Blogging About Hurricane Bill #7

000
WTNT33 KNHC 202035
TCPAT3
BULLETIN
HURRICANE BILL ADVISORY NUMBER 22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
500 PM AST THU AUG 20 2009

...LARGE AND POWERFUL HURRICANE BILL CHURNING NORTHWESTWARD...
SPREADING HIGH SWELLS OVER THE WESTERN ATLANTIC...

AT 5 PM AST...2100 UTC...THE BERMUDA WEATHER SERVICE HAS ISSUED A
TROPICAL STORM WARNING FOR BERMUDA. A TROPICAL STORM WARNING MEANS
THAT TROPICAL STORM CONDITIONS ARE EXPECTED SOMEWHERE WITHIN THE
WARNING AREA WITHIN 24 HOURS.

A HURRICANE WATCH REMAINS IN EFFECT FOR BERMUDA. A HURRICANE WATCH
MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE WITHIN THE WATCH
AREA...GENERALLY WITHIN 36 HOURS.

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. FOR STORM INFORMATION SPECIFIC TO YOUR AREA
OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.

AT 500 PM AST...2100 UTC...THE EYE OF HURRICANE BILL WAS LOCATED
NEAR LATITUDE 23.8 NORTH...LONGITUDE 63.2 WEST OR ABOUT 595 MILES...
960 KM...SOUTH OF BERMUDA AND ABOUT 1080 MILES...1735 KM...SOUTHEAST
OF CAPE HATTERAS NORTH CAROLINA.

BILL HAS BEEN MOVING STEADILY TOWARD THE NORTHWEST NEAR 18 MPH...30
KM/HR. THIS MOTION SHOULD CONTINUE THROUGH SATURDAY WITH A GRADUAL
TURN TO THE NORTH-NORTHWEST AND NORTH ON SATURDAY. ON THIS
FORECAST TRACK...THE CORE OF HURRICANE BILL IS EXPECTED TO PASS
OVER THE OPEN WATERS BETWEEN BERMUDA AND THE EAST COAST OF THE
UNITED STATES EARLY SATURDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 125 MPH...205
KM/HR...WITH HIGHER GUSTS. BILL IS A CATEGORY THREE HURRICANE ON
THE SAFFIR-SIMPSON SCALE. ALTHOUGH SOME FLUCTUATIONS IN INTENSITY
ARE LIKELY DURING THE 12 TO 24 HOURS...BILL STILL HAS THE POTENTIAL
TO REGAIN CATEGORY FOUR STATUS ON FRIDAY.

BILL IS A LARGE HURRICANE AND ITS 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 MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RECONNAISSANCE
AIRCRAFT A FEW HOURS AGO WAS 948 MB...27.99 INCHES.

LARGE SWELLS GENERATED BY THIS HURRICANE ARE AFFECTING THE NORTHERN
LEEWARD ISLANDS...PUERTO RICO AND HISPANIOLA...AND SHOULD BEGIN
AFFECTING THE BAHAMAS...BERMUDA...MOST OF THE U.S. EAST COAST...AND
THE ATLANTIC MARITIMES OF CANADA 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.

...SUMMARY OF 500 PM AST INFORMATION...
LOCATION...23.8N 63.2W
MAXIMUM SUSTAINED WINDS...125 MPH
PRESENT MOVEMENT...NORTHWEST OR 305 DEGREES AT 18 MPH
MINIMUM CENTRAL PRESSURE...948 MB

AN INTERMEDIATE ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE
CENTER AT 800 PM AST FOLLOWED BY THE NEXT COMPLETE ADVISORY AT 1100
PM AST.

$$
FORECASTER AVILA/BLAKE

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000
WTNT43 KNHC 202036
TCDAT3
HURRICANE BILL DISCUSSION NUMBER 22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
500 PM AST THU AUG 20 2009

BOTH NOAA AND AIR FORCE RECONNAISSANCE PLANES HAVE BEEN SENDING VERY
VALUABLE DATA FROM HURRICANE BILL. THE LATEST MINIMUM PRESSURE WAS
DOWN TO 948 MB AND THE PEAK FLIGHT-LEVEL WIND WAS 135 KNOTS. THE
SFMR REPORTED EARLIER A PEAK WIND OF 101 KNOTS. SINCE THEN...THE
SATELLITE PRESENTATION HAS IMPROVED AND THE EYE IS NOW BETTER
DEFINED. IN FACT...GOES SATELLITE SUPER-RAPID SCAN SHOWS THE
STRUCTURE OF THE EYEWALL AND SEVERAL MESOVORTICES INSIDE THE
EYE...TYPICAL OF STRONG HURRICANES. BASED ON THE AIRCRAFT DATA AND
THE CURRENT SATELLITE PRESENTATION...THE INITIAL INTENSITY IS
ADJUSTED UPWARD TO 110 KNOTS. THE LARGE SCALE ENVIRONMENT
CONTINUES TO BE CONDUCIVE FOR REINTENSIFICATION SINCE BILL IS ABOUT
TO ENCOUNTER THE WARMEST WATERS ALONG ITS PATH SO FAR.
FURTHERMORE...GLOBAL MODELS SHOW BILL EMBEDDED IN A WELL DEFINED
200 MB ANTICYCLONE. GIVEN THE FAVORABLE ENVIRONMENT...THE OFFICIAL
FORECAST CALLS FOR RESTRENGTHENING AND BILL IS EXPECTED TO REACH
CATEGORY FOUR STATUS AGAIN WITHIN THE NEXT 12 TO 36 HOURS.
THEREAFTER...THE HURRICANE SHOULD GRADUALLY BEGIN TO INTERACT WITH
A MID-LATITUDE TROUGH AND BY 96 HOURS IT SHOULD BE EXTRATROPICAL.

THERE IS PRACTICALLY NO CHANGE IN THE FORECAST TRACK. BILL IS MOVING
TOWARD THE NORTHWEST OR 305 DEGREES AT 16 KNOTS EMBEDDED IN VERY
STRONG AND WELL DEFINED STEERING CURRENTS AROUND THE SOUTHWESTERN
PORTION OF THE AZORES-BERMUDA HIGH. HOWEVER...IN A DAY OR SO A
LARGE MID-LATITUDE TROUGH IS EXPECTED TO SWEEP ACROSS THE EASTERN
UNITED STATES AND THE FLOW BETWEEN THE TROUGH AND THE SUBTROPICAL
HIGH SHOULD FORCE THE HURRICANE TO MOVE ON A NORTHERLY AND THEN
NORTHEASTERLY TRACK. THE DYNAMICAL TRACK GUIDANCE IS EXTREMELY
TIGHTLY CLUSTERED DURING THE FIRST 48 HOURS...INCREASING
CONSIDERABLY THE CONFIDENCE IN THE OFFICIAL TRACK FORECAST FOR THAT
PERIOD. ON THIS TRACK...THE CORE OF THE HURRICANE WILL MOVE OVER
THE OPEN WATERS BETWEEN BERMUDA AND THE EAST COAST OF THE UNITED
STATES SATURDAY MORNING AND BY SUNDAY...THE HURRICANE WILL BE
APPROACHING THE WATERS SOUTH OF NOVA SCOTIA.

LARGE SWELLS GENERATED BY THIS HURRICANE ARE AFFECTING THE NORTHERN
LEEWARD ISLANDS...PUERTO RICO...HISPANIOLA AND SHOULD BEGIN
AFFECTING THE BAHAMAS...BERMUDA...MOST OF THE EASTERN U.S.
COAST...AND THE ATLANTIC MARITIMES OF CANADA 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.

THE NOAA AND THE 53RD AIR FORCE RESERVE HURRICANE HUNTERS ARE
CURRENTLY CONDUCTING A TWO-AIRCRAFT SYNOPTIC SURVEILLANCE MISSION
AROUND HURRICANE BILL TO IMPROVE THE INITIAL ANALYSIS FOR THE
NUMERICAL MODELS. THIS INFORMATION WILL BE INCLUDED FOR THE 0000
UTC MODEL RUN.


FORECAST POSITIONS AND MAX WINDS

INITIAL 20/2100Z 23.8N 63.2W 110 KT
12HR VT 21/0600Z 25.6N 65.2W 115 KT
24HR VT 21/1800Z 28.3N 67.1W 115 KT
36HR VT 22/0600Z 31.0N 68.5W 115 KT
48HR VT 22/1800Z 34.5N 69.0W 105 KT
72HR VT 23/1800Z 42.5N 64.5W 85 KT
96HR VT 24/1800Z 49.0N 49.5W 60 KT...EXTRATROPICAL
120HR VT 25/1800Z 53.5N 24.0W 50 KT...EXTRATROPICAL

$$
FORECASTER AVILA/BLAKE