[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 292346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ADDED TO THE 1800 UTC SURFACE ANALYSIS ALONG
22W/23W SOUTH OF 16N BASED SATELLITE PICTURES...SURFACE DATA AND
ASCAT PAST FROM AROUND 1134 UTC THAT SHOWED THE WIND SHIFT
ASSOCIATED WITH THE WAVE AND SOME CYCLONIC CIRCULATION NEAR 11N.
IN ADDITION...THE HOVMOLLER DIAGRAM INDICATES THE WWD
PROPAGATION OF THIS SYSTEM AND THE WAVE SHOWS UP VERY WELL IN
THE TPW PRODUCT FROM CIMSS WHERE A BULGE OF MOISTURE IS SEEN.
THIS IS THE 60TH TROPICAL WAVE TPC/NHC HAS TRACKED THIS SEASON.
SCATTERED MODERATE CONVECTION IS WITHIN 80-100 NM EITHER SIDE OF
THE WAVE AXIS FROM 11N-13N. THE WAVE IS CURRENTLY APPROACHING
THE CAPE VERDE ISLANDS.

A TROPICAL WAVE IS ALONG 52W/53W S OF 16N MOVING W 10-15 KT. THE
WAVE IS BENEATH STRONG UPPER SLY FLOW AHEAD OF AN UPPER-LEVEL
TROUGH WITH AXIS ACROSS THE TROPICAL NORTH ATLC. MAINLY HIGH
CLOUDS ARE NOTED BEHIND THE WAVE AXIS WITH SOME SHOWER ACTIVITY
NEAR THE INTERSECTION OF THE WAVE LINE AND THE ITCZ.

A TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN ALONG 65W SOUTH OF
19N MOVING W 10-15 KT. AN INVERTED-V SIGNATURE IS SEEN ON LATEST
VIS SATELLITE IMAGERY FOR THE DAY. THIS SYSTEM IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE VIRGIN ISLANDS AND
PARTS OF PUERTO RICO EARLY THIS EVENING. SOME SHOWER ACTIVITY IS
ALSO APPROACHING THE ABC ISLANDS.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 11N15W 10N30W 11N39W 8N50W 8N60W. A
SURFACE TROUGH REMAINS EMBEDDED WITHIN THE ITCZ ALONG 41W FROM
8N-15N WITH A 1012 MB LOW ALONG THE TROUGH NEAR 11N. THIS
FEATURE IS DRIFTING WEST-NORTHWESTWARD. THE ASSOCIATED SHOWER
ACTIVITY REMAINS DISORGANIZED WITH A COUPLE OF CLUSTERS OF
MODERATE/ISOLATED STRONG CONVECTION NEAR 18N38W...AND JUST NE OF
THE LOW CENTER NEAR 12N41W. UPPER-LEVEL WINDS ARE FORECAST TO
REMAIN UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT DURING THE NEXT
COUPLE OF DAYS. ELSEWHERE...SCATTERED MODERATE CONVECTION IS
FROM 6N-8N BETWEEN 24W-27W AND FROM 9N-11N BETWEEN 43W-49W.

...DISCUSSION...

GULF OF MEXICO...
HIGH PRES CENTERED OVER THE SE CONUS EXTENDS A RIDGE OVER THE
ENTIRE GULF REGION. THE RIDGE ALSO ENVELOPS THE FLORIDA
PENINSULA...MUCH OF CUBA...THE YUCATAN PENINSULA AND EASTERN
MEXICO GIVING THE AREA A MOSTLY DRY AND STABLE ATMOSPHERE. WINDS
ARE BEGINNING TO VEER TO THE NE GRADUALLY MODIFYING THE AIR
MASS. THIS TREND WILL CONTINUE AS HIGH PRES MOVES TOWARD THE
CAROLINAS DURING THE NEXT COUPLE OF DAYS. ALOFT...THE GULF IS
DOMINATED BY WESTERLY UPPER WINDS. A JET STREAM BRANCH WITH CORE
WINDS OF 70 KT CROSSES THE CENTRAL GULF AND SOUTH FLORIDA INTO
THE W ATLC. A BAND OF TRANSVERSE HIGH CLOUDS IS ASSOCIATED WITH
THIS JET. COLD AIR STRATOCUMULUS CLOUDS CONTINUES TO AFFECT THE
SE QUADRANT OF THE GULF...AND ARE MOVING TOWARD THE YUCATAN
PENINSULA UNDER A NELY WIND FLOW. THE FAR N GULF REMAINS CLEAR
THIS EVENING.

CARIBBEAN SEA...
DUE TO THE COLD AIR ADVECTION ACROSS THE FLORIDA PENINSULA AND
THE STRAITS OF FLORIDA...SEVERAL NEW LOW TEMPERATURE RECORDS
WERE SET IN WEST-CENTRAL CUBA EARLY THIS MORNING. THE TOWN OF
GUINES REPORTED THE LOWEST TEMPERATURE WITH 9.0 DEGREES
CELSIUS OR 48.0 FAHRENHEIT FOLLOWED BY TAPASTE WHERE THE MERCURY
DROPPED TO 9.2 DEGREES. THE COLD FRONT THAT BROUGHT THOSE COLD
TEMPERATURES EXTENDS ACROSS THE WINDWARD PASSAGE AND JAMAICA TO
NEAR CABO GRACIAS A DIOS NICARAGUA. THE FRONT IS GENERATING
SCATTERED SHOWERS AND ISOLATED TSTMS. UPPER DIFFLUENCE IS ALSO
ENHANCING CONVECTION OVER THE SW CARIBBEAN AND SOUTHERN CENTRAL
AMERICA.  LOW LEVEL CLOUDS WITH EMBEDDED LIGHT RAIN IS NOTED
NEAR THE FRONTAL BOUNDARY OVER HONDURAS. BROKEN COLD AIR
STRATOCUMULUS CLOUDS ARE OBSERVED BEHIND THE FRONT COVERING THE
NW CARIBBEAN. NELY WINDS ARE ALSO ADVECTING COLD AIR
STRATOCUMULUS CLOUDS FROM THE W ATLC ACROSS THE BAHAMAS INTO
CUBA. THE UPPER LEVELS OF THE CARIBBEAN ARE DOMINATED BY AN
UPPER-LEVEL RIDGE ANCHORED ON A HIGH OVER CENTRAL AMERICA. THE
TAIL END OF AN UPPER-LEVEL TROUGH LOCATED OVER THE TROPICAL N
ATLC ENTERS THE SE CARIBBEAN THROUGH THE WINDWARD ISLANDS.

ATLANTIC OCEAN...
A DEEP LAYERED TROUGH EXTENDS FROM THE NE CONUS TO THE NORTHERN
BAHAMAS WITH A JETSTREAM OF WINDS 90 TO 110 KT N OF 28N W OF
65W. AS OF 2100 UTC...THE ATTENDANT COLD FRONT ENTERS THE
FORECAST AREA NEAR 31N60W THEN CONTINUES SW ACROSS THE WINDWARD
PASSAGE AND THE CARIBBEAN SEA. A BAND OF MAINLY LOW CLOUDS WITH
EMBEDDED SHOWERS IS ASSOCIATED WITH THE FRONT OVER THE ATLC.
FURTHER EAST...A NARROW UPPER-LEVEL TROUGH EXTENDS INTO THE
CENTRAL ATLC WITH A SURFACE TROUGH EXTENDING FROM 31N52W TO
23N57W. A CUT OFF UPPER LOW IS IN THE W TROPICAL ATLC NEAR
15N55W JUST TO THE W OF THE TROPICAL WAVE ALONG 52W/53W. AN
UPPER TROUGH IS OVER THE E ATLC JUST SOUTH OF THE CANARY
ISLANDS. THE ASSOCIATED COLD FRONT IS CURRENTLY DISSIPATING AND
EXTENDS FROM A 1007 MB LOW INLAND OVER NW AFRICA ALONG 22N20W
23N30W 30N39W. A STRONG UPPER RIDGE COVERS THE REMAINDER OF THE
TROPICAL ATLC ANCHORED INLAND OVER WEST AFRICA. THIS RIDGE IS
HELPING TO INDUCE CONVECTION EMBEDDED WITHIN THE ITCZ AS WELL AS
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES AND THE BROAD
AREA OF LOW PRES LOCATED NEAR 11N41W.

$$
GR




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