Blogging About Hurricane Bill #13

WOCN31 CWHX 220000
Hurricane Bill information statement issued by the canadian
Hurricane centre of Environment Canada at 9.00 PM ADT Friday
21 August 2009.

The next statement will be issued by 3.00 AM ADT

...Bill continuing to threaten the Atlantic provinces...

1. Current position, strength, central pressure and motion

At 9.00 PM ADT... Hurricane Bill was located near latitude 30.2 N
And longitude 67.0 W... About 200 nautical miles or 325 km
Southwest of Bermuda . Maximum sustained winds are estimated at
90 knots... 165 km/h.. And central pressure at 954 MB. Bill is
Moving north northwest at 17 knots... 31 km/h.

2. Forecast position, central pressure and strength

Date time lat lon MSLP Max wind
ADT MB kts kmh
Aug 21 9.00 PM 30.2N 67.0W 954 90 165
Aug 22 9.00 AM 33.0N 68.1W 961 100 185
Aug 22 9.00 PM 37.1N 68.2W 968 95 176
Aug 23 9.00 AM 41.3N 65.8W 973 85 157 transitioning
Aug 23 9.00 PM 45.2N 60.7W 980 75 139 transitioning
Aug 24 9.00 AM 48.2N 52.5W 985 65 120 transitioning
Aug 24 9.00 PM 50.5N 42.5W 989 60 111 post-tropical
Aug 25 9.00 AM 52.8N 32.0W 991 50 93 post-tropical

3. Public weather impacts and warnings summary

At this point it is too early for watches or warnings to be issued
As Bill remains well to our south. Watches and warnings.. If
Necessary.. Will be considered for the Maritimes on Saturday
morning..
And for Newfoundland Saturday evening.

The main rainfall associated with Bill will move into Nova Scotia..
Southern New Brunswick..And Prince Edward Island on Sunday. Rainfall
amounts of up to 100 to 150 mm will impact these areas with lesser
amounts for Northern New Brunswick. The rain will spread into
Newfoundland late Sunday night into Monday..Giving upwards of 100 mm.

Winds possibly exceeding 90 km/h will impact Nova Scotia on
Sunday..Mainly along the coast. For Monday winds possibly
Exceeding 120 km/h will affect coastal areas of Southeastern
Newfoundland. Warnings for wind and rainfall amounts will be
Issued tonight or tomorrow.

Swell from hurricane Bill will arrive along the Atlantic coast
Of Nova Scotia on Saturday. Swell heights near 2 m
Will generate rough surf and hazardous rip currents along some
beaches. Breaking wave heights on the shoreline may exceed 3 m
Along parts of the Atlantic coast of Nova Scotia Saturday.

Significant wave heights of up to 12 metres will move onto the
Scotian shelf on Sunday and waves of up to 10 metres will
Move onto the Southwestern Grand Banks on Monday. Waves of up to
8 metres will reach the Northern Grand Banks late on Monday.
For Atlantic coastal Nova Scotia strong surf and waves possibly
exceeding 6 to 8 m will impact certain areas. For coastal
Newfoundland waves also may exceed 6 to 8 m..Especially south
To southwest facing coastlines from the Burin Peninsula to cape
Race.

Residents are advised to exercise extreme caution if venturing
Near the shoreline.

Some of the largest spring tides of the year will be occurring this
weekend. This may combine with large waves and storm surge
Over the Atlantic coast of Eastern Nova Scotia late on Sunday..As
well as the South Coast of Newfoundland overnight into Monday.

4. Marine weather impacts and warnings summary

Given the current CHC track hurricane Bill is expected to begin
To impact maritime marine areas Saturday night and Newfoundland
marine areas Sunday night. Winds will rapidly increase on Sunday
Over southern maritime marine areas starting over southwestern
Areas. Over Southern Newfoundland waters winds will rapidly
Increase from west to east Sunday night and Monday. It
Appears very likely that hurricane and storm force winds will
Spread over portions of the southern marine areas of the
Maritimes and Newfoundland as a result of Bill. Marine warnings
Will be issued tonight or tomorrow.

5. Technical discussion for meteorologists

A. Analysis
Following nhc on position and intensity.

Based on a hurricane hunter flight this afternoon it seems that Bill
is going through an eyewall replacement cycle and has weakened
somewhat. Warm waters and low shear will give Bill a chance to
re-strengthen somewhat over the next 12 to 24 hours then gradually
weaken as it moves into cooler waters.

B. Prognostic

There is no change in forecast philosophy for the next 60 hours..
But tweaking track slightly northward as it crosses Newfoundland
To account for some model guidance showing a more northerly track..
And also to address the chance of significant storm surge and wave
activity for the south coast marine areas.

Bill is tracking northwestward south of Bermuda. Bill is expected
To begin a gradual turn north-northwest today and northward on
Saturday in response to a deep-layer trough forecast to move over
The Eastern United States and an upper-level ridge building
Over the Atlantic. On Sunday Bill will curve and accelerate
northeastward ahead of the trough. Track guidance is tightly
clustered for the first couple of days but then becomes divergent
On both direction and speed later in the forecast period.

Cyclone phase space diagrams indicate Bill will begin to undergo
extra-tropical transition on the 23rd and will be completed
On the 24th.

C. Public weather

As the storm begins transitioning on the 23rd we should be seeing
The rain shield extending to the left and forward of track and
The wind field starting to expand away from the storm centre.
For Northern New Brunswick a predecessor rain band associated with
the hurricane will form Saturday and pulses of rain associated
With it may give up to 50 mm into Sunday.

D. Marine weather

Predicted wind radii (NM)
Time gales storms hurricane
Ne se sw nw ne se sw nw ne se sw nw
22/00Z 250 200 120 200 130 110 60 130 100 45 30 90
22/12Z 250 210 125 195 120 105 60 115 95 45 25 80
23/00Z 245 225 135 190 110 100 60 90 85 45 20 55
23/12Z 240 225 145 190 105 105 75 80 65 50 15 25
24/00Z 230 240 165 170 110 120 85 75 45 40 10 10
24/12Z 230 255 155 135 125 135 85 65 15 15 0 0
25/00Z 240 260 150 120 145 145 90 60 0 0 0 0
25/12Z 250 260 160 120 75 75 45 30 0 0 0 0


End nickerson/mercer/bowyer




WOCN31 CWHX 220000
HURRICANE BILL INFORMATION STATEMENT ISSUED BY THE CANADIAN
HURRICANE CENTRE OF ENVIRONMENT CANADA AT 9.00 PM ADT FRIDAY
21 AUGUST 2009.

THE NEXT STATEMENT WILL BE ISSUED BY 3.00 AM ADT

...BILL CONTINUING TO THREATEN THE ATLANTIC PROVINCES...

1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION

AT 9.00 PM ADT... HURRICANE BILL WAS LOCATED NEAR LATITUDE 30.2 N
AND LONGITUDE 67.0 W... ABOUT 200 NAUTICAL MILES OR 325 KM
SOUTHWEST OF BERMUDA . MAXIMUM SUSTAINED WINDS ARE ESTIMATED AT
90 KNOTS... 165 KM/H.. AND CENTRAL PRESSURE AT 954 MB. BILL IS
MOVING NORTH NORTHWEST AT 17 KNOTS... 31 KM/H.

2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH

DATE TIME LAT LON MSLP MAX WIND
ADT MB KTS KMH
AUG 21 9.00 PM 30.2N 67.0W 954 90 165
AUG 22 9.00 AM 33.0N 68.1W 961 100 185
AUG 22 9.00 PM 37.1N 68.2W 968 95 176
AUG 23 9.00 AM 41.3N 65.8W 973 85 157 TRANSITIONING
AUG 23 9.00 PM 45.2N 60.7W 980 75 139 TRANSITIONING
AUG 24 9.00 AM 48.2N 52.5W 985 65 120 TRANSITIONING
AUG 24 9.00 PM 50.5N 42.5W 989 60 111 POST-TROPICAL
AUG 25 9.00 AM 52.8N 32.0W 991 50 93 POST-TROPICAL

3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY

AT THIS POINT IT IS TOO EARLY FOR WATCHES OR WARNINGS TO BE ISSUED
AS BILL REMAINS WELL TO OUR SOUTH. WATCHES AND WARNINGS.. IF
NECESSARY.. WILL BE CONSIDERED FOR THE MARITIMES ON SATURDAY MORNING..
AND FOR NEWFOUNDLAND SATURDAY EVENING.

THE MAIN RAINFALL ASSOCIATED WITH BILL WILL MOVE INTO NOVA SCOTIA..
SOUTHERN NEW BRUNSWICK..AND PRINCE EDWARD ISLAND ON SUNDAY. RAINFALL
AMOUNTS OF UP TO 100 TO 150 MM WILL IMPACT THESE AREAS WITH LESSER
AMOUNTS FOR NORTHERN NEW BRUNSWICK. THE RAIN WILL SPREAD INTO
NEWFOUNDLAND LATE SUNDAY NIGHT INTO MONDAY..GIVING UPWARDS OF 100 MM.

WINDS POSSIBLY EXCEEDING 90 KM/H WILL IMPACT NOVA SCOTIA ON
SUNDAY..MAINLY ALONG THE COAST. FOR MONDAY WINDS POSSIBLY
EXCEEDING 120 KM/H WILL AFFECT COASTAL AREAS OF SOUTHEASTERN
NEWFOUNDLAND. WARNINGS FOR WIND AND RAINFALL AMOUNTS WILL BE
ISSUED TONIGHT OR TOMORROW.

SWELL FROM HURRICANE BILL WILL ARRIVE ALONG THE ATLANTIC COAST
OF NOVA SCOTIA ON SATURDAY. SWELL HEIGHTS NEAR 2 M
WILL GENERATE ROUGH SURF AND HAZARDOUS RIP CURRENTS ALONG SOME
BEACHES. BREAKING WAVE HEIGHTS ON THE SHORELINE MAY EXCEED 3 M
ALONG PARTS OF THE ATLANTIC COAST OF NOVA SCOTIA SATURDAY.

SIGNIFICANT WAVE HEIGHTS OF UP TO 12 METRES WILL MOVE ONTO THE
SCOTIAN SHELF ON SUNDAY AND WAVES OF UP TO 10 METRES WILL
MOVE ONTO THE SOUTHWESTERN GRAND BANKS ON MONDAY. WAVES OF UP TO
8 METRES WILL REACH THE NORTHERN GRAND BANKS LATE ON MONDAY.
FOR ATLANTIC COASTAL NOVA SCOTIA STRONG SURF AND WAVES POSSIBLY
EXCEEDING 6 TO 8 M WILL IMPACT CERTAIN AREAS. FOR COASTAL
NEWFOUNDLAND WAVES ALSO MAY EXCEED 6 TO 8 M..ESPECIALLY SOUTH
TO SOUTHWEST FACING COASTLINES FROM THE BURIN PENINSULA TO CAPE
RACE.

RESIDENTS ARE ADVISED TO EXERCISE EXTREME CAUTION IF VENTURING
NEAR THE SHORELINE.

SOME OF THE LARGEST SPRING TIDES OF THE YEAR WILL BE OCCURRING THIS
WEEKEND. THIS MAY COMBINE WITH LARGE WAVES AND STORM SURGE
OVER THE ATLANTIC COAST OF EASTERN NOVA SCOTIA LATE ON SUNDAY..AS
WELL AS THE SOUTH COAST OF NEWFOUNDLAND OVERNIGHT INTO MONDAY.

4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY

GIVEN THE CURRENT CHC TRACK HURRICANE BILL IS EXPECTED TO BEGIN
TO IMPACT MARITIME MARINE AREAS SATURDAY NIGHT AND NEWFOUNDLAND
MARINE AREAS SUNDAY NIGHT. WINDS WILL RAPIDLY INCREASE ON SUNDAY
OVER SOUTHERN MARITIME MARINE AREAS STARTING OVER SOUTHWESTERN
AREAS. OVER SOUTHERN NEWFOUNDLAND WATERS WINDS WILL RAPIDLY
INCREASE FROM WEST TO EAST SUNDAY NIGHT AND MONDAY. IT
APPEARS VERY LIKELY THAT HURRICANE AND STORM FORCE WINDS WILL
SPREAD OVER PORTIONS OF THE SOUTHERN MARINE AREAS OF THE
MARITIMES AND NEWFOUNDLAND AS A RESULT OF BILL. MARINE WARNINGS
WILL BE ISSUED TONIGHT OR TOMORROW.

5. TECHNICAL DISCUSSION FOR METEOROLOGISTS

A. ANALYSIS
FOLLOWING NHC ON POSITION AND INTENSITY.

BASED ON A HURRICANE HUNTER FLIGHT THIS AFTERNOON IT SEEMS THAT BILL
IS GOING THROUGH AN EYEWALL REPLACEMENT CYCLE AND HAS WEAKENED
SOMEWHAT. WARM WATERS AND LOW SHEAR WILL GIVE BILL A CHANCE TO
RE-STRENGTHEN SOMEWHAT OVER THE NEXT 12 TO 24 HOURS THEN GRADUALLY
WEAKEN AS IT MOVES INTO COOLER WATERS.

B. PROGNOSTIC

THERE IS NO CHANGE IN FORECAST PHILOSOPHY FOR THE NEXT 60 HOURS..
BUT TWEAKING TRACK SLIGHTLY NORTHWARD AS IT CROSSES NEWFOUNDLAND
TO ACCOUNT FOR SOME MODEL GUIDANCE SHOWING A MORE NORTHERLY TRACK..
AND ALSO TO ADDRESS THE CHANCE OF SIGNIFICANT STORM SURGE AND WAVE
ACTIVITY FOR THE SOUTH COAST MARINE AREAS.

BILL IS TRACKING NORTHWESTWARD SOUTH OF BERMUDA. BILL IS EXPECTED
TO BEGIN A GRADUAL TURN NORTH-NORTHWEST TODAY AND NORTHWARD ON
SATURDAY IN RESPONSE TO A DEEP-LAYER TROUGH FORECAST TO MOVE OVER
THE EASTERN UNITED STATES AND AN UPPER-LEVEL RIDGE BUILDING
OVER THE ATLANTIC. ON SUNDAY BILL WILL CURVE AND ACCELERATE
NORTHEASTWARD AHEAD OF THE TROUGH. TRACK GUIDANCE IS TIGHTLY
CLUSTERED FOR THE FIRST COUPLE OF DAYS BUT THEN BECOMES DIVERGENT
ON BOTH DIRECTION AND SPEED LATER IN THE FORECAST PERIOD.

CYCLONE PHASE SPACE DIAGRAMS INDICATE BILL WILL BEGIN TO UNDERGO
EXTRA-TROPICAL TRANSITION ON THE 23RD AND WILL BE COMPLETED
ON THE 24TH.

C. PUBLIC WEATHER

AS THE STORM BEGINS TRANSITIONING ON THE 23RD WE SHOULD BE SEEING
THE RAIN SHIELD EXTENDING TO THE LEFT AND FORWARD OF TRACK AND
THE WIND FIELD STARTING TO EXPAND AWAY FROM THE STORM CENTRE.
FOR NORTHERN NEW BRUNSWICK A PREDECESSOR RAIN BAND ASSOCIATED WITH
THE HURRICANE WILL FORM SATURDAY AND PULSES OF RAIN ASSOCIATED
WITH IT MAY GIVE UP TO 50 MM INTO SUNDAY.

D. MARINE WEATHER

PREDICTED WIND RADII (NM)
TIME GALES STORMS HURRICANE
NE SE SW NW NE SE SW NW NE SE SW NW
22/00Z 250 200 120 200 130 110 60 130 100 45 30 90
22/12Z 250 210 125 195 120 105 60 115 95 45 25 80
23/00Z 245 225 135 190 110 100 60 90 85 45 20 55
23/12Z 240 225 145 190 105 105 75 80 65 50 15 25
24/00Z 230 240 165 170 110 120 85 75 45 40 10 10
24/12Z 230 255 155 135 125 135 85 65 15 15 0 0
25/00Z 240 260 150 120 145 145 90 60 0 0 0 0
25/12Z 250 260 160 120 75 75 45 30 0 0 0 0


END NICKERSON/MERCER/BOWYER