[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 030544
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST MON NOV 03 2008

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
0445 UTC.

...SPECIAL FEATURE...
A SURFACE TROUGH EXTENDS FROM A 1010 MB SURFACE LOW IN THE SW
CARIBBEAN NEAR 12N81W TO 16N79W TO E CUBA NEAR 20N75W. LOW LEVEL
CONVERGENCE NEAR THE TROUGH AND LOW...COMBINED WITH DEEP
MOISTURE IN THE PRESENCE OF DIFFLUENT UPPER LEVEL FLOW OVER THE
W CARIBBEAN...IS SUPPORTING SCATTERED MODERATE CONVECTION WITHIN
150 NM OF THE SURFACE LOW AND ISOLATED MODERATE CONVECTION FROM
14N-20N BETWEEN 76W-82W. UPPER-LEVEL WINDS ARE FAVORABLE FOR
SOME DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 7N11W 4N25W 5N37W 9N46W 7N61W.
SCATTERED MODERATE CONVECTION IS FROM 7N-9N BETWEEN 11W-14W.
ISOLATED MODERATE CONVECTION IS FROM 2N-5N BETWEEN 10W-15W.
ALSO...ISOLATED MODERATE CONVECTION IS FROM 2N-11N BETWEEN
20W-28W...WHICH IS BEING ENHANCED BY UPPER LEVEL DIVERGENCE.
ALSO...SCATTERED MODERATE CONVECTION IS WITHIN 240 NM S OF THE
ITCZ AXIS BETWEEN 34W-40W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL LOW IS OVER SW GEORGIA NEAR 31N84W...WITH
INSTABILITY AND UPPER LEVEL MOISTURE NEAR THIS LOW RESULTING IN
ISOLATED SHOWERS AND THUNDERSTORMS N OF 28N E OF 88W. THIS LOW
IS EMBEDDED WITHIN A BROAD UPPER LEVEL TROUGH THAT COVERS MUCH
OF THE GULF...WITH DEEP LAYER DRY AIR ROTATING CYCLONICALLY
AROUND THE BASE OF THIS TROUGH ACROSS THE S AND W GULF WHERE
MAINLY FAIR WEATHER CONDITIONS ARE PRESENT. MEANWHILE...A
SURFACE RIDGE OF HIGH PRESSURE IS AFFECTING MUCH OF THE W GULF.
THIS SURFACE RIDGE IS ANCHORED BY A 1037 MB SURFACE HIGH OVER
THE NE CONUS. ADDITIONALLY...STRONG N TO NE SURFACE WINDS ARE
BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC RESULTING IN GALE
FORCE WINDS IN THE E PACIFIC REGION.

THE CARIBBEAN SEA...
AN UPPER HIGH IS OVER THE E CARIBBEAN NEAR 14N69W...WITH
ANTICYCLONIC FLOW AROUND THE HIGH COVERING MUCH OF THE
CARIBBEAN. DEEP MOISTURE AND UPPER LEVEL DIFFLUENCE W OF THE
HIGH...AS WELL AS LOW LEVEL CONVERGENCE AROUND A SURFACE LOW AND
SURFACE TROUGH IN THE W CARIBBEAN...ARE SUPPORTING CONVECTION
OVER THE W CARIBBEAN. PLEASE SEE THE SPECIAL FEATURE SECTION FOR
MORE INFORMATION ON THIS SYSTEM. FARTHER TO THE E...UPPER LEVEL
DIVERGENCE W OF THE UPPER HIGH IS SUPPORTING ISOLATED MODERATE
CONVECTION FROM 11N-16N BETWEEN 69W-73W. DEEP LAYER DRY AIR E OF
THE UPPER HIGH IS RESULTING IN MAINLY FAIR WEATHER CONDITIONS
ACROSS THE E CARIBBEAN. ALSO...DEEP LAYER DRY AIR IN THE BASE OF
THE UPPER TROUGH OVER THE GULF OF MEXICO IS MOVING INTO THE FAR
NW CARIBBEAN.

THE ATLANTIC OCEAN...
OVER THE W ATLC...STRONG WEST-SOUTHWESTERLY FLOW ALOFT IS
PRESENT BETWEEN AN UPPER LOW OVER SW GEORGIA NEAR 31N84W AND AN
UPPER HIGH OVER THE E CARIBBEAN NEAR 14N69W. UPPER LEVEL
DIVERGENCE SW OF A MAXIMUM IN MID/UPPER-LEVEL WIND SPEED OVER
THE W ATLC IS INDUCING DEEP ATMOSPHERIC LIFT OVER PORTIONS OF
THE W ATLC. ADDITIONALLY...A SURFACE STATIONARY FRONT EXTENDS
FROM 32N49W TO 25N62W TO 22N74W...AND A SURFACE TROUGH EXTENDS
FROM 22N74W TO E CUBA NEAR 20N75W. TO THE W...A SURFACE TROUGH
EXTENDS FROM 29N75W TO 27N75W TO 24N74W. LOW LEVEL CONVERGENCE
NEAR THE SURFACE TROUGHS AND SURFACE STATIONARY FRONT...COMBINED
WITH DEEP MOISTURE MOVING NORTHEASTWARD FROM THE W CARIBBEAN AND
THE ATMOSPHERIC LIFT...IS SUPPORTING ISOLATED SHOWERS FROM
20N-29N BETWEEN 61W-77W. OVER THE NEXT DAY...COMPUTER MODEL
GUIDANCE INDICATES THAT ATMOSPHERIC LIFT OVER THESE BOUNDARIES
WILL INCREASE AS THE UPPER LOW OVER SW GEORGIA NEAR 31N84W
APPROACHES THE W ATLC. ACCORDINGLY...THE GUIDANCE INDICATES THAT
THE STATIONARY FRONT WILL MOVE NORTHWARD OVER THE W ATLC AS A
WARM FRONT W OF 72W. AT THE SAME TIME...A SURFACE LOW IS
EXPECTED TO FORM ALONG THE WARM FRONT AROUND 200 NM E OF THE
FLORIDA COAST NEAR 28N76W. THIS SURFACE LOW IS ALSO FORECAST TO
BECOME ACCOMPANIED BY A NORTH-TO-SOUTH SURFACE TROUGH...WITH
INCREASED NORTHERLY WINDS TO THE W OF THE SURFACE TROUGH.
FARTHER TO THE E...A SURFACE TROUGH EXTENDS FROM 21N62W TO
16N57W TO 12N53W...WITH DEEP LAYER DRY AIR PREVENTING DEEP
CONVECTION NEAR THIS FEATURE. ALSO...AN UPPER LEVEL TROUGH IS
PRESENT WITH AN AXIS THAT EXTENDS FROM AN UPPER LOW NEAR 31N34W
TO 21N43W TO 9N45W. NEAR THIS UPPER LEVEL TROUGH...SATELLITE
IMAGERY INDICATES THAT TWO SURFACE TROUGHS ARE PRESENT. ONE
SURFACE TROUGH EXTENDS FROM 20N44W TO 16N45W TO A 1012 MB
SURFACE LOW NEAR 13N46W...WITH ISOLATED MODERATE CONVECTION FROM
12N-14N BETWEEN 43W-46W. THE OTHER SURFACE TROUGH EXTENDS FROM
16N33W TO 12N33W....WITH ISOLATED MODERATE CONVECTION FROM
12N-18N BETWEEN 28W-37W. FARTHER TO THE E...A DEEP LAYER TROUGH
IS N OF 28N E OF 35W...WHICH IS SUPPORTING A SURFACE COLD FRONT
THAT EXTENDS FROM THE W COAST OF AFRICA NEAR 21N16W TO 21N19W
AND A SURFACE TROUGH THAT EXTENDS FROM 21N19W TO 23N26W TO
28N34W. DEEP LAYER DRY AIR IS PREVENTING DEEP CONVECTION ALONG
THE SURFACE COLD FRONT AND SURFACE TROUGH. OVER THE TROPICAL
ATLC...AN EAST-TO-WEST UPPER RIDGE IS ALONG 11N BETWEEN THE
AFRICAN COAST AND 34W.

$$
COHEN



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