[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061040
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

MID-OCEANIC TROPICAL WAVE IS ALONG 42W/43W S OF 17N MOVING W
10-15 KT. WAVE IS BEING INFLUENCING BY STRONG WESTERLIES WHICH
IS PRODUCING WESTERLY SHEAR ACROSS THE WAVE. THUS THE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE REMOVED TO THE E OF THE WAVE
FROM 10N-16N BETWEEN 30W-35W. CONDITIONS ARE EXPECTED TO REMAIN
UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT.

TROPICAL WAVE APPROACHING BARBADOS AND THE LESSER ANTILLES IS
ALONG 58W/59W 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. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE E OF
AXIS FROM 11N-21N BETWEEN 51W-55W. CONDITIONS ARE EXPECTED TO
REMAIN UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT.

W CARIBBEAN TROPICAL WAVE IS ALONG 87W/88W S OF 17N MOVING W 10
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. NUMEROUS STRONG CONVECTION IS OVER BELIZE S OF
17N W OF 88W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 30 NM
OF LINE FROM N BELIZE NEAR 18N88W OVER HONDURAS TO NEAR 15N84W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 16N10W 8N26W 10N41W 8N51W 10N63W.
SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75 NM OF LINE
9N23W-5N28W AND MOVING OFF THE COAST OF GUINEA BISSAU WITHIN 100
NM ALONG THE COAST. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 45 NM OF LINE FROM 6N15W TO INLAND OVER
SIERRA LEONE NEAR 8N12W. CLUSTERS OF SIMILAR CONVECTION ARE
WITHIN 90 NM OF LINE 11N46W TO THE COAST OF SOUTH AMERICA NEAR
GUYANA.

...DISCUSSION...

GULF OF MEXICO...
BUILDING MID/UPPER LEVEL RIDGE EXTENDS FROM OVER THE CARIBBEAN
ACROSS THE YUCATAN PENINSULA AND THE GULF INTO 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/NUMEROUS STRONG
CONVECTION W OF A SURFACE TROUGH THAT EXTENDS FROM
26N94W-18N94W. 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 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...CONDITIONS ARE DETERIORATING OVER THE E GULF AS
MID/HIGH CIRRUS ARE FANNING E ACROSS THE AREA TO INCLUDING
FLORIDA AND W CUBA.

CARIBBEAN...
DIVERGENT UPPER LEVEL FLOW AND DEEP TROPICAL MOISTURE REMAINS ON
THE W SIDE OF A SHARP RIDGE EXTENDING FROM PANAMA ACROSS THE
YUCATAN PENINSULA CONTINUING TO PRODUCE ENHANCED CONVECTIVE
ACTIVITY INLAND OVER CENTRAL AMERICA. OVER THE CENTRAL
CARIBBEAN...LARGE MID/UPPER LEVEL LOW JUST N OF PUERTO RICO
EXTENDS A TROUGH S TO THE COAST OF COLOMBIA NEAR 11N75W. THE
TROPICAL MOISTURE AND CONVECTION ARE BEING DRAWN S AT THE BASE
OF THIS UPPER TROUGH ALONG THE COAST OF PANAMA INLAND OVER N
COLOMBIA AND VENEZUELA. STRONG SUBSIDENCE/DRY AIR AT THE UPPER
LEVELS ON THE BACK/WEST SIDE OF THE TROUGH IS SUPPRESSING
CONVECTIVE ACTIVITY OVER MUCH OF THE GREATER ANTILLES AND THE
CENTRAL CARIBBEAN. SCATTERED LOW LEVEL SHOWERS ARE N OF 14N FROM
66W-76W. EAST OF THE TROUGH...DIVERGENT FLOW IS SUPPORTING
WIDELY SCATTERED SHOWERS OVER THE LESSER ANTILLES.

SUBTROPICAL ATLANTIC...
MID/UPPER LEVEL RIDGE EXTENDS FROM FLORIDA NE OVER THE W ATLC TO
NEAR 28N62W. 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 FROM 60W-78W ESPECIALLY JUST W OF AN UPPER LOW NEAR PUERTO
RICO. OVER THE CENTRAL ATLC...MID/UPPER LEVEL TROUGH EXTENDS
FROM 28N58W 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 LARGE CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 18N-27N
BETWEEN 47W-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 TO JUST S OF 20N RESTRICTING CONVECTIVE
ACTIVITY TO THE ITCZ WITHIN THE TROPICAL ATLC. AT THE
SURFACE...STRONG 1030 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. NEAR STATIONARY 1025 MB
HIGH IS POSITIONED OVER THE CENTRAL ATLC NEAR 35N46W WITH RIDGE
AXIS EXTENDING SE TO 22N30W.

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 43W AND 59W.

$$
WALLACE



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