[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021827 AAA
TWDAT

TROPICAL WEATHER DISCUSSION...UPDATED
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 02 2011

UPDATED SPECIAL FEATURES

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...

THE CENTER OF UPGRADED HURRICANE KATIA AT 02/1500 UTC IS NEAR
17.5N 52.4W OR ABOUT 705 MI E OF THE NORTHERN LEEWARD ISLANDS
MOVING WNW OR 300 DEGREES AT 12 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 991 MB. MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH
GUSTS TO 80 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADER MIATCPAT2/WTNT32 KNHC FOR FULL DETAILS. NUMEROUS MODERATE
TO STRONG CONVECTION IS FROM 16N-23N BETWEEN 47W-55W.

THE CENTER OF UPGRADED TROPICAL STORM LEE AT 02/1800 UTC IS NEAR
27.4N 91.5W OR 200 MI SE OF CAMERON LOUISIANA OR ABOUT 210 MI SW
OF THE MOUTH OF THE MISSISSIPPI RIVER MOVING NW OR 325 DEGREES
AT 2 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCPAT3/ WTNT33
KNHC FOR FULL DETAILS. NUMEROUS MODERATE TO STRONG CONVECTION IS
WITHIN 240 NM IN THE SE SEMICIRCLE EXCEPT 180 NM IN THE NE
QUADRANT OF LEE. VERY HEAVY RAINFALL WILL OCCUR ALONG THE
NORTHERN GULF COAST AS DESCRIBED IN MORE DETAIL IN THE GULF OF
MEXICO SECTION BELOW.

1006 MB LOW PRES IS NEAR 38N63W OR ABOUT 460 MI S-SE OF HALIFAX
NOVA SCOTIA MOVING NE AROUND 10 KT. CONVECTION REMAINS SHEARED
AND REMOVED OFF TO THE NE OF THE LOW CENTER AND ENVIRONMENTAL
CONDITIONS ARE BECOMING UNFAVORABLE FOR A TROPICAL CYCLONE TO
DEVELOP. THUS THIS LOW NOW HAS A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE IN THE ATLANTIC OCEAN FROM 17N28W TO 1012 MB LOW
PRES NEAR 10N30W MOVING WNW AROUND 15 KT. SCATTERED MODERATE
CONVECTION IS WITHIN 180-240 NM IN THE W QUADRANT OF THE LOW
WITH ONLY SCATTERED SHOWERS EVIDENT ELSEWHERE WITHIN 120-180 NM
W OF THE TROPICAL WAVE AXIS. THIS WAVE IS COINCIDENT WITH A
MOISTURE MAXIMUM INDICATED BY TOTAL PRECIPITABLE WATER SATELLITE
IMAGERY.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM 13N25W TO 07N37W TO 09N42W THEN
RESUMES IN THE CENTRAL CARIBBEAN SEA NEAR THE COAST OF COLOMBIA
NEAR 12N71W TO THE COSTA RICA/HONDURAS BORDER NEAR 11N84W. NO
INTERTROPICAL CONVERGENCE ZONE AXIS IS EVIDENT IN THE ATLANTIC
OCEAN. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION IS
WITHIN 120 NM EITHER SIDE OF THE MONSOON TROUGH W OF 74W.

...DISCUSSION...

GULF OF MEXICO...
THE MAIN AREA OF INTEREST IN THE GULF IS RECENTLY UPGRADED
TROPICAL STORM LEE AS DESCRIBED ABOVE IN THE SPECIAL FEATURES
SECTION. EXPERIMENTAL NHC RAINFALL GRAPHICS FORECAST MAXIMUM
RAINFALL AMOUNTS OVER 15 INCHES IN SE LOUISIANA DURING THE NEXT
24 HOURS. THE LATEST HPC FORECAST IS 10-15 INCHES OVER SOUTHERN
LOUISIANA...SOUTHERN MISSISSIPPI AND SOUTHERN ALABAMA THROUGH
SUNDAY WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 20 INCHES.
THESE RAINS ARE EXPECTED TO CAUSE EXTENSIVE FLOODING...
ESPECIALLY IN URBAN AREAS. TROPICAL STORM FORCE WINDS ARE
EXPECTED TO REACH LAND IN THE TROPICAL STORM WARNING AREA IN THE
LATE AFTERNOON OR EVENING. A STORM SURGE OF 2-4 FT ABOVE GROUND
LEVEL IS EXPECTED ALONG THE NORTHERN GULF COAST IN AREAS OF
ONSHORE FLOW...AND DANGEROUS RIP CURRENTS ARE ALSO LIKELY ALONG
THE NORTHERN GULF COAST. ISOLATED TORNADOES AREA POSSIBLE OVER
PORTIONS OF SOUTHERN LOUISIANA TONIGHT. REFER TO FLOOD PRODUCTS
AND HURRICANE LOCAL STATEMENTS ISSUED BY LOCAL NWS FORECAST
OFFICES FOR MORE DETAILED INFORMATION ON THESE THREATS.

THE HEAVY RAINFALL WILL ALSO DIMINISH VISIBILITIES BELOW 5 NM
OVER THE N CENTRAL GULF CREATING AN ADDITIONAL HAZARD FOR
MARINERS.

CARIBBEAN SEA...
A 1114 UTC WINDSAT SCATTEROMETER PASS CAPTURED NE-E 15-20 KT
WINDS OVER THE CENTRAL CARIBBEAN PRODUCING SEAS TO 8 FT NEAR THE
COAST OF COLOMBIA. THESE STRONGER WINDS ARE DUE TO A TIGHT PRES
GRADIENT BETWEEN AN ABNORMALLY NORTHWARD MONSOON TROUGH IN THE
SW CARIBBEAN AND RIDGING NE OF THE AREA. WINDS ARE EXPECTED TO
DIMINISH TO 5-15 KT ACROSS THE BASIN THIS WEEKEND AS THE REGION
WILL BE UNDER WEAK FLOW CAUGHT BETWEEN HURRICANE KATIA NE OF THE
AREA AND TROPICAL STORM LEE NW OF THE AREA. THE DIMINISHING
WINDS WILL ALSO ALLOW FOR SEAS TO SUBSIDE TO 2-4 FT ACROSS THE
MAJORITY OF THE BASIN THIS WEEKEND...LOCALLY TO 5 FT NEAR THE
COAST OF COLOMBIA.

ATLANTIC OCEAN...
THE MAIN AREA OF INTEREST IN THE ATLANTIC OCEAN IS HURRICANE
KATIA AS DESCRIBED IN THE SPECIAL FEATURES SECTION ABOVE. OTHER
THAN THE CONVECTION DESCRIBED ABOVE...SCATTERED MODERATE
CONVECTION IS FROM 06N-10N E OF 23W WHERE SW MONSOONAL FLOW IS
CONVERGING NEAR THE COAST OF AFRICA. A NEARLY STATIONARY 1025 MB
AREA OF HIGH PRES IS CENTERED JUST N OF THE AREA NEAR 33N39W
WITH BROAD RIDGING AND MAINLY FAIR WEATHER IN PLACE OVER THE
AREA N OF 26N E OF 60W. A CONVERGENCE AXIS EXTENDS FROM NEAR
BERMUDA TO THE S-SW NEAR 25N69W. SCATTERED MODERATE CONVECTION
IS OCCURRING WITHIN 120-180 NM E OF THIS FEATURE. A SURFACE
TROUGH EXTENDS FROM 1011 MB CENTERED NEAR 32N68W TO 29N77W.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING WITHIN 60-90
NM EITHER SIDE OF THIS TROUGH. THIS TROUGH WILL LINGER IN THE SW
N ATLANTIC THROUGH SAT DISSIPATING ON SUN.

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

$$
LEWITSKY





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