWHERE TWO
PROMINENT SURFACE TROUGHS ARE EVIDENT...ONE EXTENDING FROM
17N40W TO 26N37W AND A SECOND ONE FROM 27N51W TO 28N46W TO
30N40W.  THE FIRST...THE REMNANTS OF T.D. 10...SHOWED A BRIEF
FLAREUP OF MODERATE TO STRONG CONVECTION EAST OF THE TROUGH
AXIS...BUT NOW ONLY HAS MODERATE CONVECTION WITHIN 180 NM WEST
OF THE TROUGH AXIS SOUTH OF 18N.  THERE MAY BE AN EXTENSION OF
THIS TROUGH WESTWARD...THOUGH THIS IS NOT CURRENTLY SHOWN IN THE
18 UTC MAP.  THE SECOND TROUGH HAS NO SIGNIFICANT DEEP
CONVECTION CURRENTLY.  ELSEWHERE...WIDESPREAD SHOWERS AND
ISOLATED MODERATE CONVECTION IS OCCURRING NORTH OF 25N BETWEEN
THE FLORIDA PENINSULA AND 60W...THOUGH NO SIGNIFICANT SURFACE
FEATURE IS ASSOCIATED WITH THESE SHOWERS AND CONVECTION.  EXCEPT
FOR SOME 20 KT SURFACE WINDS NEAR THE COAST OF WEST AFRICA AND
THE CIRCULATION AROUND T.D. TWELVE...THE TRADEWINDS ARE QUITE
WEAK ACROSS THE TROPICAL NORTH ATLANTIC TODAY.  THIS SHOULD
CONTINUE FOR THE NEXT DAY OR TWO AS THE SURFACE HIGH NORTH OF
THE AREA REMAINS RELATIVELY WEAK.  IN THE UPPER LEVELS...A
RATHER STRONG RIDGE ALONG 18N PROVIDING EASTERLY FLOW ACROSS THE
ATLANTIC ON THE EQUATORWARD SIDE.

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

$$

LANDSEA





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