[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281750
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI AUG 28 2009

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

TROPICAL STORM DANNY IS CENTERED NEAR 30.1N 75.7W AT 28/1800 UTC
OR ABOUT 310 NM S OF CAPE HATTERAS NORTH CAROLINA AND ABOUT 720
NM SSW OF NANTUCKET MASSACHUSETTS MOVING NNW AT 9 KT. THE
MINIMUM CENTRAL PRESSURE MEASURE BY AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT WAS 1007 MB. MAXIMUM SUSTAINED WIND
SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC INTERMEDIATE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC
AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. THE LOW LEVEL CENTER IS
COMPLETELY EXPOSED AS THE DEEP CONVECTION IS TO THE E.
SCATTERED/MODERATE STRONG CONVECTION IS WITHIN 75 NM OF LINE
FROM 27N70W TO 31N73W WITH SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS DOT THE REMAINDER OF THE AREA FROM 26N-31N BETWEEN
69W-75W.

TROPICAL WAVE WAS ADJUSTED TO ALONG 36W BASED ON THE 1011 MB
SURFACE LOW POSITION. THE LOW IS CENTERED NEAR 10.5N36W. THE
SYSTEM IS MOVING W NEAR 20 KT OVER THE PAST 24 HOURS. THIS
WAVE/LOW COINCIDES WITH A BROAD AREA OF LOW LEVEL CYCLONIC
CURVATURE FOCUSED AROUND THE SURFACE LOW AND IS EMBEDDED IN AN
AREA OF DEEP LAYERED MOISTURE AS INDICATED BY PRECIPITABLE WATER
IMAGERY. ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR FURTHER
DEVELOPMENT OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.
SCATTERED MODERATE/STRONG CONVECTION IS W OF TE WAVE FROM 8N-12N
BETWEEN 39W-42W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 11N-15N BETWEEN 34W-39W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 54W S OF 16N MOVING W 15-20 KT OVER THE
PAST 24 HOURS. WAVE IS LOCATED AT AN INVERTED PEAK IN MAXIMUM
MOISTURE AS INDICATED BY PRECIPITABLE WATER IMAGERY. HOWEVER...
THE LOWER LEVELS ARE DRY SO THERE IS NO ASSOCIATED
SHOWERS/CONVECTION.

TROPICAL WAVE IS ALONG 83W/84W S OF 16N MOVING W 15-20 KT OVER
THE PAST 24 HOURS. WAVE IS BEGINNING TO MOVE INLAND OVER CENTRAL
AMERICA AND IS BENEATH AN UPPER TROUGH WITH DEEP LAYERED DRY
STABLE AIR...SO NO ASSOCIATED SHOWERS/CONVECTION.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 14N15W 10N30W 7N41W 9N50W 11N60W
THEN ACROSS THE N PORTION OF SOUTH AMERICA INTO THE E PACIFIC
REGION OVER E PANAMA. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS FROM 10N-14N BETWEEN 15W-20W INCLUDING THE COAST
OF W AFRICA. CLUSTERS OF SIMILAR CONVECTION ARE FROM 10N-16N
BETWEEN 20W-28W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS INTO THE GULF ACROSS THE FLORIDA
PANHANDLE W OF TALLAHASSEE THROUGH APALACHEE BAY ALONG 26N86W TO
23N91W GENERATING SCATTERED SHOWERS/THUNDERSTORMS E OF THE
TROUGH TO INLAND OVER THE W COAST OF FLORIDA PENINSULA N OF FORT
MYERS. THIS SURFACE TROUGH IS SUPPORTED BY AN UPPER LEVEL TROUGH
THAT COVERS THE GULF N OF 25N AND AN UPPER LOW OVER CENTRAL
ALABAMA. AN UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE GULF
ANCHORED BY AN UPPER LEVEL HIGH S MEXICO. DIFFLUENCE ALOFT OVER
THE SW GULF IS GENERATING SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS S OF 23N INTO THE BAY OF CAMPECHE BETWEEN
92W-96W. THE NEXT FRONTAL BOUNDARY THAT IS EXPECTED TO MOVE INTO
THE NW GULF ON SUN IS CURRENTLY INLAND OVER TEXAS WITH SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS AHEAD OF THE FRONT WITHIN 90 NM
ALONG THE COAST OF W LOUISIANA W OF VERMILION BAY AND E TEXAS N
OF MATAGORDA BAY.

CARIBBEAN SEA...
AN UPPER LEVEL LOW COVERS THE W CARIBBEAN TO THE YUCATAN
PENINSULA CENTERED NEAR 16N80W. AN UPPER HIGH OVER THE W/CENTRAL
ATLC COVERS THE E CARIBBEAN DRAWING UPPER LEVEL MOISTURE OVER
THE CENTRAL CARIBBEAN BUT DUE TO THE DRY AIR OVER THE ARE IS
ONLY ABLE TO PRODUCE SOME ISOLATED SHOWERS S OF 16N FROM
74W-78W. THE ITCZ CROSSES THE N PORTION OF SOUTH AMERICA AND
PANAMA INTO THE E PACIFIC REGION WITH SCATTERED MODERATE/STRONG
CONVECTION WITHIN 75 NM ALONG THE COAST OF PANAMA AND COSTA
RICA. MODERATE/STRONG EASTERLY TRADE WINDS ARE ACROSS THE
CARIBBEAN BASIN USHERING IN ISOLATED LOW LEVEL FAST MOVING
SHOWERS MAINLY N OF 15N E OF 68W TO OVER THE LEEWARD ISLANDS TO
PUERTO RICO. OTHERWISE THE REMAINDER OF THE CARIBBEAN REMAINS
RATHER TRANQUIL TODAY.

ATLANTIC OCEAN...
ATTENTION REMAINS FOCUSED ON TROPICAL STORM DANNY IN THE W ATLC.
THE REMAINDER OF THE W ATLC REMAINS FAIRLY TRANQUIL AS AN UPPER
LEVEL RIDGE IS TO THE W OF DANNY. AN UPPER HIGH IS OVER THE
CENTRAL ATLC AND INTO THE E CARIBBEAN CENTERED NEAR 25N67W. AN
UPPER LOW TO THE NE NEAR 29N45W IS GENERATING ISOLATED SHOWERS
FROM 28N-32N BETWEEN 42W-48W. THE REMAINDER OF THE CENTRAL AND E
ATLC ARE DOMINATED BY BENIGN UPPER LEVEL FEATURES AND A SURFACE
RIDGE ANCHORED BY A 1036 MB HIGH NE OF THE AZORES AND A WEAKER
1024 MB HIGH NE OF BERMUDA.

$$
WALLACE






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