[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 031212 CCA
TWDAT

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

...CORRECTED END TIME OF GALE FOR GULF OF TEHUANTEPEC...

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
1115 UTC.

...SPECIAL FEATURE...
IN THE W CARIBBEAN...A SURFACE TROUGH EXTENDS FROM N OF PANAMA
NEAR 10N80W...TO A 1010 MB SURFACE LOW IN THE SW CARIBBEAN NEAR
12N80W...TO E CUBA NEAR 21N76W. LOW LEVEL CONVERGENCE NEAR THE
TROUGH AND LOW...COMBINED WITH DEEP MOISTURE AND UPPER LEVEL
DIVERGENCE OVER THE W CARIBBEAN...IS SUPPORTING ISOLATED SHOWERS
AND THUNDERSTORMS S OF 18N W OF 76W. UPPER-LEVEL WINDS ARE
FAVORABLE FOR SOME DEVELOPMENT OF THIS SYSTEM OVER THE NEXT
COUPLE OF DAYS.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 7N10W 4N22W 3N35W 4N46W 5N59W.
SCATTERED MODERATE CONVECTION IS WITHIN 180 NM EITHER SIDE OF
THE ITCZ AXIS BETWEEN 12W-16W. ISOLATED MODERATE CONVECTION IS
FROM 2N-12N BETWEEN 20W-33W...WHICH IS BEING ENHANCED BY UPPER
LEVEL DIVERGENCE. SCATTERED MODERATE CONVECTION IS FROM 2N-5N
BETWEEN 34W-39W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS OVER SOUTH CAROLINA NEAR 34N82W...WITH
INSTABILITY AND UPPER LEVEL MOISTURE NEAR THIS LOW RESULTING IN
ISOLATED SHOWERS AND THUNDERSTORMS IN THE GULF N OF 27N E OF
85W. THIS LOW IS EMBEDDED WITHIN A BROAD UPPER LEVEL TROUGH THAT
COVERS MUCH OF THE GULF. DEEP LAYER DRY AIR ROTATING
CYCLONICALLY AROUND THE BASE OF THIS TROUGH IS RESULTING IN
MAINLY FAIR WEATHER CONDITIONS ACROSS THE S AND W GULF.
MEANWHILE...A SURFACE RIDGE OF HIGH PRESSURE IS AFFECTING MUCH
OF THE W GULF. ADDITIONALLY...STRONG N TO NE SURFACE WINDS ARE
BLOWING THROUGH THE ISTHMUS OF TEHUANTEPEC RESULTING IN GALE
FORCE WINDS IN THE E PACIFIC REGION. THESE WINDS ARE EXPECTED TO
SUBSIDE TO BELOW GALE FORCE BY 03/1200 UTC.

CARIBBEAN SEA...
AN UPPER LEVEL HIGH IS OVER THE E CARIBBEAN NEAR 15N70W...WITH
ANTICYCLONIC FLOW AROUND THE HIGH COVERING MUCH OF THE
CARIBBEAN. DEEP MOISTURE AND UPPER LEVEL DIVERGENCE W OF THE
HIGH...AS WELL AS LOW LEVEL CONVERGENCE AROUND A SURFACE LOW AND
SURFACE TROUGH IN THE W CARIBBEAN...ARE SUPPORTING ISOLATED
SHOWERS AND THUNDERSTORMS 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 12N-18N BETWEEN
68W-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.

ATLANTIC OCEAN...
OVER THE W ATLC...STRONG SOUTHWESTERLY FLOW ALOFT IS PRESENT
BETWEEN AN UPPER LOW OVER SOUTH CAROLINA NEAR 34N82W AND AN
UPPER HIGH OVER THE E CARIBBEAN NEAR 15N70W. UPPER LEVEL
DIVERGENCE TO THE S 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 TROUGH EXTENDS FROM E
CUBA NEAR 21N76W TO A 1012 MB SURFACE LOW NEAR 22N76W...WITH A
WARM FRONT EXTENDING FROM THE LOW TO 25N67W TO 27N59W...AND A
STATIONARY FRONT EXTENDING TO THE NE FROM 27N59W TO 29N54W TO
31N51W. FURTHER TO THE NE...THE STATIONARY FRONT IS WEAKENING.
LOW LEVEL CONVERGENCE NEAR THESE SURFACE FEATURES...COMBINED
WITH DEEP MOISTURE MOVING NORTHEASTWARD FROM THE W CARIBBEAN AND
THE DEEP ATMOSPHERIC LIFT...IS SUPPORTING ISOLATED MODERATE
CONVECTION FROM 22N-30N BETWEEN 62W-76W AND SCATTERED MODERATE
CONVECTION FROM 27N-32N BETWEEN 45W-50W. OVER THE NEXT
DAY...COMPUTER MODEL GUIDANCE INDICATES THAT ATMOSPHERIC LIFT
OVER THESE BOUNDARIES WILL INCREASE AS THE UPPER LOW OVER SOUTH
CAROLINA NEAR 34N82W APPROACHES THE W ATLC. ACCORDINGLY...THE
GUIDANCE INDICATES THAT THE WARM FRONT WILL BECOME A DOMINANT
FRONT AS IT MOVES NORTHWARD WITH THE SURFACE LOW...AND THAT A
COLD FRONT WILL FORM SW OF THE SURFACE LOW WITH A SURFACE TROUGH
PERSISTING NW OF THE SURFACE LOW. INCREASED NORTHERLY WINDS TO
THE W OF THE SURFACE TROUGH AND COLD FRONT ARE EXPECTED. FARTHER
TO THE E...AN UPPER LEVEL TROUGH IS PRESENT WITH AN AXIS THAT
EXTENDS FROM AN UPPER LOW NEAR 32N33W TO 19N42W TO 5N50W...WITH
AN ACCOMPANYING SURFACE TROUGH THAT EXTENDS FROM 19N43W TO
15N45W TO 11N49W. INCREASED CLOUDINESS COINCIDES WITH THIS
SURFACE TROUGH...WITH THE INCREASED CLOUDINESS EXTENDING FROM
11N49W TO 13N55W TO 17N59W DUE TO LOW LEVEL CONVERGENCE
RESULTING FROM REGIONAL VARIATIONS IN LOW LEVEL WIND SPEED.
FARTHER TO THE E...A DEEP LAYER TROUGH IS N OF 24N E OF
34W...WHICH IS SUPPORTING A SURFACE COLD FRONT THAT EXTENDS FROM
THE W COAST OF AFRICA NEAR 19N16W TO 20N19W AND A SURFACE TROUGH
THAT EXTENDS FROM 20N19W TO 21N26W TO 28N33W. 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 13N BETWEEN THE AFRICAN COAST AND 33W.

$$
COHEN



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