[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 152357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT AUG 15 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
TROPICAL STORM ANA IS CENTERED NEAR 14.4N 50.4W AT 16/0000 UTC
OR ABOUT 635 NM EAST-SOUTHEAST OF THE LEEWARD ISLANDS MOVING W
AT 15 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SCATTERED
MODERATE CONVECTION IS WITHIN 70 NM W SEMICIRCLE. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC
FOR MORE DETAILS.

TROPICAL STORM BILL IS CENTERED NEAR 11.3N 35.2W AT 15/2100
UTC OR ABOUT 710 NM WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS.
MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
SCATTERED MODERATE CONVECTION IS WITHIN 220 NM S SEMICIRCLE. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/
WTNT23 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 18W S OF 16N MOVING W NEAR 15 KT.
ANALYSIS OF THE BAMAKO MALI UPPER-AIR TIME SECTION AND RECENT
5-DAY SATELLITE HOVMOLLER DIAGRAMS INDICATE THIS WAVE PASSED
BAMAKO NEAR 15/0000 UTC AND IS CURRENTLY PASSING DAKAR SENEGAL
AND EMERGING INTO THE FAR ERN TROPICAL ATLANTIC OCEAN WATERS.
LOW TO MIDDLE LEVEL CYCLONIC TURNING IS NOTED IN THE CLOUD MASS
IN CLOSE PROXIMITY TO THE WAVE AXIS WITH SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 7N-16N E OF 22W.

TROPICAL WAVE IS ALONG 84W S OF 20N MOVING W NEAR 15 KT. THIS
WAVE IS ASSOCIATED WITH A MAXIMUM IN DEEP LAYER MOISTURE BASED
ON THE TPW PRODUCT FROM CIMSS. LAST FEW VISIBLE SATELLITE IMAGES
OF THE DAY INDICATE CYCLONIC TURNING ASSOCIATED WITH LOW LEVEL
CLOUDS NEAR THE WAVE AXIS. SCATTERED MODERATE TO STRONG
CONVECTION IS WITHIN 200 NM EITHER SIDE OF THE WAVE AXIS S OF
20N. THE CONVECTION IS BEING SUPPORTED BY ATMOSPHERIC
INSTABILITY ASSOCIATED WITH AN UPPER LEVEL LOW CENTERED NEAR
19N84W AND AN UPPER TROUGH EXTENDING FROM THIS UPPER LOW TO
10N81W.

...ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 11N19W 12N30W 10N38W 8N45W
10N62W. ASIDE FROM CONVECTION ASSOCIATED WITH THE TROPICAL WAVES
MENTIONED ABOVE...WIDELY SCATTERED MODERATE CONVECTION IS WITHIN
100 NM OF THE AXIS BETWEEN 55W-62W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH EXTENDS FROM AN UPPER LEVEL LOW OVER THE
WRN GULF NEAR 25N91W TO SRN MISSISSIPPI NEAR 30N89W. ATMOSPHERIC
INSTABILITY ASSOCIATED WITH THE UPPER LOW AND TROUGH IS
SUPPORTING SCATTERED SHOWERS AND TSTMS FROM 24N-30N BETWEEN
86W-94W. ALSO...LOW LEVEL CONVERGENCE NEAR A PAIR OF SURFACE
TROUGHS OVER THE NE GULF ARE SUPPORTING NUMEROUS SHOWERS AND
SCATTERED TSTMS E OF 86W TO OVER THE FLORIDA PENINSULA. FURTHER
ENHANCING THIS ACTIVITY IS UPPER LEVEL DIFFLUENCE IN MOIST SELY
FLOW ALOFT BETWEEN AN UPPER LEVEL HIGH OVER THE SW NORTH ATLC
AND AN UPPER LEVEL LOW OVER THE NW CARIBBEAN. ACROSS THE SW
GULF...DEEP LAYER DRY AIR AND SUBSIDENCE ASSOCIATED WITH A 1016
MB HIGH CENTERED NEAR 20N97W IS SUPPORTING GENERALLY FAIR
WEATHER.

CARIBBEAN SEA...
SCATTERED MODERATE TO STRONG CONVECTION IS OCCURRING OVER THE
WRN CARIBBEAN ASSOCIATED WITH THE TROPICAL WAVE ALONG 84W S OF
20N. THE UPPER LEVEL LOW CENTERED NEAR 19N84W AND ASSOCIATED
UPPER LEVEL TROUGH THAT EXTENDS TO NEAR PANAMA IS FURTHER
ENHANCING THIS ACTIVITY. ACROSS MUCH OF THE CENTRAL AND ERN
CARIBBEAN...DEEP LAYER DRY AIR AND GENERALLY FAIR WEATHER IS
OCCURRING. FRESH TRADE WINDS S OF A SURFACE RIDGE ARE ADVECTING
POCKETS OF LOW LEVEL MOISTURE AND ISOLATED SHOWERS WWD E OF 73W.
ACROSS THE FAR SE CARIBBEAN...AN UPPER LEVEL TROUGH IN ELY FLOW
ALOFT IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS
THE WINDWARD ISLANDS S OF 15N E OF 66W.

ATLANTIC OCEAN...
AN UPPER LEVEL HIGH IS CENTERED OVER THE SW NORTH ATLC NEAR
29N78W. TO THE W OF THIS UPPER LEVEL HIGH...ATMOSPHERIC LIFT IN
MOIST SWLY FLOW ALOFT IS SUPPORTING SCATTERED SHOWERS AND TSTMS
ACROSS INTERIOR PORTIONS OF THE FLORIDA PENINSULA WITH SCATTERED
SHOWERS REMAINING WITHIN 90 NM OFFSHORE W OF 78W. TO THE E...
ATMOSPHERIC INSTABILITY ASSOCIATED WITH AN UPPER LEVEL LOW NEAR
24N67W IS SUPPORTING ISOLATED SHOWERS FROM 23N-29N BETWEEN
64W-72W. ADDITIONALLY...SCATTERED SHOWERS ARE OCCURRING WITHIN
120 NM EITHER SIDE OF A SURFACE TROUGH EXTENDING FROM 23N63W TO
30N61W. ATMOSPHERIC LIFT IN SLY FLOW ALOFT TO THE E OF AN
NORTH-TO-SOUTH-ELONGATED UPPER LEVEL LOW CENTERED NEAR 27N52W IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS NW OF TROPICAL
STORM ANA FROM 19N-28N BETWEEN 49W-56W. FARTHER TO THE E...A
DEEP LAYER RIDGE IS PRESENT WITH AN ASSOCIATED 1024 MB SURFACE
HIGH CENTERED NEAR 33N34W.

$$
HUFFMAN




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