[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 111750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 11 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...SPECIAL FEATURE...

TROPICAL DEPRESSION SEVEN HAS OPENED UP INTO AN OPEN TROPICAL
WAVE...AS OF 1500 UTC. THE CENTER WAS LOCATED AT 13.3N
58.9W...OR ABOUT 35 NM E OF BARBADOS AND ABOUT 150 NM SE OF
MARTINIQUE MOVING W AT 21 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 1011 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO
40 KT. THE WAVE IS EXPECTED TO CONTINUE TO MOVE WESTWARD INTO
THE EASTERN CARIBBEAN. SEE LATEST NHC PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT2/WTNT32 KNHC AND NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
FOR MORE DETAILS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 13N-18N BETWEEN 54W-60W...AND FROM 9N-13N BETWEEN
59W-64W.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 24N26W TO A 1010 MB SURFACE LOW AT
19N27W. THE WAVE/LOW IS MOVING W AT 15 KT. THE SYSTEM COINCIDES
WITH A CUT-OFF AREA OF DEEP MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY INDICATES A BROAD
AREA OF LOW-LEVEL CYCLONIC FLOW IS AROUND THE WAVE AND LOW.
HOWEVER...DRY AIR IS INHIBITING ANY DEEP CONVECTION AT THIS
TIME.

WEAK TROPICAL WAVE EXTENDS FROM 22N93W TO 17N93W MOVING W NEAR
15 KT. THE WAVE LOST MOST OF ITS ENERGY DUE TO INTERACTION WITH
AN UPPER LEVEL LOW WHILE OVER THE CARIBBEAN. THE WAVE DOES HAVE
A LOW-AMPLITUDE MOISTURE SIGNAL MOVING WITH IT EVIDENT IN TOTAL
PRECIPITABLE WATER IMAGERY. NO DEEP CONVECTION IS ASSOCIATED
WITH THE WAVE AT THIS TIME.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE SURFACE LOW AT THE BASE OF A
TROPICAL WAVE NEAR 19N27W. IT CONTINUES FROM THE LOW ALONG
11N36W 13N45W. NO DEEP CONVECTION IS NOTED AT THIS TIME.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS SUPPORTS A FRONTAL
BOUNDARY N OF THE DISCUSSION AREA. DIFFLUENCE ALOFT AROUND THE
TROUGH IS HELPING SUPPORT SHOWERS/THUNDERSTORMS ALONG THE
NORTHERN GULF OF MEXICO COAST N OF 28N BETWEEN 83W-94W. A FEW
SHOWERS/POSSIBLE THUNDERSTORMS ARE ALSO IN THE FLORIDA STRAIGHTS
N OF WESTERN CUBA ASSOCIATED WITH AN UPPER LEVEL LOW IN THE NW
CARIBBEAN. THE REMAINDER OF THE BASIN IS MOSTLY DRY WITH LIGHT
ANT-CYCLONIC FLOW PRESENT ACROSS THE NORTHERN GULF. A TROPICAL
WAVE IS IN THE SW GULF...BUT DUE TO DRY AIR ALOFT...NO
SHOWERS/THUNDERSTORMS ARE ASSOCIATED WITH THE WAVE AT THIS TIME.
EXPECT THE WAVE TO MOVE WESTWARD AND INLAND INTO MEXICO WHERE IT
WILL DISSIPATE IN ABOUT 24 HOURS. WEAK SURFACE RIDGING WITH
REMAIN OVER THE GULF WITH SHOWERS/THUNDERSTORMS LIKELY ALONG THE
NORTHERN GULF COAST.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IN THE NW CARIBBEAN NEAR 18N86W IS PRODUCING
SCATTERED SHOWERS/THUNDERSTORMS FROM 15N-23N BETWEEN 80W-85W.
SIMILAR ACTIVITY IS OVER THE SW CARIBBEAN S OF 12N BETWEEN
76W-83W ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS THROUGH
COSTA RICA AND PANAMA TO NORTHERN COLOMBIA. THE CENTRAL
CARIBBEAN IS EXPERIENCING MOSTLY FAIR WEATHER DUE TO DRY AIR
ALOFT AROUND AN UPPER LEVEL TROUGH EXTENDING FROM AN UPPER LEVEL
LOW IN THE CENTRAL ATLC ACROSS THE NORTHERN LEEWARD ISLANDS TO
VENEZUELA. HOWEVER...THE UPPER TROUGH IS HELPING ENHANCE
CONVECTION TO THE E NEAR THE REMNANTS OF T.D. SEVEN. SOME
SHOWERS/THUNDERSTORMS ARE BEGINNING TO HIT THE WINDWARD ISLANDS.
SEE SPECIAL FEATURES FOR MORE DETAILS. TRADEWIND FLOW OF 15-20
KT IS PRESENT ACROSS MUCH OF THE EASTERN AND CENTRAL CARIBBEAN.
EXPECT MOIST CONDITIONS TO REMAIN OVER THE WESTERN
CARIBBEAN...AND INCREASE OVER THE EASTERN CARIBBEAN AS THE
TROPICAL WAVE OF WHAT WAS T.D. SEVEN MOVES WESTWARD INTO THE
BASIN.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE COVERS THE W ATLC SUPPORTING A 1022 MB HIGH
NEAR 34N63W. HOWEVER...AN UPPER LEVEL TROUGH OVER THE EASTERN
CONUS IS HELPING SUPPORTS SCATTERED SHOWERS/THUNDERSTORMS FROM
THE NW BAHAMAS NORTHWARD N OF 26N BETWEEN 74W-80W. A WEAK
SURFACE TROUGH IS ALONG 28N69W TO 25N74W. ISOLATED SHOWERS ARE
WITHIN 90 NM EITHER SIDE OF THE AXIS. AN UPPER LEVEL LOW
CENTERED NEAR 25N54W IS ALSO CAUSING SHOWERS/THUNDERSTORMS
25N-30N BETWEEN 50W-58W. THE REMAINDER OF THE BASIN IS DOMINATED
BY SURFACE RIDGING AROUND A 1026 MB HIGH S OF THE AZORES ISLANDS
NEAR 36N29W. IT IS SUPPORTED BY AN UPPER LEVEL RIDGE COVERING
MUCH OF THE TROPICAL EASTERN ATLC. SATELLITE IMAGERY INDICATES
THAT AN AREA OF DUST IS ACROSS THE FAR EASTERN ATLC E OF THE
TROPICAL WAVE/LOW NEAR 27W.

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

$$
WALTON







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