[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 120014
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 11 2005

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

HURRICANE OPHELIA IS CENTERED NEAR 31.5N 76.0W...OR ABOUT 250
MILES EAST-SOUTHEAST OF CHARLESTON SOUTH CAROLINA AND ABOUT 255
MILES SOUTH OF CAPE HATTERAS NORTH CAROLINA...AT 11/2100 UTC
WITH NEARLY STATIONARY MOVEMENT.  ESTIMATED MINIMUM CENTRAL
PRESSURE IS 978 MB.  MAXIMUM SUSTAINED WIND SPEED IS 65 KT WITH
GUSTS TO 80 KT.  SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC AND THE PUBLIC ADVISORY
UNDER HEADERS MIATCPAT1/WTNT31 KNHC FOR MORE DETAILS. DEEP
CONVECTION HAS DECREASED W OF THE CENTER DUE TO SOME DRY AIR
WRAPPING AROUND THE CENTER.  A 80-100 KT UPPER LEVEL OUTFLOW JET
IS RACING EWD OUT OF THE NE QUADRANT...BUT IS MORE RESTRICTED
OVER THE REST OF THE STORM.  SCATTERED MODERATE CONVECTION IS
FROM 30N-34N BETWEEN 74W-78W.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE IS ALONG 42W S OF 22N MOVING W
15-20 KT. VISIBLE IMAGERY INDICATES A WELL-DEFINED CIRCULATION
AROUND THE WAVE THAT IS TILTED FROM NE TO SW. THE WAVE IS
SURROUNDED BY A LARGE AREA OF DRY SAHARAN AIR...BUT A SMALL
PATCH OF MOISTURE HAS CONVERGED WITHIN 150 NM OF THE PRESUMED
MID-LEVEL CENTER. ISOLATED SHOWERS ARE POSSIBLE WITHIN THIS
REGION FROM 12N-21N BETWEEN 37W-44W. OTHER DEEPER CONVECTION IS
LOCATED NEAR THE ITCZ.

EAST CARIBBEAN TROPICAL WAVE IS ALONG 70W S OF 21N MOVING W
15-20 KT. STRONG LOW-LEVEL CONVERGENCE IS OCCURRING AT THE NRN
TIP OF THE WAVE WHERE SELY FLOW BEHIND THE AXIS IS MERGING WITH
THE FLOW AROUND THE S SIDE OF THE SUBTROPICAL HIGH...AND
SCATTERED CLUSTERS OF MODERATE CONVECTION LIE N OF THE LESSER
ANTILLES FROM 18N-24N BETWEEN 61W-75W.  AN UPPER LEVEL LOW NEAR
16N70W IS ALSO ABOVE THE WAVE AXIS.

WEST CARIBBEAN TROPICAL WAVE IS ALONG 84W S OF 20N MOVING W
15-20 KT. THE WAVE IS LOCATED NEAR AN APEX IN THE LOW-LEVEL FLOW
AT 84W.  SCATTERED MODERATE CONVECTION IS OVER NICARAGUA FROM
10N-15N BETWEEN 82W-86W.  SCATTERED MODERATE CONVECTION IS ALSO
OVER THE YUCATAN PENINSULA FROM 16N-22N BETWEEN 88W-91W.

TROPICAL WAVE LOCATED OVER THE ISTHMUS OF TEHAUNTEPEC ALONG 96W
S OF 18N MOVING W 15-20 KT. THE WAVE IS EMBEDDED WITHIN SOME
CURVATURE TO THE FLOW OVER THE PACIFIC OCEAN...BUT IS NOT
ASSOCIATED WITH MUCH WEATHER FARTHER N INTO THE BAY OF CAMPECHE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N10W 5N20W 10N40W 10N50W 12N60W.
SCATTERED MODERATE TO STRONG CONVECTION IS ALONG THE COAST OF W
AFRICA FROM 9N-12N BETWEEN 13W-16W.  WIDELY SCATTERED MODERATE
CONVECTION IS WITHIN 75 NM OF THE AXIS BETWEEN 20W-45W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING IS PRODUCING LIGHT EASTERLY FLOW OVER THE
GULF OF MEXICO.  A SURFACE TROUGH IS OVER S FLORIDA ALONG 26N80W
25N84W.  SCATTERED SHOWERS ARE WITHIN 15 NM OF THE TROUGH.  IN
THE UPPER LEVELS...AN UPPER LEVEL LOW IS OVER THE W GULF NEAR
26N92W.  UPPER LEVEL DIFFLUENCE AND LOW LEVEL ONSHORE FLOW IS
PRODUCING SCATTERED MODERATE CONVECTION OVER S TEXAS FROM
26N-29N BETWEEN 97W-101W.  ANOTHER UPPER LEVEL LOW IS CENTERED
OVER THE YUCATAN PENINSULA NEAR 18N89W.  UPPER LEVEL DIFFLUENCE
FROM THIS SYSTEM AND INTERACTION FROM A TROPICAL WAVE IS
PRODUCING CONVECTION OVER THE YUCATAN PENINSULA FROM 16N-22N
BETWEEN 88W-91W.  EXPECT CONTINUED EASTERLY FLOW OVER THE GULF
DURING THE NEXT 24 HOURS WITH THE GREATEST CONVECTION POTENTIAL
OVER THE W GULF FROM THE YUCATAN PENINSULA TO S TEXAS.

CARIBBEAN...
TWO TROPICAL WAVES DOMINATED THE SURFACE FLOW OVER THE CARIBBEAN
SEA.  SEE ABOVE FOR ASSOCIATED CONVECTION.  IN ADDITION...A 1005
MB SURFACE LOW OVER N COLOMBIA AT 5N76W IS PRODUCING SCATTERED
MODERATE TO STRONG CONVECTION FROM 6N-11N BETWEEN 72W-76W.  IN
THE UPPER LEVELS...BESIDES THE UPPER LOW OVER THE YUCATAN
PENINSULA...ANOTHER UPPER LOW IS CENTERED S OF HISPANIOLA NEAR
16N71W.  EXPECT THE HIGHEST POTENTIAL OF CONVECTION OVER CENTRAL
AMERICA FROM PANAMA TO THE YUCATAN PENINSULA.  ALSO EXPECT
CONVECTION OVER E CUBA.

ATLANTIC...
HURRICANE OPHELIA SITS JUST N OF THE AREA OFF THE SOUTH CAROLINA
COAST BUT THE CIRCULATION STILL EXTENDS SWD TOWARDS THE NRN
BAHAMAS. A SURFACE TROUGH EXTENDS AROUND THE S SIDE OF THE STORM
FROM S FLORIDA ACROSS GRAND BAHAMA AND GREAT ABACO TO 29N72W.
SCATTERED SHOWERS ARE WITHIN 15 NM OF THE TROUGH.  A 1020 MB
HIGH IS CENTERED NEAR 27N62W.  A COLD FRONT IS OVER THE CENTRAL
ATLANTIC ALONG 32N37W 28N40W 24N50W.  ISOLATED SHOWERS ARE
WITHIN 30 NM OF THE FRONT.  A 1024 MB HIGH IS OVER THE E
ATLANTIC NEAR 37N17W.  AFRICAN DUST COVERS THE ENTIRE ATLANTIC
FROM 10N-25N E OF 55W MOVING W .  IN THE UPPER LEVELS...A LARGE
HIGH WITH SIGNIFICANT SUBSIDENCE IS OVER THE CENTRAL ATLANTIC
NEAR 25N55W.  A LOW IS FURTHER E AT 18N45W.  A LARGE UPPER LEVEL
RIDGE IS OVER W AFRICA AND THE E ATLANTIC FROM 10N-25N...E OF
38W.

$$
FORMOSA


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