[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 041747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 20W/21W SOUTH OF 20N
MOVING WEST 10 KT. ITCZ PRECIPITATION GOES FROM THE AREA OF
THE WAVE SOUTHWESTWARD. NO REALLY DISTINCT AREA OF CONVECTIVE
PRECIPITATION JUST ACCOMPANIES THIS WAVE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 47W/48W SOUTH OF 20N
MOVING WEST 10 TO 15 KT. THIS WAVE IS MOVING THROUGH THE AREA
OF A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER AND
AN ACCOMPANYING TROUGH. IT IS NOT EASY AT ALL TO DEFINE
ANY DEEP CONVECTIVE PRECIPITATION THAT EXISTS SOLELY BECAUSE
OF THIS TROPICAL WAVE. THIS WAVE HAS BEEN RE-POSITIONED BASED
ON THE MOVEMENTS OF LOW CLOUDS THAT ARE IN THE AREA.

A TROPICAL WAVE IS ENTERING THE EASTERN CARIBBEAN SEA IS ALONG
61W/62W SOUTH OF 19N MOVING WEST 10 KT. ISOLATED MODERATE
SHOWERS AND POSSIBLE THUNDERSTORMS ARE FROM 10N TO 16N BETWEEN
59W AND 62W. STRONG SHOWERS AND THUNDERSTORMS FROM 13N TO 16N
BETWEEN 63W AND 65W MORE LIKELY ARE ASSOCIATED WITH A 16N69W
CARIBBEAN SEA MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER.

...THE ITCZ...
12N21W 9N30W 8N40W 8N50W 8N60W. SCATTERED MODERATE TO STRONG
SHOWERS AND THUNDERSTORMS ARE WITHIN 120 NM TO 150 NM ON EITHER
SIDE OF 13N19W 8N30W 6N44W...BECOMING ISOLATED MODERATE SHOWERS
WITHIN 60 NM TO 90 NM ON EITHER SIDE OF 6N44W 7N53W 10N60W.

...DISCUSSION...

THE GULF OF MEXICO...AND THE ATLANTIC OCEAN WEST OF 70W
WITH A STATIONARY FRONT AND TROUGH...
THE MIDDLE TO UPPER LEVEL TROUGH THAT HAS BEEN MOVING THROUGH
MEXICO TOWARD THE GULF OF MEXICO DURING THE LAST FEW DAYS
HAS STALLED SOMEWHAT. MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW
ON THE EASTERN SIDE OF THE TROUGH PASSES THROUGH COASTAL MEXICO
NEAR 24N98W...ACROSS THE NORTHERN HALF OF THE GULF OF MEXICO...
AND BEYOND THE FLORIDA PANHANDLE...GEORGIA...AND SOUTH CAROLINA.
UPPER LEVEL ANTICYCLONIC FLOW MOVES FROM THE NORTHWESTERN
CARIBBEAN SEA AND THE YUCATAN CHANNEL...TO SOUTH FLORIDA
AND NORTHEASTWARD IN THE ATLANTIC OCEAN. DRY AIR IN SUBSIDENCE
IS PRACTICALLY EVERYWHERE EXCEPT NEAR THE UPPER LEVEL
ANTICYCLONIC FLOW. A STATIONARY FRONT PASSES THROUGH 32N71W
TO 27N76W TO A 1013 MB LOW PRESSURE CENTER NEAR 24N83W. A TROUGH
CONTINUES FROM THE 24N83W LOW CENTER TO THE NORTHEASTERN CORNER
OF THE YUCATAN PENINSULA...TO A NORTHWESTERN CARIBBEAN SEA
1011 MB LOW PRESSURE CENTER NEAR 18N86W. WIDELY SCATTERED
MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE WITHIN
60 NM TO 90 NM ON EITHER SIDE OF THE LINE THROUGH 32N69W 28N76W
25N79W...AND ELSEWHERE IN THE BAHAMAS WEST OF 78W...AND IN THE
SOUTHEASTERN GULF OF MEXICO SOUTH OF 26N EAST OF 88W.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL 16N69W CYCLONIC CIRCULATION CENTER IS
SPREADING CYCLONIC FLOW FROM 8N IN COLOMBIA AND VENEZUELA
TO 24N IN THE ATLANTIC OCEAN BETWEEN 60W AND 80W. MIDDLE TO
UPPER LEVEL DRY AIR IN SUBSIDENCE IS WRAPPING AROUND THE
CENTER...FROM THE ATLANTIC OCEAN JUST TO THE NORTHEAST OF THE
NORTHEASTERN CARIBBEAN SEA ISLANDS...TOWARD 24N70W...AND THEN
CURVING THROUGH THE WINDWARD PASSAGE...AND EVENTUALLY TOWARD
COLOMBIA AND VENEZUELA. STRONG SHOWERS AND THUNDERSTORMS ARE
FROM 13N TO 16N BETWEEN 63W AND 65W. ISOLATED TO WIDELY
SCATTERED MODERATE SHOWERS HAVE DEVELOPED ON THE SOUTHERN SIDE
OF THE CYCLONIC CENTER...BETWEEN IT AND THE COASTS OF COLOMBIA
AND VENEZUELA...BETWEEN 65W AND 76W. A 1011 MB LOW PRESSURE
CENTER IS IN THE NORTHWESTERN CORNER OF THE AREA NEAR 18N86W.
A TROUGH EXTENDS FROM THIS LOW CENTER...ALONG THE EASTERN COAST
OF THE YUCATAN PENINSULA AND THROUGH THE YUCATAN CHANNEL TOWARD
THE FLORIDA KEYS. STRONG SHOWERS AND THUNDERSTORMS ARE WITHIN
A 45 NM RADIUS OF 18N88W IN THE SOUTHEASTERN YUCATAN PENINSULA.
SCATTERED MODERATE TO STRONG SHOWERS AND THUNDERSTORMS IN
CLUSTERS HAVE DEVELOPED IN AN AREA OF UPPER LEVEL DIFFLUENT
FLOW...IN BETWEEN UPPER LEVEL ANTICYCLONIC FLOW MOVING TOWARD
THE YUCATAN CHANNEL...AND THE ADVANCING CYCLONIC FLOW AROUND
THE 16N69W CYCLONIC CENTER. ISOLATED MODERATE SHOWERS ARE
ELSEWHERE SOUTH OF 16N BETWEEN 78W AND CENTRAL AMERICA.

THE ATLANTIC OCEAN...
LARGE SCALE UPPER LEVEL ANTICYCLONIC FLOW FROM A RIDGE COVERS
THE AREA FROM NORTHEASTERN FLORIDA...WELL NORTH OF THE AREA
TO THE CANADIAN MARITIMES...AND SOUTHWARD TO 30N30W.
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR
23N51W. CYCLONIC FLOW COVERS THE AREA FROM 10N TO 30N BETWEEN
40W AND 60W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORMS ARE FROM 13N TO 18N BETWEEN 39W AND 57W. ISOLATED
MODERATE SHOWERS ARE FROM 20N TO 25N BETWEEN 45W AND 54W.
THE 47W/48W TROPICAL WAVE IS MOVING THROUGH THE AREA COVERED
BY CYCLONIC FLOW FROM THE 23N51W CYCLONIC CENTER. A 48W/49W
SURFACE TROUGH FROM 22N TO 32N DOES NOT APPEAR TO BE PRODUCING
MUCH IF ANY DEEP CONVECTIVE PRECIPITATION.

$$
MT


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