[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 082347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 08 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE 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.

...TROPICAL WAVES...
A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 48W S OF 21N MOVING W
NEAR 15 KT. THE WAVE IS WELL DEFINED ON SATELLITE IMAGERY WITH
AN INVERTED-V STRUCTURE NOTED. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS MAINLY EMBEDDED IN THE ITCZ FROM 9N TO 13N
BETWEEN 45W-52W. MODERATE TO STRONG UPPER LEVEL WINDS ACROSS
THIS REGION ARE SPREADING ITS MOISTURE FARTHER EAST.

A WEAK TROPICAL WAVE IS ALONG 62W S OF 16N MOVING W NEAR 15 KT.
THIS WAVE HAS LITTLE SIGNATURE ASSOCIATED WITH IT AND THE PSN IS
BASED ON CONTINUITY. SCATTERED MODERATE CONVECTION IS FOUND ON
THE SOUTH END OF THE WAVE OVER TRINIDAD AND TOBAGO AND NE
VENEZUELA. THIS ACTIVITY IS PROBABLY BEING ENHANCED BY AN UPPER
TROUGH LOCATED OVER THE EASTERN CARIBBEAN.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 72W S OF 19N
MOVING W 10 TO 15 KT. LITTLE WAVE STRUCTURE IS NOTED ON VIS
IMAGES. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION HAS DEVELOPMENT ON BOTH EXTREMES OF THE WAVE AXIS
OVER HISPANIOLA...NORTHERN COLOMBIA AND AROUND LAKE MARACAIBO.

...THE ITCZ...
ITCZ AXIS IS CENTERED 11N16W 10N30W 11N46W 9N50W 8N60W. CLUSTER
OF MODERATE/ISOLATED STRONG CONVECTION ARE INLAND OVER WESTERN
AFRICA FROM 8N-14N BETWEEN 10W-15W. SIMILAR CONVECTION IS WITHIN
AROUND 100 NM SOUTH OF THE AXIS BETWEEN 35W-45W.

...DISCUSSION...
THE GULF OF MEXICO...
A LARGE CUT-OFF LOW IS STILL SPINNING OVER THE SE U.S. WITH THE
BASE OF THE TROUGH OVER THE STRAITS OF FLORIDA. THE UPPER LOW
ALSO COVERS THE EASTERN GULF AND THE FLORIDA PENINSULA. STRONG
SUBSIDENCE ACCOMPANIES THE TROUGH PRODUCING VERY DRY AIR
ALOFT NOTED ON WATER VAPOR IMAGES E OF 86W N OF 25N. AS OF 2100
UTC...THE ASSOCIATED SLOW MOVING COLD FRONT EXTENDS FROM CENTRAL
FLORIDA WESTWARD TO NEAR 26N92W. ONLY A NARROW BAND OF LOW
CLOUDS REPRESENT THIS BOUNDARY. A NARROW SQUASHED RIDGE EXTENDS
FROM THE YUCATAN PENINSULA NWD TO LOUISIANA WHILE A SHORT WAVE
TROUGH IS OVER THE BAY OF CAMPECHE. ABUNDANT MID-HIGH LEVEL
MOISTURE IS OVER THE REMAINDER OF THE GULF. A SFC TROUGH REMAINS
OVER THE WESTERN PORTION OF THE AREA AND RUNS FROM 27N96W TO
20N95W. ONLY ISOLATED SHOWERS ARE ALONG THE TROUGH AXIS...
PARTICULARLY OVER THE BAY OF CAMPECHE. LOOKING FURTHER AHEAD...A
POTENTIALLY STRONG COLD FRONT FOR THIS TIME OF YEAR MAY ENTER
THE NRN GULF BY MID-WEEK. GALE CONDITIONS ARE EXPECTED LATE THU
AND FRI FOR THE WRN GULF ZONES.

THE CARIBBEAN SEA...
A LARGE AREA OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
PERSISTS OVER THE WESTERN CARIBBEAN. THIS CONVECTIVE ACTIVITY IS
BEING HIGHLY ENHANCED BY A DIFFLUENT PATTERN ALOFT AND EXTENDS
FROM 12N-20N WEST OF 80W. UPPER AIR DATA SHOWS SOME CYCLONIC
TURNING AT LOW LEVELS OVER THIS REGION. A VORTICITY MAXIMUM IS
ALSO OBSERVED AT 850 MB OVER THE GULF OF HONDURAS...WHICH IS
EXPECTED TO MOVE INLAND ON MONDAY. THE CAYMAN ISLANDS REPORTED
HEAVY TSTMS AND GUSTY WINDS OF 23 KT DURING THE AFTERNOON. A
WESTERLY JET WITH CORE WINDS BETWEEN 50-60 KT BASED ON UW-CIMSS
DERIVED WINDS IS CARRYING SOME OF THIS MOISTURE ACROSS CUBA INTO
THE BAHAMAS AND THE W ATLC. SCATTERED MODERATE CONVECTION IS
OVER COSTA RICA DUE TO THE CLOSE PROXIMITY OF THE ITCZ.  AN
UPPER TROUGH COVERS THE FAR E CARIBBEAN AND THE LESSER ANTILLES
GIVING THE E CARIBBEAN E OF 70W DRY AIR AND MODERATE TO STRONG
SUBSIDENCE...THUS LIMITED SHOWER ACTIVITY. MODERATE TO STRONG
ELY WINDS DOMINATES THE BASIN WITH THE STRONG WINDS OF 20-25 KT
JUST OF OF THE COLOMBIAN COAST.

THE ATLANTIC OCEAN...
A TROUGH/RIDGE/TROUGH PATTERN IS WELL ESTABLISHED ACROSS THE
ATLC BASIN. A LARGE UPPER LEVEL TROUGH COVERS MUCH OF THE
EASTERN U.S. AND WRN ATLC W OF 70W N OF 24N ANCHORED BY A LARGE
UPPER LOW OVER SE GEORGIA. MODERATE TO STRONG DRY STABLE AIR IS
ASSOCIATED WITH THE TROUGH. AS OF 2100 UTC...THE ATTENDANT COLD
FRONT EXTENDS FROM A 1015 MB LOW NEAR 32N78W TO 28N79W THEN SW
ACROSS CENTRAL FLORIDA. A MID-UPPER LEVEL HIGH REMAINS E OF THE
TROUGH AND COVERS THE REGION BETWEEN 38W AND 63W LIMITING ANY
SHOWER ACTIVITY. A SWLY JET EXISTS BETWEEN THESE FEATURES AND IS
ADVECTING A SWATH OF DEEP TROPICAL MOISTURE BETWEEN 63W AND 70W.
A SFC TROUGH GOES FROM 31N70W TO THE EASTERN BAHAMAS. THIS
FEATURE IS GENERATING CLUSTERS OF MODERATE CONVECTION OVER THE
EASTERN PORTION OF CUBA AND THE EASTERN BAHAMAS. AN ELONGATED
UPPER TROUGH ENTERS THE E ATLC NEAR 31N24W THEN CONTINUES SW TO
NEAR 20N40W. AN UPPER LOW HAS BECOME CUT OFF FROM THIS TROUGH
AND IS MOVING SLOWLY W CENTERED NEAR 20N60W. AN UPPER RIDGE
DOMINATES WESTERN AFRICA. AT THE SURFACE...A BROAD RIDGE COVERS
THE ATLC EAST OF 60W WITH A STATIONARY 1022 MB HIGH LOCATED NEAR
31N49W. ORGANIZED SHOWERS AND TSTMS IN THE CNTRL AND ERN ATLC
ARE CONFINED TO THE ITCZ AND TROPICAL WAVES.

$$
GR





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