[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 302324
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT SEP 30 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...SPECIAL FEATURES...
HURRICANE ISAAC IS CENTERED NEAR 31.6N 59.5W AT 30/2100 UTC
MOVING NORTHWEST AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS
989 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85
KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. THE EYE HAS BECOME
BETTER DEFINED OVER PAST FEW HOURS HAS THE WINDS HAVE INCREASED.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 30N-34N
BETWEEN 58W-62W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 36W S OF 22N MOVING W 15 KT. WEAK
INVERTED-V SIGNATURE WITH A SMALL LOW LEVEL SWIRL ALONG THE N
PORTION OF THE WAVE AXIS. WAVE IS EMBEDDED WITHIN DRY AIR...THUS
NO SHOWERS/CONVECTION NOTED.

TROPICAL WAVE IS ALONG 62W/63W S OF 18N MOVING W 15 KT. WAVE HAS
PASSED THE LESSER ANTILLES MASKING THE TYPICAL INVERTED-V
SIGNATURE. CONVECTION IN THE AREA IS ASSOCIATED WITH UPPER LEVEL
FEATURES.

TROPICAL WAVE IS ALONG 72W MOVING W AT 15 KT. WEAK WAVE
INVERTED-V SIGNATURE WITH AFTERNOON THUNDERSTORMS FIRING UP OVER
HISPANIOLA IN RESPONSE TO THE PASSING OF THE WAVE AXIS AND DEEP
CONVECTION IS INLAND OVER COLOMBIA.

TROPICAL WAVE IS ALONG 95W/96W OVER S MEXICO AND THE E PACIFIC
REGION WITH SCATTERED SHOWERS EXTENDING OVER THE BAY OF CAMPECHE
S OF 20N FROM 93W-95W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N14W 7N23W 8N43W 10N62W. SCATTERED
CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM 2N-10N
BETWEEN 14W-35W.

...DISCUSSION...
GULF OF MEXICO...
DEEP LAYERED TROUGH COVERS THE E HALF OF THE US INTO THE GULF N
OF 26N WITH THE LEADING EDGE OF THE UPPER TROUGH AND ASSOCIATED
FRONTAL BOUNDARY IN THE W ATLC. A SHORTWAVE TROUGH AND SECOND
FRONTAL BOUNDARY ARE MOVING THROUGH THE UPPER MISSISSIPPI
VALLEY. BROAD UPPER RIDGE ANCHORED OVER CENTRAL AMERICA AND IN
THE E PACIFIC REGION COVERS THE REMAINDER OF THE S GULF. A
SURFACE RIDGE EXTENDS FROM THE NW ATLC ALONG THE US E COAST
COVERS THE GULF WITH A 1020 MB HIGH SITUATED OVER THE
MISSISSIPPI DELTA. THIS IS GIVING THE ENTIRE GULF FAIR
CONDITIONS THIS EVENING.

CARIBBEAN SEA...
BROAD UPPER RIDGE ANCHORED OVER CENTRAL AMERICA AND IN THE E
PACIFIC REGION COVERS THE W CARIBBEAN W OF 73W WITH AN EXTENSION
OF THE RIDGE EXTENDING ACROSS E CUBA INTO THE W ATLC. HEAVY
SHOWERS/SCATTERED THUNDERSTORMS COVER MUCH OF CUBA AND THE
SURROUNDING AREA INCLUDING JAMAICA AND THE CAYMAN ISLANDS WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE REMAINDER OF
THE NW CARIBBEAN. A 1008 MB LOW IS IN THE SW CARIBBEAN NEAR
11N79W AND WITH THE ITCZ AXIS THAT CROSSES INTO THE E PACIFIC
REGION IN THE VICINITY ARE GENERATING SCATTERED MODERATE/
ISOLATED STRONG CONVECTION S OF 12N FROM COLOMBIA TO CENTRAL
AMERICA. AN UPPER LOW IN THE NE CARIBBEAN IS S OF THE MONA
PASSAGE NEAR 16N68W COVERING THE REMAINDER OF THE CARIBBEAN WITH
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 15N BETWEEN
60W-68W INCLUDING THE WINDWARD ISLANDS.

ATLANTIC OCEAN...
DEEP LAYERED TROUGH OVER THE E US EXTENDS INTO THE W ATLC W OF
73W WITH THE ASSOCIATED COLD FRONT ENTERING THE AREA NEAR 32N68W
SW TO THE SE FLORIDA COAST NEAR MIAMI. A SURFACE PRE-FRONTAL
TROUGH EXTENDS FROM 26N74W ACROSS THE BAHAMAS TO OVER CENTRAL
CUBA. SCATTERED SHOWERS/THUNDERSTORMS COVER THE W ATLC W OF A
LINE FROM THE WINDWARD PASSAGE TO BEYOND 32N67W AND E OF 79W
WITH THE EXCEPTION OF SOME ISOLATED SHOWERS IN THE STRAITS OF
FLORIDA. JUST TO THE E IS A SURFACE TROUGH...PREVIOUSLY THE N
PORTION OF A TROPICAL WAVE IN THE CARIBBEAN...EXTENDS FROM
25N65W TO THE N COAST OF THE DOMINICAN REPUBLIC NEAR 19N69W WITH
ISOLATED SHOWERS FROM 22N-26N BETWEEN 62W 68W. A CUT-OFF UPPER
LOW IS IN THE CENTRAL ATLC NEAR 20N46W DRIFTING WESTWARD FROM
THE UPPER TROUGH IN THE E ATLC THAT IS N OF 20N FROM 27W-41W. A
WEAK SURFACE REFLECTION IN THE FORM OF A SURFACE TROUGH EXTENDS
FROM 26N45W-19N48W. HOWEVER...THE ENTIRE AREA FROM 30-60W IS
RATHER DRY THUS NO SHOWERS OR CONVECTION. BROAD UPPER RIDGE
COVERS THE E ATLC E OF 27W WITH A 1019 MB HIGH CENTERED W OF THE
CANARY ISLANDS NEAR 29N25W. DIFFLUENCE BETWEEN THE UPPER TROUGH
OF THE NE ATLC AND THE UPPER RIDGE IS GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS N OF 26N FROM 25W-31W.

$$
WALLACE






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