[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 132358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 13 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 FEATURES...

TROPICAL STORM FRANKLIN IS CENTERED NEAR 39.7N 55.5W AT 13/2100
UTC MOVING ENE AT 19 KT. ESTIMATED CENTRAL PRESSURE IS 1004 MB.
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUST TO 45 KT.
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM 38N-43N
BETWEEN 49W-53W. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

A 1013 MB LOW IS CENTERED NEAR 19N54W MOVING WNW AT 15-20 KT. A
SURFACE TROUGH IS ANALYZED FROM 22N56W TO THE LOW CENTER.
SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE FROM 18N-24N
BETWEEN 51W-57W. WHILE UPPER-LEVEL WINDS ARE CURRENTLY NOT
FAVORABLE FOR DEVELOPMENT...ENVIRONMENTAL CONDITIONS COULD BECOME
MORE CONDUCIVE FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS.
THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE
DURING THE NEXT 48 HOURS.

A 1012 MB LOW IS NEAR 27N61W...ABOUT 400 NM SE OF BERMUDA.
SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE WITHIN 50 NM
AROUND THE LOW CENTER. THE CLOUD STRUCTURE IS BECOMING BETTER
ORGANIZED...AND IF CURRENT TRENDS CONTINUE...ADVISORIES COULD BE
INITIATED LATER TONIGHT. THIS SYSTEM HAS A HIGH CHANCE OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS THE
SYSTEM MOVES WNW AT 10-12 KT.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 16N37W TO 10N36W MOVING W AT 10-15
KT. THE WAVE LIES E OF AN AREA OF ENHANCED MOISTURE EVIDENT IN
TOTAL PRECIPITABLE WATER IMAGERY. WHILE THE WAVE IS CURRENTLY
INACTIVE AND HAS NO ASSOCIATED DEEP CONVECTION...MODEL GUIDANCE
SHOWS ENHANCED CONVECTION AND SOME DEVELOPMENT OF THE WAVE IN A
FEW DAYS.

TROPICAL WAVE IS OVER THE YUCATAN PENINSULA ANALYZED FROM 21N87W
TO 16N90W MOVING W AT 10-12 KT. MOST OF THE CONVECTION IS INLAND
OVER THE YUCATAN PENINSULA...REACHING TO 40 NM OFF THE COASTAL
WATERS OF THE PENINSULA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF MAURITANIA
NEAR 17N16W ALONG 13N23W TO 10N34W. THE ITCZ IS ANALYZED FROM
10N50W TO THE COAST OF SOUTH AMERICA NEAR 8N60W. ISOLATED
SHOWERS ARE WITHIN 20 NM ON EITHER SIDE OF THE ITCZ. SIMILAR
ACTIVITY IS WITHIN 100 NM EITHER SIDE OF THE MONSOON TROUGH.
SCATTERED SHOWERS ARE OVER THE COASTAL WATERS OF GUINEA...SIERRA
LEONE...AND LIBERIA FROM 3N-9N E OF 20W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER RIDGE OF HIGH PRESSURE IS SETTLING ACROSS THE
CONUS. THIS FEATURE IS PROVIDING A DRY NE FLOW ALOFT ACROSS THE
DISCUSSION AREA. AT LOWER LEVELS...RIDGING IS ACROSS THE AREA
CENTERED AROUND A 1015 MB HIGH NEAR 27N90W. WINDS ARE LIGHT AND
VARIABLE NEAR THE HIGH CENTER WHILE ANTICYCLONIC 8-10 KT WINDS
ARE ELSEWHERE ACROSS THE BASIN. A TROPICAL WAVE IS INLAND OVER
THE YUCATAN PENINSULA GENERATING SHOWERS AND THUNDERSTORMS
WITHIN 40 NM OVER THE COASTAL WATERS OF YUCATAN. SIMILAR
ACTIVITY IS OVER THE COASTAL WATERS OF CUBA W OF
80W...ASSOCIATED TO A WEAK UPPER LEVEL TROUGH OVER THE FAR NW
CARIBBEAN EXTENDING INTO THE SE GULF. EXPECT WEAK SURFACE
RIDGING TO REMAIN ACROSS THE BASIN OVER THE NEXT 24 HOURS. THE
TROPICAL WAVE WILL CONTINUES TO MOVE INTO THE BAY OF CAMPECHE
OVER THE NEXT DAY WHICH MAY INCREASE THE CHANCE OF SHOWER
ACTIVITY ACROSS THE SRN GULF.

CARIBBEAN SEA...
A LARGE CLUSTER SHOWERS AND THUNDERSTORMS IS IN THE SW CARIBBEAN
S OF 16N W OF 76W ASSOCIATED WITH THE MONSOON TROUGH THAT
EXTENDS ACROSS COSTA RICA TO NORTHERN COLOMBIA. THE ACTIVITY IS
FURTHER ENHANCED BY AN ELONGATED UPPER LEVEL CYCLONIC
CIRCULATION COVERING THE SAME REGION. A WEAK UPPER LEVEL TROUGH
OVER THE FAR NW CARIBBEAN IS ALSO GENERATING SIMILAR CONVECTION
WITHIN 40 NM OVER THE COASTAL WATERS OF THE YUCATAN PENINSULA
AND CUBA W OF 80W. THE REMAINDER OF THE BASIN IS INFLUENCED BY
DRY AIR ALOFT ADVECTING FROM THE W TROPICAL ATLC AND SUPPORTING
MOSTLY FAIR WEATHER ACROSS THE CENTRAL AND ERN CARIBBEAN WITH
5-15 KT ELY TRADE WINDS. DOPPLER RADAR IMAGERY FROM THE NWS
PUERTO RICO INDICATED SCATTERED SHOWERS ACROSS THE WATERS NEAR
PUERTO RICO AND THE VIRGIN ISLANDS N OF 15N BETWEEN 64W-68W...
ASSOCIATED TO THE SURFACE TROUGH IN THE ATLC N OF PUERTO RICO.
EXPECT CONVECTION TO REMAIN OVER THE SW CARIBBEAN ASSOCIATED
WITH THE MONSOON TROUGH...AND ACROSS THE WATERS NEAR HISPANIOLA
ASSOCIATED WITH THE SURFACE TROUGH N OF PUERTO RICO.

ATLANTIC OCEAN...
A NEARLY STATIONARY FRONTAL BOUNDARY SKIRTS ACROSS THE NW
PORTION OF THE DISCUSSION AREA ALONG 32N BETWEEN 65W AND THE
COAST OF SOUTH CAROLINA SUPPORTING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS N OF 29N W OF 74W. SIMILAR ACTIVITY IS
WITHIN 30 NM ALONG AN IMAGINARY LINE FROM 25N76W TO 29N68W. NEAR
THIS AREA OF CONVECTION...A WEAK 1018 MB HIGH IS CENTERED AROUND
27N67W...PROVIDING FAIR WEATHER ACROSS MUCH OF THE BAHAMAS.
THREE AREA OF SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE TO
THE E OF THIS FEATURE BETWEEN 52W-70W...ASSOCIATED WITH TWO LOW
PRESSURE SYSTEMS AND A SURFACE TROUGH N OF PUERTO RICO. THE
SURFACE TROUGH IS ANALYZED FROM 24N32W TO 18N64W. SEE SPECIAL
FEATURES ABOVE FOR MORE DETAILS ON THE TWO LOWS. A BROAD SURFACE
RIDGE DOMINATES THE REMAINDER OF THE ATLC...ANCHORED BY A 1024
MB HIGH NEAR 32N42W. LAST VISIBLE SATELLITE PICTURES OF THE DAY
INDICATED A BROAD AREA OF AFRICAN DUST EXTENDING E OF THE TWO
SURFACE LOW PRESSURE SYSTEMS TO THE AFRICAN COAST.

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

$$

GARCIA




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