[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 091802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN SEP 09 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
1645 UTC.

...SPECIAL FEATURE...

TROPICAL STORM GABRIELLE IS CENTERED NEAR 35.3N 76.3W OR ABOUT
40 NM WNW OF CAPE HATTERAS NORTH CAROLINA AT 09/1800 UTC MOVING
N AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB.
MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT.
PLEASE REFER TO THE NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER
MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. RADAR IMAGERY AND
RECONNAISSANCE AIRCRAFT DATA INDICATED GABRIELLE MADE LANDFALL
ALONG THE NORTH CAROLINA COAST AT 1545 UTC ALONG THE CAPE
LOOKOUT NATIONAL SEASHORE. HOWEVER...THE STRONGEST WINDS AND
HEAVIEST RAINS ARE JUST REACHING THE COAST AND WILL BE SPREADING
FURTHER ONSHORE DURING THE NEXT FEW HOURS. GABRIELLE IS EXPECTED
TO TURN TO THE NNE LATER TODAY AND TOWARD THE NE TONIGHT.
GABRIELLE HAS BEEN INTERACTING WITH LAND OVER THE PAST FEW HOURS
AND NO ADDITIONAL STRENGTHENING IS EXPECTED. HEAVY RAIN AND
EMBEDDED THUNDERSTORMS ARE MOSTLY OFFSHORE FROM 33N-35N BETWEEN
75W-77W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS...IN
SPIRAL RAINBANDS COVER A LARGER AREA FROM 32N-37N BETWEEN
74W-78W. GABRIELLE IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 1 TO 3 INCHES ACROSS COASTAL SECTIONS OF NORTH
CAROLINA AND FAR SOUTHEASTERN VIRGINIA...WITH ISOLATED MAXIMUM
AMOUNTS OF 5 INCHES.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 33W/34W S OF 16N MOVING W NEAR 15 KT WITH
A 1012 MB LOW ALONG THE WAVE NEAR 10N. WAVE REMAINS EMBEDDED IN
A BROAD MONSOON-LIKE TROUGH THAT EXTENDS WSW FROM THE AFRICAN
COAST NEAR 12N16W TO 7N45W. LARGE CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 90 NM OF LINE
FROM 13N32W TO  9N39W. WHILE THERE ARE NO SIGNS OF SIGNIFICANT
ORGANIZATION AT THIS TIME...THIS SYSTEM DOES HAVE SOME POTENTIAL
FOR SLOW DEVELOPMENT DURING THE NEXT FEW DAYS.

TROPICAL WAVE IS ALONG 57W S OF 21N MOVING W 10-15 KT WITH A
WEAKENING 1012 MB LOW ALONG THE WAVE NEAR 14N. THE LOW LEVEL
SWIRL THAT HAS BEEN ANALYZED OVER THE PAST 12 HOURS IS WEAK AND
LOOKS TO BE DISSIPATING. HOWEVER...AN AREA OF DEEP CONVECTION
WITH MID LEVEL ROTATION IS FORMING ALONG THE N PORTION OF THE
WAVE AND A SECOND SURFACE LOW IS EXPECTED TO FORM THERE.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 16N-20N
BETWEEN 55W-58W WITH SCATTERED SHOWERS/THUNDERSTORMS FROM
12N-16N BETWEEN 57W-60W.

TROPICAL WAVE IS ALONG 91W S OF 22N MOVING W 10-15 KT. THIS WAVE
IS WELL-DEFINED IN THE E PACIFIC REGION WITH NO ASSOCIATED
SHOWERS/DEEP CONVECTION IN THE GULF OF MEXICO AND OVER S MEXICO.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 14N15W 11N31W 8N40W 9N62W. IN
ADDITION TO ACTIVITY ASSOCIATED WITH THE TROPICAL
WAVES...CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE
WITHIN 180 NM N OF THE AXIS FROM 40W-50W. SCATTERED MODERATE
CONVECTION IS WITHIN 75/90 NM OF 9N FROM 20W-27W. SCATTERED
THUNDERSTORMS DOT THE AREA FROM 6N-16N E OF 25W TO THE COAST OF
W AFRICA AND FROM 4N-9N BETWEEN 34W-50W.

DISCUSSION...

GULF OF MEXICO...
THE S GULF IS VERY ACTIVE TODAY AS A SURFACE TROUGH EXTENDS FROM
THE W ATLC ACROSS CENTRAL FLORIDA FROM DAYTONA BEACH TO FORT
MYERS CONTINUING ACROSS THE GULF ALONG 26N84W 26N87W TO 24N91W.
THIS SURFACE TROUGH IS ASSOCIATED WITH AN UPPER TROUGH THAT
EXTENDS ACROSS NE FLORIDA A MID/UPPER LEVEL LOW IN THE S GULF
NEAR 22N91W AND IS BEING MONITORED BUT DEVELOPMENT IS NOT
EXPECTED AT THIS TIME. THE SURFACE TROUGH IS MOVING NW WITH
CLUSTERS OF HEAVY SHOWERS/THUNDERSTORMS ARE S OF THE TROUGH AND
DRY UPPER AIR IS BEING ADVECTED N OF THE TROUGH. THE REMAINDER
OF THE GULF IS RATHER TRANQUIL WITH LIGHT/MODERATE WINDS. THE
EXCEPTION IS A SMALL AREA OF THUNDERSTORMS N OF THE ABOVE
SURFACE TROUGH WITHIN A 75 NM RADIUS OF 27N85W AND SCATTERED
SHOWERS/THUNDERSTORMS IN THE SW GULF FROM 20N-23N BETWEEN 93W
AND THE COAST OF MEXICO ASSOCIATED WITH THE MID/UPPER
LOW/TROUGH.

CARIBBEAN SEA...
AN UPPER RIDGE COVERS THE W CARIBBEAN EXTENDING FROM CENTRAL
AMERICA ACROSS CENTRAL CUBA PRODUCING ENOUGH DIFFLUENCE BETWEEN
THE UPPER TROUGH OF THE GULF OF MEXICO TO GENERATE SCATTERED
SHOWERS/THUNDERSTORMS N OF 20N ACROSS CUBA AND THROUGH THE
YUCATAN CHANNEL W OF 80W TO OVER THE YUCATAN PENINSULA. WEAK
UPPER TROUGH EXTENDS ACROSS THE LEEWARD ISLANDS TO NEAR 14N80W
GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF A LINE
FROM COLOMBIA NEAR 11N75W TO NICARAGUA NEAR 14N84W INCLUDING W
PANAMA. MODERATE/STRONG EASTERLY TRADE WINDS ACROSS THE REGION
ARE GENERATING A MALL AREA OF SCATTERED SHOWERS/THUNDERSTORMS
WITHIN 60 NM OF LINE FROM 14N73W TO 13N78W. THE FAR E CARIBBEAN
IS UNDER SOMEWHAT DRY STABLE AIR BUT CONDITIONS ARE EXPECTED TO
TURN WET WITH THE APPROACH OF THE TROPICAL WAVE CURRENTLY ALONG
57W. WIDELY ISOLATED SHOWERS/THUNDERSTORMS DOT THE REMAINDER OF
THE CARIBBEAN W OF 65W.

ATLANTIC OCEAN...
T.S. GABRIELLE IS THE PRIMARY FOCUS TODAY AS IT CONTINUES ACROSS
THE OUTER BANKS OF NORTH CAROLINA...SEE SPECIAL FEATURES ABOVE.
AN UPPER TROUGH EXTENDS FROM 31N79W ACROSS NE FLORIDA INTO THE
GULF OF MEXICO WITH AN ASSOCIATED SURFACE TROUGH EXTENDING FROM
30N79W ACROSS FLORIDA NEAR DAYTONA BEACH. AN UPPER RIDGE EXTENDS
ACROSS THE REMAINDER OF THE W ATLC FROM THE CARIBBEAN ACROSS
CENTRAL CUBA TO BEYOND 32N72W. THIS IS PRODUCING ENOUGH
DIFFLUENCE TO GENERATE SCATTERED SHOWERS/THUNDERSTORMS FROM
23N-26N W OF 78W TO OVER S FLORIDA WITH ISOLATED SHOWERS/
THUNDERSTORMS DOTTING THE AREA N OF 26N W OF 73W. A DEEP LAYERED
RIDGE IS OVER THE W/CENTRAL ATLC ANCHORED BY A 1024 MB HIGH N OF
BERMUDA. A DEEP LAYERED TROUGH IS OVER THE CENTRAL ATLC WITH AN
ASSOCIATED COLD FRONT ENTERING THE AREA NEAR 32N38W EXTENDING
SW TO 26N50W BECOMING NEAR STATIONARY ALONG 25N56W TO 26N62W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120/150 NM S
AND E OF THE FRONTAL BOUNDARY. TYPICAL E/W UPPER RIDGE
DOMINATES THE REMAINDER OF THE ATLC WITH DRY STABLE AIR AND A
SURFACE RIDGE EXTENDING THROUGH 32N24W TO A 1022 MB HIGH NEAR
29N28W TO NEAR 20N50W.

$$
WALLACE





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