[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 060535
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED 06 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS MID WAY BETWEEN AFRICA AND THE LESSER ANTILLES
ALONG 40W/41W S OF 17N MOVING W 10-15 KT. WAVE IS BENEATH THE
WESTERN PERIPHERY OF AN UPPER RIDGE WHICH IS PRODUCING WESTERLY
SHEAR ACROSS THE WAVE. THUS THE CONVECTION IS REMOVED TO THE E
OF THE WAVE. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 30N-16N BETWEEN 30W-38W. CONDITIONS ARE
EXPECTED TO REMAIN UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT.

TROPICAL WAVE IS LOCATED ABOUT 125 NM E OF BARBADOS ALONG
57W/58W S OF 25N MOVING W 10-15 KT. THE WAVE IS INTERACTING WITH
A MID/UPPER LEVEL TROUGH AND A MID/UPPER LEVEL RIDGE WHICH IS
PRODUCING A BROAD AREA OF CONVECTION AND SEVERAL AREAS OF
LOW-LEVEL ROTATION. THE CURRENT POSITION IS BASED ON CONTINUITY.
14N55W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION LOCATED E
OF AXIS FROM 12N-20N BETWEEN 50W-55W. CONDITIONS ARE EXPECTED TO
REMAIN UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT.

W CARIBBEAN TROPICAL WAVE IS ALONG 86W/87W S OF 20N MOVING W
10-15 KT. WAVE IS UNDER A MID/UPPER LEVEL RIDGE THAT EXTENDS
OVER CENTRAL AMERICA THUS IS PREVENTING ANY AREAS OF DEEP
CONVECTION IN THE CARIBBEAN. THE WESTERN COAST OF CENTRAL
AMERICA AND IN THE E PACIFIC REGION IS SUPPORTING AREAS OF
NUMEROUS STRONG CONVECTION BUT SCATTERED SHOWERS ARE ALL THAT
REMAIN OVER THE CARIBBEAN.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N10W 8N26W 10N37W 7N49W 10N65W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 75 NM OF
LINE 10N20W-7N23W AND 7N25W-4N27W. SCATTERED MODERATE
CONVECTION IS MOVING OFF THE COAST OF AFRICA WITHIN 75 NM OF
LINE 5N14W TO INLAND OVER LIBERIA AND SIERRA LEONE NEAR 7N12W.

...DISCUSSION...

GULF OF MEXICO...
BUILDING MID/UPPER LEVEL RIDGE EXTENDS FROM OVER THE CARIBBEAN
THROUGH THE YUCATAN CHANNEL ACROSS THE GULF AND THE SE UNITED
STATES AHEAD OF A DEVELOPING TROUGH OVER THE SW UNITED STATES
AND NW MEXICO. THIS PATTERN IS GENERATING UPPER LEVEL DIVERGENT
FLOW OVER THE W GULF AND PRODUCING SCATTERED TO NUMEROUS
SHOWERS/THUNDERSTORMS E OF A SURFACE TROUGH THAT EXTENDS FROM
25N94W-21N96W INTO THE BAY OF CAMPECHE TO 18N95W. ASSOCIATED
MOISTURE IS CURRENTLY SURGING N AND IS EXPECTED TO REMAIN OVER
THE W GULF DUE TO A STATIONARY FRONT WHICH CURRENTLY EXTENDS
ACROSS N FLORIDA ...THE MISSISSIPPI DELTA...TO S TEXAS DURING
THE NEXT 24 HOURS. AT THE SAME TIME...THE UPPER TROUGH OVER
MEXICO WILL BECOME INCREASINGLY AMPLIFIED WITH AN UPPER JET
FORMING OVER THE SE UNITED STATES. THIS WILL SET THE STAGE FOR A
RATHER UNSETTLED/STORMY PATTERN OVER THE NW GULF AND TEXAS COAST
TODAY INTO THURSDAY. ELSEWHERE OVER THE GULF...DRY TRANQUIL
CONDITIONS OF YESTERDAY ARE GIVING WAY TO HIGH CIRRUS FANNING E
ACROSS THE AREA TO INCLUDING FLORIDA AND W CUBA.

CARIBBEAN...
THERE HAS BEEN LITTLE CHANGE OVER THE CARIBBEAN DURING THE LAST
24 HOURS. DIVERGENT UPPER LEVEL FLOW AND DEEP TROPICAL MOISTURE
ON THE EQUATORWARD SIDE OF A SHARP RIDGE EXTENDING FROM PANAMA
THROUGH THE YUCATAN CHANNEL CONTINUES TO PRODUCE ENHANCED
CONVECTIVE ACTIVITY INLAND OVER CENTRAL AMERICA. WHILE THIS
ACTIVITY HAS BEEN PRIMARILY FOCUSED ALONG THE CARIBBEAN SIDE OF
CENTRAL AMERICA... THE OVERALL MOISTURE AXIS HAS MOVED WESTWARD
AND IS NOW OVER THE W COAST OF CENTRAL AMERICA INTO THE E
PACIFIC REGION. OVER THE CENTRAL CARIBBEAN...LARGE MID/UPPER
LEVEL LOW JUST N OF PUERTO RICO EXTENDS A TROUGH S TO THE COAST
OF COLOMBIA NEAR 11N74W. STRONG SUBSIDENCE/DRY AIR AT ALL LEVELS
ON THE BACK/WEST SIDE OF THE TROUGH IS SUPPRESSING CONVECTIVE
ACTIVITY OVER MUCH OF THE GREATER ANTILLES AND THE CENTRAL
CARIBBEAN. EAST OF THE TROUGH...DIVERGENT FLOW IS SUPPORTING
WIDELY SCATTERED SHOWERS/THUNDERSTORMS OVER THE LESSER ANTILLES.
NUMERICAL GUIDANCE INDICATES LITTLE OVERALL CHANGE IN THE LARGE
SCALE PATTERN DURING THE NEXT DAY OR TWO.

SUBTROPICAL ATLANTIC...
MID/UPPER LEVEL RIDGE EXTENDS FROM FLORIDA NE OVER THE W ATLC TO
NEAR 30N60W. THE RIDGE CONTINUES TO BLOCK UPSTREAM DISTURBANCES
KEEPING THE AREA W OF 60W UNDER FAIR WEATHER CONDITIONS.
ADDITIONALLY...STRONG SUBSIDENCE COVERS A GOOD PORTION OF THE
AREA W OF 60W ESPECIALLY JUST W OF AN UPPER LOW NEAR PUERTO
RICO. OVER THE CENTRAL ATLC...MID/UPPER LEVEL TROUGH EXTENDS
FROM 30N55W TO A STRONG MID/UPPER LOW JUST N OF PUERTO RICO.
INDUCED RIDGING AND DIVERGENT FLOW EAST OF THE TROUGH IS
PRODUCING A LARGE AREA OF CLOUDINESS WITH SCATTERED SHOWERS/
STRONG THUNDERSTORMS FROM 20N-30N BETWEEN 46W-59W. THE FLOW
BECOMES INCREASINGLY CONVERGENT OVER THE E ATLC IN ASSOCIATION
WITH A MID/UPPER LEVEL TROUGH EXTENDING FROM THE CANARY ISLANDS
TO 20N40W. ASSOCIATED SUBSIDENCE PENETRATES JUST S OF 20N
RESTRICTING CONVECTIVE ACTIVITY TO THE ITCZ WITHIN THE TROPICAL
ATLC. AT THE SURFACE...STRONG 1029 MB HIGH MIGRATING E OVER THE
E UNITED STATES IS PUSHING A COLD/STATIONARY FRONT OFF THE E
COAST OF THE UNITED STATES ROUGHLY HALFWAY IN BETWEEN THE NORTH
CAROLINA OUTER BANKS AND BERMUDA TO N FLORIDA. MOST OF THE UPPER
DYNAMICS WITH THIS FRONT ARE CONFINED N OF THE AREA AND ONLY A
FEW ISOLATED SHOWERS ACCOMPANY THE BOUNDARY. STATIONARY 1027 MB
HIGH IS POSITIONED OVER THE CENTRAL ATLC NEAR 35N43W WITH RIDGE
AXIS EXTENDING SE TO THE COAST OF AFRICA NEAR W SAHARA.

TROPICAL ATLANTIC...
MID/UPPER LEVEL TROUGH OVER THE SUBTROPICAL E ATLC PENETRATES
INTO THE TROPICAL ATLC JUST W OF THE CANARY ISLANDS WITH
ASSOCIATED SUBSIDENCE REACHING THE ITCZ E OF 40W. MID/UPPER
LEVEL RIDGE PREVAILS W OF 30W IS SUPPORTING EXTENSIVE ITCZ
RELATED CLOUDS/CONVECTION ESPECIALLY IN THE VICINITY OF TROPICAL
WAVES NEAR 40W AND 57W.

$$
WALLACE


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