[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202338
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 20 2009

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS TILTED FROM 21N39W TO 14N41W MOVING W NEAR 15
KT. THE WAVE POSITION IS BASED ON THE DEEP LAYERED MOISTURE
MAXIMUM AS OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY AND THE
CURVATURE OBSERVED IN THE VISIBLE SATELLITE IMAGERY. DENSE CLOUD
COVER WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVER THE AREA FROM 15N-22N BETWEEN 37W-43W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N12W 4N28W 6N44W 6N59W. SMALL
CLUSTERS OF ISOLATED MODERATE CONVECTION ARE WITHIN 45 NM OF THE
ITCZ BETWEEN 18W-24W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS ACROSS LOUISIANA ENTERING THE GULF JUST
W OF VERMILION BAY TO OFF THE TEXAS COAST NEAR 27N97W SUPPORTED
BY AN UPPER TROUGH MOVING ACROSS THE MISSISSIPPI VALLEY. A
SECOND SURFACE TROUGH IS IN THE SE GULF EXTENDING FROM 26N84W TO
THE YUCATAN NEAR 22N88W. AN UPPER RIDGE EXTENDS FROM S/CENTRAL
MEXICO INTO THE GULF NEAR TAMPICO NE TO NEAR PANAMA CITY FLORIDA
WITH A SECOND UPPER RIDGE OVER THE SE GULF S OF A LINE FROM
TAMPA TO THE NE YUCATAN PENINSULA. THIS IS CREATING AN INVERTED
UPPER TROUGH BETWEEN THESE TWO UPPER RIDGES. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE WITHIN 90 NM OF A LINE FROM 23N92W TO
NEAR 26N84W WITH SCATTERED/NUMEROUS SHOWERS/THUNDERSTORMS ARE
INLAND AND WITHIN 60 NM ALONG THE COAST OF FLORIDA S OF 29N TO
JUST N OF THE FLORIDA KEYS. OTHERWISE THE REMAINDER OF THE GULF
REMAINS TRANQUIL THIS EVENING.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE COVERS THE W CARIBBEAN ANCHORED OVER
CENTRAL CUBA COVERING THE AREA N OF 15N W OF 72W WITH AN UPPER
TROUGH EXTENDING FROM THE CENTRAL ATLC OVER THE NE CARIBBEAN N
OF 16N E OF 71W ACROSS THE LEEWARD ISLANDS. THE S CARIBBEAN IS
UNDER WESTERN UPPER FLOW DUE TO AN UPPER RIDGE ANCHORED OVER
SOUTH AMERICA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER
THE W CARIBBEAN W OF A LINE FROM E CUBA NEAR 20N75W TO THE
HONDURAS/ NICARAGUA BORDER INCLUDING JAMAICA. SIMILAR ACTIVITY
IS N OF 17N TO OVER THE GREATER ANTILLES BETWEEN VIRGIN ISLANDS
TO HAITI. THE REMAINDER OF THE CARIBBEAN REMAINS TRANQUIL THIS
EVENING.

ATLANTIC OCEAN...
A SURFACE TROUGH IS IN THE W ATLC EXTENDING FROM 31N71W THROUGH
A WEAKENING 1016 MB LOW NEAR 29N72W TO 27N72W WITH ISOLATED
SHOWERS WITHIN 60 NM OF THE SURFACE TROUGH. AN UPPER RIDGE
ANCHORED OVER CENTRAL CUBA COVERS THE SW ATLC S OF 29N W OF 70W
ENHANCING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 24N29N W
OF 77W TO OVER THE FLORIDA PENINSULA. AN UPPER LOW IS TO THE E
CENTERED NEAR 24N61W COVERING THE AREA FROM 16N-27N BETWEEN
50W-70W WITH A SURFACE TROUGH EXTENDING FROM 29N61W TO 23N63W
AND GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN
60 NM OF THE SURFACE TROUGH. SIMILAR ACTIVITY IS ALONG THE S
PERIPHERY OF THE UPPER LOW WITHIN 90 NM OF LINE FROM 18N54W TO
21N64W. A LONG UPPER TROUGH EXTENDS FROM THE E ATLC ACROSS TO
THE CENTRAL ATLC THROUGH A PAIR OF UPPER LOWS CENTERED NEAR
30N28W AND 28N46W SUPPRESSING THE ITCZ TO THE S. A WEAK SURFACE
RIDGE DOMINATES THE ATLC WITH A 1025 MB HIGH NEAR 33N41W.

$$
WALLACE






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