[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230458
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN SEP 23 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.

...SPECIAL FEATURE...
A 1009 MB LOW LOCATED 840 NM WSW OF THE AZORES NEAR 36N45W IS ON
THE VERGE OF BECOMING A SUBTROPICAL OR TROPICAL CYCLONE.
CONVECTION IS LOCATED IN A SPIRAL BAND AROUND THE LOW CENTER.
SCATTERED MODERATE CONVECTION IS WITHIN 160 NM OF THE CENTERED
IN THE W SEMICIRCLE AND N QUADRANT. THIS SYSTEM IS EXPECTED TO
MOVE LITTLE OVER THE NEXT 12 TO 24 HOURS THEN MOVE TO THE NE
OVER THE OPEN ATLC.

THE BROAD AREA OF LOW PRESSURE...ANALYZED AS A 1010 MB LOW IS
ABOUT 500 NM S OF THE CAPE VERDE ISLANDS NEAR 8N24W MOVING WNW
AT 15-20 KT. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION
ARE FROM 3N-13N BETWEEN 22W-30W. THIS SYSTEM REMAINS
WELL-ORGANIZED AND HAS THE POTENTIAL TO BECOME A TROPICAL
DEPRESSION DURING THE NEXT FEW DAYS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 34W S OF 17N MOVING W 15 KT. NARROW LOW
LEVEL INVERTED-V CURVATURE WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS EMBEDDED WITHIN THE ITCZ WITHIN 120 NM OF LINE
FROM 5N32W TO 8N38W.

TROPICAL WAVE IS ALONG 49W S OF 17N MOVING W 15-20 KT. BROAD
WAVE WITH A FAINT INVERTED-V CURVATURE. SCATTERED MODERATE/
STRONG CONVECTION IS W OF THE WAVE AXIS WITHIN 120 NM OF LINE
FROM 14N52W TO 9N56W.

TROPICAL WAVE IS IN THE CARIBBEAN ALONG 79W S OF 20N MOVING W 15
KT. WAVE IS BENEATH AN AREA OF STRONG UPPER NORTHERLY WINDS
BETWEEN AN UPPER RIDGE TO THE W AND AN UPPER LOW TO THE E. THIS
COUPLED WITH DRY STABLE AIR AT THE SURFACE IS LIMITING ANY
SHOWER ACTIVITY OR CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N16W THROUGH THE 1010 MB LOW IN
THE SPECIAL FEATURES THEN ALONG 7N28W 11N47W 8N62W. IN ADDITION
TO ACTIVITY ASSOCIATED WITH THE TROPICAL WAVES AND 1010 MB LOW
IN THE E TROPICAL ATLC...SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS MOVING OFF THE COAST OF W AFRICA FROM 11N-15N E OF
19W.

DISCUSSION...

GULF OF MEXICO...
BROAD UPPER LOW COVER THE W GULF CENTERED ALONG THE NE MEXICAN
COAST JUST S OF BROWNSVILLE TEXAS COVERING THE AREA W OF 90W.
BROAD UPPER RIDGE EXTENDS FROM THE YUCATAN CHANNEL/YUCATAN
PENINSULA OVER THE E GULF TO NE FLORIDA GENERATING DIFFLUENCE
AND ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE TO PRODUCE
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS E OF A LINE FROM THE
MISSISSIPPI COAST TO THE YUCATAN NEAR MERIDA. THIS IS LEAVING
THE REMAINDER OF THE GULF CLEAR TONIGHT.

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS THE W CARIBBEAN W OF 78W ANCHORED BY AN
UPPER HIGH IN THE GULF OF HONDURAS AND EXTENDING A RIDGE AXIS N
OVER THE E GULF OF MEXICO. A 1008 MB LOW IS OVER THE YUCATAN
NEAR N BELIZE WITH A WEAK SURFACE TROUGH EXTENDING JUST INTO THE
S GULF OF MEXICO. THIS LOW HAS THE POTENTIAL FOR SOME
DEVELOPMENT AFTER IT MOVES OVER OPEN WATER. THIS UPPER RIDGE IS
ALSO GENERATING DIFFLUENCE AND ADVECTING AN ABUNDANCE OF
TROPICAL MOISTURE TO PRODUCE CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS W OF 79W. AN UPPER LOW IS OVER THE
CENTRAL CARIBBEAN NEAR 14N73W COVERING THE AREA FROM 12N-18N
BETWEEN 67W-75W...THUS PRODUCING STRONG NORTHERLY UPPER WINDS
OVER THE TROPICAL WAVE ALONG 79W. UPPER RIDGE FROM THE TROPICAL
ATLC COVERS THE REMAINDER OF THE CARIBBEAN.

ATLANTIC OCEAN...
BROAD UPPER RIDGE THAT EXTENDS FROM THE CARIBBEAN AND THE E GULF
OF MEXICO COVERS THE W ATLC W OF 70W GENERATING DIFFLUENCE AND
ADVECTING AN ABUNDANCE OF TROPICAL MOISTURE TO PRODUCE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS W OF A LINE FROM 31N74W TO
CENTRAL CUBA NEAR 22N79W. A LONG DRAWN OUT SURFACE TROUGH
BISECTS THE CENTRAL ATLC EXTENDING FROM 31N47W ALONG 24N54W TO
16N59W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120
NM OF A LINE FROM 20N58W 26N49W TO BEYOND 32N40W. THIS SURFACE
TROUGH LIES ON THE BOUNDARY BETWEEN AN UPPER TROUGH TO THE W
AND A BROAD UPPER RIDGE COVERING THE TROPICAL ATLC CENTERED NEAR
16N47W. A SECOND UPPER TROUGH IS OVER THE E ATLC EXTENDING FROM
AN UPPER LOW NEAR 32N22W W OF THE CAPE VERDE ISLANDS TO NEAR
13N31W BUT IS NOT PRODUCING ANY SIGNIFICANT ACTIVITY. A SURFACE
RIDGE COVERS THE W ATLC ANCHORED BY A 1021 MB HIGH N OF THE
REGION NEAR 36N68W AND A SECOND SURFACE RIDGE COVERS THE E ATLC
ANCHORED BY A 1027 MB HIGH E OF THE AZORES.

$$
WALLACE




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