[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 100621
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT SEP 10 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURES...

THE CENTER OF HURRICANE OPHELIA IS NEAR 30.4N 77.0W AT
10/0300 UTC MOVING NORTHEAST 8 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 985 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 65 KT
WITH GUSTS TO 80 KT. PLEASE REFER TO THE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE
DETAILS. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 30N TO
31N BETWEEN 77W AND 78W. SCATTERED MODERATE SHOWER TO ISOLATED
STRONG THUNDERSTORMS FROM 31N TO 33N BETWEEN 73W AND 76W.
THE PRESSURE INSIDE OPHELIA ROSE SINCE THE LAST REPORT...
WEAKENING A BIT COMPARATIVELY SPEAKING. SOME SOUTHWESTERLY WIND
SHEAR AND THE INTRUSION OF DRY AIR APPEAR TO HAVE DISRUPTED THE
STRUCTURE OF THE PRECIPITATION AROUND OPHELIA...AT LEAST
TEMPORARILY.

THE CENTER OF TROPICAL STORM NATE IS NEAR 34.8N 49.6W
AT 10/0300 UTC MOVING EAST 21 KT. THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 994 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 55 KT
WITH GUSTS TO 65 KT. PLEASE REFER TO THE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE
DETAILS. NATE CONSISTS ONLY OF A SWIRL OF LOW-LEVEL CLOUDS.
SHEAR OF 32 KT AND DRY AIR HAVE COMBINED TO WEAKEN NATE. NATE
WILL CONTINUE OVER COLDER TEMPERATURE WATERS AND IN A STRONG
SHEAR ENVIRONMENT. NATE SHOULD WEAKEN AT A MODERATE RATE...AND
IT WILL BEGIN TO TRANSITION INTO AN EXTRATROPICAL CYCLONE
AROUND 36 HOURS...BUT WILL LACK SUFFICIENT BAROCLINIC SUPPORT
FOR RE-INTENSIFICATION.

THE CENTER OF TROPICAL STORM MARIA IS NEAR 42.5N 39.8W AT
10/0300 UTC MOVING NORTHEAST 14 KT. THE ESTIMATED MINIMUM
CENTRAL PRESSURE IS 989 MB. THE MAXIMUM SUSTAINED WIND SPEEDS
ARE 50 KT WITH GUSTS TO 60 KT. PLEASE REFER TO THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS. SCATTERED MODERATE SHOWERS FROM 42N TO 48N
BETWEEN 37W AND 42W.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 29W SOUTH OF 22N MOVING
WEST 15 KT WITH A WEAK AND ILL-DEFINED 1012 MB NEAR 10.5N.
NO DEEP CONVECTIVE ACTIVITY ACCOMPANIES THIS WAVE.

TROPICAL WAVE ALONG 54W/56W SOUTH OF 23N MOVING WEST 15 KT.
ISOLATED MODERATE SHOWERS...WHICH REALLY MAY HAVE NOTHING TO DO
WITH THIS WAVE...FROM 15N TO 20N BETWEEN 50W AND 60.

EASTERN CARIBBEAN SEA TROPICAL WAVE ALONG 69W SOUTH OF 20N
MOVING WEST 15 KT. THE WAVE CONTINUES TO INTERACT WITH AN UPPER
LEVEL ATLANTIC OCEAN LOW PRESSURE CENTER WITHIN 230 NM OF THE
NORTHERN COAST OF THE DOMINICAN REPUBLIC.

WESTERN CARIBBEAN SEA TROPICAL WAVE ALONG 83W SOUTH OF 20N
MOVING WEST 15 TO 20 KT. THIS WAVE IS ALSO INTERACTING
WITH A LARGE UPPER LEVEL NORTHWESTERN CARIBBEAN SEA LOW PRESSURE
CENTER. SHOWERS AND THUNDERSTORMS IN CENTRAL AMERICA AND IN THE
CARIBBEAN SEA FROM 10N TO 20N WEST OF 80W HAVE BEEN RELATED TO
THIS WAVE.

...ITCZ...

ITCZ A20N17W 10N27W 7N41W 8N54W. WIDELY SCATTERED MODERATE
SHOWERS TO ISOLATED STRONG FROM 5N TO 10N BETWEEN 45W AND 54W.
ONE OF SHRINKING COVERAGE IN SENEGAL STILL IS SEEING STRONG
SHOWERS AND THUNDERSTORMS FROM 14N TO 17N BETWEEN 13W AND 15W.
ISOLATED MODERATE SHOWERS ARE WITHIN 60 TO 120 NM NORTH OF THE
ITCZ AXIS BETWEEN 20W AND 45W.
...DISCUSSION...

GULF OF MEXICO...
ONE UPPER LEVEL LOW PRESSURE CENTER IS IN THE NORTHWESTERN
CARIBBEAN SEA. A SECOND UPPER LEVEL LOW PRESSURE CENTER IS IN
NORTH CENTRAL MEXICO. THE UPPER FLOW IS PRIMARILY DOMINATED BY
THE EASTERN UPPER LOW WITH N/NE WINDS EXTENDING S OF 27N INTO
THE BAY OF CAMPECHE AND YUCATAN PENINSULA. THE WESTERN LOW OVER
MEXICO IS HELPING TO MOVE TROPICAL PACIFIC MOISTURE OVER THE
EASTERN HALF OF MEXICO AND THE FAR WESTERN GULF. ISOLATED
MODERATE SHOWERS ARE NORTH OF 23N WEST OF 90W. DRY AIR IS BEING
BROUGHT DOWN THE BACK SIDE OF HURRICANE OPHELIA AND HAS SPREAD
OVER MOST OF THE NORTHEASTERN GULF AND FLORIDA...NORTH OF 24N
BETWEEN 80W AND 90W.

CARIBBEAN...
THE LARGE NORTHWESTERN CARIBBEAN SEA UPPER LOW OVER THE NW
CARIBBEAN NEAR 19N84W HAS BEEN PRESENTED ALREADY WITH REGARD
TO GULF OF MEXICO WEATHER AND THE TROPICAL WAVE ALONG 83W.
SHOWERS AND THUNDERSTORMS. SHOWERS AND THUNDERSTORMS IN CENTRAL
AMERICA AND IN THE CARIBBEAN SEA FROM 10N TO 20N WEST OF 80W
HAVE BEEN RELATED TO THE 83W WAVE. SOME SHOWERS ARE ON TOP OF
HAITI AND SOME ARE IN THE EASTERN CARIBBEAN SEA.

WEST ATLANTIC...
AN UPPER LEVEL LOW IS CENTERED NORTH OF THE DOMINICAN REPUBLIC
REPUBLIC NEAR 23N68W MOVING QUICKLY NORTHWESTWARD...AND IS
PRODUCING SCATTERED SHOWERS/THUNDERSTORMS FROM THE SOUTHERN
BAHAMAS ISLANDS TO 30N BETWEEN 60W AND 75W.

EAST/CENTRAL ATLANTIC...
A LARGE UPPER LEVEL HIGH IS CENTERED OVER THE CENTRAL ATLC
WATERS NEAR 28N50W WITH A RIDGE AXIS EXTENDING WWD TOWARDS
OPHELIA AND SWWD TOWARDS THE LESSER ANTILLES. A SURFACE TROUGH
EXTENDING SOUTH OF T.S. NATE WAS PRODUCING A FEW SHOWERS EARLIER
TODAY BUT THE SUBSIDENCE ASSOCIATED WITH THE UPPER HIGH JUST
ABOUT HAS STOPPED THAT DEVELOPMENT. THE HIGH IS QUITE EXPANSIVE
AND IS DRIVING DEEP EASTERLIES ACROSS THE TROPICS FROM THE CAPE
VERDES TO THE LESSER ANTILLES. A STATIONARY UPPER LEVEL TROUGH
EXTENDS FROM NEAR THE CANARY ISLANDS SW TO 20N27W AND IS BEING
REINFORCED BY A WEAK UPPER LOW DROPPING DOWN THE BACK SIDE OF
THE TROUGH NEAR 20N36W. WHILE MOST OF THE AREA IS FREE OF ANY
WIDESPREAD AREAS OF DEEP CONVECTION...SKIES ARE PROBABLY RATHER
HAZY AND MILKY DUE TO A LARGE AREA OF SAHARAN DUST EXTENDING
ACROSS THE ENTIRE AREA...AND A LARGE CANOPY OF HIGH LEVEL CIRRUS
EXTENDING N OF 25N BETWEEN 23W-50W.

$$
MT



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