[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 052354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE SEP 05 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.

...SPECIAL FEATURE...
FLORENCE...THE SIXTH NAMED STORM OF THE 2006 TROPICAL SEASON IS
CENTERED NEAR 17.4N 48.5W OR ABOUT 960 MILES EAST OF THE
NORTHERN LEEWARD ISLANDS AT 05/2100Z. IT IS MOVING WNW AT 12
KT. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. THE
MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT.
PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT1/WTNT21 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. FLORENCE IS GETTING A
LITTLE STRONGER OVER THE OPEN ATLANTIC. THE LOW-LEVEL
CIRCULATION CENTER...AS WELL AS CONVECTIVE BANDING FEATURES HAS
BECOME BETTER DEFINED IN VISIBLE SATELLITE IMAGERY. THUNDERSTORM
ACTIVITY HAS ALSO BEGUN TO DEVELOP IN THE INNER CORE REGION. A
CLUSTER OF MODERATE TO STRONG CONVECTION IS FROM 17N-20N BETWEEN
44W-47W. THIS TROPICAL CYCLONE WILL CONTINUE TO MOVE ON A
GENERAL WEST-NORTHWESTWARD MOTION THROUGH 96 HOURS...REMAINING
OVER THE WARM OCEAN WATERS. IT IS FORECAST TO REACH MINIMAL
HURRICANE INTENSITY ON FRIDAY.

...TROPICAL WAVES...
AN E ATLC TROPICAL WAVE IS ALONG 33W SOUTH OF 21N...SEVERAL
HUNDRED MILES WEST OF THE CAPE VERDE ISLANDS. SHOWER AND
THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS SYSTEM CONTINUE
TO SHOW SIGNS OF ORGANIZATION.  ENVIRONMENTAL CONDITIONS APPEAR
SOMEWHAT FAVORABLE FOR A TROPICAL DEPRESSION TO DEVELOP DURING
THE NEXT COUPLE OF DAYS AS THE SYSTEM MOVES WESTWARD AT ABOUT 10
MPH.

A HIGH-AMPLITUDE TROPICAL WAVE IS ALONG 60/61W SOUTH OF 23N
MOVING W NEAR 10 KT. THIS WAVE CONTINUES TO SHOW A WELL DEFINED
INVERTED V CLOUD PATTERN. A MOIST ELY SURGE JUST AHEAD OF THIS
SYSTEM IS GENERATING SCATTERED MODERATE/ISOLATED STRONG
CONVECTION OVER THE EASTERN CARIBBEAN...INCLUDING THE VIRGIN
ISLANDS AND PARTS OF PUERTO RICO. THIS WAVE WILL MOVE ACROSS THE
VIRGIN ISLANDS AND PUERTO RICO TONIGHT TROUGH WEDNESDAY BRINGING
A NOTICEABLE INCREASE IN SHOWER AND TSTM ACTIVITY. THE SAN JUAN
DOPPLER RADAR IS ALREADY SHOWING BAND OF SHOWERS WITH EMBEDDED
TSTM MOVING WWD ACROSS THESE ISLANDS.

A CARIBBEAN SEA TROPICAL WAVE IS ALONG 77W SOUTH OF 21N MOVING
WEST NEAR 10 KT. A NARROW UPPER TROUGH IN THE AREA IS MASKING
THE LOW-LEVEL SIGNATURE. SOME POSSIBLE INTERACTION FROM THIS
WAVE AND THE UPPER TROUGH IS TRIGGERING SCATTERED SHOWERS AND
TSTMS OVER JAMAICA AND EASTERN CUBA.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 7N11W 10N30W 12N40W 10N50W 11N59W.
OUTSIDE THE CONVECTION ASSOCIATED WITH TROPICAL STORM FLORENCE
AND THE TROPICAL WAVES...A CLUSTER OF SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS MOVING OUT OF AFRICAN COAST FROM
10N-14N E OF 17W.

...DISCUSSION...

THE GULF OF MEXICO...
A MID-UPPER LOW SITUATED OVER THE EASTERN GULF NEAR 23N89W IS
PRODUCING A BROAD AREA OF SHOWERS AND TSTMS OVER THE YUCATAN
PENINSULA AND NORTHERN GUATEMALA. AN UPPER HIGH IS ANCHORED OVER
NW MEXICO WITH A RIDGE EXTENDING NEWD ACROSS THE SOUTH U.S. AND
THE NORTHERN GULF WATERS. THE RIDGE ALSO COVERS A GOOD PORTION
OF MEXICO. ABUNDANT UPPER LEVEL MOISTURE COVERS THE AREA FROM
TEXAS TO GEORGIA AND MOST OF THE GULF. AS OF 2100 UTC...A BROAD
SURFACE TROUGH EXTENDS ALONG 27N84W 22N86W 17N90W. THIS TROUGH
AND A DIFFLUENT PATTERN ALOFT ARE KEEPING SOUTH-CENTRAL FLORIDA
IN A VERY WET ENVIRONMENT.  A STATIONARY FRONT EXTENDS FROM SE
LOUISIANA TO NE MEXICO. A PRE-FRONTAL SFC TROUGH LIES ABOUT 100
NM SE OF THE FRONT FROM 27N88W TO 24N96W. A NARROW LINE OF
CLOUDS AND ISOLATED SHOWERS IS ASSOCIATED WITH THE FRONTAL
BOUNDARY WHILE SCATTERED SHOWERS AND TSTM ARE WITHIN 60 NM AHEAD
OF THE TROUGH. A MOIST AND UNSTABLE ATMOSPHERE WILL PERSIST OVER
SOUTH-CENTRAL FLORIDA TONIGHT AND TOMORROW.

THE CARIBBEAN SEA...
AN UPPER TROUGH EXTENDS FROM THE SE BAHAMAS ACROSS E CUBA AND
JAMAICA TO NEAR CABO GRACIAS A DIOS NICARAGUA. THIS TROUGH ALONG
WITH A TROPICAL WAVE IS SUPPORTING THE DEVELOPMENT OF SCATTERED
SHOWERS AND TSTM OVER E CUBA...JAMAICA AND PARTS OF NICARAGUA
AND HONDURAS. SIMILAR CONVECTIVE ACTIVITY IS OVER COSTA RICA AND
PANAMA DUE TO THE CLOSE PROXIMITY OF THE ITCZ. AN UPPER HIGH
LOCATED OVER PUERTO RICO DOMINATES THE EASTERN CARIBBEAN. THIS
FEATURE IS ALSO ENHANCING THE SHOWER/TSTM ACTIVITY OVER THE
AREA. A NEW CLUSTER OF MODERATE/ISOLATED STRONG CONVECTION HAS
DEVELOPED OVER NW VENEZUELA NEAR THE LAKE MARACAIBO AREA
PROBABLY ASSOCIATED WITH THE ITCZ. TRADE WINDS ARE GENERALLY IN
THE 15-20 KT RANGE E OF 80W...LIGHTER WINDS W OF THERE.

THE ATLANTIC OCEAN...
A BROAD TROUGH OF LOW PRESSURE NEAR FLORIDA IS PRODUCING A LARGE
AREA OF SHOWERS AND THUNDERSTORMS OVER THE NORTHWESTERN
BAHAMAS...FLORIDA AND THE ADJACENT WATERS. THUNDERSTORM ACTIVITY
REMAINS DISORGANIZED AND DEVELOPMENT...IF ANY...IS EXPECTED TO BE
SLOW TO OCCUR AS THE SYSTEM MOVES SLOWLY NORTH-NORTHEASTWARD.
AN UPPER TROUGH IS OVER THE W ATLC W OF 70W. CONSIDERABLE
MOISTURE LIES UNDER THE INFLUENCE OF THIS TROUGH. AN UPPER LEVEL
HIGH IS CENTERED TO THE NE OF THE TROUGH NEAR 32N65W. ANOTHER
UPPER HIGH IS OVER PUERTO RICO. A DEEP LAYER TROUGH REMAINS OVER
THE CENTRAL ATLC...GENERATING MODERATE SWLY VERTICAL WIND SHEAR
OVER T.S. FLORENCE AND LIMITING THE DEVELOPMENT OF THIS TROPICAL
CYCLONE. THE ASSOCIATED FRONTAL BOUNDARY ENTERS THE AREA NEAR
31N34W AND EXTENDS SW TO 26N60W.  A CUT-OFF UPPER LEVEL LOW
APPEARS TO BE DEVELOPING NEAR THE TAIL END OF THE SFC FRONT
ENHANCING SOME SHOWER ACTIVITY FROM 23N-28N BETWEEN 49W-59W.
FARTHER EAST...A BROAD MID-UPPER LEVEL RIDGE COVERS THE
REMAINDER OF THE REGION WITH THE MAIN HIGH CENTER NEAR 21N31W.
THE CIMSS SAL TRACKING PRODUCT SHOWS THAT A NEW SURGE OF AFRICAN
DUST HAS PUSHED OFF THE COAST SPREADING TO ABOUT 30W.

$$
GR



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