Thursday, July 20, 2006

TS BERYL TO BRUSH ATLANTIC COAST OF NOVA SCOTIA LATE FRIDAY

WOCN31 CWHX 201200 CCA
CORRECTED TROPICAL STORM BERYL INFORMATION STATEMENT ISSUED BY THE
CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 9.00 AM ADT
THURSDAY 20 JULY 2006.

THE NEXT STATEMENT WILL BE ISSUED BY 3.00 PM ADT

... CORRECTIONS DUE TO TYPOGRAPHICAL ERRORS ...

... TS BERYL TO BRUSH ATLANTIC COAST OF NOVA SCOTIA LATE FRIDAY...

1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION

AT 9.00 AM ADT... TROPICAL STORM BERYL WAS LOCATED NEAR LATITUDE
38.2 N AND LONGITUDE 73.0 W... ABOUT 105 NAUTICAL MILES OR 190 KM
SOUTHEAST OF ATLANTIC CITY . MAXIMUM SUSTAINED WINDS ARE
ESTIMATED AT 50 KNOTS... 93 KM/H... AND CENTRAL PRESSURE AT 1001
MB. BERYL IS MOVING NORTH NORTHEAST AT 9 KNOTS... 17 KM/H.

2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH

DATE TIME LAT LON MSLP MAX WIND
ADT MB KTS KMH
JUL 20 9.00 AM 38.2N 73.0W 1001 50 93
JUL 20 9.00 PM 39.8N 71.7W 998 55 102
JUL 21 9.00 AM 41.8N 68.9W 998 50 93
JUL 21 9.00 PM 44.3N 64.5W 1000 45 83 POST-TROPICAL
JUL 22 9.00 AM 46.4N 56.9W 1001 45 83 POST-TROPICAL
JUL 22 9.00 PM 47.6N 50.3W 1002 45 83 POST-TROPICAL
JUL 23 9.00 AM 49.3N 46.6W 1002 40 74 POST-TROPICAL
JUL 23 9.00 PM 51.0N 43.5W 1003 35 65 POST-TROPICAL
JUL 24 9.00 AM 54.1N 40.8W 1004 35 65 POST-TROPICAL
JUL 24 9.00 PM 58.3N 40.2W 1004 35 65 POST-TROPICAL

3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY
20 TO 30 MM OF RAIN ARE FORECAST OVER PORTIONS OF THE MARITIMES
ON FRIDAY WITH HIGHER AMOUNTS POSSIBLE WITH THIS SYSTEM. RAINFALL
WARNINGS MAY BE REQUIRED LATER TODAY. GUSTS OF 80 KM/H MAY BRUSH
ALONG THE ATLANTIC COAST OF NOVA SCOTIA LATE FRIDAY. WIND WARNINGS
MAY BE REQUIRED BUT HAVE NOT BEEN ISSUED AT THIS TIME.

4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY
GALE WARNINGS HAVE BEEN POSTED IN SOUTHWESTERN MARITIME WATERS AND
GALES ARE CARRIED FORWARD IN THE EXTENDED MARINE FORECASTS BASED ON
OUR FORECAST TRACK OF BERYL.

5. TECHNICAL DISCUSSION

A. ANALYSIS
?HERE WAS A WESTWARD ADJUSTMENT OF THE STORM CENTRE BASED ON AIR
RECON AT 06Z. IR SATELLITE IMAGERY SUGGESTS THAT THE STORM CENTRE
IS CURRENTLY LOCATED NEAR THE NORTHERN EDGE OF THE HEAVIEST
CONVECTION. 12Z POSITION BASED ON NHC UPDATED MESSAGE INDICATING IT
IS A RECON FIX.

B. PROGNOSTIC
TRACK FOLLOWS NHC GUIDANCE. ?HE 06Z ADJUSTMENT RESULTED IN A WESTWARD
ADJUSTMENT IN OUR FORECAST TRACK. WE GENERALLY FOLLOW NHC GUIDANCE
OVER NEXT 36 TO 48 HOURS. AS A RESULT BERYL NOW CROSSES THE
COASTLINE OF NOVA SCOTIA.

BERYL WILL SHOW SLIGHT STRENGHTENING OVER NEXT 24 HOURS
AS IT MOVES OVER WARM WATER. ONCE BERYL PASSES NORTH OF 41N IT
MOVES INTO COLDER WATER AND SHOULD GRADUALLY WEAKEN.
AT 00Z UPPER ANALYSIS SHOWED A VORT TROUGH OVER LAKE MICHIGAN
WHICH WEAKENS AS IT MOVES TO LIE ABOUT 6 DEG NORTHWEST OF BERYL
BY 12Z FRIDAY. AT THIS TIME BERYL COMES UNDER INCREASING WESTERLY
UPPER FLOW AND BEGINS ITS EXTRATROPICAL TRANSITION.

A COLD FRONT APPROACHES FROM THE WEST TO LIE OVER NE NEW BRUNSWICK
BY 00Z SATURDAY. MOISTURE FROM BERYL IS EXPECTED TO FEED INTO THIS
FRONTAL SYSTEM THUS LEADING TO HEAVIER PCPN OVER NB.
THE GFS AND CDN GBL MODELS GRAB BERYL AND PLACE IT ON FRONT AT 48HR.
GEM MAKES A GOOD JOB OF KEEPING BERYL OFF SOUTH SHORE OF NS ALBEIT A
BIT CLOSE TO THE COAST. USED 500 MB VORT MAX ASSOCIATED WITH
BERYL WHICH GFS AND GLOBAL PRESERVED DESPITE THEIR SURFACE
INTERACTION WITH FRONT. FOLLOWED THIS VORT TROUGH AND
CORRESPONDING UPPER FLOW TO KEEP BERYL SOUTH OF THE BURIN
PENINSULA SATURDAY MORNING. THEREFORE HAVE FORECAST A TRACK
SOMEWHAT SOUTH AND MUCH FASTER UNDER WESTERLY FLOW ALOFT
COMPARED TO PREVIOUS FORECAST. GFS LOSES VORT IDENTITY
ONCE BERYL PASSES THROUGH CAPE RACE SO UTILISED CDN GLB
THROUGH REMAINING CANADIAN WATERS. THEREAFTER THE REMNANTS OF
BERYL SLIDES TOWARD GREENLAND UP THE REAR FLANK OF AN UPPER RIDGE.
THIS AGREES WITH NOGAPS EXCEPT THAT IT PUSHES BERYL THROUGH UPPER
RIDGE.

THE 0533Z RUN OF THE GFDL TAKES BERYL ON A MORE WESTWARD TRACK
THROUGH THE FORECAST PERIOD BUT IT REMAINS AS AN OUTLIER... HOWEVER
THE CURRENT MOTION WOULD LEAN ONE TO THINK IT LOOKS MORE APPROPRIATE
IN THE IMMEDIATE FUTURE. WE ARE WATCHING THIS.

FSU CYCLONE PHASE SPACE FOR NOGAPS AND GFS SHOW RAPID TRANSITION
ON THE 21ST... SUCH THAT TRANSITION MAY BE COMPLETED BY THE TIME
IT REACHES WESTERN MARITIME WATERS. INTERESTINGLY THESE MODELS
MOVE IT ALMOST DIRECTLY FROM SYMMETRIC WARM CORE TO ASYMMETRIC
COLD CORE . . . BUT THE TRANSITION IS RATHER QUICK. OTHER MODELS
KEEP IT LOOKING MOSTLY TROPICAL HOWEVER IT IS HARD TO NOT EXPECT
TRANSITION CONSIDERING THE STRENGTH OF THE UPPER FLOW THAT WILL BE
DRIVING IT THROUGH CANADIAN WATERS.

OF COURSE THERE IS UNCERTAINTY IN ALL OF THIS. TO WHAT DEGREE
WILL THE FRONT INTERACT WITH BERYL IS A TROUBLING QUESTION..
ESPECIALLY NOW THAT BERYL WAS REPORTED FARTHER WEST THAN EXPECTED
AT 06Z. TO THIS POINT WE ARE FAVOURING BERYL AS AN ENTITY THAT IS
SEPARATE FROM THE FRONT.

C. PUBLIC WEATHER
A TRACK THAT IS FARTHER WEST WILL REQUIRE A RE-THINK ON OUR RAIN
AMOUNTS. BERYL IS CAUGHT IN THE WESTERLIES AS IT PASSES THROUGH
NS.. HOWEVER SINCE ITS INTERACTION WITH THE FRONT IS STILL
UNCERTAIN THIS MAY REQUIRE A RETHINK OF OUR P.E.I. AMOUNTS
ESPECIALLY OVER NOVA SCOTIA. WIND MAY BE MORE OF AN ISSUE AS ASPC
FORECASTS HAVE GUSTS TO 70 KM/H OVER SOUTH SHORE LATE FRIDAY WHICH
MATCHES THEIR CURRENT MARINE WARNINGS.

D. MARINE WEATHER
A FARTHER WESTWARD TRACK MAY REQUIRE AN ADJUSTMENT OF ASPC MARINE
FORECASTS ESPECIALLY WITH RESPECT TO DIRECTION.

PREDICTED WIND RADII (NM)
TIME GALES STORMS HURRICANE
NE SE SW NW NE SE SW NW NE SE SW NW
20/12Z 120 90 60 50 90 60 20 40 0 0 0 0
21/00Z 120 90 60 50 90 60 20 40 0 0 0 0
21/12Z 120 90 60 50 90 60 20 40 0 0 0 0
22/00Z 150 100 70 60 0 0 0 0 0 0 0 0
22/12Z 150 100 70 60 0 0 0 0 0 0 0 0
23/00Z 160 120 70 80 0 0 0 0 0 0 0 0
23/12Z 180 120 70 90 0 0 0 0 0 0 0 0
24/00Z 180 120 70 90 0 0 0 0 0 0 0 0
24/12Z 180 120 70 90 0 0 0 0 0 0 0 0
25/00Z 180 120 70 90 0 0 0 0 0 0 0 0

END CAMPBELL/BOWYER

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