[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 302343
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 30 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS NEAR 29W S OF 21N MOVING W ABOUT 10 KT WITH
A 1011 MB LOW NEAR 14N29.5W. THIS WAVE STILL APPEARS TO BE
INTO FAR ATLANTIC MONSOON CYCLONIC GYRE THAT IS OBSERVED FROM
10N-18N BETWEEN 27W-34W. CONVECTION REMAINS VERY MINIMAL WITH
ONLY ISOLATED SHOWERS AND TSTMS WITHIN 150 NM NW OF THE LOW.
BROKEN LOW AND MID CLOUDS WITH ISOLATED SHOWERS ARE SEEN WITHIN
300 NM W OF THE WAVE.

TROPICAL WAVE IS ALONG 52W/53W S OF 18W MOVING W 15 KT WITH A
1010 MB LOW ON THE WAVE AXIS NEAR 11N53W. RECENT SATELLITE
IMAGERY SHOWS THAT THE OVERALL CLOUD STRUCTURE OF THIS WAVE
HAS BECOME BETTER DEFINED WITH MORE REPRESENTATION OF CYCLONIC
TURNING NOTED IN THE LOW CLOUDS SWIRLING INTO THE LOW. SCATTERED
MODERATE TO STRONG CONVECTION IS WITHIN 120 NM NE OF THE LOW.
ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE WITHIN 180 NM W OF
THE WAVE FROM 11N-14N. THE CIMSS 850 MB WAVETRACKER CONTINUES TO
VERY WELL DISPLAY 850 MB VORTICITY ASSOCIATED WITH THE LOW AS
IN PREVIOUS DAYS. THIS SYSTEM HAS THE POTENTIAL TO BECOME A
TROPICAL DEPRESSION OVER THE NEXT COUPLE OF DAYS AS IT NEARS
THE EASTERN CARIBBEAN SEA.

TROPICAL WAVE IS ALONG 75W/76W S OF 23N MOVING W 10-15 KT. LAST
VISIBLE SATELLITE IMAGERY SHOWED SOMEWHAT OF A GRADUAL INVERTED
V SHAPE PATTERN TO THE LOW CLOUD FIELD ASSOCIATED WITH THE
WAVE N OF 13N BETWEEN 74W-77W WHICH WAS DIFFICULT TO SEE
24 HOURS AGO. THE NORTHERN PART OF THE WAVE CONTINUES TO BE
MASKED BY THE UPPER LEVEL TROUGH NNE OF HISPANIOLA. SCATTERED
MODERATE CONVECTION IS SEEN WITHIN 120 NM W OF THE WAVE AXIS
FROM 14N-16N...WHILE ISOLATED SHOWERS AND TSTMS ARE ELSEWHERE
WITHIN 180 NM W OF THE WAVE S OF 17N.

THE TROPICAL WAVE THAT MOVED ACROSS THE BAY OF CAMPECHE THE PAST
18-24 HRS IS NOW ANALYZED AS A 1012 MB LOW JUST INLAND THE
MEXICAN COAST NEAR 20N96W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 120 NM NE OF THE LOW. LOW LEVEL CLOUDS
MOVING NW ARE SEEN FEEDING INTO THIS SYSTEM OFF THE WESTERN
YUCATAN PENINSULA.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N16W 14N28W 9N35W 10N45W 11N53W
TO INLAND S AMERICA NEAR 9N63W. IN ADDITION TO CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 33W-37W.
ISOLATED SHOWERS AND TSTMS ARE WITHIN 120 NM S OF THE AXIS
BETWEEN 45W-50W.

DISCUSSION...
GULF OF MEXICO...
UNSETTLED WEATHER COVERS MUCH OF THE SW AND S/CENTRAL PORTIONS
OF THE GULF PRIMARILY DUE TO THE AFOREMENTIONED 1012 MB LOW NEAR
20N96W AND AND ABUNDANT MID/UPPER LEVEL TROPICAL MOISTURE BEING
CHANNELED ENE TO THE EAST OF THE LOW UNDER A WEAK UPPER
DIFFLUENT PATTERN ASSOCIATED WITH MID/UPPER LEVEL TROUGHING
THAT STRETCHES FROM NEAR SE LOUISIANA SOUTHWESTWARD TO 23N96W.
ASSOCIATED CONVECTION IS DESCRIBED ABOVE UNDER TROPICAL WAVES
WITH 1012 MB LOW. WEAK ANTICYCLONIC FLOW COVERS THE GULF TO THE
W OF THE MID/UPPER LEVEL TROUGH. LIGHT TO MODERATE WINDS WITH
THE RIDGE ARE SPREADING UPPER LEVEL DEBRIS CLOUDINESS FROM
SCATTERED MODERATE CONVECTION OCCURRING ALONG AND INLAND THE
TEXAS COAST SOUTHWESTWARD TOWARDS SOUTHERN TEXAS AND NORTHERN
MEXICO. BROKEN TO SCATTERED LOW AND MID LEVEL CLOUDS WITH
SCATTERED SHOWERS AND ISOLATED TSTMS ARE ELSEWHERE S OF 26N AND
WEST OF 85W. SCATTERED LOW CLOUDS WITH ISOLATED SHOWERS AND
TSTMS ARE OVER THE REMAINDER OF THE GULF W OF 84W. PRECIP
POTENTIAL GUIDANCE INDICATES THAT UNSETTLED WEATHER CAN BE
EXPECTED FOR THE MUCH OF THE WESTERN GULF DURING THE NEXT 2-3
DAYS AS TROPICAL MOISTURE ATTENDING THE TROPICAL WAVE AND UPPER
LEVEL DIFFLUENT FLOW TO THE E OF THE WAVE CONTINUE TO PRODUCE
SCATTERED SHOWERS AND TSTMS OVER THIS PART OF THE GULF.

CARIBBEAN SEA...
BROAD MID/UPPER LEVEL RIDGING COVERS THE NORTHWEST PORTION OF
THE CARIBBEAN W OF LINE FROM WESTERN CUBA TO HONDURAS. THE
SOUTHERN EXTENSION OF AN ATLANTIC MID/UPPER LEVEL TROUGH
STRETCHES SOUTHWESTWARD INTO THE CARIBBEAN ACROSS HISPANIOLA TO
15N75W. ASSOCIATED BROAD CYCLONIC FLOW COVERS THE AREA S OF 18N
BETWEEN 70W-79W. THE MID/UPPER FLOW IS GENERALLY CONFLUENT
BETWEEN THE ANTICYCLONE AND THE TROUGH ADVECTING A NLY SURGE OF
SOMEWHAT DRIER WSW OVER THE WESTERN CARIBBEAN. AN UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED OVER VENEZUELA NEAR 8N65W
EXTENDS A RIDGE NORTHWESTWARD THROUGH 10N69W TO 13N72.5W.
MID/UPPER SATELLITE-DERIVED WINDS INDICATE THAT UPPER LEVEL NLY
WINDS ARE PRETTY LIGHT OVER THE THE CARIBBEAN...EXCEPT FOR THE
WESTERN PORTION W OF 82W WHERE UPPER NLY WINDS ARE STRONGER AS
WELL AS OVER THE FAR SW PORTION OF THE SEA. MOST OF THE EASTERN
AND REMAINDER OF THE CENTRAL CARIBBEAN ARE UNDER RATHER DRY AIR
AS AMPLE MODERATE TO STRONG SUBSIDENCE SPREADS INTO THE SEA FROM
THE ATLANTIC BASIN. ONLY SCATTERED LOW CLOUDS MOVING WESTWARD
ABOUT 15 KT WITH ISOLATED SHOWERS ARE FOUND THROUGHOUT THIS PART
OF THE CARIBBEAN...WITH THE EXCEPTION OF S OF 14N WHERE AMPLE
UPPER LEVEL DEBRIS MOISTURE FROM CONVECTION OVER THE NORTHERN
PORTION OF S AMERICA IS SPREADING NORTH-NORTHEASTWARD IN
ANTICYCLONIC DUE TO THE RIDGE OVER S AMERICA.

ATLANTIC OCEAN...
MID/UPPER LEVEL TROUGH EXTENDS FROM 32N55W SOUTHWESTWARD TO
25N61W WHERE IT IS THEN IDENTIFIED AS MID/UPPER LEVEL SHEAR AXIS
SOUTHWESTWARD THROUGH 23N63W TO SMALL AND WEAK MID/UPPER LEVEL
CYCLONIC CIRCULATION NEAR 21N65W...AND CONTINUES SOUTHWESTWARD
FROM THERE TO HISPANIOLA. TO THE W OF THE TROUGH...THE MID/UPPER
FLOW BECOMES ANTICYCLONIC FLOW WESTWARD TO THE BAHAMAS AND
FLORIDA...EXCEPT FOR THE AREA N OF 25N BETWEEN 70W-75W WHERE
WEAK MID/UPPER LEVEL TROUGHING IS FOUND. A 1010 MB NEARLY
STATIONARY SURFACE LOW MOVING SSE 10 KT IS NEAR 30.5N 76W WITH
AN ATTENDED TROUGH SW TO THE WESTERN BAHAMAS. ISOLATED MODERATE
CONVECTION IS NOTED WITHIN 180 NM TO THE E AND SE OF THE LOW AND
TROUGH. SCATTERED LOW CLOUDS WITH ISOLATED SHOWERS AND TSTMS
MOVING S ARE N OF THE BAHAMAS...WHILE SIMILAR CLOUDS ALSO WITH
ISOLATED SHOWERS AND TSTMS ARE SEEN MOVING N TO THE E OF THE
BAHAMAS TO 60W. THE LOW IS FORECAST TO BEGIN TO MORE MORE E AND
ENE OVER THE NEXT 3-4 DAYS.

THE MID/UPPER LEVEL FLOW BECOMES ANTICYCLONIC TO THE EAST OF THE
TROUGH N OF 15N BETWEEN THE TROUGH AND 48W WITH AN UPPER LEVEL
ANTICYCLONE CENTERED NEAR 23.5N53W. MODERATE SUBSIDENCE AND
ASSOCIATED DRY AIR IS FOUND HERE WITH SURFACE HIGH PRES NOTED
N OF 16N AND E OF 66W. A WEAK UPPER LEVEL TROUGH EXTENDS SSW
INTO THE AREA THROUGH 32N39W...AND EXTENDS SW THROUGH 25N43W TO
NEAR 20N48W. PATCHES OF LOW AND MID LEVEL CLOUDS MOVING WESTWARD
WITH EMBEDDED ISOLATED SHOWERS ARE SEEN N OF 19N E OF 50W. BROAD
MID/UPPER LEVEL RIDGING COVERS THE FAR EASTERN PORTION OF THE
ATLANTIC EAST OF ABOUT 40W. A WEAK UPPER ANTICYCLONE MOVING
WESTWARD IS SEEN ON SATELLITE WATER VAPOR IMAGERY TO BE NEAR
13N43W. DEEP TROPICAL MOISTURE...MOSTLY IN THE FORM OF MID AND
HIGH CLOUDS...ORIGINATING FROM AFRICA IS SEEN ADVECTING WESTWARD
IN DEEP EASTERLY FLOW OFF THE COAST OF AFRICA AND TO FAR EASTERN
ATLANTIC. NEXT POSSIBLE TROPICAL WAVE TO EMERGE OFF THE AFRICAN
COAST SHOULD TAKE PLACE IN ABOUT 2 DAYS.

$$
AGUIRRE




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