[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221053
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE SEP 22 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 15N35W TO 6N37W MOVING W NEAR 15 KT.
SATELLITE IMAGERY AND SATELLITE DERIVED WINDS INDICATE BROAD LOW
LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS. A LARGE
AREA OF SAHARAN DUST TRAILS THE WAVE MAINLY E OF 33W INHIBITING
MOST DEEP CONVECTION NEAR THE WAVE. HOWEVER...A FEW CLUSTERS OF
ISOLATED MODERATE CONVECTION ARE N OF THE WAVE AXIS FROM 15N-17N
BETWEEN 35W-38W...E OF THE WAVE AXIS FROM 7N-8N BETWEEN
34W-36W...AND W OF THE WAVE AXIS FROM 7N-10N BETWEEN 41W-42W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 9N25W 11N34W 7N45W 6N56W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-18N
BETWEEN 11W-18W. ISOLATED MODERATE CONVECTION IS WITHIN 100 NM S
OF THE AXIS BETWEEN 23W-28W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF OF MEXICO REMAINS FAIRLY CALM THIS MORNING AS A WEAK
SURFACE RIDGE BUILDS FROM THE E ALONG 30N. AN UPPER LEVEL RIDGE
COVERS THE MAJORITY OF THE BASIN CENTERED OVER MEXICO NEAR
20N103W. A FEW ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE NOTED
ACROSS THE SRN PORTIONS OF THE GULF DUE TO UPPER LEVEL DIFFLUENT
FLOW BETWEEN THE UPPER RIDGE AND A SHORTWAVE UPPER TROUGH THAT
DIGS ACROSS THE NW BAHAMAS TO THE STRAITS OF FLORIDA CONTINUING
TO THE NRN YUCATAN PENINSULA. MODERATE SURFACE WINDS ARE ACROSS
MUCH OF THE BASIN FLOWING ANTI-CYCLONICALLY AROUND THE SURFACE
RIDGE ACROSS THE FAR N GULF. EXPECT THE RIDGE TO LIFT N OF THE
AREA AS A COLD FRONT MOVES OFF THE COAST OF TEXAS LATER THIS
EVENING.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE COVERS THE W CARIBBEAN W OF 70W WHILE AN
UPPER LEVEL TROUGH COVERS THE REMAINDER OF THE BASIN EXTENDING
FROM THE ATLC. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER
RIDGE...THE UPPER TROUGH...AND THE AFOREMENTIONED SHORTWAVE UPPER
TROUGH EXTENDING FROM THE NE BAHAMAS ACROSS THE STRAITS OF
FLORIDA TO THE NRN YUCATAN PENINSULA IS SUPPORTING ISOLATED
SHOWERS/THUNDERSTORMS ACROSS THE NRN CARIBBEAN N OF 17N W OF
66W. NUMEROUS SHOWERS/THUNDERSTORMS ARE ACROSS THE SW CARIBBEAN
S OF 10N W OF 76W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC
ITCZ AND A 1007 MB LOW OVER COLOMBIA NEAR 8N74W. THE REMAINDER
OF THE ERN CARIBBEAN REMAINS FAIRLY TRANQUIL. FRESH TRADE WINDS
ARE ACROSS MUCH OF THE S CENTRAL CARIBBEAN WITH STRONGER WINDS
NEAR THE COAST OF COLOMBIA AND ACROSS THE ERN CARIBBEAN.

ATLANTIC OCEAN...
A WEAKENING 1018 MB SURFACE LOW IS IN THE WRN ATLC NEAR 31N76W
WITH A SURFACE TROUGH EXTENDING FROM THE LOW TO 24N79W. SURFACE
CONVERGENCE NEAR THE LOW AND TROUGH IS SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS FROM 26N-31N BETWEEN 73W-77W. THE SHOWER
ACTIVITY IS ALSO ENHANCED BY DIFFLUENT FLOW ALOFT BETWEEN A
SHORTWAVE UPPER LEVEL TROUGH ACROSS THE NW BAHAMAS AND AN UPPER
LEVEL RIDGE CENTERED NEAR 34N77W. A SURFACE TROUGH EXTENDS FROM
31N60W TO 27N61W. SURFACE CONVERGENCE NEAR THE TROUGH IS
SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS N OF 28N BETWEEN
60W-63W. ANOTHER SURFACE TROUGH EXTENDS FROM 23N59W TO 21N62W.
THIS SURFACE TROUGH IS SUPPORTED BY AN UPPER LEVEL TROUGH WITH
AXIS ALONG 58W. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE FROM
18N-21N BETWEEN 61W-64W. THE UPPER LEVEL TROUGH IS ALSO
SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS FROM 19N-20N
BETWEEN 51W-59W. A 1011 MB LOW IS CENTERED NEAR 14N48W. THE
TROPICAL WAVE THAT WAS PREVIOUSLY JUST E OF THE LOW IS NOW
ANALYZED A SURFACE TROUGH THAT EXTENDS THROUGH THE LOW CENTER
FROM 21N44W TO 11N49W. SURFACE CONVERGENCE NEAR THE TROUGH AND
LOW IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 17N-22N
BETWEEN 41W-46W...AND ISOLATED SHOWERS FROM 13N-17N BETWEEN
44W-47W. THE REMAINDER OF THE ATLC REMAINS FAIRLY CALM UNDER THE
INFLUENCE OF A WEAK SURFACE RIDGE ACROSS THE BASIN. IN THE UPPER
LEVELS...AN UPPER LEVEL RIDGE DOMINATES THE CENTRAL ATLC BETWEEN
30W-50W. AN UPPER LEVEL LOW CENTERED NEAR 31N25W COVERS THE ERN
ATLC SUPPORTING ISOLATED SHOWERS N OF 27N BETWEEN 18W-25W. A
BROAD UPPER LEVEL RIDGE COVERS THE TROPICAL ATLC E OF 50W
CENTERED NEAR 17N28W ENHANCING CONVECTION NEAR THE SURFACE LOW
NEAR 14N48W.

$$
WALTON







This weather bulletin was brought to you by:
www.nashvilleweather.net