[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 241054
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1000 UTC.

...TROPICAL WAVES...

AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 23W S OF
17N MOVING W NEAR 15 KT. A 1009 MB LOW IS CENTERED ALONG THE
WAVE AXIS NEAR 12N. HOWEVER...BASED ON THE FIRST VISIBLE
SATELLITE IMAGES AND A 0754 UTC QUIKSCAT PASS...IT APPEARS THAT
THE LOW CENTER IS LOCATED NEAR 12N27W WITH THE WAVE AXIS TILTS
NE TO SW THROUGH THE LOW CENTER. THE WAVE WILL MOST LIKELY BE
RELOCATED ON THE NEXT SURFACE ANALYSIS TO BETTER ALIGN WITH THIS
NEW DATA. 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
12N-18N BETWEEN 20W-29W...AND FROM 7N-11N BETWEEN 19W-24W.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 49W/50W 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. THIS MAY
INDICATE THAT THE WAVE AXIS IS ABOUT TO FRACTURE. ISOLATED
MODERATE/STRONG CONVECTION IS FROM 17N-26N BETWEEN 44W-49W...AND
FROM 8N-14N BETWEEN 49W-54W. THIS ACTIVITY IS ALSO ENHANCED BY
DIFFLUENT FLOW ALOFT.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 17N16W 11N24W 6N35W 12N48W
10N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN
100 NM BOTH SIDES OF THE AXIS BETWEEN 34W-45W.

...DISCUSSION...

THE GULF OF MEXICO...
AS OF 0900 UTC...A STATIONARY FRONT EXTENDS ACROSS THE NW GULF
FROM S CENTRAL LOUISIANA NEAR 30N92W ALONG 24N96W TO THE SW BAY
OF CAMPECHE NEAR 18N94W. SCATTERED SHOWERS/THUNDERSTORMS ARE
FROM 16N-21N W OF 93W. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS
ARE WITHIN 200 NM AHEAD OF THE FRONT...AND WITHIN 75 NM BEHIND
THE FRONT. N SURFACE WINDS UP TO 20 KT ARE BEHIND THE FRONT. A
SURFACE TROUGH IS ACROSS THE YUCATAN PENINSULA FROM 23N89W TO
13N89W SUPPORTING ISOLATED SHOWERS ACROSS THE YUCATAN CHANNEL S
OF 23N. ANOTHER SURFACE TROUGH EXTENDS OFF THE W FLORIDA COAST
FROM 30N85W TO 24N85W. SURFACE CONVERGENCE NEAR THE TROUGH IS
SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 24N-25N BETWEEN
83W-86W...AND ISOLATED SHOWERS WITHIN 50 NM OF THE AXIS FROM
28N-30N. IN THE UPPER LEVELS...AN ELONGATED UPPER LEVEL RIDGE
COVERS THE BASIN WITH AXIS FROM CENTRAL PENNSYLVANIA TO SRN
ALABAMA CONTINUING ACROSS THE NW GULF TO CENTRAL MEXICO NEAR
23N101W. EXPECT THE TROUGH OVER THE YUCATAN PENINSULA TO MOVE
WWD AND MERGE WITH THE REMNANT OF THE FRONT BY FRI.

THE CARIBBEAN SEA...
SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS THE WRN CARIBBEAN
FROM 11N-21N BETWEEN 80W-85W. THIS ACTIVITY IS ENHANCED BY A
BROAD AREA OF DIFFLUENT FLOW ALOFT BETWEEN THE UPPER RIDGE OVER
THE GULF AND A BROAD UPPER LEVEL TROUGH COVERING THE W ATLC
CENTERED NEAR 27N65W EXTENDING INTO THE CARIBBEAN. THE REMAINDER
OF THE CARIBBEAN REMAINS FAIRLY CALM THIS MORNING. FRESH
TRADEWINDS ARE ACROSS MUCH OF THE BASIN BECOMING STRONG IN THE
ERN CARIBBEAN.

THE ATLANTIC OCEAN...
AS OF 0900 UTC...A SURFACE TROUGH EXTENDS OFF THE E COAST OF
FLORIDA FROM 31N77W TO 28N77W. SURFACE CONVERGENCE NEAR THE
TROUGH IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM
27N-29N BETWEEN 75W-77W. A FEW ISOLATED SHOWERS ARE OFF THE SE
COAST OF FLORIDA S OF 28N W OF 77W ENHANCED BY WEAK DIFFLUENT
FLOW BETWEEN THE UPPER RIDGE OVER THE GULF OF MEXICO AND THE
UPPER LEVEL TROUGH COVERING THE W ATLC CENTERED NEAR 27N65W.
THIS UPPER LEVEL TROUGH IS SUPPORTING A SURFACE TROUGH FROM
32N63W TO 24N65W...AND A SECOND SURFACE TROUGH FROM 32N53W TO
30N56W. SURFACE CONVERGENCE NEAR THESE TROUGHS IS SUPPORTING
SCATTERED SHOWERS/THUNDERSTORMS N OF 26N BETWEEN 53W-62W...AND
ISOLATED SHOWERS FROM 26N-32N BETWEEN 62W-68W. A THIRD SURFACE
TROUGH EXTENDS FROM 19N54W TO 23N52W SUPPORTING ISOLATED SHOWERS
FROM 23N-25N BETWEEN 49W-54W. A BROAD SURFACE RIDGE COVERS THE
REMAINDER OF THE ATLC. IN THE UPPER LEVELS...A BROAD UPPER RIDGE
COVERS THE AREA E OF 55W 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