[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032323
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN 03 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...SPECIAL FEATURES...
NONE.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 42W/43W SOUTH OF 18N MOVING WEST NEAR 15
KT.  CONVECTION HAS INCREASED DURING THE LAST FEW HOURS WITH AN
AREA OF NUMEROUS STRONG ACTIVITY NOW FROM 16N-20N BETWEEN
34W-39W. HOWEVER...THE WAVE CONTINUES TO EXPERIENCE WESTERLY
SHEAR WAVE AND ASSOCIATED CONVECTION IS DISPLACED E OF THE AXIS
PREVENTING ORGANIZATION.

TROPICAL WAVE APPROXIMATELY 550 NM E OF BARBADOS ALONG 50W/51W
SOUTH OF 19N MOVING WEST 10 TO 15 KT.  THE WAVE IS LOCATED NEAR
THE W PERIPHERY OF A MID/UPPER LEVEL RIDGE WHICH IS PROVIDING A
DIVERGENT UPPER LEVEL PATTERN AND ENHANCING CONVECTIVE
ACTIVITY.  HOWEVER...WLY SHEAR IS PREVENTING ORGANIZATION.
SCATTERED MODERATE CONVECTION FROM 12N-15N BETWEEN 45W-52W.

TROPICAL WAVE OVER THE CENTRAL CARIBBEAN ALONG 71W SOUTH OF 20N
MOVING W NEAR 15 KT.  THE WAVE IS LOCATED WITHIN AN AREA OF
STRONG UPPER LEVEL WLY FLOW AND MODERATE SUBSIDENCE.  A SMALL
AREA OF SCATTERED SHOWERS ACCOMPANY THE WAVE FROM 14N-17N
BETWEEN 67W-73W.

TROPICAL WAVE OVER S MEXICO/W GUATEMALA ALONG 92W SOUTH OF 20N
MOVING WEST NEAR 15 KT. THE WAVE IS PRODUCING AN AREA OF
SCATTERED MODERATE CONVECTION OVER THE BAY OF CAMPECHE AND
COASTAL PORTIONS OF MEXICO FROM 18N-22N BETWEEN 94W-98W.

...ITCZ...
ITCZ IS CENTERED ALONG 10N15W 5N35W 11N50W 8N60W 11N70W 7N80W.
SCATTERED MODERATE CONVECTION FROM 4N-10N BETWEEN 25W-40W.
SIMILAR ACTIVITY FROM 7N-12N BETWEEN 42W-47W. WIDELY SCATTERED
MODERATE CONVECTION FROM 8N-12N BETWEEN 59W-64W.

...DISCUSSION...
THE GULF OF MEXICO...
LARGE MIDDLE TO UPPER LEVEL RIDGE DOMINATES THE GLFMEX EXTENDING
FROM CENTRAL MEXICO NEAR MEXICO CITY NEWD OVER FLORIDA.  THE
RIDGE IS PARTIALLY SPLIT IN THE UPPER LEVELS BY A WEAK TROUGH
EXTENDING FROM N FLORIDA TO THE CENTRAL GLFMEX NEAR 26N90W. THIS
FEATURE IS PRODUCING A FEW SHOWERS/THUNDERSTORMS OVER N FLORIDA
BUT IS OTHERWISE BENIGN.  FURTHER S...A TROPICAL WAVE OVER THE
BAY OF CAMPECHE IS PRODUCING SOME SHOWERS/THUNDERSTORMS WITHIN
100 NM OF THE COAST OF MEXICO FROM THE ISTHMUS OF TEHUANTEPEC TO
TAMPICO.  WIDELY SCATTERED SHOWERS/THUNDERSTORMS ARE ALSO NOTED
OVER THE SE GLFMEX IN ASSOCIATION WITH A WEAK LOW LEVEL TROUGH
EXTENDING FROM JUST N OF THE YUCATAN PENINSULA TO S FLORIDA.
ELSEWHERE...MODERATE TO STRONG SUBSIDENCE IS PRODUCING DRY
CONDITIONS.

THE CARIBBEAN SEA...
THE MAIN WEATHER MAKER CONTINUES TO BE A MID-UPPER LEVEL
LOW/TROUGH WHICH IS RETROGRADING ACROSS CENTRAL AMERICA INTO S
MEXICO AND THE E PACIFIC. WATER VAPOR IMAGERY INDICATES THAT THE
UPPER LOW IS DEGENERATING INTO A TROUGH AXIS ALONG 92W.
DIFFLUENT FLOW E OF THE TROUGH COUPLED WITH COPIOUS LOW LEVEL
MOISTURE IS PRODUCING AN IMPRESSIVE AREA OF NUMEROUS MODERATE TO
STRONG CONVECTION FROM 16N-20N BETWEEN 82W-90W INCLUDING BELIZE
AND THE YUCATAN PENINSULA.  SCATTERED SHOWERS/THUNDERSTORMS ALSO
COVER THE REMAINDER OF CENTRAL AMERICA AND THE SW CARIBBEAN
SEA.  THIS ENTIRE AREA HAS BEEN RAPIDLY SPREADING WESTWARD
DURING THE DAY AND THE MAIN AXIS OF MOISTURE SHOULD PUSH ACROSS
CENTRAL AMERICA/YUCATAN PENINSULA OVERNIGHT AND EXIT THE AREA
TOMORROW.  HOWEVER...NUMERICAL GUIDANCE INDICATES AN AREA OF
BROAD UPPER LEVEL DIVERGENT FLOW WILL REMAIN OVER THE NW
CARIBBEAN KEEPING SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE
AREA. ELSEWHERE...SHARP MID-UPPER LEVEL RIDGE EXTENDS FROM
COLOMBIA NW TO THE YUCATAN CHANNEL.  THE RIDGE DELINEATES
AVAILABLE MOISTURE AS A MODERATE SUBSIDENCE PREVAILS TO THE EAST
IN ASSOCIATION WITH A MID/UPPER LEVEL TROUGH OVER THE E
CARIBBEAN.  THE TROUGH HAS REMAINED ESSENTIALLY STATIONARY OVER
THE LAST 24 HOURS EFFECTIVELY SHEARING A TROPICAL WAVE MOVING
THROUGH THE CENTRAL CARIBBEAN AND KEEPING AN AREA OF CLOUDINESS
AND SHOWERS/THUNDERSTORMS OVER THE LESSER ANTILLES. WATER VAPOR
IMAGERY SHOWS A SHORTWAVE TROUGH DIVING INTO THE WESTERN SIDE OF
THE TROUGH WHICH SHOULD KEEP IT IN PLACE FOR ANOTHER 24 HOURS.

THE SUBTROPICAL ATLANTIC OCEAN...
LARGE MIDDLE TO UPPER LEVEL RIDGE PREVAILS OVER THE W ATLC
EXTENDING FROM FLORIDA NEWD OVER BERMUDA. THE RIDGE IS BLOCKING
UPSTREAM DYNAMICS AND MOISTURE KEEPING THE AREA W OF 60W UNDER
MODERATE SUBSIDENCE AND DRY/TRANQUIL CONDITIONS.  FURTHER
E...NEARLY STATIONARY MID/UPPER LEVEL TROUGH BETWEEN 55W-65W
CONTINUES TO PRODUCE CLOUDINESS AND SCATTERED SHOWERS/
THUNDERSTORMS OVER THE CENTRAL ATLC BETWEEN 50W-60W. THE
MAJORITY OF THIS ACTIVITY IS FOCUSED WITHIN 60 NM EITHER SIDE OF
A LINE FROM 20N56W TO 30N54W. OVER THE E ATLC...WELL DEFINED
MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM A LARGE CYCLONIC
CIRCULATION JUST W OF THE CANARY ISLANDS NEAR 29N22W SW TO
20N40W.  CONFLUENT FLOW AND MODERATE SUBSIDENCE COVERS THE AREA
POLEWARD OF THE TROUGH AXIS WITH DIFFLUENT FLOW AND A 50-70 KT
UPPER JET TO THE SOUTH PRODUCING EXTENSIVE HIGH CLOUDINESS AND
WIDELY SCATTERED SHOWERS WITHIN 200 NM EITHER SIDE OF A LINE
FROM 19N35W TO THE COAST OF W SAHARA.

THE TROPICAL ATLANTIC OCEAN...
WELL DEFINED MIDDLE TO UPPER LEVEL RIDGE OVER W AFRICA EMERGES
INTO THE E ATLC NEAR DAKAR EXTENDING SW TO 13N50W. THE RIDGE IS
DISRUPTED W OF 50W BY THE S EXTENT OF A TROUGH OVER THE CENTRAL
ATLC. DEEP ELY FLOW COVERS THE AREA S OF THE RIDGE.
HOWEVER...THE RIDGE HAS BEEN DISPLACED FURTHER S THAN USUAL WITH
STRONG WLY FLOW PENETRATING WELL INTO THE TROPICAL ATLC WATERS.
THIS PATTERN IS GENERALLY UNFAVORABLE FOR TROPICAL WAVE
DEVELOPMENT AND THE WAVES CURRENTLY MOVING ACROSS THE AREA ARE
STRONGLY SHEARED.

$$
RHOME



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