[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 292350
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON 29 NOV 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN
COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS
BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

SPECIAL FEATURE...
DEEP LAYERED NON-TROPICAL AREA OF LOW PRESSURE IS CENTERED IN
THE NORTH- CENTRAL ATLC NEAR 30N49W 1000 MB...MOVING NW 10 KT.
THIS POSITION IS ABOUT 925 NM E OF BERMUDA. THIS SYSTEM
CONTINUES TO SHOW SOME POTENTIAL FOR SUBTROPICAL DEVELOPMENT
DURING THE NEXT COUPLE OF DAYS. VISIBLE SATELLITE IMAGERY
INDICATES THAT THE LOW-LEVEL CIRCULATION ASSOCIATED WITH THE LOW
HAS BECOME MORE COMPACT AND THE OVERALL SYSTEM LOOKS A LITTLE
BETTER ORGANIZED. GALE FORCE WINDS ARE N OF 31N. SMALL AREA OF
SCATTERED MODERATE CONVECTION IS NW OF THE LOW CENTER FROM
30N-32N BETWEEN 49W-51W. ANOTHER AREA OF SCATTERED MODERATE
CONVECTION IS E OF THE LOW FROM 29N-32N BETWEEN 46W-48W.  A
SURFACE TROUGH EXTENDS S FROM THE LOW CENTER TO 24N50W 20N53W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 5N1W 5N20W 7N40W 12N50W 5N80W.
WIDELY SCATTERED MODERATE CONVECTION IS 4N-10N BETWEEN 34W-41W
...AND FROM 10N-13N BETWEEN 53W-58W.  SCATTERED MODERATE
CONVECTION IS FROM 15N-18N BETWEEN 39W-42W.

...DISCUSSION...

GULF OF MEXICO INTO W ATLANTIC AND NW CARIBBEAN...
SPRAWLING MID/UPPER LEVEL HIGH DOMINATES THIS AREA WHICH EXTENDS
AS FAR E AS THE BAHAMAS AND SOUTHWARD ACROSS CUBA...JAMAICA...
AND NW CARIBBEAN N OF 15N TO OVER YUCATAN PENINSULA. A MID-LEVEL
ANTICYCLONIC CIRCULATION CENTER IS OVER W CUBA NEAR 22N84W.
UPPER LEVEL FLOW IS ANTICYCLONIC OVER THIS REGION...WITH WATER
VAPOR IMAGERY AND RAWINSONDE DATA INDICATING DRY AIR IN THE MID
LEVELS PREVAILING ACROSS MUCH OF THE AREA. SW UPPER LEVEL WINDS
INCREASE TO 70-80 KT ALONG THE U.S. GULF COAST WHERE AN INCREASE
IN UPPER LEVEL MOISTURE IS NOTED. AT THE SURFACE...A WEAKENING
COLD FRONT EXTENDS ACROSS CENTRAL CUBA TO THE CAYMAN ISLANDS.
THE HIGH IS EXPECTED TO MOVE LITTLE OVER THE NEXT 24-36 HOURS...
KEEPING MAINLY DRY CONDITIONS ACROSS THE AREA. A COLD FRONT
CURRENTLY OVER N TEXAS IS FORECAST TO MOVE INTO THE NW GULF OF
MEXICO IN 24-30 HOURS...WITH INCREASING MOISTURE AND SCATTERED
SHOWERS/ISOLATED TSTMS EXPECTED ALONG THE FRONT.

W ATLANTIC BETWEEN 60W-75W AND REMAINDER CARIBBEAN...
MID/UPPER LEVEL FLOW IS PREDOMINANTLY W-NW ACROSS THIS AREA WITH
AN EMBEDDED SHORTWAVE TROUGH FROM 32N60W TO 23N58W. MUCH OF THIS
AREA IS UNDER MODERATE SUBSIDENCE...WITH CONFLUENT UPPER FLOW W
OF TROUGH PRODUCING LOCALLY STRONG SUBSIDENCE/DRY AIR NOTED OVER
CARIBBEAN SEA S OF HISPANIOLA. AT THE SURFACE...A COLD FRONT
EXTENDS FROM VICINITY OF BERMUDA AT 32N63W SW TO 26N66W TO
22N78W OVER CENTRAL CUBA.   ISOLATED SHOWERS/TSTMS ARE ALONG THE
FRONT MAINLY N OF 26N...WITH WIDELY SCATTERED SHOWERS/TSTMS
FURTHER E NEAR MID/UPPER SHORTWAVE TROUGH AXIS. MOST OF
CARIBBEAN SEA REMAINS FREE OF SIGNIFICANT CLOUD COVER. ONLY
EXCEPTIONS ARE OVER SW CARIBBEAN WHERE BROKEN/OVERCAST LOW/MID
CLOUDS WITH ISOLATED SHOWERS ARE MOVING W ON THE LEADING EDGE OF
STRONGER SURFACE NE WINDS APPROACHING THE CENTRAL AMERICA
COAST...AND NEAR THE COLOMBIA AND WESTERN VENEZUELA COAST WHERE
BROKEN/OVERCAST LOW-MID CLOUDS WERE ALSO NOTED. SHORTWAVE TROUGH
IS EXPECTED TO MOVE EASTWARD OVER THE NEXT 24-48 HOURS...KEEPING
AREA UNDER MOSTLY DRY NORTHERLY FLOW ALOFT.

CENTRAL ATLANTIC BETWEEN 40W-60W...
THIS AREA IS DOMINATED BY THE DEEP LAYERED NON-TROPICAL LOW
DESCRIBED IN THE SPECIAL FEATURES SECTION. CYCLONIC MID/UPPER
LEVEL CIRCULATION IS NEAR 31N49W...JUST NW OF THE SURFACE
LOW...WITH MID/UPPER TROUGH AXIS EXTENDING SW TO 18N58W. UPPER
LEVEL FLOW IS PREDOMINANTLY W-SW AND CYCLONIC N OF TROUGH...WITH
ZONAL FLOW S OF TROUGH. THE DEEP LAYERED LOW IS EXPECTED TO MOVE
NW-N OVER THE NEXT 24-48 HOURS AS THE MID/UPPER TROUGH DROPS SE
AND REMAINS ACROSS THIS AREA. THIS WILL HELP TO CONTINUE
PRODUCING SHOWERS/TSTMS MAINLY BETWEEN 40W-50W IN STRONGLY
DIFFLUENT UPPER FLOW.

ATLANTIC E OF 40W...
MID/UPPER RIDGE FROM 26N33W THROUGH 32N35W IS WEDGED BETWEEN THE
DEEP-LAYERED LOW DESCRIBED IN THE SPECIAL FEATURES SECTION AND
ANOTHER DEEP LAYERED LOW CENTERED N OF AREA NEAR 34N15W. UPPER
FLOW IS STRONGLY CYCLONIC N OF 27N E OF 30W IN ASSOCIATION WITH
THE LOW NEAR 34N15W. SATELLITE-DERIVED UPPER LEVEL WINDS OF
60-70 KT ARE N OF 28N E OF 27W...DROPPING S TO NEAR 28N21W...
THEN NE ACROSS CANARY ISLANDS. SURFACE COLD FRONT EXTENDS FROM E
OF THE CANARY ISLANDS AT 32N12W S TO NEAR 24N17W...WITH A NARROW
BAND OF BROKEN/OVERCAST MULTI-LAYERED CLOUDS AND POSSIBLE
SHOWERS E OF FRONT TO THE COAST OF MOROCCO. BROKEN/OVERCAST LOW
CLOUDS WITH SCATTERED SHOWERS ARE ALSO OVER NE PORTION OF AREA
JUST S OF THE LOW CENTER.  ZONAL FLOW CONTINUES ACROSS TROPICAL
PORTION OF AREA ALL THE WAY TO THE AFRICAN COAST NEAR 19N16W. S
OF THIS AREA...A MID/UPPER LEVEL HIGH IS CENTERED N OF BRAZIL
COAST NEAR 6N41W. DIFFLUENT FLOW BETWEEN THE HIGH AND THE SW
FLOW FARTHER TO THE N IS ENHANCING ITCZ CONVECTION W OF 30W.
UPPER FLOW IS EXPECTED TO AMPLIFY ACROSS THE AREA DURING THE
NEXT 24-48 HOURS AS LOW NEAR 34N16W MOVES E AND DOWNSTREAM RIDGE
STRENGTHENS NEAR 35W.

$$
FORMOSA



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