[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 112348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 11 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 2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM MARIA IS CENTERED NEAR 19.8N 65.2W AS OF 2100
UTC...OR ABOUT 100 NM NNE OF SAN JUAN PUERTO RICO. MARIA IS
CURRENTLY MOVING WNW AT 8 KT. MINIMUM CENTRAL PRESSURE IS 1005
MB WITH MAXIMUM SUSTAINED WIND SPEEDS OF 50 KT WITH GUSTS TO 60
KT. PLEASE READ THE LATEST FORECAST/ADVISORY UNDER AWIPS/WMO
HEADER MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. THE SYSTEM
CONTINUES TO BE SHEARED WITH MOST OF THE CONVECTION TO THE E AND
N OF THE CENTER. CURRENTLY NUMEROUS STRONG CONVECTION IS FROM
16N-19N BETWEEN 60W-63W...AND FROM 18N-22N BETWEEN 62W-65W.
NUMEROUS MODERATE CONVECTION IS ELSEWHERE FROM 15N-23N BETWEEN
59W-66W. SOME OF THIS HEAVY RAINFALL IS CURRENTLY OVER THE NRN
LEEWARD ISLANDS AND THE VIRGIN ISLANDS.

TROPICAL DEPRESSION NATE...DOWNGRADED AT 2100 UTC...IS CURRENTLY
INLAND NEAR 20.6N 97.6W...OR ABOUT 25 NM SSW OF TUXPAN MEXICO.
NATE IS MOVING WNW NEAR 7 KTS. MINIMUM CENTRAL PRESSURE IS 1010
MB WITH MAXIMUM SUSTAINED WIND SPEED OF 30 KT WITH GUSTS TO 40
KT. THIS SYSTEM IS EXPECTED TO CONTINUE TO WEAKEN AND DISSIPATE
IN 24 HOURS. PLEASE READ THE LATEST FORECAST/ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 250 NM OF
THE CENTER.

...TROPICAL WAVES...

TROPICAL WAVE IN THE ATLC ALONG 19N47W TO 8N53W IS MOVING WWD AT
15-20 KT. THE WAVE LIES AHEAD OF A LARGE SURGE OF DEEP LAYER
MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE
IMAGERY AND SATELLITE DERIVED WINDS ALSO INDICATE BROAD CYCLONIC
FLOW AROUND THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS
WITHIN 120 NM EITHER SIDE OF THE AXIS.

TROPICAL WAVE IS IMPACTING THE WRN CARIBBEAN ALONG 20N84W TO
11N83W MOVING W NEAR 10 KT. SIGNIFICANT DEEP LAYER MOISTURE
COVERS THE WRN CARIBBEAN EVIDENT IN TOTAL PRECIPITABLE WATER
IMAGERY. THE SRN EXTENT OF THE WAVE LIES JUST N OF THE MONSOON
TROUGH. SCATTERED MODERATE/STRONG CONVECTION IS FROM 12N-16N
BETWEEN 75W-82W...AND FROM 11N-19N BETWEEN 82W-87W. A CLUSTER OF
STRONG CONVECTION IS FROM 11N-15N BETWEEN 86W-89W ACROSS WRN
NICARAGUA...HONDURAS...AND EL SALVADOR. STRONG ACTIVITY IS ALSO
ACROSS THE YUCATAN PENINSULA AND PORTIONS OF CUBA. DUE TO THE
LARGE AREA OF MOISTURE PRESENT...IT IS HARD TO DETERMINE WHAT IS
SOLELY ASSOCIATED WITH THE WAVE.

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

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 20N16W
ALONG 15N22W 10N28W 8N38W. THE ITCZ CONTINUES FROM 8N38N TO
9N48W WHERE SOME WEAK SE-NE WIND CONVERGENCE HAS REFORMED BEHIND
THE WAVE STILL E OF THE LESSER ANTILLES. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 5N-12N BETWEEN 17W-23W.
ISOLATED MODERATE/STRONG CONVECTION IS FROM 3N-8N BETWEEN
23W-34W. SCATTERED MODERATE/STRONG CONVECTION IS ALSO FROM
6N-9N BETWEEN 41W-44W.

...DISCUSSION...

THE GULF OF MEXICO...
T.D. NATE IS NOW INLAND OVER MEXICO...BUT IS STILL PRODUCING
ISOLATED SHOWERS/THUNDERSTORMS OVER THE BAY OF CAMPECHE S OF
24N. STRONG SHOWERS/THUNDERSTORMS ARE ALSO MOVING OVER THE WRN
HALF OF THE YUCATAN PENINSULA AND OVER THE ERN BAY OF CAMPECHE.
THIS MAY BE INFLUENCED BY MOISTURE ASSOCIATED WITH A TROPICAL
WAVE IN THE WRN CARIBBEAN...AS WELL AS DIFFLUENCE ALOFT BETWEEN
AN UPPER LEVEL RIDGE OVER THE WRN CARIBBEAN AND A WEAK INVERTED
UPPER TROUGH OVER THE SRN BAY OF CAMPECHE. MAINLY SWLY FLOW
COVERS MUCH OF THE BASIN BETWEEN THE UPPER RIDGE IN THE WRN
CARIBBEAN AND WRN ATLC...AND AN UPPER LEVEL TROUGH OVER THE ERN
CONUS. WATER VAPOR IMAGERY INDICATES THAT DRY AIR ALOFT IS
PUSHING INTO THE NW GULF MAINTAINING FAIR CONDITIONS. A FEW
ISOLATED SHOWERS ARE S OF THIS DRY AIR BOUNDARY ALONG A LINE
FROM 28N88W TO 25N96W. A FEW STRONG STORMS ARE ALSO OVER SW
FLORIDA AND NEAR CAPE CANAVERAL FLORIDA. EXPECT WEAK SURFACE
RIDGING TO FORM OVER THE NRN GULF WHICH WILL REMAIN STATIONARY
TROUGH MUCH OF THE WEEK.

THE CARIBBEAN SEA...
A TROPICAL WAVE IN THE WRN CARIBBEAN IS PRODUCING A LARGE AREA
OF SHOWERS/THUNDERSTORMS ACROSS THE WRN HALF OF THE BASIN.
SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 12N-16N
BETWEEN 75W-82W...AND FROM 11N-19N BETWEEN 82W-87W. A CLUSTER OF
STRONG CONVECTION IS FROM 11N-15N BETWEEN 86W-89W ACROSS WRN
NICARAGUA...HONDURAS...AND EL SALVADOR. STRONG ACTIVITY IS ALSO
ACROSS THE YUCATAN PENINSULA AND PORTIONS OF CUBA. SIMILARLY
STRONG ACTIVITY IS ACROSS NRN COLOMBIA AND NW VENEZUELA MOST
LIKELY ASSOCIATED WITH THE MONSOON TROUGH EXTENDING FROM COSTA
RICA TO NRN COLOMBIA. SOME OF THE SHOWERS OVER CUBA MAY BE
ASSOCIATED WITH A WEAK SURFACE TROUGH EXTENDING FROM SE FLORIDA
TO CENTRAL CUBA. THE ERN CARIBBEAN IS FEELING THE IMPACTS OF
T.S. MARIA. STRONG SHOWERS/THUNDERSTORMS ARE CURRENTLY HITTING
THE NRN LEEWARD ISLANDS AND THE VIRGIN ISLANDS. SEE SPECIAL
FEATURES ABOVE FOR MORE DETAILS. ALOFT...AN UPPER LEVEL RIDGE
COVERS THE WRN CARIBBEAN CENTERED NEAR 20N79W. DRY AIR IS
WRAPPING AROUND THE ERN SIDE WHICH IS HELPING MAINTAIN FAIR
CONDITIONS ACROSS HISPANIOLA. UPPER LEVEL RIDGING IS ALSO OVER
THE ERN CARIBBEAN DUE TO THE OUTFLOW OF MARIA. EXPECT
SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE WRN CARIBBEAN AS
THE TROPICAL WAVE SLOWLY MOVES WWD. INTERESTS IN THE NE
CARIBBEAN SHOULD CONTINUE TO MONITOR THE PROGRESS OF T.S. MARIA.

THE ATLANTIC OCEAN...
SCATTERED SHOWERS/THUNDERSTORMS ARE BETWEEN CUBA AND THE NW
BAHAMAS/SE FLORIDA ASSOCIATED WITH A WEAK SURFACE TROUGH
EXTENDING FROM 25N80W TO S OF CENTRAL CUBA. T.S. MARIA IS JUST N
OF THE VIRGIN ISLANDS PRODUCING A LARGE AREA OF
SHOWERS/THUNDERSTORMS ACROSS THE CENTRAL ATLC. SEE SPECIAL
FEATURES FOR MORE DETAILS. AN UPPER LEVEL TROUGH ALONG
63W...SANDWICHED BETWEEN AN UPPER LEVEL RIDGE OVER THE WRN ATLC
AND THE OUTFLOW OF MARIA...IS PRODUCING SHEAR ACROSS MARIA WHICH
CONTRIBUTES TO THE ELONGATED PATTERN IN THE SHOWER ACTIVITY.
FARTHER E...A SERIES OF HIGH PRESSURE CENTERS DOT THE ERN ATLC
PRODUCING A BROAD SURFACE RIDGE WHICH IS MAINTAINING MOSTLY FAIR
WEATHER BESIDES THAT ASSOCIATED WITH A TROPICAL WAVE IN THE
TROPICAL ATLC. ALOFT...AN UPPER LEVEL TROUGH IS ALONG 39W WITH A
WEAK UPPER LEVEL RIDGE ALONG 30W. EXPECT T.S. MARIA TO BE THE
MAIN FOCUS IN THE ATLC BASIN FOR THE NEXT SEVERAL DAYS.

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

$$
WALTON





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