[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 171200
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI SEP 17 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

HURRICANE KARL IS CENTERED NEAR 19.6N 95.6W AT 17/1200 UTC OR
ABOUT 50 NM NE OF VERACRUZ MEXICO AND ABOUT 150 NM SE OF
TUXPAN MEXICO MOVING W AT 8 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 956 MB. MAXIMUM SUSTAINED WIND SPEED IS 105 KT WITH
GUSTS TO 130 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY
UNDER AWIPS/WMO HEADERS MIATCPAT3/WTNT33 AND THE FULL FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE
DETAILS. SCATTERED/NUMEROUS STRONG CONVECTION IS WITHIN 45 NM OF
THE CENTER OVER THE N SEMICIRCLE AND WITHIN 60 NM OF THE CENTER
IN OVER THE S SEMICIRCLE. SCATTERED MODERATE/STRONG CONVECTION
COVERS THE REMAINDER OF THE AREA FROM S OF 21N W OF 93W TO
INLAND OVER THE S MEXICO. KARL IS EXPECTED TO MAKE LANDFALL
LATER TODAY.

HURRICANE IGOR IS CENTERED NEAR 22.7N 59.8W AT 17/1200 UTC OR
ABOUT 730 NM SSE OF BERMUDA MOVING NW AT 8 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 935 MB. MAXIMUM SUSTAINED WIND SPEED IS 110
KT WITH GUSTS TO 135 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.
SCATTERED/NUMEROUS STRONG CONVECTION IS FROM 21N-23N BETWEEN
59W-61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS
THE REMAINDER OF THE AREA WITHIN 150 NM OF LINE FROM 20N55W TO
23N61W. OUTER RAINBANDS OF SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION ARE WITHIN 120 NM OF LINE FROM 15N55W 23N52W 27N56W
26N60W TO 22N61W.

HURRICANE JULIA IS CENTERED NEAR 23.8N 45.1W AT 17/0900 UTC OR
ABOUT 1260 NM SW OF THE AZORES MOVING WNW AT 21 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 981 MB. MAXIMUM SUSTAINED WIND SPEED
IS 75 KT WITH GUSTS TO 90 KT. SEE LATEST NHC FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
SCATTERED STRONG CONVECTION IS WITHIN 45 NM OF THE CENTER OVER
THE NW QUADRANT. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS COVERS THE REMAINDER OF THE AREA FROM 22N-25N BETWEEN
43W-46W.

...TROPICAL WAVES...

TROPICAL WAVE IS APPROACHING THE CAPE VERDE ISLANDS ALONG
20W/21W S OF 17N MOVING W 10-15 KT. SATELLITE IMAGERY SHOWS
BROAD CYCLONIC TURNING NEAR AND TO THE WEST OF THE WAVE AXIS
ALONG 13N. NO ASSOCIATED SHOWER ACTIVITY/CONVECTION.

...ITCZ...

THE ITCZ/MONSOONAL TROUGH REMAINS ACROSS THE ATLC BASIN FROM
10N23W 13N33W TO 11N46W. CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 10N-15N BETWEEN 22W-38W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 7N-11N BETWEEN 43W-47W.

...DISCUSSION...

GULF OF MEXICO...
THE PRIMARY CONCERN FOR THE S GULF OF MEXICO IS HURRICANE KARL
THAT COULD BECOME A MAJOR HURRICANE BEFORE MAKING LANDFALL LATER
TODAY OVER MEXICO...SEE SPECIAL FEATURES ABOVE. THE BROAD UPPER
RIDGE ASSOCIATED WITH KARL COVERS THE GULF PROVIDING DIFFLUENCE
ALOFT TO SUPPORT OUTER RAINBANDS WITH CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS COVERING MOST OF THE GULF WATERS
TO GULF COAST FROM LOUISIANA TO FLORIDA INCLUDING THE FLORIDA
KEYS AND TO INLAND OVER NE MEXICO. EMBEDDED WITHIN THIS UPPER
FLOW IS A WEAK SURFACE TROUGH THAT EXTENDS FROM ALONG 84W FROM
27N TO OVER TALLAHASSEE. A SHORTWAVE UPPER TROUGH REMAINS OVER E
TEXAS FROM SAN ANTONIO TO NEAR BROWNSVILLE GENERATING SCATTERED
SHOWERS/THUNDERSTORMS N OF 25N TO THE COAST OF LOUISIANA AND W
OF 89W TO INLAND OVER TEXAS.

CARIBBEAN SEA...
THE BROAD UPPER RIDGE ASSOCIATED WITH KARL REMAINS OVER THE W
CARIBBEAN W OF 80W BRINGING MOSTLY HIGH CLOUDS TO THE AREA WITH
SOME ISOLATED SHOWERS/THUNDERSTORMS DOTTING THE AREA N OF 16N W
OF 90W. AN UPPER RIDGE ANCHORED S OF HURRICANE IGOR IN THE W
TROPICAL ATLC IS GIVING THE E CARIBBEAN S TO SW FLOW ALOFT
INDUCING AN INVERTED UPPER TROUGH THAT EXTENDS FROM W COLOMBIA
NEAR 9N76W TO HAITI NEAR 18N72W. THE INVERTED TROUGH COUPLED
WITH THE CONVERGING SURFACE FLOW OVER THE SW CARIBBEAN IS
GENERATING ISOLATED SHOWERS/ISOLATED THUNDERSTORMS S OF 13N
BETWEEN 71W-83W. STRONG SUBSIDENCE WITH DRY STABLE AIR COVERS
THE CARIBBEAN N OF 13N BETWEEN 66W-80W GIVING THE AREA MOSTLY
CLEAR SKIES THIS MORNING.

ATLANTIC OCEAN...
HURRICANE IGOR REMAINS A CONCERN FOR THE ATLC WATERS THIS
MORNING WHILE BERMUDA BRACES FOR THIS LARGE AND DANGEROUS
HURRICANE...SEE SPECIAL FEATURES ABOVE. A SURFACE RIDGE REMAINS
OVER THE W ATLC. STRONG SUBSIDENCE AND DRY AIR ALOFT COVERS THE
W ATLC FROM 66W-80W GIVING THE AREA FAIR WEATHER THIS MORNING.
THE UPPER RIDGE ASSOCIATED WITH HURRICANE IGOR COVERS THE
CENTRAL ATLC FROM 16N-30N BETWEEN 50W-65W. HURRICANE JULIA IS
ABOUT TO ENCOUNTER AN UPPER LEVEL JET WHICH IS PART OF THE
OUTFLOW FROM IGOR AND SHOULD INDUCE SIGNIFICANT SHEAR THUS
WEAKENING JULIA. AN E/W UPPER RIDGE HAS ONCE AGAIN DOMINATED THE
E TROPICAL ATLC ALONG 20N TO 36W. THE FIRST VISIBLE SATELLITE
IMAGES SHOWS DRY SAHARAN AIR AND DUST COVERING THE E ATLC FROM
16N-26N E TO 38W WHICH IS JUST E OF HURRICANE JULIA.

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

$$
PAW





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