[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 120002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT SEP 11 2010

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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND
RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

TROPICAL STORM IGOR IS CENTERED NEAR 17.4N 41.2W AT 11/2100 UTC
OR ABOUT 990 NM W OF THE CAPE VERDE ISLANDS MOVING W AT 16 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED
WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. INTENSIFICATION IS
EXPECTED OVER THE NEXT COUPLE OF DAYS AND IGOR IS EXPECTED TO
REACH HURRICANE STRENGTH TONIGHT OR EARLY TOMORROW. CONVECTION
HAS INCREASED NEAR THE STORM CENTER WITH NUMEROUS STRONG
CONVECTION NOW FROM 16N-18N BETWEEN 40W-43W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-17N BETWEEN
42W-46W...AND ALSO N OF THE CENTER IN A FORMING BANDING FEATURE
ALONG 21N37W 20N42W 18N44W. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.

A 1009 MB SURFACE LOW IS IN THE ERN CARIBBEAN CENTERED NEAR
15N66W MOVING W NEAR 15 KT. BROAD LOW-LEVEL CYCLONIC FLOW COVERS
THE AREA FROM N OF PUERTO RICO TO THE VENEZUELA COAST BETWEEN
60W-72W. UPPER LEVEL ANTI-CYCLONIC FLOW IS CENTERED NE OF PUERTO
RICO NEAR 20N64W PROVIDING DIFFLUENCE ALOFT NEAR THE SURFACE LOW
CENTER HELPING ENHANCE MODERATE CONVECTION FROM 14N-20N BETWEEN
62W-71W. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN
FAVORABLE FOR DEVELOPMENT..AND A TROPICAL CYCLONE COULD FORM
OVER THE NEXT FEW DAYS.

A TROPICAL WAVE IS ALONG THE W AFRICAN COASTLINE ALONG 19N16W TO
8N17W MOVING W NEAR 10-15 KT. SATELLITE IMAGERY INDICATES
LOW-LEVEL CYCLONIC FLOW ABOUT THE WAVE AXIS CONCENTRATED NEAR A
1007 MB LOW ANALYZED ALONG THE WAVE NEAR 13N17W. NUMEROUS STRONG
CONVECTION IS W OF THE LOW CENTER FROM 12N-14N BETWEEN 18W-20W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 8N-11N
BETWEEN 18W-23W. THE WAVE IS ABOUT TO MOVE FARTHER OVER WATER
AND INTO LOW-LEVEL MONSOONAL FLOW WHICH WILL CONTRIBUTE TO THE
CYCLONIC FLOW ALREADY IN PLACE. AS THIS HAPPENS OVER THE NEXT
COUPLE OF DAYS...TROPICAL CYCLONE DEVELOPMENT IS POSSIBLE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N19W 10N26W 14N33W RESUMING NEAR
10N43W ALONG 10N53W 12N61W. ISOLATED MODERATE CONVECTION IS FROM
7N-11N BETWEEN 26W-37W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 9N-12N BETWEEN 41W-48W. SIMILAR ACTIVITY IS
FROM 8N-11N BETWEEN 54W-57W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING COVERS THE MAJORITY OF THE GULF OF MEXICO
ANCHORED BY A 1017 MB HIGH IN THE CENTRAL GULF NEAR 26N89W
MAINTAINING FAIR CONDITIONS ACROSS MUCH OF THE AREA. THE SURFACE
RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED OVER CENTRAL
TEXAS MAINTAINING NE-E FLOW ALOFT ACROSS THE BASIN ACCOMPANIED
BY DRY AIR. A WEAK SURFACE TROUGH IS IN THE BAY OF CAMPECHE
ALONG 23N95W TO 19N92W SUPPORTING A FEW ISOLATED
SHOWERS/THUNDERSTORMS. SEABREEZE CONVERGENCE ACROSS THE FLORIDA
PENINSULA ALONG WITH DAYTIME HEATING IS SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS ALONG THE WRN COAST OF FLORIDA. EXPECT
WEAK SURFACE RIDGING TO REMAIN ACROSS THE BASIN OVER THE NEXT 24
HRS.

CARIBBEAN SEA...
MAINLY ELY FLOW ALOFT COVERS THE WRN CARIBBEAN AROUND AN UPPER
LEVEL RIDGE CENTERED OVER CENTRAL TEXAS. DAYTIME HEATING AND
INSTABILITY ARE ENHANCING SHOWERS/THUNDERSTORMS ACROSS CUBA AND
THE IMMEDIATE SRN COASTAL WATERS. SOME OF THESE MAY BE
INFLUENCED BY A SURFACE TROUGH EXTENDING FROM S OF THE ISLE OF
YOUTH NEAR 21N83W ALONG 15N83W TO 11N79W. A FEW ISOLATED SHOWERS
ARE WITHIN 150 NM EITHER SIDE OF THE TROUGH. NUMEROUS
SHOWERS/ISOLATED THUNDERSTORMS HAVE ALSO FLARED UP ACROSS MUCH
OF CENTRAL AMERICA ESPECIALLY ACROSS HONDURAS AND NICARAGUA NEAR
A WEAK INVERTED UPPER LEVEL TROUGH OVER GUATEMALA. A BROAD AREA
OF LOW PRESSURE IS IMPACTING THE ERN CARIBBEAN E OF 72W. SEE
SPECIAL FEATURES ABOVE FOR MORE DETAILS. EXPECT
SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE ERN CARIBBEAN
SPREADING INTO THE CENTRAL CARIBBEAN AS THIS SYSTEM MOVES WWD.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH COVERS THE NW ATLC SUPPORTING A STATIONARY
FRONT THAT CLIPS THE NRN DISCUSSION AREA ALONG 31N69W 30N75W
32N81W. A PRE-FRONTAL TROUGH IS S OF THE BOUNDARY ALONG 30N67W
TO 28N76W. ISOLATED SHOWERS ARE WITHIN 60 NM S OF THE TROUGH
WITH A FEW EXTENDING SW ACROSS THE NW BAHAMAS. SCATTERED SHOWERS
ARE N OF THE ERN CARIBBEAN ISLANDS ASSOCIATED WITH A BROAD LOW
PRESSURE SYSTEM IN THE CARIBBEAN. FARTHER E...A 1015 MB SURFACE
LOW IS CENTERED NEAR 30N50W SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS FROM 29N-35N BETWEEN 45W-51W. A SURFACE
TROUGH IS TO THE S...NO LONGER CONNECTED TO THE LOW
CENTER...ALONG 25N52W 19N52W 15N48W. POSSIBLE ISOLATED SHOWERS
ARE WITHIN 120 NM EITHER SIDE OF THE AXIS. TROPICAL STORM IGOR
IS DUE E OF THE SURFACE TROUGH. SEE SPECIAL FEATURES ABOVE FOR
MORE DETAILS. BROAD SURFACE RIDGING COVERS THE E ATLC KEEPING
CONDITIONS FAIR. ALOFT...A BROAD UPPER LEVEL RIDGE COVERS THE
AREA E OF 55W CENTERED NW OF IGOR NEAR 22N49W. AN UPPER LEVEL
TROUGH IS ACROSS THE FAR ERN ATLC EXTENDING FROM JUST W OF
PORTUGAL ACROSS THE CANARY ISLANDS AND DOWN THE NW AFRICAN
COAST.

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

$$
WALTON





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