[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141743
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED SEP 14 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 25.6N 69.6W AT 14/1800 UTC
OR ABOUT 265 NM NE OF THE SOUTHEASTERN BAHAMAS AND ABOUT 475 NM
S-SW OF BERMUDA MOVING N AT 12 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1001 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH
GUSTS TO 60 KT. SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS FROM 21N-28N BETWEEN 64W-70W...PRIMARILY LOCATED
WITHIN 240 NM OF THE EASTERN SEMICIRCLE. THIS IS DUE IN PART TO
WESTERLY MIDDLE TO UPPER LEVEL SHEAR AND THE UPPER LEVEL TROUGH
THAT HAS PROGRESSED ACROSS THE FLORIDA PENINSULA AND FAR WESTERN
SW NORTH ATLC WATERS OVER THE PAST 24-36 HOURS. WITH THIS UPPER
LEVEL TROUGH IN PLACE...MARIA IS EXPECTED TO TRACK NORTHWARD
BRINGING INCREASED CHANCES OF RAINFALL TO BERMUDA THROUGH EARLY
THURSDAY. 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.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED FROM 19N93W ACROSS THE ISTHMUS OF
TEHUANTEPEC AND INTO THE E PACIFIC REGION MOVING W AT 5-10 KT.
WHILE MOST OF THE ACTIVE CONVECTION AND CYCLONIC TURNING OF THE
LOW-LEVEL CLOUD FIELD IS LOCATED IN THE E PACIFIC WATERS...TOTAL
PRECIPITABLE WATER IMAGERY INDICATES ELEVATED VALUES OF MOISTURE
ACROSS THE SW GULF OF MEXICO. A FEW ISOLATED SHOWERS ARE ALSO
NOTED ON SATELLITE IMAGERY S OF 20N BETWEEN 92W-95W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W
ALONG 11N20W TO 11N30W TO 10N40W. THE INTERTROPICAL CONVERGENCE
ZONE AXIS EXTENDS FROM 10N40W TO 10N46W THEN RESUMES NEAR 08N48W
TO 07N58W. A 1011 MB LOW IS LOCATED ALONG THE MONSOON TROUGH
NEAR 11N20W AND CONTINUES TO PRODUCE ISOLATED MODERATE
CONVECTION WITHIN 180 NM OF CENTER IN THE NW QUADRANT. ELSEWHERE
ALONG THE MONSOON TROUGH...WIDELY SCATTERED MODERATE CONVECTION
IS FROM 04N-10N BETWEEN 10W-24W. FARTHER WEST...A SURFACE TROUGH
IS EMBEDDED WITHIN THE ITCZ FROM 08N-12N ALONG 46W. AN EARLIER
MORNING WINDSAT PASS AROUND 14/0922 UTC CAPTURED THE SURFACE
TROUGH AXIS WITH STRONGER NE WINDS LOCATED NORTH OF THE AXIS.
ISOLATED MODERATE CONVECTION IS FROM 09N-14N BETWEEN 44W-50W.

...DISCUSSION...

GULF OF MEXICO...
NW FLOW ALOFT IS DOMINATE OVER THE GULF BASIN THIS AFTERNOON AS
AN UPPER LEVEL TROUGH WITH AXIS ALONG 80W CONTINUES TO PROGRESS
SLOWLY EASTWARD AND INTO THE W ATLC WATERS. A LARGE ANTICYCLONIC
CIRCULATION IS POSITIONED OVER WEST-CENTRAL MEXICO NEAR 21N104W
THAT IS PROVIDING MUCH OF THE GULF WITH MIDDLE TO UPPER LEVEL
DRY AIR AND SUBSIDENCE. THIS UPPER LEVEL RIDGING IS SUPPORTIVE
OF A 1016 MB SURFACE HIGH CENTERED NEAR 27N91W THAT IS FORECAST
TO REMAINS NEARLY STATIONARY THROUGH EARLY THURSDAY. CURRENTLY
MUCH OF THE GULF IS UNDER MOSTLY CLEAR SKIES AND FAIR WEATHER
CONDITIONS HOWEVER A FEW ISOLATED LOW-TOPPED SHOWERS ARE WITHIN
90 NM OF 27N84W IN THE EAST-CENTRAL GULF AND IN THE VICINITY OF
THE LOWER FLORIDA KEYS. LATE THURSDAY INTO EARLY FRIDAY...A
DEVELOPING LOW PRESSURE AREA...CURRENTLY OVER NW ARKANSAS...WILL
INTRODUCE A WEAK COLD FRONT INTO THE NORTH-CENTRAL AND FAR NE
GULF WATERS WHICH IS FORECAST TO STALL AND BECOME DIFFUSE OVER
THE REMAINDER OF THE UPCOMING WEEKEND.

CARIBBEAN SEA...
WHILE TROPICAL STORM MARIA CONTINUES ON A NORTHWARD TRACK ACROSS
THE SW NORTH ATLC...LINGERING ISOLATED SHOWERS AND TSTMS ARE
OCCURRING N OF 15N BETWEEN 65W-70W...INCLUDING PORTIONS OF
PUERTO RICO...FAR EASTERN HISPANIOLA AND ADJACENT WATERS
SURROUNDING THE MONA PASSAGE. A LOW-LEVEL CONVERGENT BOUNDARY IS
ANALYZED AS A SURFACE TROUGH ALONG 18N70W TO 14N72W. EARLIER
SCATTEROMETER PASSES FROM WINDSAT AND ASCAT DEPICT 15-20 KT SE
WINDS ACROSS THE EASTERN CARIBBEAN E OF THAT PARTICULAR SURFACE
TROUGH. ANOTHER LOW-LEVEL CONVERGENCE BOUNDARY IS ALONG 20N75W
TO 15N79W AND IS LOCATED WITHIN A MUCH WEAKER WIND FIELD REGIME.
EARLIER MORNING SCATTEROMETER PASSES INDICATE WINDS REMAIN
PRIMARILY NE TO E THE RANGE OF 5 TO 10 KT. ELSEWHERE THE
REMAINDER OF THE BASIN REMAINS UNDER FAIRLY TRANQUIL CONDITIONS.
HOWEVER A FEW ISOLATED SHOWERS AND TSTMS LINGER OVER THE SW
CARIBBEAN S OF 12N W OF 80W AND WITHIN 120 NM OF THE GULF OF
HONDURAS.

ATLANTIC OCEAN...
TROPICAL STORM MARIA IS TRACKING NORTHWARD ACROSS THE SW NORTH
ATLC WATERS THIS AFTERNOON AND CONTINUES TO BE INFLUENCED BY AN
UPPER LEVEL TROUGH TO ITS WEST WITH AXIS ALONG 80W. WATER VAPOR
IMAGERY INDICATES THAT VERY DRY AIR IS ALOFT W OF 75W WHICH IS
MAINTAINING FAIR SKIES OVER THE NW BAHAMAS AND FLORIDA
PENINSULA. WHILE DEEP CONVECTION IS LOCATED IN THE VICINITY OF
MARIA...WIDELY SCATTERED SHOWERS COVER THE REMAINDER OF THE W
ATLC FROM 18N-32N BETWEEN 60W-75W. FARTHER EAST...A CUT OFF
UPPER LEVEL LOW IS CENTERED NEAR 22N47W. A FEW ISOLATED SHOWERS
ARE OCCURRING FROM 22N-25N BETWEEN 46W-50W. OTHERWISE THE
REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE
OF A BROAD SURFACE RIDGE N OF 15N E OF 60W ANCHORED BY A 1025 MB
HIGH CENTERED NEAR 35N50W.

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

$$
HUFFMAN




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