[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 30 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

TROPICAL STORM NOEL IS CENTERED NEAR 21.0N 77.7W AT 30/1800
UTC...OR ABOUT 25 NM S-SE OF CAMAGUEY CUBA AND ABOUT 240 NM S OF
NASSAU IN THE NW BAHAMAS...MOVING W NEAR 7 KT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1002 MB. MAXIMUM SUSTAINED WINDS ARE NOW
NEAR 35 KT WITH GUSTS TO 45 KT. LITTLE CHANGE IN STRENGTH IS
FORECAST DURING THE NEXT 24 HOURS AS NOEL REMAINS INLAND OVER
CUBA THROUGH TONIGHT...BEFORE EMERGING OFF THE NORTHERN COAST OF
CUBA BY TOMORROW. SEE THE NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC AND/OR THE PUBLIC ADVISORY UNDER
MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. SATELLITE
IMAGERY...SURFACE OBSERVATIONS AND RADAR FROM CAMAGUEY CUBA
INDICATE THAT CENTER OF NOEL REMAINS INLAND OVER EASTERN CUBA.
HOWEVER...RAINBANDS CONTINUE TO EXTEND WELL AWAY FROM THE CENTER
AND ARE SPREADING INTO THE BAHAMAS. NOEL IS EXPECTED TO PRODUCE
SIGNIFICANT RAINFALL ACCUMULATIONS OVER
HISPANIOLA...SOUTHEASTERN CUBA... AND THE BAHAMAS.  THESE
RAINS...PARTICULARLY IN HISPANIOLA... ARE EXPECTED TO CAUSE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. IN ADDITION TO THE
RAINFALL THREAT...THE INTERACTION BETWEEN NOEL...STRONG HIGH
PRESSURE OVER THE VIRGINIAS...AND A STATIONARY FRONT EXTENDING
ENE FROM CENTRAL FLORIDA IS PRODUCING STRONG GUSTY ENE WINDS
OVER PORTIONS OF FLORIDA AND THE ADJACENT WATERS. THIS HAS
ALLOWED SEAS TO BUILD INTO THE 10-15 FT RANGE IN THE AREA
OFFSHORE FLORIDA AND THE BAHAMAS. THESE SEAS ARE EXPECTED TO
BUILD FURTHER THROUGH MIDWEEK AS NOEL MOVES NW INTO THE
AREA...SEE HIGH SEAS FORECASTS UNDER AWIPS HEADER NFDHSFAT1 AND
STATEMENTS FROM LOCAL WEATHER OFFICES FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE PREVIOUSLY ALONG 63W HAS BEEN ADJUSTED SLIGHTLY TO
THE W TO 66W ON THE 30/1200 UTC MAP...BASED ON THE SURGE
OF MOISTURE NOTED MOVING THROUGH THE AREA IN THE UW-CIMSS TPW
PRODUCT OVER THE LAST COUPLE OF DAYS...VISIBLE IMAGERY...AND 850
MB SATELLITE DERIVED VORTICITY. HOWEVER...THE WAVE MAY
EVENTUALLY NEED TO BE DROPPED SOMETIME OVER THE NEXT DAY OR SO
AS THE ASSOCIATED MOISTURE/ENERGY MOVES NW WITH SE FLOW AHEAD OF
T.S. NOEL...AND POSSIBLY GETS ABSORBED BY THE TROPICAL CYCLONE.
THE WAVE ITSELF ONLY APPEARS TO BE GENERATING ISOLATED
SHOWERS/TSTMS WITHIN 90 NM OF THE AXIS.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 8N13W 8N30W 5N45W 3N52W. A
FAIRLY LARGE AREA OF ACTIVE WEATHER IS NEAR THE ITCZ BETWEEN
20W-45W. SPECIFICALLY...NUMEROUS MODERATE WITH EMBEDDED AREAS OF
STRONG CONVECTION ARE WITHIN 150NM N AND 90NM S OF THE AXIS
BETWEEN 21W-44W. IT IS PROBABLE THAT AT LEAST ONE LOW AMPLITUDE
TROPICAL WAVE IS EMBEDDED IN THIS REGION. THE DAKAR RAOB DATA
SHOWED A CLEAR WAVE PASSAGE AROUND 12Z ON OCTOBER 27...WITH THE
SAL SOUNDING DATA SHOWING A SIMILAR PASSAGE ABOUT A DAY LATER.
BASED SOLELY ON FORWARD EXTRAPOLATION...THIS WOULD MEAN THAT A
LOW AMPLITUDE TROPICAL WAVE IS SOMEWHERE IN THE VICINITY OF 33W.
THIS ALSO COINCIDES TO WHERE THE MOST POLEWARD INFLECTION OF THE
ITCZ IS. THERE APPEARS TO BE SOME SUBTLE LOW LEVEL CYCLONIC
TURNING IN THIS REGION...BUT THE FEATURE IS NOT WELL-DEFINED.
GIVEN THE RATHER POOR SATELLITE APPEARANCE AT THE MOMENT...AND
THE FACT THAT THE WAVE WILL UNDOUBTEDLY BE DIFFICULT TO
TRACK...HAVE OPTED TO LEAVE THE FEATURE OFF AT THE MOMENT. WILL
REVISIT THIS ON FUTURE MAPS.

DISCUSSION...
GULF OF MEXICO...
A STATIONARY FRONT EXTENDS FROM CENTRAL FLORIDA W ACROSS
THE MIDDLE GULF AND THEN SSW TO THE CENTRAL BAY OF
CAMPECHE...GENERALLY ALONG 28N82W 26N92W 18N93W. ISOLATED
SHOWERS AND TSTMS ARE MAINLY WITHIN 120 NM AHEAD OF THE WRN
PORTION OF THE FRONT N OF THE YUCATAN. THE FRONT REMAINS EVIDENT
IN SATELLITE IMAGERY AS A RAGGED LINE OF BROKEN LOW TO MID
CLOUDS. ASIDE FROM THAT THOUGH...THE FRONT IS NOT CLASSIC WITH
NE WINDS ON BOTH SIDES OF THE BOUNDARY. A DEWPOINT GRADIENT
REMAINS EVIDENT HOWEVER...WITH THE 70 DEGREE ISODROSOTHERM THE
MAIN PARAMETER USED IN THE FRONTAL PLACEMENT. REGARDLESS...THE
GULF PORTION OF THE FRONT IS EXPECTED TO CONTINUE BECOMING
DIFFUSE OVER THE NEXT DAY OR SO. ELSEWHERE AT THE SFC...STRONG
HIGH PRES CENTERED OVER VIRGINIA IS INTERACTING WITH THE FRONT
AND THE GRADIENT AROUND T.S. NOEL OVER CUBA TO PRODUCE FRESH TO
STRONG NE WINDS OVER MUCH OF THE BASIN. A GALE WARNING REMAINS
IN EFFECT FOR THE FAR SW GULF BUT IS EXPECTED TO BE ALLOWED TO
EXPIRE BY TONIGHT. ALOFT...FLOW IS FAIRLY UNIFORM SW AHEAD OF A
SHORTWAVE TROUGH NEARING THE COAST OF TEXAS.

CARIBBEAN SEA...
TROPICAL STORM NOEL REMAINS INLAND OVER CUBA...SEE SPECIAL
FEATURE SECTION. TROUGHING S OF THE TROPICAL CYCLONE DOMINATES
MUCH OF THE WRN CARIBBEAN. LOW LEVEL S/SW FLOW BETWEEN THE COAST
OF COLOMBIA AND ERN CUBA IS CONVERGING WITH MORE OF A MODERATE E
TO SE FLOW IN THE EASTERN CARIBBEAN...PRODUCING NUMEROUS SHOWERS
WITH EMBEDDED TSTMS BETWEEN 71W-78W. THIS ACTIVITY MAY ALSO BE
GETTING SOME SUPPORT BY AN UPPER COL REGION BETWEEN ANTICYCLONES
OVER THE E AND W PORTIONS OF THE BASIN. SCATTERED
SHOWERS/ISOLATED TSTMS ARE ALSO OVER THE SW CARIBBEAN S OF
14N...AND JUST OFF THE S COAST OF BELIZE S OF 18N W OF 87W.
ELSEWHERE...DEEP CONVECTION IS MINIMAL. TRADE FLOW IS EXPECTED
TO REMAIN DISRUPTED OVER THE WRN CARIBBEAN OVER THE NEXT COUPLE
OF DAYS DUE TO THE TROUGHING S OF T.S. NOEL. LIGHT TO MODERATE
TRADES ARE ANTICIPATED OVER THE ERN CARIBBEAN.

ATLANTIC OCEAN...
THE MAIN STORY CONTINUES TO BE TROPICAL STORM NOEL OVER CUBA.
NOEL IS INTERACTING WITH STRONG HIGH PRES OVER THE MID ATLC
STATES AND A STATIONARY FRONT EXTENDING ENE FROM CENTRAL
FLORIDA...WHICH IS PRODUCING STRONG GUSTY WINDS AND LARGE SEAS
OVER MUCH OF THE WRN ATLC. SEE DETAILS ABOVE IN SPECIAL FEATURE
SECTION. NUMEROUS SHOWERS/SCATTERED TSTMS ASSOCIATED WITH NOEL
ARE MAINLY S OF 26N BETWEEN 66W-78W. UPPER DIFFLUENCE IS ALSO
ENHANCING THIS ACTIVITY...BETWEEN AN UPPER LOW JUST N OF ERN
CUBA...AND RIDGING EXTENDING N INTO THE ATLC FROM THE ERN
CARIBBEAN. A WEAK SFC TROUGH IS OVER THE CENTRAL ATLC ALONG
32N53W 24N59W. WHILE WINDS ARE FAIRLY LIGHT IN THE VICINITY OF
THIS TROUGH...THERE IS A CLEAR CYCLONIC SHIFT IN WIND DIRECTION
AROUND THE BOUNDARY. HOWEVER...THE FEATURE ONLY APPEARS TO
BE GENERATING ISOLATED SHOWER ACTIVITY WITHIN 30NM OF THE AXIS.
AN UPPER LOW NEAR 19N52W IS GENERATING HIGH CLOUDS AND POSSIBLE
ISOLATED SHOWERS FROM 15N-23N BETWEEN 43W-50W. THE REMAINDER OF
THE E ATLC IS MOSTLY QUIET WITH TYPICAL PATCHES OF STABLE
STRATOCUMULUS CLOUDS. TRADES ARE MOSTLY MODERATE OVER THE AREA S
OF 25N E OF 65W...WITH SLIGHTLY STRONGER NE WINDS NOTED JUST OFF
THE COAST OF NW AFRICA IN THE VICINITY OF THE CANARY ISLANDS. A
BROAD UPPER TROUGH IS OVER THE NE PORTION OF THE AREA...BUT DOES
NOT APPEAR TO BE GENERATING SIGNIFICANT WEATHER.

$$
WILLIS




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