[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 291027
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 29 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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
1015 UTC.

...SPECIAL FEATURES...

KAREN IS HOLDING STEADY UNDER STRONG UPPER LEVEL SOUTHWESTERLY
FLOW AS A MINIMAL TROPICAL STORM OVER THE OPEN WATERS OF THE
CENTRAL ATLANTIC. AT 29/0900 UTC KAREN IS NEAR 16.6N 52.9W OR
ABOUT 590 MILES...950 KM...EAST OF THE LEEWARD ISLANDS...
MOVING WEST NORTHWEST NEAR 10 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1008 MB.  MAXIMUM SUSTAINED WINDS ARE 35 KT WITH
GUSTS TO 45 KT. SEE LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS.  KAREN HAS LITTLE
CONVECTION NEAR THE CENTER AND A LOT E OF THE CENTER.  A GRADUAL
WEAKENING IS FORECAST FOR THE NEXT FEW DAYS DUE TO THE
UNFAVORABLE UPPER WIND ENVIRONMENT.  SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 17N-19N BETWEEN 46W-53W...AND FROM
13N-17N BETWEEN 47W-51W.

TROPICAL STORM MELISSA AT 29/0900 UTC IS NEAR 14.1N 27.4W OR
ABOUT 260 MILES...420 KM...WEST-SOUTHWEST OF THE CAPE VERDE
ISLANDS MOVING WEST NEAR 2 KT.  ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1006 MB.  MAXIMUM SUSTAINED WINDS ARE 35 KT WITH
GUSTS TO 45 KT.  SEE LATEST NHC FORECAST ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE PUBLIC ADVISORY
UNDER MIATCPAT4/WTNT34 KNHC FOR MORE DETAILS.  THE CLOUD PATTERN
HAS REMAINED THE SAME FOR THE PAST 24 HOURS.  THE CENTER IS IS
ON THE W SIDE OF THE ELLIPTICAL SIZED CONVECTION AREA.  THE
SYSTEM IS FORECAST TO REMAIN A TROPICAL STORM FOR A FEW
DAYS...THEN DISSIPATE TO A REMNANT LOW BY 120 HOURS DUE TO
PERSISTENT VERTICAL SHEAR.  PRESENTLY SCATTERED MODERATE TO
STRONG CONVECTION IS FROM 13N-16N BETWEEN 25W-28W.

...TROPICAL WAVES...

A TROPICAL WAVE IS BETWEEN T.S. MELISSA AND T.S. KAREN ALONG 36W
SOUTH OF 20W MOVING W 10-15 KT.  THE WAVE SHOWS UP IN LOW LEVEL
SATELLITE DERIVED WINDS AND VORTICITY...AND THE UW CIMSS TPW
PRODUCTS WITH A LOW AMPLITUDE MOISTURE SURGE.  WIDELY SCATTERED
MODERATE CONVECTION IS FROM 4N-6N BETWEEN 30W-36W.

A TROPICAL WAVE IS OVER THE CARIBBEAN ALONG 83W S OF 21N MOVING
W NEAR 10-15 KT.  SCATTERED MODERATE CONVECTION IS ALONG THE
COAST OF NICARAGUA FROM 10N-12N BETWEEN 82W-84W.  THE WAVE IS
ALSO ENHANCING SCATTERED MODERATE CONVECTION OVER JAMAICA FROM
16N-18N BETWEEN 76W-79W.  MOISTURE FROM THIS WAVE WILL CONTINUE
TO AFFECT CUBA AND CENTRAL AMERICA TODAY.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 8N18W 12N25W 9N35W 13N50W
10N62W.  BESIDES THE CONVECTION MENTIONED ABOVE WITH TROPICAL
CYCLONES AND THE TROPICAL WAVE OVER THE EASTERN ATLANTIC...
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS ALONG THE
COAST OF W AFRICA FROM 10N-12N BETWEEN 16W-18W.

DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS OVER THE NORTHERN GULF WATERS FROM N FLORIDA TO
E TEXAS NEAR CORPUS CHRISTI ALONG 30N81W 29N90W 28N96W.  THE
FRONT IS DELINEATED BY A WIND SHIFT AND SLIGHT THERMAL COOLING.
NO SHOWERS OR CONVECTION ARE ALONG THE FRONT.  A SURFACE TROUGH
EXTENDS N/S OVER THE W GULF OF MEXICO ALONG 26N98W 20N97W.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 20N-27N BETWEEN
95W-98W.  THE REMAINDER OF THE GULF OF MEXICO HAS LIGHT ELY
SURFACE FLOW WITH MOSTLY FAIR WEATHER.  IN THE UPPER LEVELS...AN
UPPER HIGH WITH SIGNIFICANT UPPER LEVEL MOISTURE IS OVER THE W
GULF NEAR 23N94W WITH A RIDGE AXIS EXTENDING N TO LOUISIANA.
THE BASE OF A TROUGH WITH STRONG SUBSIDENCE IS OVER NE GULF AND
N FLORIDA N OF 27N AND E OF 90W.  THIS UPPER LEVEL TROUGH IS
HOSTING THE FRONTAL SYSTEM MENTIONED ABOVE.  EXPECT THE COLD
FRONT TO PUSH DOWN TO S FLORIDA DURING THE NEXT 24 HOURS.
EXPECT CONVECTION OVER S FLORIDA.  ALSO EXPECT ONSHORE FLOW TO
PRODUCE CONVECTION ALONG THE TEXAS COAST DURING THE NEXT 24
HOURS.

CARIBBEAN SEA...
A TROPICAL WAVE IS MOVING WWD ACROSS THE W CARIBBEAN WITH
CONVECTION. SEE TROPICAL WAVE SECTION.  SCATTERED MODERATE TO
STRONG CONVECTION IS INLAND OVER N COLOMBIA FROM 7N-10N BETWEEN
73W-76W.  TRADEWINDS REMAIN LIGHT TO MODERATE ACROSS THE BASIN.
IN THE UPPER LEVELS...A SMALL UPPER LEVEL LOW IS OVER THE NW
CARIBBEAN NEAR 19N83W.  AN UPPER LEVEL HIGH IS N OF COLOMBIA
NEAR 12N77W.  ANTICYCLONIC FLOW IS OVER THE CENTRAL AND EASTERN
CARIBBEAN.  SIGNIFICANT UPPER LEVEL MOISTURE AND BROKEN HIGH
CLOUDS COVERS THIS AREA.  EXPECT CONVECTION OVER MOST OF THE
CARIBBEAN AND CENTRAL AMERICA W OF 65W DURING THE NEXT 24 HOURS.

ATLANTIC OCEAN...
A SURFACE TROUGH IS OVER THE W ATLANTIC EXTENDING S TO CENTRAL
CUBA ALONG 30N76W 23N79W.  CLUSTERS OF ISOLATED MODERATE
CONVECTION IS E OF THE TROUGH AXIS FROM 22N-32N BETWEEN 70W-77W.
A 1022 MB HIGH IS OVER THE CENTRAL ATLANTIC NEAR 37N51W.
ANOTHER 1019 MB HIGH IS OVER THE E ATLANTIC NEAR 26N24W.  IN THE
UPPER LEVELS...A TROUGH IS OVER THE W ATLANTIC N OF 25N W OF
75W.  A RIDGE IS N OF 20N BETWEEN 70W-75W.  A LARGE UPPER LEVEL
LOW IS CENTERED OVER THE CENTRAL ATLANTIC NEAR 26N61W.  WLY FLOW
IS OVER THE E ATLANTIC N OF 20N E OF 40W.  A LARGE UPPER LEVEL
HIGH IS OVER THE TROPICS NEAR 12N35W.  ANTICYCLONIC FLOW IS FROM
EQ-20N BETWEEN 20W-50W.

$$
FORMOSA










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