[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 021103
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT 02 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
TROPICAL STORM LISA WAS UPGRADED AGAIN TO HURRICANE AT 02/0900
UTC. HURRICANE LISA IS CENTERED NEAR 40.8N 40.5W OR ABOUT 600 NM
WNW OF THE AZORES AT 02/0900 UTC MOVING NE AT 21 KT. MAXIMUM
SUSTAINED WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 987 MB. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC FOR MORE
DETAILS. DESPITE BEING OVER VERY COOL WATERS...LISA REMAINS
IMPRESSIVE. LISA IS NOW CIRCLING AROUND A MID/UPPER LEVEL RIDGE.
ASSOCIATED DEEP CONVECTION STILL SURROUNDS THE WELL DEFINED EYE.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM OF
A LINE FROM 42N36W-40N42W.

...TROPICAL WAVES...
EASTERN MOST TROPICAL WAVE IS ALONG 33W/34W S OF 18N MOVING W
10-15 KT. WAVE REMAINS ALONG THE WESTERN EDGE OF A UPPER RIDGE
WHICH IS STILL OBSCURING THE SIGNATURE CURVATURE. ASSOCIATED
DEEP CONVECTION IS WELL E OF THE WAVE AXIS AND MAY BE DUE TO THE
UPPER RIDGE. SEE TROPICAL ATLANTIC BELOW.

MID ATLC TROPICAL WAVE IS ALONG 47W S OF 17N MOVING W 10-15 KT.
WEAK LOW LEVEL CIRCULATION REMAINS ALONG THE WAVE NEAR 11.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 10N-11N BETWEEN
45W-47W.

TROPICAL WAVE IS NOW OVER THE LESSER ANTILLES ALONG 61W/62W S OF
20N MOVING W 10-15 KT. THE N PORTION OF THIS WAVE IS BEING
ENHANCED BY THE UPPER LOW OVER THE CENTRAL ATLC. SCATTERED
SHOWERS/THUNDERSTORMS ARE FROM 13N-20N BETWEEN 58W-62W WHICH
INCLUDES PORTIONS  OF THE WINDWARD AND LEEWARD ISLANDS.

TROPICAL WAVE IN THE W CARIBBEAN IS ALONG 84W/85W S OF 19N
MOVING W 10-15 KT. WAVE IS INTERACTING WITH A STRONG UPPER LOW
WHICH IS ENHANCING THE SHOWERS/CONVECTION. SEE CARIBBEAN SECTION
BELOW.

...ITCZ...
ITCZ IS CENTERED ALONG 16N10W 9N26W 12N37W 11N59W 6N64W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 2N-14N BETWEEN 10W-44W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 14N-20N BETWEEN 27W-35W.

...DISCUSSION...
GULF OF MEXICO...
STRONG UPPER LEVEL HIGH IS CENTERED OFF THE TEXAS COAST NEAR
27N95W WITH RIDGE AXIS EXTENDING E ACROSS THE GULF TO THE
FLORIDA PENINSULA NEAR 28N83W. ANTICYCLONIC FLOW AND STRONG
SUBSIDENCE/DRY AIR COVERS THE GULF FROM 22N-30N. THIS HAS KEPT
MOST OF THE GULF SHOWER FREE. AN AREA OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS INLAND OVER E TEXAS ASSOCIATED
WITH A COLD FRONT NW OF THE REGION. CONVERGENT FLOW OVER THE
YUCATAN BETWEEN THE ANTICYCLONIC FLOW IN THE GULF AND THE
CYCLONIC FLOW FROM THE CARIBBEAN IS GENERATING SCATTERED
MODERATE/ISOLATED STRONG CONVECTION S OF 20N TO INLAND OVER S
MEXICO FROM 91W-94W.

CARIBBEAN SEA...
BROAD...STRONG MID/UPPER LOW OVER THE W CARIBBEAN IS THE PRIMARY
FOCUS TODAY. IT IS CENTERED ALONG THE TIP OF HONDURAS/NICARAGUA
NEAR 15N84W AND ENCOMPASSES THE AREA FROM 10N-24N BETWEEN
72W-90W. THIS LOW IS INTERACTING WITH A TROPICAL WAVE WHICH IS
GENERATING MULTILAYERED CLOUDS WITH SHOWERS AND AREAS OF DEEP
CONVECTION. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE
FROM 11N-15N BETWEEN 77W AND THE COAST OF NICARAGUA. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM ALONG THE
COAST OF HONDURAS E OF 87W. CLUSTERS OF SCATTERED SHOWERS/
THUNDERSTORMS DOT THE REMAINDER OF THE AREA FROM 65W-87W.

SUBTROPICAL ATLANTIC...
WEAK SHORTWAVE TROUGH IS OFF THE E U.S. COAST EXTENDING FROM
34N72W TO NEAR GRAND BAHAMA ISLAND. SMALL INDUCED UPPER LEVEL
HIGH IS OVER THE REMAINDER OF THE W ATLC CENTERED NEAR 27N70W
WITH MODERATE SUBSIDENCE PREVENTING SHOWERS OVER THE AREA. LARGE
UPPER LEVEL LOW IS IN THE CENTRAL ATLC NEAR 25N55W WITH CYCLONIC
FLOW FROM 15N-34N BETWEEN 50W-65W. THIS LOW IS AIDING THE
TROPICAL WAVE ENTERING THE CARIBBEAN IN GENERATING SHOWERS THAT
ARE MOVING OVER THE LEEWARD ISLANDS. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE DEVELOPING ALONG THE E SIDE OF THE UPPER LOW
WITHIN 60/75 NM OF LINE FROM 22N62W-24N57W-28N55W. THE TROUGH
OVER THE E ATLC EXTENDS FROM A UPPER LOW NEAR 30N23W WSW TO NEAR
25N40W. CYCLONIC FLOW IS N OF 23N FROM THE CANARY ISLANDS  TO
40W.

TROPICAL ATLANTIC...
UPPER LEVEL HIGH IS IN THE SW TROPICAL ATLC NEAR 4N45W WITH
ANTICYCLONIC FLOW S OF 11N FROM 38W-60W. STRONG SUBSIDENCE IS
PREVENTING SHOWERS FROM DEVELOPING S OF 10N BUT AN AREA
SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 10N-14N BETWEEN
51W-61W. THIS INTERACTION FROM STRONG UPPER LOW IN THE CENTRAL
ATLC. BROAD MID/UPPER LEVEL HIGH IS IN THE FAR SE ATLC 10N30W
WITH RIDGE AXIS EXTENDING NE TO 22N22W. ANTICYCLONIC FLOW IS S
OF 22N E OF 36W. EASTERN MOST TROPICAL WAVE IS ALONG THE WESTERN
EDGE OF THE FLOW WHICH IS AIDING IN THE GENERATION OF DEEP
CONVECTION.

$$
WALLACE



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