[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 221140
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED SEP 22 2010

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
1015 UTC.

...SPECIAL FEATURES...

TROPICAL STORM LISA IS CENTERED NEAR 18.0N 30.5W AT 22/0900 UTC
OR ABOUT 390 NM WNW OF THE CAPE VERDE ISLANDS MOVING ENE AT 4
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. SOME
STRENGTHENING IS FORECAST OVER THE NEXT 48 HOURS AS THE TROPICAL
CYCLONE REMAINS SOUTH OF AN EASTERN ATLC UPPER LEVEL TROUGH IN A
RELATIVELY LOW VERTICAL WIND SHEAR ENVIRONMENT. ISOLATED
MODERATE CONVECTION IS WITHIN 120 NM OF THE CENTER IN THE S
QUADRANT AND WITHIN 180 NM OF THE CENTER IN THE NE QUADRANT. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/
WTNT24 KNHC FOR MORE DETAILS.

TROPICAL WAVE EXTENDS FROM 10N67W TO 14N68W TO 17N67W MOVING W
AT 10-15 KT. A 1009 MB LOW IS ANALYZED ALONG THE WAVE AXIS
CENTERED NEAR 12N67W. WHILE PREDOMINATELY NORTHEAST TO EASTERLY
FLOW IS OCCURRING AT THE SURFACE OVER THE EASTERN AND CENTRAL
CARIBBEAN SEA N OF THE LOW CENTER...MODEL GUIDANCE INDICATES A
MID-LEVEL...700 MB...CIRCULATION COINCIDES WITH THE SURFACE LOW.
THESE FEATURES ARE FORECAST TO TRACK OVER THE FAR SOUTHERN
CARIBBEAN SEA AND THE ABC ISLANDS OVER THE NEXT 24 HOURS. WIDELY
SCATTERED MODERATE CONVECTION IS OCCURRING FROM 10N-16N BETWEEN
64W-72W.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 09N20W TO 20N22W MOVING W AT 10-15
KT. A 1008 MB LOW IS ANALYZED ALONG THE WAVE AXIS NEAR 16N21W.
CIMSS WAVETRAK MODEL GUIDANCE INDICATES AN AREA OF MAXIMUM 850
MB RELATIVE VORTICITY IS ASSOCIATED WITH THE WAVE AXIS LOCATED
EAST OF THE CAPE VERDE ISLANDS FROM 12N-18N BETWEEN 18W-24W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 16N-20N BETWEEN
20W-24W.

...ITCZ...

A MONSOONAL TROUGH IS ANALYZED FROM SW OF T.S. LISA NEAR 14N32W
TO 11N50W. THE ITCZ AXIS THEN RESUMES NEAR 10N53W AND EXTENDS TO
11N66W. SCATTERED MODERATE CONVECTION IS FROM 03N-08N BETWEEN
18W-26W...AND FROM 07N-12N BETWEEN 46W-57W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL RIDGE EXTENDS ACROSS MUCH OF THE GULF OF MEXICO W
OF 89W STEMMING FROM AN UPPER LEVEL ANTICYCLONE CENTERED OVER
NORTHERN MEXICO NEAR 29N104W. THIS ANTICYCLONE IS PROVIDING
STABLE NORTHERLY FLOW ALOFT OVER THE WESTERN GULF WHILE
SUPPORTING BROAD SURFACE RIDGING. THE SURFACE RIDGE AXIS EXTENDS
FROM A 1023 MB HIGH CENTERED IN THE W ATLC NEAR 36N66W...ACROSS
NORTHERN FLORIDA TO THE TEXAS GULF COAST NEAR GALVESTON.
HOWEVER...AN UPPER LEVEL SHORTWAVE TROUGH IS LOCATED OVER THE NE
GULF AND IS BECOMING EMBEDDED WITHIN A STRONGER UPPER LEVEL
TROUGH PRESENT OVER THE FAR W ATLC AND FLORIDA PENINSULA. THIS
MID-LEVEL TROUGHING IS GENERATING AN AREA OF ISOLATED SHOWERS
FROM 22N-28N BETWEEN 83W-88W. THE REMAINDER OF THE GULF IS UNDER
THE INFLUENCE OF E-SE SURFACE WINDS WITH ISOLATED SHOWERS
EMBEDDED WITHIN THAT FLOW PRIMARILY IN AN AREA FROM 21N-29N W OF
90W.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH EXTENDS FROM THE FAR W ATLC ACROSS WESTERN
CUBA TO NEAR 20N84W. DRY AIR ALOFT ASSOCIATED WITH THE TROUGHING
IS PROVIDING MOSTLY FAIR CONDITIONS OVER MUCH OF CUBA THIS
MORNING...HOWEVER WITH THE TROUGH AXIS EXTENDING OVER THE NW
CARIBBEAN WATERS...WIDELY SCATTERED SHOWERS ARE FROM 19N-23N
BETWEEN 78W-88W. FARTHER EAST...AN UPPER LEVEL ANTICYCLONE IS
CENTERED IN THE SW NORTH ATLC NEAR 23N70W AND EXTENDS AN UPPER
LEVEL RIDGE AXIS FROM THE ANTICYCLONE TO 11N77W IN THE SW
CARIBBEAN. THIS UPPER LEVEL RIDGE IS PROVIDING AN OVERALL
DIFFLUENT ENVIRONMENT OVER A LARGE PORTION OF THE BASIN AND
ALONG WITH THE TROPICAL WAVE ALONG 67W MOVING WESTWARD...BROAD
AREAL COVERAGE OF SCATTERED SHOWERS AND ISOLATED TSTMS ARE NOTED
ON SATELLITE IMAGERY FROM 09N-20N BETWEEN 72W-83W. THIS AREA IS
ASIDE FROM THE MID-LEVEL CIRCULATION AND CONVECTION ASSOCIATED
WITH THE TROPICAL WAVE MENTIONED ABOVE IN THE SPECIAL FEATURES
SECTION.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH AXIS EXTENDS ACROSS THE FAR W ATLC AND
FLORIDA PENINSULA FROM 32N75W TO WESTERN CUBA NEAR 23N82W AND
INTO THE NW CARIBBEAN SEA. EAST OF THE UPPER LEVEL TROUGH
AXIS...ADVECTION OF MID-LEVEL MOISTURE FROM THE CENTRAL
CARIBBEAN SEA IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS
OVER THE SE AND CENTRAL BAHAMAS...AND TURKS AND CAICOS ISLANDS
FROM 21N-26N BETWEEN 68W-77W. THE REMAINDER OF THE W ATLC FALLS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1023 MB
HIGH CENTERED NORTH OF THE AREA NEAR 36N66W. ISOLATED SHOWERS
ARE MOVING WESTWARD ON EASTERLY WINDS OF 10-20 KT FROM 26N-29N W
OF 66W. ACROSS THE CENTRAL ATLC...AN UPPER LEVEL ANTICYCLONE IS
CENTERED NEAR 28N53W AND SUPPORTS OVERALL SURFACE RIDGING
BETWEEN 45W-65W ANCHORED BY A 1018 MB HIGH CENTERED NEAR 26N56W.
WITH THE PASSAGE OF AN UPPER LEVEL TROUGH AXIS NORTH OF THE AREA
IN THE VICINITY OF 40W...THE REMNANT LOW OF JULIA CONTINUES AS A
1007 MB LOW CENTERED NEAR 35N40W. THIS LOW EXTENDS A SURFACE
TROUGH FROM THE LOW TO 32N39W TO 27N43W. MID-LEVEL INSTABILITY
ALONG THE SURFACE TROUGH AXIS IS GENERATING SCATTERED SHOWERS
AND ISOLATED TSTMS FROM 27N-33N BETWEEN 37W-39W. ELSEWHERE OVER
THE EASTERN ATLC...AN UPPER LEVEL TROUGH DIPS TO 20N AND REMAINS
E OF 33W...WITH EXTENSIVE CLOUDINESS AND POSSIBLE SHOWERS N OF
21N E OF 27W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN




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