Blogging About Hurricane Bill #9

000
WTNT33 KNHC 210242
TCPAT3
BULLETIN
HURRICANE BILL ADVISORY NUMBER 23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
1100 PM AST THU AUG 20 2009

...POWERFUL HURRICANE BILL REMAINS ON TRACK...

A TROPICAL STORM WARNING AND A HURRICANE WATCH ARE IN EFFECT FOR
BERMUDA. A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM
CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 24
HOURS. A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 36 HOURS.

INTERESTS ALONG THE COAST OF NEW ENGLAND AND IN THE CANADIAN
MARITIMES SHOULD MONITOR THE PROGRESS OF BILL.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE OF THE UNITED
STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE. FOR STORM INFORMATION SPECIFIC TO YOUR
AREA IN THE UNITED STATES...INCLUDING POSSIBLE INLAND WATCHES AND
WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL
WEATHER SERVICE FORECAST OFFICE.

AT 1100 PM AST...0300 UTC...THE CENTER OF HURRICANE BILL WAS LOCATED
NEAR LATITUDE 24.9 NORTH...LONGITUDE 64.3 WEST OR ABOUT 510 MILES...
825 KM...SOUTH OF BERMUDA AND ABOUT 975 MILES...1570 KM...SOUTHEAST
OF CAPE HATTERAS NORTH CAROLINA.

BILL IS MOVING TOWARD THE NORTHWEST NEAR 18 MPH...30 KM/HR. THIS
MOTION SHOULD CONTINUE THROUGH TONIGHT WITH A GRADUAL TURN TO THE
NORTH-NORTHWEST ON FRIDAY...FOLLOWED BY A TURN TOWARD THE NORTH ON
SATURDAY. ON THE FORECAST TRACK...THE CORE OF THE HURRICANE IS
EXPECTED TO PASS BETWEEN BERMUDA AND THE EAST COAST OF THE UNITED
STATES ON SATURDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 125 MPH...205 KM/HR...WITH HIGHER
GUSTS. BILL IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON
SCALE. SOME FLUCTUATIONS IN INTENSITY ARE LIKELY DURING THE NEXT 12
TO 24 HOURS...AND BILL COULD REGAIN CATEGORY FOUR STRENGTH ON
FRIDAY. GRADUAL WEAKENING IS EXPECTED TO BEGIN ON SATURDAY.

BILL IS A LARGE TROPICAL CYCLONE. HURRICANE FORCE WINDS EXTEND
OUTWARD UP TO 115 MILES...185 KM...FROM THE CENTER...AND TROPICAL
STORM FORCE WINDS EXTEND OUTWARD UP TO 260 MILES...415 KM.

THE LATEST MINIMUM CENTRAL PRESSURE ESTIMATE BY A NOAA HURRICANE
HUNTER PLANE WAS 943 MB...27.85 INCHES.

BILL IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 2 TO 4
INCHES OVER BERMUDA...WITH POSSIBLY SOME AMOUNTS OF 6 INCHES.

SIGNIFICANT COASTAL FLOODING IS EXPECTED ALONG PORTIONS OF THE
BERMUDA COASTLINE OVER THE NEXT DAY OR TWO DUE TO LARGE AND
DANGEROUS BREAKING WAVES GENERATED BY BILL.

LARGE SWELLS GENERATED BY THIS HURRICANE ARE AFFECTING PUERTO
RICO...HISPANIOLA...THE BAHAMAS...AND BERMUDA...AND SHOULD BEGIN
AFFECTING MOST OF THE U.S. EAST COAST AND THE ATLANTIC MARITIMES OF
CANADA DURING THE NEXT DAY OR TWO. THESE SWELLS WILL LIKELY CAUSE
EXTREMELY DANGEROUS SURF AND LIFE-THREATENING RIP CURRENTS. PLEASE
CONSULT STATEMENTS ISSUED BY YOUR LOCAL WEATHER OFFICE FOR MORE
DETAILS.

...SUMMARY OF 1100 PM AST INFORMATION...
LOCATION...24.9N 64.3W
MAXIMUM SUSTAINED WINDS...125 MPH
PRESENT MOVEMENT...NORTHWEST OR 310 DEGREES AT 18 MPH
MINIMUM CENTRAL PRESSURE...943 MB

AN INTERMEDIATE ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE
CENTER AT 200 AM AST FOLLOWED BY THE NEXT COMPLETE ADVISORY AT 500
AM AST.

$$
FORECASTER BROWN/PASCH

-------------------------------------------------------------------------------------

000
WTNT43 KNHC 210248
TCDAT3
HURRICANE BILL DISCUSSION NUMBER 23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
1100 PM AST THU AUG 20 2009

THE SATELLITE PRESENTATION OF BILL HAS CHANGED LITTLE THIS EVENING.
THE LARGE EYE REMAINS VERY WELL-DEFINED...HOWEVER THE CLOUD TOPS
SURROUNDING THE EYE HAVE WARMED SLIGHTLY DURING THE PAST COUPLE OF
HOURS. THE NOAA RECONNAISSANCE AIRCRAFT THAT HAS BEEN SAMPLING THE
CORE OF THE HURRICANE THIS EVENING REPORTED A PEAK BELIEVABLE
FLIGHT-LEVEL WIND OF 127 KT. ALTHOUGH HIGHER WIND SPEEDS WERE
REPORTED...THE METEOROLOGISTS ON THE AIRCRAFT DID NOT CONSIDER
THOSE HIGHER WINDS TO BE VALID. DVORAK DATA T-NUMBERS HAVE
DECREASED SLIGHTLY. BASED ON ALL OF THE DATA...THE INITIAL
INTENSITY IS HELD AT 110 KT. ENVIRONMENTAL FACTORS ARE EXPECTED TO
REMAIN CONDUCIVE FOR SOME RESTRENGTHENING DURING THE NEXT 24 HOURS
OR SO. AFTERWARDS...SOME COOLING OF THE SSTS WILL LIKELY INDUCE A
SLOW WEAKENING TREND. VERTICAL WIND SHEAR IS PREDICTED BY THE
SHIPS MODEL TO REMAIN LIGHT UNTIL THE HURRICANE NEARS THE CANADIAN
MARITIMES IN ABOUT 72 HOURS. HOWEVER...SSTS ALONG THE FORECAST
TRACK WILL BEGIN TO COOL MORE RAPIDLY AROUND THAT TIME...AND SHEAR
IS FORECAST TO INCREASE SIGNIFICANTLY VERY SOON THEREAFTER. THE
OFFICIAL WIND SPEED FORECAST IS GENERALLY BETWEEN THE SHIPS AND
LGEM GUIDANCE

BILL CONTINUES TO MOVE NORTHWESTWARD OR 310/16 KT. THERE IS NOT MUCH
NEW TO SAY ABOUT THE TRACK FORECAST. BILL IS EXPECTED TO TURN
NORTHWARD AHEAD OF A STRONG MID-LATITUDE TROUGH THAT WILL MOVE INTO
THE EASTERN U.S. DURING THE NEXT COUPLE OF DAYS...AND RECURVE AHEAD
OF THAT TROUGH THEREAFTER. THE NEW TRACK FORECAST IS VIRTUALLY
UNCHANGED FROM THE PREVIOUS ADVISORY AND IS ONCE AGAIN IN EXCELLENT
AGREEMENT WITH THE TIGHTLY CLUSTERED MODEL GUIDANCE.

LARGE SWELLS GENERATED BY THIS HURRICANE ARE AFFECTING...OR WILL
AFFECT...A LARGE PORTION OF THE WESTERN NORTH ATLANTIC COASTAL AREA
DURING THE NEXT FEW DAYS. THESE SWELLS WILL LIKELY CAUSE EXTREMELY
DANGEROUS SURF AND LIFE-THREATENING RIP CURRENTS. PLEASE CONSULT
STATEMENTS ISSUED BY YOUR LOCAL WEATHER OFFICE FOR MORE DETAILS.

DATA FROM A TWO-AIRCRAFT SYNOPTIC SURVEILLANCE MISSION CONDUCTED BY
NOAA AND U.S. AIR FORCE RESERVE AIRCRAFT THIS EVENING SHOULD BE
ASSIMILATED INTO THE INITIALIZATION OF THE 0000 UTC MODEL RUNS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 21/0300Z 24.9N 64.3W 110 KT
12HR VT 21/1200Z 26.9N 66.1W 115 KT
24HR VT 22/0000Z 29.6N 67.9W 115 KT
36HR VT 22/1200Z 32.7N 68.9W 110 KT
48HR VT 23/0000Z 36.4N 68.6W 100 KT
72HR VT 24/0000Z 44.3N 62.0W 80 KT
96HR VT 25/0000Z 50.5N 43.0W 55 KT...EXTRATROPICAL
120HR VT 26/0000Z 55.0N 20.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BROWN/PASCH