[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 17 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

LARGE TROPICAL WAVE IS ALONG 40W/41W S OF 22N MOVING W 10-15 KT.
THIS WAVE IS WELL DEFINED ON THE NIGHT CHANNEL SATELLITE
IMAGERY.  A SMALL CYCLONIC LOW LEVEL SWIRL IS OVER THE NORTHERN
EXTENT OF THE WAVE AXIS NEAR 22N40W.  STRONG SWLY SHEAR
CONTINUES TO PROVIDE A VERY UNFAVORABLE ENVIRONMENT STRETCHING
CLOUDINESS WELL TO THE NE OF THE WAVE.  DEEP CONVECTION IS
MOSTLY CONFINED TO THE ITCZ.  SCATTERED MODERATE CONVECTION IS
FROM 6N-9N BETWEEN 40W-43W.

TROPICAL WAVE IS OVER THE LESSER ANTILLES ALONG 60W/61W S OF 15N
MOVING W 10-15 KT.  THIS WAVE IS VERY WEAK ONLY PRODUCING
ISOLATED SHOWERS FROM 10N-14N BETWEEN 57W-62W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N12W 7N20W 9N35W 8N60W.  IN
ADDITION TO THE CONVECTION DUE TO THE TROPICAL WAVES...
SCATTERED MODERATE TO STRONG CONVECTION IS ALONG THE COAST OF W
AFRICA FROM 7N-14N BETWEEN 5W-16W.  WIDELY SCATTERED MODERATE
CONVECTION IS FROM 3N-12N BETWEEN 24W-32W...AND FROM 8N-12N
BETWEEN 47W-51W...AND FROM 10N-12N BETWEEN 55W-57W.

DISCUSSION...

GULF OF MEXICO...
A TIGHTENING SURFACE PRESSURE GRADIENT OVER THE NW GULF OF
MEXICO IS PRODUCING 20-30 KT SOUTHERLY WINDS N OF 24N AND W OF
90W.  THE REMAINDER OF THE GULF HAS 10-20 KT SOUTHERLY WINDS.
ISOLATED MODERATE CONVECTION REMAINS OVER THE CENTRAL GULF FROM
24N-26N BETWEEN 91W-94W.  SCATTERED MODERATE CONVECTION IS ALSO
INLAND OVER THE YUCATAN PENINSULA FROM 19N-21N BETWEEN 89W-91W.
SCATTERED SHOWERS ARE OVER THE NE GULF AND FLORIDA N OF 25N AND
E OF 86W.  IN THE UPPER LEVELS...AN UPPER LEVEL HIGH IS CENTERED
OVER THE W GULF NEAR 23N93W.  A RIDGE AXIS EXTENDS NE TO BEYOND
N FLORIDA NEAR 30N81W.  UPPER LEVEL MOISTURE COVERS THE E GULF E
OF 93W.  STRONG SUBSIDENCE IS OVER THE W GULF W OF 93W.
EXPECT...CONTINUED CONVECTION OVER THE E GULF AND FLORIDA DURING
THE NEXT 24 HOURS DUE TO UPPER LEVEL DIFFLUENCE FROM THE HIGH.

CARIBBEAN SEA...
A TROPICAL WAVE IS OVER THE LESSER ANTILLES.  SEE ABOVE. IN
ADDITION... SELY SURFACE FLOW AND SELY UPPER LEVEL FLOW OVER
CUBA PRODUCED ISOLATED MODERATE CONVECTION OVER THE HIGHER
ELEVATIONS OF CUBA BETWEEN 75W-83W.  MODERATE TRADEWINDS
DOMINATE THE REMAINDER OF THE CARIBBEAN.  IN THE UPPER LEVELS...
AN UPPER LEVEL LOW IS CENTERED S OF THE CAYMAN ISLANDS NEAR
18N82W MOVING W.  UPPER LEVEL DIFFLUENCE E OF THE CENTER IS
PRODUCING SCATTERED MODERATE CONVECTION OVER THE CENTRAL
CARIBBEAN FROM 10N-19N BETWEEN 72W-77W.  EXPECT... THE TROPICAL
WAVE TO PRODUCE SHOWERS OVER THE WINDWARD ISLANDS OVER THE NEXT
24 HOURS.  ALSO EXPECT THE CONVECTION OVER THE CENTRAL CARIBBEAN
DUE TO THE UPPER LEVEL LOW TO MOVE W.

ATLANTIC OCEAN...
A WEAK 1012 MB LOW IS OFF THE FLORIDA COAST NEAR 28N79W DRIFTING
NE.  ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE LOW.  A
DISSIPATING COLD FRONT IS OVER THE CENTRAL ATLANTIC ALONG 32N36W
25N50W 26N60W.  SCATTERED SHOWERS ARE WITHIN 60 NM OF THE
TROUGH.  A 1019 MB HIGH IS OVER THE E ATLANTIC NEAR 24N29W.  A
SURFACE RIDGE AXIS EXTENDS W FROM THE HIGH TO 22N48W.  THIS IS
PRODUCING MAINLY LIGHT WINDS OVER THE SUBTROPICAL E AND CENTRAL
ATLC...WHILE MODERATE TRADES PERSIST IN THE TROPICS.  IN THE
UPPER LEVELS...AN UPPER LEVEL RIDGE IS OVER THE W ATLANTIC N OF
20N AND W OF 65W.  THE BASE OF AN UPPER LEVEL TROUGH IS OVER THE
CENTRAL ATLANTIC N OF 20N BETWEEN 50W-65W.  A RIDGE IS OVER THE
E ATLANTIC N OF 25N AND E OF 40W.  A SMALL UPPER LEVEL LOW IS
OVER THE TROPICAL E ATLANTIC NEAR 19N38W.  FURTHER E...AN UPPER
LEVEL HIGH SWLY IS OVER THE TROPICAL E ATLANTIC NEAR 8N26W.
UPPER LEVEL WINDS ARE THUS UNFAVORABLE NEAR THE CAPE VERDE
ISLANDS FOR TROPICAL CYCLONE FORMATION.

$$
FORMOSA





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