[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 290000
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU OCT 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...SPECIAL FEATURES...

A 1009 MB SURFACE LOW IS OVER THE WESTERN ATLC CENTERED NEAR
25N61W. THIS LOW IS EMBEDDED IN A LARGE SCALE UPPER LEVEL
CYCLONIC CIRCULATION CENTERED NEAR 23N69W. SCATTERED MODERATE
AND ISOLATED MODERATE CONVECTION CONTINUES TO BE SHEARED NORTH
OF THE LOW LEVEL CIRCULATION FROM 26N TO 30N BETWEEN 58W AND
64W. ENVIRONMENTAL CONDITIONS ARE FORECAST TO REMAIN SOMEWHAT
CONDUCIVE FOR THE DEVELOPMENT OF A TROPICAL OR SUBTROPICAL
DEPRESSION THROUGH FRIDAY...HOWEVER UPPER-LEVEL WINDS ARE
EXPECTED TO BECOME LESS FAVORABLE AFTER THAT. THERE IS A HIGH
CHANCE OF THIS SYSTEM BECOMING A SUBTROPICAL OR TROPICAL CYCLONE
BEFORE IT MERGES WITH A COLD FRONT ON SATURDAY.

A 1010 MB SURFACE LOW IS IN THE CENTRAL ATLC CENTERED NEAR
26N41W. THE ASSOCIATED CONVECTION IS FOUND TO THE EAST OF THE
CENTER FROM 25N TO 29N BETWEEN 35W AND 41W. ALTHOUGH SHOWER AND
THUNDERSTORM ACTIVITY ASSOCIATED WITH THE LOW HAS INCREASED
DURING THE PAST FEW HOURS...UPPER-LEVEL WINDS ARE EXPECTED TO
BECOME LESS FAVORABLE FOR DEVELOPMENT ON FRIDAY. THERE IS A
MEDIUM CHANCE OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES SLOWLY WESTWARD.

A VIGOROUS TROPICAL WAVE EXTENDS FROM 14N49W TO A SFC LOW NEAR
8N51W TO 3N52W MOVING W AT 10-15 KT. THE WAVE REMAINS AS A BROAD
CYCLONIC PERTURBATION WITHIN THE ITCZ REGION...AS WELL AS
EMBEDDED IN A SURGE OF DEEP MOISTURE ON TOTAL PRECIPITABLE WATER
IMAGERY. SATELLITE DERIVED WINDS INDICATE BROAD CYCLONIC TURNING
ALONG THE WAVE AXIS. SCATTERED MODERATE AND ISOLATED STRONG
CONVECTION IS OCCURRING FROM 4N-15N BETWEEN 45W-56W. ENHANCEMENT
OF THE STRONGER ONGOING CONVECTION IS DUE TO UPPER LEVEL
DIFFLUENCE PROVIDED BY A BROAD UPPER LEVEL ANTICYCLONE CENTERED
NEAR 10N50W. THIS SYSTEM CONTINUES TO SHOW SIGNS OF ORGANIZATION
...AND ENVIRONMENTAL CONDITIONS APPEAR TO BE FAVORABLE FOR
GRADUAL DEVELOPMENT OF THIS DISTURBANCE DURING THE NEXT COUPLE
OF DAYS. THERE IS A MEDIUM CHANCE OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS. REGARDLESS OF
DEVELOPMENT...THIS SYSTEM IS EXPECTED TO BRING LOCALLY HEAVY
RAINFALL AND STRONG GUSTY WINDS TO THE WINDWARD ISLANDS...
VENEZUELA...AND NORTHERN PORTIONS OF GUYANA DURING THE NEXT
COUPLE OF DAYS.


...ITCZ...

THE ITCZ AXIS IS ANALYZED FROM THE COAST OF GUINEA NEAR 10N14W
WESTWARD ALONG 6N20W 7N30W 6N40W 8N50W. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS WITHIN 120 NM ON EITHER SIDE OF
THE AXIS E OF 28W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS ACROSS THE GULF FROM THE FLORIDA PANHANDLE
NEAR 30N84W TO THE COAST OF MEXICO ALONG 28N87W 26N93W 23N97W.
NORTHERLY WINDS RANGING FROM 10 TO 25 KT ARE OBSERVED BEHIND THE
FRONT. IN 24 HOURS THIS FRONT IS EXPECTED TO MOVE ACROSS THE
GULF RATHER QUICK EXTENDING FROM THE CENTRAL FLORIDA PENINSULA
TO THE BAY OF CAMPECHE PRODUCING GALE FORCE WINDS S OF 22N W OF
95W. A PRE-FRONTAL TROUGH EXTENDS FROM THE COLD FRONT NEAR
25N93W SOUTHWARD TO THE NEAR THE CITY OF COATZACOALCOS MEXICO.
SCATTERED SHOWERS AND TSTMS ARE WITHIN 60 NM ON EITHER SIDE OF
THE COLD FRONT. SIMILAR CONVECTION IS WITHIN 70 NM ON EITHER
SIDE OF THE TROUGH. FAIR CONDITIONS ARE ELSEWHERE ACROSS THE
AREA OF DISCUSSION UNDER LIGHT EASTERLY SURFACE WINDS AND A DRY
AND SUBSIDENT AIR ALOFT.

CARIBBEAN SEA...
BROAD SCALE UPPER LEVEL CYCLONIC FLOW COVERS THE CARIBBEAN BASIN
AND IS MOVING A DRY AND STABLE AIRMASS ALOFT ACROSS THE AREA OF
DISCUSSION. HOWEVER...A STREAM OF MID-LEVEL MOISTURE IS NOTED
OVER THE NE BASIN FROM N OF 15N W OF 71W. THIS MOISTURE ALONG
WITH MARGINAL LOW-LEVEL SPEED CONVERGENCE IS GENERATING WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS IN THIS AREA. OTHER
ISOLATED SHOWERS ARE NOTED ON SATELLITE IMAGERY ELSEWHERE ACROSS
THE BASIN. ISOLATED TSTMS ARE OCCURRING OVER THE SW CARIBBEAN S
OF 11N W OF 76W DUE TO CONVERGENT LOW-LEVEL FLOW AND CLOSE
PROXIMITY OF THE E PACIFIC ITCZ AXIS. IN THE NEXT 24 HOURS...A
TROPICAL WAVE WILL START TO AFFECT THE LESSER ANTILLES WITH
CONVECTION.

ATLANTIC OCEAN...
ASIDE FROM THE AREAS OF CONCERN NOTED ABOVE IN THE SPECIAL
FEATURES SECTION...DRY AND STABLE AIR ALOFT IS NOTED ELSEWHERE
ON WATER VAPOR IMAGERY. BROAD UPPER LEVEL RIDGING EXTENDS ACROSS
MOST OF THE ATLC ANCHORED BY A SET OF 1026 MB HIGHS NEAR 36N51W
AND 38N42W. THE FAR EASTERN ATLC IS UNDER THE INFLUENCE OF
ANOTHER SURFACE RIDGE ANCHORED BY A 1024 MB HIGH CENTERED NEAR
THE CANARY ISLANDS.

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

$$

GARCIA




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