[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131141
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE SEP 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1045 UTC.

...SPECIAL FEATURES...

TROPICAL STORM MARIA IS CENTERED NEAR 21.9N 67.9W AT 13/1200 UTC
OR ABOUT 280 NM E OF THE SOUTHEASTERN BAHAMAS AND ABOUT 645 NM
S-SW OF BERMUDA MOVING N-NW AT 4 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH
GUSTS TO 55 KT. PLEASE SEE THE LATEST FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. MARIA
CONTINUES TO BE IN SHEAR ENVIRONMENT WITH SCATTERED MODERATE/
STRONG CONVECTION COVERING THE AREA FROM 17N-21N BETWEEN 64W-68W
INCLUDING THE VIRGIN ISLANDS AND PUERTO RICO. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 20N-23N BETWEEN
62W-65W. MARIA IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS
OF 2-4 INCHES WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES OVER THE
THE VIRGIN ISLANDS...PUERTO RICO...AND PORTIONS OF THE NORTHERN
LEEWARD ISLANDS THROUGH THIS EVENING.

...TROPICAL WAVES...

TROPICAL WAVE IS IN THE W TROPICAL ATLC EXTENDING FROM 20N56W TO
10N58W MOVING W 15-20 KT. WAVE IS EMBEDDED WITHIN DEEP LAYER
MOISTURE AS DEPICTED ON THE TOTAL PRECIPITABLE WATER IMAGERY.
WAVE IS WELL DEFINED IN THE UPPER LEVEL SATELLITE WINDS. WAVE IS
BENEATH THE OUTFLOW FROM TROPICAL STORM MARIA TO THE NW
ENHANCING CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION WITHIN 90/120 NM OF LINE FROM 11N61W TO 22N54W.

TROPICAL WAVE IS IN THE NW CARIBBEAN ALONG 87W S OF 20N MOVING W
NEAR 5 KT. WAVE WAS REPOSITIONED SLIGHTLY TO THE E BASED A LATE
EVENING ASCAT PASS AND SATELLITE SIGNATURE. ABUNDANCE OF
TROPICAL MOISTURE COVERS THE ENTIRE CARIBBEAN AND S GULF OF
MEXICO INCLUDING THE YUCATAN PENINSULA AS DEPICTED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. CLUSTERS OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION ARE S OF 19N W OF 83W TO INLAND OVER
CENTRAL AMERICA AND THE YUCATAN PENINSULA.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA ENTERING THE E TROPICAL
ATLC NEAR 17N16W ALONG 12N19W 9N28W 8N39W TO 6N44W. THE 1013 MB
LOW THAT WAS NEAR 9N38W IS NO LONGER DISCERNIBLE. THERE
CONTINUES TO BE NO CONVERGING NE/SE FLOW...SO NO ITCZ AXIS.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 10N-15N E OF 20W TO
THE COAST OF W AFRICA INCLUDING GUINEA-BISSAU...GAMBIA...AND
SENEGAL. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE WITHIN 90 NM ALONG THE COAST OF W AFRICA BETWEEN
LIBERIA AND GUINEA. SCATTERED MODERATE CONVECTION IS FROM 5N-8N
BETWEEN 30W-34W WITH CLUSTERS OF SIMILAR CONVECTION FROM 5N-10N
BETWEEN 45W-60W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH COVERS THE FAR E CONUS INTO THE GULF N OF 22N
USHERING IN DRY STABLE AIR OVER THE GULF GIVING THE AREA N OF
24N REMARKABLY CLEAR SKIES THIS MORNING. AN UPPER RIDGE ANCHORED
IN THE NW CARIBBEAN EXTENDS OVER THE FAR S GULF. DIFFLUENT FLOW
BETWEEN THE UPPER RIDGE IN THE CARIBBEAN AND THE UPPER TROUGH
OVER THE GULF IS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS IN THE BAY OF CAMPECHE S OF 20N E OF 96W AND
ISOLATED SHOWERS ACROSS THE REMAINDER OF THE S GULF S OF 24N
INCLUDING THE FLORIDA KEYS AND THE STRAITS OF FLORIDA. A WEAK
SURFACE RIDGE COVERS MUCH OF THE GULF AND AT 13/0900 UTC IS
ANCHORED BY A 1018 MB HIGH NEAR 28N89W. SURFACE RIDGE WILL
REMAIN NEARLY STATIONARY OVER THE N GULF THROUGH FRI. THE
TROPICAL WAVE IN THE NW CARIBBEAN WILL MOVE SLOWLY OVER THE
YUCATAN PENINSULA TODAY THROUGH WED THEN ACROSS THE BAY OF
CAMPECHE THU AND FRI.

CARIBBEAN SEA...
TROPICAL STORM MARIA CONTINUES TO PRODUCE CONVECTION OVER THE
FAR NE CARIBBEAN...SEE SPECIAL FEATURES SECTION ABOVE. AN UPPER
RIDGE COVERS THE NW CARIBBEAN ANCHORED ALONG THE COAST OF THE
YUCATAN NEAR 18N88W ENHANCING THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVE. EASTERLY FLOW ALOFT DOMINATES THE REMAINDER OF
THE CARIBBEAN. THE MONSOON TROUGH EXTENDS ACROSS THE SW
CARIBBEAN FROM COLOMBIA NEAR 9N75W ACROSS PANAMA ALONG 9N81W
INTO THE E PACIFIC REGION ALONG THE COSTA RICA/NICARAGUA BORDER
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 11N TO
INLAND OVER COLOMBIA AND PANAMA BETWEEN 75W-78W. SCATTERED
SHOWERS ARE MOVING OVER THE LESSER ANTILLES AHEAD OF THE
TROPICAL WAVE APPROACHING THE ISLANDS FROM THE W TROPICAL ATLC.
TROPICAL WAVE ALONG THE YUCATAN COAST WILL SLOWLY MOVE ACROSS
THE YUCATAN PENINSULA THROUGH WED. THE TROPICAL ATLC TROPICAL
WAVE WILL REACH THE LEEWARD ISLANDS TONIGHT CROSSING INTO THE E
CARIBBEAN THROUGH WED REACHING THE CENTRAL CARIBBEAN THU AND BE
OVER THE W CARIBBEAN FRI AND SAT.

ATLANTIC OCEAN...
THE UPPER TROUGH OVER THE FAR E CONUS EXTENDS OVER THE W ATLC N
OF 23N W OF 74W WITH A SHORTWAVE UPPER TROUGH EXTENDING FROM
31N77W TO THE FLORIDA COAST NEAR WEST PALM BEACH SUPPORTING A
SURFACE TROUGH THAT AT 13/0900 UTC EXTENDS FROM 32N77W ALONG
27N80W TO 25N80W GENERATING SHOWERS/THUNDERSTORMS WITHIN 60 NM
OF LINE FROM 27N80W TO 32N74W AND SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS WITHIN 90 NM OF LINE FROM 25N80W ACROSS
THE N BAHAMA ISLANDS TO BEYOND 32N73W. AN UPPER LOW IS BEGINNING
TO PULL N AWAY FROM TROPICAL STORM MARIA AND IS NOW CENTERED
NEAR 29N65W. AN UPPER TROUGH AXIS EXTENDS INTO THE CENTRAL ATLC
THROUGH 32N37W TO AN UPPER LOW NEAR 26N40W GENERATING ISOLATED
SHOWERS FROM 23N-26N BETWEEN 41W-44W. A BROAD SURFACE RIDGE
DOMINATES THE ATLC N OF 18N E OF 50W AND N OF 26N BETWEEN
50W-80W WITH A 1023 MB HIGH IN THE CENTRAL ATLC NEAR 32N56W.
TROPICAL STORM MARIA WILL MOVE NW THROUGH TODAY THEN TURN MORE
NORTHERLY AND BE N OF THE DISCUSSION AREA LATE WED. A TROUGH
WILL LINGER OVER THE W ATLC THU AND FRI MOVING W ON SAT.

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

$$
PAW




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