[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191755
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI SEP 19 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
1645 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS E OF THE CAPE VERDE ISLANDS ALONG 26W/27W S OF
18N MOVING W 5-10 KT. THIS WAVE IS BENEATH AN UPPER LEVEL RIDGE
AND NO CONVECTION IS NOTED WITH THIS WAVE.

TROPICAL WAVE IS ALONG 48W S OF 19N MOVING W NEAR 10 KT.
SCATTERED SHOWERS ARE WITHIN 60 NM OF THE WAVE AXIS FROM 13N-17N.

TROPICAL WAVE IS ALONG 63W S OF 20N MOVING W 5-10 KT. THIS WAVE
IS GENERATING CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION FROM 10N-16N BETWEEN 57W AND THE WAVE AXIS.

TROPICAL WAVE IS ALONG 73W S OF 19N MOVING W 5-10 KT. ISOLATED
SHOWERS ARE OCCURRING WITHIN 180 NM W OF THE WAVE AXIS S OF 18N.
THESE SHOWERS ARE BEING SUPPORTED BY AN UPPER LEVEL TROUGH
EXTENDING FROM CUBA TO THE CENTRAL CARIBBEAN.

TROPICAL WAVE IS ALONG 92W S OF 19N MOVING W NEAR 10 KT. WAVE IS
ALONG THE W COAST OF YUCATAN PENINSULA WITH ANY ASSOCIATED
CONVECTION INLAND OVER CENTRAL AMERICA AND THE E PACIFIC REGION.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 7N14W 8N29W 9N43W 10N55W 10N84W.
MODERATE CONVECTION IS FROM 3N-12N BETWEEN 16W-19W. SCATTERED
MODERATE CONVECTION IS FROM 10N-13N BETWEEN 58W-61W. CLUSTERS OF
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 10N-15N BETWEEN
75W-85W...ENHANCED BY UPPER LEVEL DIFFLUENCE E OF AN UPPER RIDGE
OVER THE W CARIBBEAN.

...DISCUSSION...

GULF OF MEXICO...
A WEAK SURFACE TROUGH IS OVER THE W GULF EXTENDING FROM 27N94W
TO 21N94W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS CONTINUE
TO DEVELOP OVER THE WESTERN GULF IN RESPONSE TO SURFACE
CONVERGENCE WITH THE TROUGH. A WEAKER SURFACE TROUGH IS FROM
29N87W TO 24N85W. UPPER LEVEL SUPPORT FROM AN UPPER LEVEL TROUGH
OVER THE SOUTHEAST CONUS AND N GULF IS ENHANCING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS ALONG THE FL AND AL
COASTLINE. AN UPPER LEVEL RIDGE EXTENDS FROM AN UPPER HIGH OVER
CENTRAL MEXICO TO THE NE BRINING MAINLY DRY NW FLOW TO MUCH OF
THE CENTRAL AND E GULF WHERE FAIR WEATHER CONDITIONS
PREDOMINATE.

CARIBBEAN SEA...
TWO TROPICAL WAVES ARE OVER THE CARIBBEAN SEA AND CENTRAL
AMERICA. SEE ABOVE. DIFFLUENCE IN NORTHERLY FLOW ALOFT IN THE SW
CARIBBEAN IS GENERATING SEVERAL CLUSTERS OF MODERATE WITH
ISOLATED STRONG CONVECTION S OF 16N W OF 75W TO INLAND OVER
CENTRAL AMERICA. MOIST SOUTHWESTERLY FLOW ALOFT OVER THE CENTRAL
AND E CARIBBEAN IN A BROAD UPPER LEVEL TROUGH THAT EXTENDS FROM
CENTRAL CUBA TO NICARAGUA IS PROMOTING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 15N W OF 75W TO INLAND OVER CENTRAL
AMERICA. THE SHOWER ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE
ALONG 63W IS MORE WIDESPREAD DUE TO LOW LEVEL SUPPORT E OF THE
TROPICAL WAVE ALONG 63W. DEEP LAYER DRY AIR OVER THE NW
CARIBBEAN IS LIMITING CONVECTION THERE.

ATLANTIC OCEAN...
TWO TROPICAL WAVES ARE OVER THE ATLANTIC OCEAN. SEE ABOVE. A
STATIONARY FRONT EXTENDS FROM A 1014 MB LOW NEAR 31N73W SW TO
26N79W. THIS FRONT CONTINUES TO WEAKEN...WITH NO CONVECTION
NOTED IN THE VICINITY OF THE FRONT. A PRE-FRONTAL SURFACE TROUGH
EXTENDS FROM 29N74W TO 24N79W WITH SCATTERED SHOWERS AND
THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF TROUGH AXIS INCLUDING
THE CENTRAL AND N BAHAMA ISLANDS. THIS ACTIVITY IS FURTHER BEING
ENHANCED BY SOUTHWESTERLY FLOW EAST OF AN UPPER LEVEL TROUGH
ALONG THE CONUS E COAST. AN UPPER LEVEL LOW NEAR 25N45W IS
GENERATING CLOUDINESS AND POSSIBLE ISOLATED SHOWERS WITHIN 100
NM OF THE LOW CENTER. AN UPPER TROUGH EXTENDING FROM A DEEP LOW
NEAR 34N19W IS BRINING CLOUDY CONDITIONS N OF 24N AND E OF 19W
ALONG THE NW AFRICAN COAST INCLUDING THE CANARY ISLANDS. IN THE
W TROPICAL ATLC SCATTERED MODERATE CONVECTION IS WITHIN 90 NM E
OF THE LESSER ANTILLES IN RESPONSE TO DIFFLUENCE W OF AN UPPER
HIGH CENTERED NEAR 12N54W. OTHERWISE...THE TYPICAL LARGE E/W
UPPER LEVEL RIDGE IS ACROSS THE REMAINDER OF THE TROPICAL ATLC
TO 40W BRINGING FAIR WEATHER TO THE CENTRAL AND E TROPICAL ATLC.

$$
COHEN/WALLACE



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