[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041049
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT OCT 04 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 20W S OF 18N MOVING W NEAR 10 KT. WAVE IS
EMBEDDED WITHIN DEEP LAYERED MOISTURE AS INDICATED BY MIMIC TPW
ANIMATION. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE
FROM 11N-19N BETWEEN 17W-24W.

TROPICAL WAVE IS TILTED FROM 20N49W TO 10N51W BASED ON MIMIC TPW
ANIMATION... SATELLITE IMAGERY...AND LATEST QUIKSCAT PASS MOVING
W 10-15 KT. DEEP CONVECTION IS WELL E OF THE WAVE AXIS DUE TO
UPPER LEVEL FEATURES.

TROPICAL WAVE IS TILTED FROM 19N60W TO 9N61W MOVING W NEAR 10
KT. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE FROM 13N TO THE COAST OF SOUTH AMERICA BETWEEN 60W-64W WITH
ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE REMAINDER OF
THE WAVE.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 13N15W 14N21W 7N39W 13N52W
12N60W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE
WITHIN 180 NM N OF THE ITCZ FROM 24W-30W AND FROM 3N TO THE ITCZ
FROM 20W-43W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH IS MOVING INTO THE NW ATLC BUT CONTINUES
TO DOMINATE THE GULF WITH DRY STABLE AIR OVER THE GULF WATERS
WITH THE EXCEPTION OF S FLORIDA AND THE FLORIDA STRAITS S OF 25N
E OF 83W. THIS DEEP TROUGH CONTINUES TO SUPPORT A QUASI-
STATIONARY FRONT IN THE W ATLC INTO THE FLORIDA STRAITS WHERE A
1014 MB LOW HAS DEVELOPED NEAR 24N81W AND A SURFACE TROUGH
CONTINUING SW TO THE N COAST OF CUBA NEAR 23N83W AND GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 26N E OF 85W. LOW
LEVEL CONVERGENCE CONTINUES IN THE BAY OF CAMPECHE GIVING THE
AREA LOW CLOUDS AND POSSIBLE ISOLATED SHOWERS S OF 20N W OF 92W.
THE REMAINDER OF THE GULF REMAINS RATHER CLEAR AGAIN THIS
MORNING WITH DEW POINTS REMAINING IN THE 60 DEG RANGE ACROSS THE
GULF N OF 26N.

CARIBBEAN SEA...
A WEAK 1010 MB SURFACE LOW REMAINS IN THE NW CARIBBEAN NEAR
18N86W WITH AN UPPER RIDGE ANCHORED NEAR THE CAYMAN ISLANDS
COVERING THE NW CARIBBEAN. THIS UPPER RIDGE COUPLED WITH THE
DEEP LAYERED TROUGH OVER THE GULF OF MEXICO CONTINUES TO PROVIDE
MOIST UPPER FLOW OVER THE NW CARIBBEAN AND GENERATING SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ACROSS THE AREA W OF 77W TO OVER
CUBA AND CENTRAL AMERICA AND TO THE YUCATAN CHANNEL. AN UPPER
LOW IS S OF THE MONA PASSAGE NEAR 17N67W COVERING THE CENTRAL
CARIBBEAN BETWEEN THE LESSER ANTILLES AND 76W GENERATING
ISOLATED SHOWERS WITHIN 200 NM OF THE UPPER LOW. DIFFLUENCE
ALOFT IS GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS OVER THE S/CENTRAL CARIBBEAN S OF 15N TO INLAND
OVER COLOMBIA BETWEEN 70W-76W. THIS UPPER FLOW IS ALSO DRAWING
THE DRIER STABLE AIR FROM THE W ATLC OVER THE N/CENTRAL
CARIBBEAN.

ATLANTIC OCEAN...
DEEP LAYERED TROUGH OVER THE FAR E US CONTINUES TO MOVE OVER THE
NE ATLC AND THE CANADIAN MARITIMES CLIPPING THE W ATLC N OF 27N
W OF 74W WITH THE ASSOCIATED QUASI-STATIONARY FRONT ENTERING THE
REGION FROM A 1018 MB LOW NEAR 33N72W ALONG 28N75W EXTENDING
INTO THE FLORIDA STRAITS WHERE A 1014 MB LOW HAS DEVELOPED NEAR
24N81W AND A SURFACE TROUGH CONTINUES SW TO THE N COAST OF CUBA
NEAR 23N83W. DRY STABLE AIR REMAINS N OF 28N W OF 76W TO OVER
THE SE US WITH MOIST SW UPPER FLOW FROM THE CARIBBEAN ACROSS
CUBA GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF
27N W OF 77W TO INLAND OVER S FLORIDA AND ISOLATED SHOWERS
WITHIN 90 NM OF THE REMAINDER OF THE FRONTAL BOUNDARY. AN UPPER
RIDGE COVERS THE REMAINDER OF THE W ATLC ANCHORED NEAR 33N55W
SUPPORTING DRY STABLE AIR ACROSS THE W ATLC INTO THE CENTRAL
ATLC. AN UPPER LOW CONTINUES TO UNDERCUT THIS UPPER RIDGE
CENTERED IN THE CARIBBEAN S OF THE MONA PASSAGE AND COVERS THE
SW ATLC S OF 23N FROM 60W-75W INCLUDING THE TURKS AND CAICOS. A
SECOND CUT-OFF UPPER LOW IN THE CENTRAL ATLC IS CENTERED NEAR
23N49W GENERATING ISOLATED SHOWERS FROM 19N-26N BETWEEN 46W-51W.
A SURFACE TROUGH IS JUST TO THE N EXTENDING FROM 32N48W ALONG
28N49W TO 24N49W. DIFFLUENCE ALOFT TO THE SE OF THIS UPPER LOW
IS GENERATING SCATTERED MODERATE/STRONG CONVECTION WITHIN 90/120
NM OF LINE FROM 15N49W TO 19N39W AND SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM WITHIN 120 NM OF LINE FROM 20N42W TO 26N47W.
AN UPPER TROUGH IS OVER THE NE ATLC EXTENDING THROUGH 32N14W SW
TO 27N26W COVERING THE AREA N OF 24N FROM 27W TO OVER NW AFRICA.
THE TYPICAL E/W UPPER RIDGE AXIS EXTENDS FROM W AFRICA ALONG
14N16W TO NEAR 10N36W PUSHING THE ITCZ FURTHER TO THE SOUTH.

$$
WALLACE





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