[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 240521
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU SEP 24 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH WWW UTC.

...TROPICAL WAVES...

AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 21W S OF
19N MOVING W NEAR 10 KT. A 1010 MB LOW IS CENTERED ALONG THE
WAVE AXIS NEAR 12N. LOW-LEVEL CYCLONIC FLOW AROUND THE WAVE AXIS
AND CONCENTRATED AROUND THE LOW CENTER IS WELL DEFINED IN
SATELLITE IMAGERY AS WELL AS A 2232 UTC ASCAT SCATTEROMETER
PASS. A LARGE AREA OF AFRICAN DUST SURROUNDS THE SYSTEM TO THE N
AND WRAPPING AROUND THE W SIDE. DESPITE THE PRESENCE OF THE
DUST...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM
14N-17N BETWEEN 22W-27W...AND FROM 7N-12N BETWEEN 18W-22W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 48W/49W S OF 20N MOVING
W 15-20 KT. SATELLITE IMAGERY AND SATELLITE DERIVED WINDS
INDICATE AN INVERTED-V LOW-LEVEL CLOUD PATTERN. THE WAVE ALSO
COINCIDES WITH TWO DEEP LAYER MOISTURE MAXIMUMS...ONE NEAR THE
NRN PORTION OF THE WAVE AND ANOTHER ALONG THE ITCZ. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 19N-24N BETWEEN
45W-49W...AND FROM 7N-12N BETWEEN 46W-53W. THIS ACTIVITY IS ALSO
ENHANCED BY DIFFLUENT FLOW ALOFT.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 18N17W 11N23W 8N33W 11N47W
10N62W. SCATTERED MODERATE CONVECTION IS FROM 18N-19N BETWEEN
15W-17W. SIMILAR ACTIVITY IS WITHIN 150 NM S OF THE AXIS BETWEEN
24W-28W...AND BETWEEN 34W-41W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 0300 UTC...A STATIONARY FRONT EXTENDS ACROSS THE NW GULF
FROM 30N92W NEAR LAFAYETTE LOUISIANA ALONG 27N95W 25N96W
CONTINUING AS A COLD FRONT TO 19N95W. SCATTERED
SHOWERS/THUNDERSTORMS ARE BEHIND THE FRONT FROM 25N-28N BETWEEN
94W-97W...AND FROM 20N-23N BETWEEN 96W-98W. A FEW ISOLATED
SHOWERS ARE WITHIN 150 NM AHEAD OF THE FRONT N OF 24N. NE
SURFACE WINDS UP TO 20 KT ARE BEHIND THE FRONT. A SURFACE
TROUGH IS ACROSS THE YUCATAN PENINSULA FROM 23N87W TO 17N90W
SUPPORTING ISOLATED SHOWERS S OF 25N BETWEEN 86W-89W...AND
SCATTERED SHOWERS/THUNDERSTORMS S OF 20N BETWEEN 90W-92W IN THE
SE BAY OF CAMPECHE. ANOTHER SURFACE TROUGH EXTENDS ALONG THE W
FLORIDA COAST FROM 31N83W TO 26N83W. SURFACE CONVERGENCE NEAR
THE TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS WITHIN
100 NM W OF THE TROUGH AXIS BETWEEN 25N-28N...AND ALONG THE
TROUGH AXIS N OF 28N. IN THE UPPER LEVELS...AN UPPER LEVEL RIDGE
COVERS THE MAJORITY OF THE BASIN CENTERED NEAR 26N93W. A
SHORTWAVE UPPER LEVEL E-W TROUGH EXTENDS INTO THE FAR SE GULF
CONTRIBUTING TO THE SHOWERS OFF THE SW COAST OF FLORIDA. EXPECT
THE FRONT TO REMAIN RELATIVELY STATIONARY OVER THE NEXT 24 HRS.

THE CARIBBEAN SEA...
SCATTERED SHOWERS/THUNDERSTORMS ARE OFF THE COASTS OF NICARAGUA
AND HONDURAS FROM 13N-18N BETWEEN 80W-84W. THIS ACTIVITY IS
ENHANCED BY A BROAD AREA OF DIFFLUENT FLOW ALOFT BETWEEN A
SHORTWAVE UPPER LEVEL TROUGH ACROSS CUBA EMBEDDED IN A BROAD
UPPER LEVEL TROUGH COVERING THE W ATLC EXTENDING INTO THE
CARIBBEAN AND THE UPPER LEVEL RIDGE OVER THE GULF. THIS BROAD
DIFFLUENT FLOW ALOFT AROUND THE BROAD UPPER TROUGH CENTERED NEAR
27N65W IS ALSO SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS ACROSS
HISPANIOLA AND PUERTO RICO N OF 18N BETWEEN 66W-73W. THE
REMAINDER OF THE CARIBBEAN REMAINS FAIRLY CALM. FRESH TRADEWINDS
ARE ACROSS MUCH OF THE BASIN BECOMING STRONG IN THE ERN
CARIBBEAN.

THE ATLANTIC OCEAN...
A FEW ISOLATED SHOWERS ARE OFF THE SE COAST OF FLORIDA FROM
26N-29N W OF 74W ENHANCED BY WEAK DIFFLUENT FLOW BETWEEN THE
UPPER RIDGE OVER THE GULF OF MEXICO AND AN UPPER LEVEL TROUGH
COVERING THE W ATLC CENTERED NEAR 27N65W. THIS UPPER LEVEL
TROUGH IS ALSO SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS S OF
21N BETWEEN 66W-73W OVER PORTIONS OF PUERTO RICO AND HISPANIOLA.
A SURFACE TROUGH EXTENDS FROM 32N63W TO 25N65W. SURFACE
CONVERGENCE NEAR THE TROUGH AND SUPPORT FROM THE UPPER LOW NEAR
27N65W ARE GENERATING SCATTERED SHOWERS/THUNDERSTORMS FROM
28N-32N BETWEEN 52W-61W...AND ISOLATED SHOWERS FROM 25N-28N
BETWEEN 53W-66W. ANOTHER SURFACE TROUGH EXTENDS FROM 23N52W TO
16N56W. NO SHOWERS ARE CURRENTLY ASSOCIATED WITH THE TROUGH. A
BROAD SURFACE RIDGE COVERS THE REMAINDER OF THE ATLC. IN THE
UPPER LEVELS...A BROAD UPPER RIDGE COVERS THE AREA E OF 53W E OF
THE UPPER TROUGH CENTERED NEAR 27N65W. A LARGE AREA OF AFRICAN
DUST IS E OF 40W.

$$
WALTON



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