[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251804
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 25 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
1715 UTC.

...SPECIAL FEATURE...

AN ATLANTIC OCEAN SURFACE 1010 MB LOW PRESSURE CENTER IS NEAR
14N35W AT 25/1200 UTC MOVING WEST 10 KT. THE TROPICAL WAVE HAS
BEEN ORIENTED FROM NORTHEAST-TO-SOUTHWEST FROM 16N34W TO THE
LOW CENTER TO 10N39W BASED ON VISIBLE SATELLITE IMAGERY. WIDELY
SCATTERED MODERATE SHOWERS AND ISOLATED STRONG THUNDERSTORMS
FROM 13N TO 17N BETWEEN 31W AND 37W. THIS WAVE AND LOW FEATURE
IS MOVING THROUGH THE AREA OF AN ALREADY-EXISTING MIDDLE TO
UPPER LEVEL LOW CENTER NEAR 16N45W...WITH A TROUGH WHICH EXTENDS
TO 10N50W. ITCZ SHOWERS AND THUNDERSTORMS FROM 7N TO 10N BETWEEN
42W AND 53W ARE BEING PUSHED NORTHWARD BEING ALONG THE EDGE OF
THE BASE OF THE TROUGH. IT IS POSSIBLE THAT THIS SYSTEM MAY
DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 36 TO 48 HOURS.

...TROPICAL WAVES...

EAST CARIBBEAN SEA TROPICAL WAVE ALONG 64W/65W SOUTH OF 20N
MOVING WEST 15 KT. SCATTERED MODERATE TO STRONG SHOWERS AND
THUNDERSTORMS FROM THE COAST OF NORTHERN SOUTH AMERICA TO 15N
BETWEEN 64W AND 69W. SCATTERED MODERATE TO ISOLATED STRONG
SHOWERS AND THUNDERSTORMS...PARTIALLY OR MOSTLY WITH THE ITCZ...
FROM 10N TO 13N BETWEEN 57W AND 63W.

CARIBBEAN SEA TROPICAL WAVE ALONG 75W SOUTH OF 19N MOVING
WEST 15 KT. IT IS NOT REALLY OBVIOUS THAT ANY OF THE SHOWERS
AND THUNDERSTORMS IN THE VICINITY OF THE WAVE NECESSARILY ARE
RELATED TO THIS WAVE. AN DEEP LAYER TROUGH CONTINUES FROM
EASTERN CUBA TO THE WEST CENTRAL CARIBBEAN SEA. PRECIPITATION
IN THE CENTRAL AND WEST-CENTRAL CARIBBEAN SEA PROBABLY ARE MORE
RELATED TO THE TROUGH THAN THE WAVE.

...ITCZ...

ITCZ 13N17W 12N24W 12N32W...9N40W 6N50W 6N60W. SCATTERED STRONG
SHOWERS AND THUNDERSTORMS FROM 8N TO 11N BETWEEN 23W AND 28W.
ISOLATED MODERATE SHOWERS ELSEWHERE FROM 7N TO 12N BETWEEN 20W
AND 28W. ISOLATED TO WIDELY SCATTERED MODERATE SHOWERS AND
THUNDERSTORMS FROM 7N TO 10N BETWEEN 37W AND 53W. WARMING CLOUD
TOP TEMPERATURES...CONVECTIVE DEBRIS CLOUDS...AND POSSIBLE
LINGERING SHOWERS ARE FOUND FROM 2N TO 8N EAST OF 15W.

...DISCUSSION...

THE GULF OF MEXICO...
SHOWERS HAVE FORMED IN SURFACE CONFLUENT FLOW...WITHIN 30 NM
ON EITHER SIDE OF THE LINE FROM THE SOUTHWESTERN CORNER OF THE
AREA NEAR 19N93W TO 22N94W TO 25N91W. A SURFACE RIDGE EXTENDS
FROM THE ATLANTIC OCEAN OFF THE GEORGIA COAST...INTO THE EAST
CENTRAL GULF OF MEXICO TO 24N94W. BROAD UPPER LEVEL ANTICYCLONIC
FLOW SPANS THE AREA. MIDDLE LEVEL CYCLONIC FLOW IS EMBEDDED IN
MIDDLE TO UPPER LEVEL DRY AIR...MOVING FROM CENTRAL TEXAS TOWARD
THE NORTHWESTERN GULF WATERS. MODEL GUIDANCE SUGGESTS THAT
A COLD FRONT COULD MOVE INTO THE N GULF WITHIN THE NEXT 48 HRS.
THIS WILL HAVE TO BE WATCHED FOR POSSIBLE DEVELOPMENT OF LOW
PRES ALONG THE TRAILING END OF THE FRONT LATER IN THE WEEK.

THE CARIBBEAN SEA...
THE SURFACE PRESSURE PATTERN IS WEAK. THE 1012 MB ISOBAR RUNS
FROM SOUTH AMERICA TO CENTRAL AMERICA...AND THEN EVENTUALLY
MOVING OVER ONLY THE NORTHWESTERN CORNER OF THE AREA. THE
1014 MB ISOBAR RUNS FROM THE SOUTHEASTERN CORNER TO THE NORTH
CENTRAL CARIBBEAN SEA...AND EVENTUALLY ACROSS WESTERN CUBA INTO
THE GULF OF MEXICO. THE COMPARATIVELY MUCH STRONGER-LOOKING AND
MORE DISCERNIBLE ATLANTIC-TO-CARIBBEAN SEA DEEP LAYER TROUGH
FROM 24 HOURS AGO IS IN MORE OR LESS THE SAME SPOT...EXCEPT FOR
HAVING SHIFTED WESTWARD A BIT IN SOME PLACES. A BIG UPPER LEVEL
RIDGE STILL IS EAST OF THIS DEEP LAYER TROUGH...FROM THE EASTERN
CARIBBEAN SEA NEAR 11N69W TO 20N60W BEYOND 32N54W IN THE
ATLANTIC OCEAN. THE DEEP LAYER TROUGH RUNS FROM NORTH OF THE
BAHAMAS NEAR 27N72W...ACROSS EASTERN CUBA...INTO THE WEST
CENTRAL CARIBBEAN SEA NEAR 14N82W. MIDDLE TO UPPER LEVEL
NORTHEASTERLY WIND IS IN THE NORTHWESTERN CORNER OF THE AREA...
BECOMING DIFFLUENT IN THE YUCATAN PENINSULA WITH RESPECT TO THE
UPPER LEVEL ANTICYCLONIC FLOW IN THE GULF OF MEXICO. THE EASTERN
CARIBBEAN SEA TROPICAL WAVE IS GENERATING SOME STRONG SHOWERS
AND THUNDERSTORMS NOW...AND MAY CONTINUE TO DO MUCH OF THE SAME
THING...FOR THE NEXT FEW DAYS.

THE ATLANTIC OCEAN...
THE DEEP LAYER ATLANTIC OCEAN-TO-CARIBBEAN SEA TROUGH OF 24 HOURS
AGO IS NOT AS WELL DEFINED IN THE WATER VAPOR IMAGERY AT THIS
MOMENT. THE DEEP LAYER TROUGH RUNS FROM NORTH OF THE BAHAMAS
NEAR 27N72W...ACROSS EASTERN CUBA...INTO THE WEST CENTRAL
CARIBBEAN SEA NEAR 14N82W. MIDDLE TO UPPER LEVEL NORTHEASTERLY
WIND IS IN THE NORTHWESTERN CORNER OF THE AREA...BECOMING
DIFFLUENT IN THE YUCATAN PENINSULA WITH RESPECT TO THE UPPER
LEVEL ANTICYCLONIC FLOW IN THE GULF OF MEXICO. A BIG UPPER LEVEL
RIDGE STILL IS EAST OF THIS DEEP LAYER TROUGH...FROM THE EASTERN
CARIBBEAN SEA NEAR 11N69W TO 20N60W BEYOND 32N54W IN THE
ATLANTIC OCEAN. THE MIDDLE TO UPPER LEVEL EASTERN ATLANTIC TROUGH
FROM 24 HOURS AGO REMAINS...THROUGH 33N34W TO 23N41W TO A LOW
CENTER NEAR 16N45W TO 10N50W. ANOTHER AREA OF MIDDLE TO UPPER
LEVEL CYCLONIC FLOW APPEARS TO BE FORMING...OR HAS FORMED...IN
THE AREA FROM 12N TO 21N BETWEEN 19W AND 26W.

$$
MT

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