[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301806
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 30 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION KATRINA WELL N OF THE AREA WAS DOWNGRADED
FROM TROPICAL STORM STATUS AT 1500 UTC AND IS LOCATED NEAR 36.3N
87.5W OR ABOUT 25 MILES SOUTH OF CLARKSVILLE TENNESSEE. THE
DEPRESSION IS MOVING NNE AT 18 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 985 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH
GUSTS TO 40 KT. THE LAST ADVISORY ON THIS SYSTEM WAS ISSUED AT
1500 UTC.

A BROAD 1008 MB ATLC TROPICAL SURFACE LOW IS CENTERED NEAR
12N37W MOVING WNW 10-15 KT. THIS LOW HAS NOT BECOME BETTER
ORGANIZED DURING THE PAST 24 HOURS...BUT MAY BECOME BETTER
ORGANIZED DURING THE NEXT 48 HOURS AS UPPER LEVEL CONDITIONS
BECOME MORE FAVORABLE. CLUSTERS OF SCATTERED MODERATE TO STRONG
CONVECTION ARE WITHIN 360 NM NE QUADRANT...240 NM NW QUADRANT
OF THE LOW CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 45 NM RADIUS OF 17N34W AND 30 NM RADIUS OF 16.5N31W.
WIDELY SCATTERED MODERATE CONVECTION IS ELSEWHERE WITHIN 300 NM
OVER S SEMICIRCLE.

...TROPICAL WAVES...

A 1013 MB LOW...FORMERLY T.D. THIRTEEN...IS LOCATED SEVERAL
HUNDREDS MILES SE OF BERMUDA NEAR 24N54W 1013 MB MOVING W 10 KT.
SCATTERED STRONG CONVECTION IS WITHIN 480 NM NE AND 420 NM
NW OF THE LOW.

WEAK CARIBBEAN TROPICAL WAVE IS CENTERED ALONG 72W S OF 18N
MOVING W 10-15 KT. THIS WAVE EMBEDDED IN THE BROAD SYNOPTIC
ELY FLOW...AND CONTINUES TO SHOW NO VISIBLE SIGNATURE IN THE
LOW CLOUD MOTION AS OBSERVED ON SATELLITE IMAGERY. ISOLATED
MODERATE CONVECTION WITHIN 30 NM OF THE WAVE AXIS MAINLY N OF
16N.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 14N18W 16N35W 10N48W THEN SW TO
COAST OF S AMERICA NEAR 8.5N61W. SCATTERED STRONG CONVECTION
IS WITHIN 180 NM S AND 90 NM N OF THE ITCZ BETWEEN 17W-22W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM
OF THE AXIS BETWEEN 38W-41W.

...DISCUSSION...

GULF OF MEXICO...
WITH TROPICAL DEPRESSION NOW WELL N OF THE AREA...THE MAIN
FEATURE AFFECTING THE GULF...SOMEWHAT INDIRECTLY...IS A BROAD
ANTICYCLONIC CIRCULATION CENTERED JUST SE OF THE GEORGIA COAST
NEAR 32N82W.THE CIRCULATION AROUND THIS ANTICYCLONIC CIRCULATION
IS ADVECTING BROKEN HIGH CLOUDINESS WESTWARD ACROSS THE GULF
WITHIN 90 NM EITHER SIDE OF LINE 19N96W 25N90W TO ACROSS NE
FLORIDA. SATELLITE DERIVED UPPER LEVEL WINDS ARE FROM THE NE IN
THE RANGE OF 40-55 KT ARE NOTED WITHIN THIS AREA. SCATTERED
MODERATE CONVECTION IS SEEN WITHIN 30 NM OF LINE 24N86W 27N86W.
A LARGE MID/UPPER LEVEL TROUGH EXTENDS FROM THE CENTRAL UNITED
STATES S ACROSS TEXAS AND SE TO THE NW GULF TO NEAR 25N96W. FLOW
PATTERN BETWEEN THIS TROUGH AND THE ANTICYCLONIC CIRCULATION
NEAR 32N82W IS RESULTING IN CONFLUENT FLOW ACROSS THE NW GULF
WITH ASSOCIATED MODERATE SUBSIDENCE AND DRY AIR PUTTING A CAP IN
THE DEVELOPMENT OF OF SCATTERED CONVECTIVE ACTIVITY. THE TROUGH
IS FORECAST TO DAMPEN OUT THROUGH THE NEXT 48 HOURS AS THE
ANTICYCLONIC CIRCULATION BUILDS FURTHER W. TRAILING SURFACE
TROUGH EXTENDING SW FROM TROPICAL DEPRESSION KATRINA ENTERS THE
GULF FROM MOBILE ALABAMA SW ACROSS SE LOUISIANA TO 29N92W.
WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 45-60 NM OF THE
TROUGH.

CARIBBEAN SEA...
THE NW PORTION OF THE CARIBBEAN IS UNDER THE INFLUENCE OF STRONG
NE UPPER LEVEL WINDS GENERATED BY THE ANTICYCLONIC CIRCULATION
CENTERED NEAR 32N82W. THESE WINDS ARE ALSO BRINGING IN AMPLE
UPPER LEVEL MOISTURE TO ACROSS THE CARIBBEAN PRIMARILY N OF
16N W OF 71W. S AND E OF THIS AREA OF NE WINDS...AN INVERTED
MID/UPPER LEVEL TROUGH EXTENDS FROM NEAR 12N78W THROUGH 15N73W
TO 18N68W. THE TROUGH WILL MOVE W THROUGH THE NEXT 24-48 HOURS
BECOMING A MID/UPPER LEVEL CYCLONIC CIRCULATION THEREAFTER OVER
THE NW CARIBBEAN ENHANCING CONVECTION OVER THE NW CARIBBEAN.
TO THE E OF THE TROUGH...MID/UPPER LEVEL HIGH PRESSURE AND
ASSOCIATED MODERATE SUBSIDENCE BUILDS ACROSS THE CARIBBEAN FROM
E TO W. ELY SURGE IS BRINGING SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE WINDWARD ISLANDS. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS CONFINED TO THE SW CARIBBEAN S OF 12N W OF 77W.

ATLANTIC OCEAN...
THE ANTICYCLONIC CIRCULATION AROUND THE MID/UPPER LEVEL
ANTICYCLONE ANCHORED NEAR 32N82W IS ALSO RESULTING IN MODERATE
TO STRONG NE WINDS OVER THE AREA W OF 68W. SCATTERED TO BROKEN
OUTFLOW CIRRUS CLOUDS FROM KATRINA ARE BEING USHERED BY THE
MODERATE TO STRONG NE WINDS SOUTHWESTWARD INTO THE W ATLC. A
MID/UPPER LEVEL CYCLONIC CIRCULATION MOVING SW ABOUT 15 KT IS
NOTED NEAR 28N63W. A TROUGH EXTENDS SW FROM THE CIRCULATION TO
21N68W. AN AREA OF DIFFLUENCE E OF THE CYCLONIC CIRCULATION IS
PRODUCING SCATTERED STRONG CONVECTION N OF 26N BETWEEN 57W-60W.
TO ITS SE A MID/UPPER ANTICYCLONIC CIRCULATION IS LOCATED NEAR
22N54W. WIDELY SCATTERED TO ISOLATED MODERATE CONVECTION IS
WITHIN 90 NM OF THE ANTICYCLONIC CIRCULATION. RIDGE EXTENDS SW
FROM THE ANTICYCLONIC CIRCULATION SW THROUGH 19N60W INTO THE E
CARIBBEAN SEA NEAR 17N67W. BROAD MID/UPPER LEVEL HIGH COVERS THE
FAR E ATLANTIC E OF ABOUT 40W. STRONG SOUTHERLY UPPER LEVEL
WINDS ARE OCCURRING FROM 10N-20N BETWEEN 31W-40W. THESE WINDS
ARE PARTLY RESPONSIBLE FOR NOT ALLOWING THERE 1008 MB TROPICAL
LOW NEAR 12N37W FROM BECOMING BETTER ORGANIZED.
ELSEWHERE...MODERATE TO STRONG SUBSIDENCE AND DRY AIR COVERS
MUCH OF THE CENTRAL ATLANTIC WITH VERY MINIMAL SHOWER ACTIVITY
BEING NOTICED OUTSIDE FEATURES ALREADY MENTIONED.
OVER THE NE ATLC...A MID/UPPER LOW CONTINUES TO MOVE NE OUT OF
THE REGION AND NOW COVERS THE AREA N OF 30N E OF 30W. A MID/UPPER
LEVEL ANTICYCLONIC CIRCULATION IS JUST W OF THE AFRICAN COAST
NEAR 16N17W WITH RIDGING EXTENDING ALONG 16N W TO 40W.

$$
AGUIRRE


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