[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 23 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...

HURRICANE BILL IS CENTERED NEAR 46.2N 57.9W AT 24/0000 UTC OR
ABOUT 200 NM W OF CAPE RACE NEWFOUNDLAND MOVING NE AT 30 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. MAXIMUM SUSTAINED
WIND SPEED IS 65 KT WITH GUSTS TO 80 KT. NUMEROUS SHOWERS ARE
FROM 46N-51N BETWEEN 48W-58W TO THE NE OF THE CENTER OF BILL.
SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 24W S OF 19N MOVING W NEAR 18 KT.
SATELLITE IMAGERY AND CIMSS WAVETRAK GUIDANCE INDICATE LOW TO
MIDDLE LEVEL CYCLONIC FLOW IN THE VICINITY OF THE WAVE AXIS.
THIS WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM
OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED SHOWERS
ARE NOTED FROM 9N-20N BETWEEN 21W-27W.

TROPICAL WAVE EXTENDS FROM 9N49W TO 17N52W MOVING W NEAR 23 KT.
AN INVERTED-V CLOUD SIGNATURE IS OBSERVED IN THE LOW-LEVEL CLOUD
FIELD ON SATELLITE IMAGERY. THE WAVE ALSO COINCIDES WITH A DEEP
LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER
IMAGERY. AS THE WAVE CONTINUES TO MOVE WWD BENEATH MOIST SLY
FLOW ALOFT DUE TO AN UPPER LEVEL LOW CENTERED NEAR 23N58W...
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-18N
BETWEEN 47W-57W AND IS FORECAST TO CONTINUE BEING ENHANCED BY
THE UPPER LEVEL FEATURE.

TROPICAL WAVE IS ALONG 70W S OF 18N MOVING W NEAR 13 KT. THIS
WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM THAT HAS BEEN
TRACKING ACROSS THE SERN AND NOW S/CENTRAL CARIBBEAN OVER THE
PAST 24 HOURS. SCATTERED MODERATE CONVECTION IS FROM 10N-15N
BETWEEN 67W-75W.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 15N17W 13N23W 12N25W 10N33W
13N48W 13N52W 11N67W. CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE FROM 12N-17N BETWEEN 16W-22W. AN AREA OF SIMILAR ACTIVITY IS
FROM 10N-13N BETWEEN 25W-28W. ELSEWHERE...SCATTERED SHOWERS ARE
WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 60W-66W ACROSS NE
VENEZUELA AND PORTIONS OF THE FAR SE CARIBBEAN SEA.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A COLD FRONT CROSSES THE CENTRAL FLORIDA
PENINSULA AND ENTERS THE ERN GULF NEAR SARASOTA CONTINUING SW TO
25N87W WHERE IT BECOMES A STATIONARY FRONT ALONG 24N92W 26N94W.
THIS FRONTAL BOUNDARY IS SUPPORTED BY A SHARP UPPER LEVEL TROUGH
WITH AXIS ALONG THE ERN CONUS TO SRN ALABAMA AND OVER THE
N/CENTRAL GULF TO 25N93W. SCATTERED SHOWERS AND ISOLATED TSTMS
ARE WITHIN 60 NM OF THE COLD FRONT AND COVER AN AREA FROM
21N-25N BETWEEN 89W-96W IN THE VICINITY OF THE STATIONARY FRONT.
AN EXTENSION OF UPPER LEVEL TROUGHING AND CYCLONIC CURVATURE IS
ALSO OVER THE CENTRAL BAY OF CAMPECHE THAT IS ENHANCING THIS
CONVECTION AS WELL AS GENERATING SCATTERED SHOWERS AND TSTMS S
OF 22N ACROSS THE YUCATAN PENINSULA. NORTH OF THE FRONTAL
BOUNDARY...A MUCH DRIER AIRMASS IS TAKING HOLD PROMOTING
SUBSIDENCE...SINKING AIR AND FAIR WEATHER CONDITIONS THIS
EVENING AND OVERNIGHT ACROSS THE NRN GULF WATERS.

CARIBBEAN SEA...
A BROAD UPPER LEVEL RIDGE DOMINATES THE CARIBBEAN CENTERED OVER
THE WINDWARD PASSAGE NEAR 19N74W. UPPER LEVEL DIFFLUENCE ON
MOIST SWLY FLOW ALOFT BETWEEN THIS RIDGE AND THE UPPER LEVEL
TROUGHING OVER THE CENTRAL BAY OF CAMPECHE IS SUPPORTING
SCATTERED SHOWERS AND TSTMS ACROSS THE YUCATAN PENINSULA AND
PORTIONS OF CENTRAL CUBA. ON THE SRN PERIPHERY OF THE UPPER
LEVEL RIDGE...UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED
SHOWERS AND ISOLATED TSTMS OVER THE SW CARIBBEAN S OF 16N W OF
79W INCLUDING PORTIONS OF NICARAGUA AND HONDURAS. FARTHER TO THE
E...UPPER LEVEL DIFFLUENCE ALONG WITH THE TROPICAL WAVE ALONG
70W IS PRODUCING SCATTERED SHOWERS AND ISOLATED TSTMS FROM
10N-15N BETWEEN 67W-75W. MODERATE TO FRESH TRADEWINDS CONTINUE
ACROSS MUCH OF THE BASIN WITH THE STRONGEST WINDS EXPECTED IN
THE CENTRAL CARIBBEAN AND NEAR THE COAST OF COLOMBIA THROUGH TUE.

ATLANTIC OCEAN...
A 1011 MB LOW IS CENTERED OVER SOUTH CAROLINA AND EXTENDS A COLD
FRONT OVER THE SW NORTH ATLC TO NEAR FLAGLER BEACH FLORIDA AND
ACROSS THE CENTRAL FLORIDA PENINSULA INTO THE GULF OF MEXICO.
SCATTERED SHOWERS AND ISOLATED TSTMS ACCOMPANY THIS FRONTAL
BOUNDARY AND ARE WITHIN 120 NM E OF THE FRONT...INCLUDING A
PORTION OF THE SE FLORIDA PENINSULA. THIS ACTIVITY IS PRIMARILY
SUPPORTED ALOFT BY AN UPPER LEVEL TROUGH ACROSS THE ERN CONUS
AND THE ASSOCIATED UPPER LEVEL DIFFLUENCE LOCATED E OF THE
TROUGH AXIS. FARTHER TO THE E OVER THE REMAINDER OF THE SW NORTH
ATLC...A SURFACE RIDGE OF HIGH PRESSURE EXTENDS FROM A 1028 MB
HIGH CENTERED NEAR 36N47W. THE RIDGE STRETCHES THROUGH BERMUDA
TO THE NW BAHAMAS. ACROSS THE CENTRAL ATLC...THE SURFACE RIDGE
REMAINS IN CONTROL HOWEVER AN UPPER LEVEL LOW IS CENTERED NEAR
23N58W AND IS PROVIDING POSSIBLE SCATTERED SHOWERS FROM 17N-27N
BETWEEN 50W-62W. THIS AREA IS LOCATED TO THE N AND NW OF THE
TROPICAL WAVE ALONG APPROXIMATELY 51W. ELSEWHERE ACROSS THE ATLC
E OF 50W...THE AFOREMENTIONED SURFACE RIDGE ANCHORED BY THE 1028
MB HIGH CENTERED NEAR 36N47W IS PROVIDING THE REMAINDER OF THE
BASIN WITH NE TO ELY TRADES OF UP TO 25 KT.

$$
HUFFMAN




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