[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 201040
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU AUG 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURES...
HURRICANE BILL IS CENTERED NEAR 21.6N 60.3W OR ABOUT 285 NM NNE
OF THE LEEWARD ISLANDS AND ABOUT 685 NM SSE OF BERMUDA MOVING NW
AT 16 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 949 MB. MAXIMUM
SUSTAINED WIND SPEED IS 110 KT WITH GUSTS TO 135 KT. SEE THE
LATEST FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS TCMAT3/WTNT23
KNHC FOR MORE DETAILS. ALTHOUGH BILL HAS WEAKENED SLIGHTLY TO A
CATEGORY 3 STORM IT IS NOT EXPECTED LONG LASTING AND COULD
BECOME A CATEGORY 4 LATER TODAY OR FRIDAY. HURRICANE BILL
CONTINUES TO DISPLAY A WELL DEFINED EYE WITH SCATTERED STRONG
CONVECTION WITHIN 45 NM OF THE CENTER IN THE NW QUADRANT AND
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERING THE
REMAINDER OF THE AREA FROM 20N-26N BETWEEN 56W-63W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 22W/23W S OF 16N MOVING W NEAR 10 KT.
WAVE IS NOW EMBEDDED WITHIN AN AREA DEEP LAYER MOISTURE MAXIMUM
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY AND IS CLEARLY
DEFINED MAINLY IN THE LOW/MID LEVELS. HOWEVER...IT REMAINS
WITHIN AN AREA OF DRY UPPER AIR...THEREFORE NO ASSOCIATED
SHOWERS/CONVECTION.

TROPICAL WAVE REMAINS SLIGHTLY TILED DUE TO HURRICANE BILL
EXTENDING FROM 15N50W TO 8N46W MOVING W 15-20 KT. WAVE REMAINS
EMBEDDED WITHIN AN AREA DEEP LAYER MOISTURE MAXIMUM OBSERVED IN
TOTAL PRECIPITABLE WATER IMAGERY AND IS WELL DEFINED IN THE
LOW/MID LEVELS. HOWEVER...DUE TO DRY UPPER AIR THERE IS NO
ASSOCIATED SHOWERS/CONVECTION.

TROPICAL WAVE IS ALONG 88W S OF 19N MOVING W 10-15 KT. WAVE IS
NOW INLAND OVER CENTRAL AMERICA AND THE YUCATAN PENINSULA.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 15N16W 8N29W 7N39W 8N55W 10N62W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 9N-12N E OF 21W TO INLAND OVER W AFRICA. SMALL CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 5N-12N BETWEEN 24W-43W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER RIDGE EXTENDS FROM OVER MEXICO NEAR TUXPAN NNE TO
OVER THE LOWER MISSISSIPPI VALLEY TO THE CAROLINAS WHILE A UPPER
LOW IN THE CARIBBEAN EXTENDS AN UPPER TROUGH OVER THE REMAINDER
OF THE GULF. THE SURFACE RIDGE FROM THE W ATLC IS CONTINUES TO
BUILD ACROSS THE E GULF. ISOLATED SHOWERS CONTINUE TO DOT THE E
GULF E OF 90W WHILE THE REMAINDER OF THE GULF IS BEGINNING TO
CLEAR.

CARIBBEAN SEA...
AN UPPER LOW REMAINS JUST OFF THE YUCATAN NEAR 18N87W COVERING
THE NW CARIBBEAN AND EXTENDING AN UPPER TROUGH N OVER THE E GULF
OF MEXICO. AN UPPER RIDGE EXTENDS FROM E PANAMA TO E CUBA ALONG
78W PROVIDING UPPER LEVEL DIFFLUENCE TO GENERATE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS S OF A LINE FROM COLOMBIA NEAR
10N75W TO NICARAGUA NEAR 13N84W. FRESH TO STRONG EASTERLY TRADE
WINDS CONTINUE ACROSS THE AREA. DRY STABLE AIR IS ACROSS THE
REMAINDER OF THE AREA E OF 80W LIMITING ANY DEEP LAYERED
SHOWERS. HOWEVER...FAST LOW LEVEL ISOLATED SHOWERS ARE ACROSS
THE E CARIBBEAN E OF 75W WITH SCATTERED SHOWERS AND POSSIBLE
ISOLATED THUNDERSTORMS AS WELL AS HIGHER SEAS AND SWELLS ACROSS
THE LEEWARD ISLANDS TO PUERTO RICO ALL COMPLIMENTS OF HURRICANE
BILL AS IT CONTINUES TO MOVE NW OF THE ISLANDS.

ATLANTIC OCEAN...
THE MAIN FOCUS THIS MORNING FOR THE ATLC IS HURRICANE BILL. A
NARROW UPPER TROUGH EXTENDS THROUGH 32N66W TO THE TURKS AND
CAICOS NEAR 23N75W GENERATING ISOLATED SHOWERS/THUNDERSTORMS
FROM 27N-31N BETWEEN 68W-71W. OTHERWISE THE ATLC BASIN IS
DOMINATED BY A SURFACE RIDGE ANCHORED IN THE W ATLC BY A 1021 MB
HIGH NW OF BERMUDA AND IN THE E ATLC BY A 1026 MB HIGH W OF THE
AZORES AND A 1024 MB HIGH NEAR 32N29W WITH A WEAKNESS OVER THE
CENTRAL ATLC DUE TO HURRICANE BILL.

$$
WALLACE






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