[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 151738
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU SEP 15 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL STORM MARIA IS CENTERED NEAR 33.8N 66.5W AT 15/1800 UTC
OR ABOUT 125 NM NW OF BERMUDA MOVING N-NE AT 28 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 991 MB. MAXIMUM SUSTAINED WIND SPEED
IS 60 KT WITH GUSTS TO 75 KT. SCATTERED MODERATE CONVECTION IS
FROM 26N-36N BETWEEN 64W-70W. THIS IS DUE IN PART TO A MODERATE
AMOUNT OF WESTERLY MIDDLE TO UPPER LEVEL SHEAR AND AN UPPER
LEVEL TROUGH LOCATED OFF THE EASTERN U.S. SEABOARD THAT EXTENDS
OVER THE FAR WESTERN SW NORTH ATLC WATERS ALONG 78W S-SW OVER
THE FLORIDA STRAITS AND INTO THE NW CARIBBEAN SEA. WITH THIS
UPPER LEVEL TROUGH IN PLACE...MARIA IS FORECAST TO CONTINUE
TRACKING QUICKLY N-NE WITH TROPICAL STORM FORCE CONDITIONS
EXPECTED ON BERMUDA THROUGH THE REMAINDER OF TODAY WITH RAINFALL
AMOUNTS OF 1 TO 3 INCHES. SEE LATEST NHC INTERMEDIATE PUBLIC
ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC AND THE
FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24
KNHC FOR MORE DETAILS.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W
ALONG 11N29W TO 07N45W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N45W TO 09N61W. A PAIR OF 1014 MB SURFACE LOWS
ARE LOCATED ALONG THE MONSOON TROUGH NEAR 11N28W AND 09N35W
WHICH CONTINUE TO FOCUS LOW-LEVEL DEEP TROPICAL MOISTURE N OF
THE EQUATOR TO 14N E OF 40W. THIS LARGE AND STRETCHED OUT
MONSOON GYRE IS PRODUCING WIDELY SCATTERED MODERATE CONVECTION
FROM 02N-11N BETWEEN 11W-40W. FARTHER WEST...ISOLATED MODERATE
CONVECTION IS FROM 09N-16N BETWEEN 46W-61W...LOCATED N OF THE
ITCZ AXIS. THIS AREA OF CONVECTION IS LIKELY ENHANCED DUE TO
SOUTHWESTERLY MIDDLE TO UPPER LEVEL FLOW ASSOCIATED WITH AN
UPPER LEVEL LOW CENTERED NEAR 19N54W.

...DISCUSSION...

GULF OF MEXICO...
NW FLOW ALOFT IS DOMINATE OVER THE GULF BASIN THIS AFTERNOON ON
THE EASTERN PERIPHERY OF A LARGE ANTICYCLONIC CIRCULATION
CENTERED OVER EAST-CENTRAL MEXICO NEAR 21N99W. WATER VAPOR
IMAGERY INDICATES THAT MUCH OF THE GULF IS UNDER THE INFLUENCE
OF MODERATE TO STRONG MIDDLE TO UPPER LEVEL SUBSIDENCE AND DRY
AIR. THIS UPPER LEVEL RIDGING IS SUPPORTIVE OF A 1017 MB SURFACE
HIGH CENTERED NEAR 28N92W THAT IS FORECAST TO WEAKEN AND DRIFT
WESTWARD AS AN APPROACHING COLD FRONT CURRENTLY ANALYZED INLAND
ACROSS THE GULF COASTAL PLAIN WILL INTRODUCE A MILDER AIRMASS TO
THE NORTH-CENTRAL AND NE GULF WATERS THROUGH EARLY SATURDAY.
CURRENTLY MUCH OF THE GULF IS UNDER MOSTLY CLEAR SKIES AND FAIR
WEATHER CONDITIONS HOWEVER A FEW ISOLATED LOW-TOPPED SHOWERS ARE
WITHIN 45 NM EITHER SIDE OF A LINE FROM 24N84W TO 26N89W. WIDELY
SCATTERED SHOWERS ARE ALSO OCCURRING S OF 20N IN THE SW GULF.

CARIBBEAN SEA...
LINGERING SURFACE TROUGHING EXTENDING FROM TROPICAL STORM MARIA
IN THE W ATLC EXTENDS ACROSS THE SE BAHAMAS TO EASTERN CUBA NEAR
20N76W THEN INTO THE WESTERN CARIBBEAN TO NEAR 17N81W. LOW-LEVEL
MOISTURE CONVERGENCE IS FOCUSED ALONG THIS BOUNDARY AND IS
GENERATING ISOLATED SHOWERS WITHIN 180 NM SE AND 120 NM NW OF
THE BOUNDARY. EARLIER SCATTEROMETER PASSES FROM WINDSAT AND
ASCAT DEPICT 15-20 KT SE WINDS ACROSS THE EASTERN AND CENTRAL
CARIBBEAN E OF 80W WHILE W OF 80W WEAKER WINDS ARE ANALYZED.
ELSEWHERE THE REMAINDER OF THE BASIN REMAINS UNDER FAIRLY
TRANQUIL CONDITIONS. HOWEVER...SCATTERED SHOWERS AND TSTMS
ASSOCIATED WITH THE E PACIFIC MONSOON TROUGH ARE OCCURRING S OF
12N BETWEEN 76W-85W.

ATLANTIC OCEAN...
TROPICAL STORM MARIA IS TRACKING QUICKLY N-NE ACROSS THE HIGH
SEAS WATERS OF THE WESTERN ATLC THIS AFTERNOON DUE TO AN UPPER
LEVEL TROUGH TO ITS WEST WITH AXIS FROM THE OUTER BANKS OF NORTH
CAROLINA NEAR 36N75W TO THE FLORIDA STRAITS NEAR 23N81W. WATER
VAPOR IMAGERY INDICATES THAT VERY DRY AIR AND STRONG SUBSIDENCE
ASSOCIATED WITH THE TROUGHING IS ALOFT AND W OF 72W WHICH IS
MAINTAINING MOSTLY FAIR SKIES OVER THE NW BAHAMAS AND FLORIDA
PENINSULA. WHILE SCATTERED MODERATE CONVECTION IS OCCURRING N OF
26N BETWEEN 64W-70W IN THE VICINITY OF MARIA...A LOW-LEVEL
CONVERGENCE BOUNDARY IS ANALYZED AS A SURFACE TROUGH FROM 25N73W
TO EASTERN CUBA NEAR 20N76W. ISOLATED SHOWERS ARE OCCURRING
WITHIN 90 NM EITHER SIDE OF THE BOUNDARY. FARTHER SE...A CUT OFF
UPPER LEVEL LOW IS CENTERED NEAR 19N54W. A FEW ISOLATED SHOWERS
AND TSTMS ARE OCCURRING FROM 17N-24N BETWEEN 52W-59W. OTHERWISE
THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE
INFLUENCE OF A BROAD SURFACE RIDGE N OF 17N E OF 62W ANCHORED BY
A 1025 MB HIGH CENTERED NEAR 35N51W.

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

$$
HUFFMAN




This weather bulletin was brought to you by:
www.nashvilleweather.net