Extratropical Storm Arthur (gale force) Update Twelve

WOCN31 CWHX 061445
INTERMEDIATE TROPICAL CYCLONE INFORMATION STATEMENT UPDATED BY THE 
CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA
AT 11:37 AM ADT SUNDAY 6 JULY 2014
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INTERMEDIATE TROPICAL CYCLONE INFORMATION STATEMENT FOR:
      NOVA SCOTIA
      PRINCE EDWARD ISLAND
      NEW BRUNSWICK.

      FOR POST-TROPICAL STORM ARTHUR.

      THIS IS A SPECIAL METEOROLOGICAL SUMMARY FOR POST-TROPICAL
      STORM ARTHUR.

      THIS IS THE FINAL STATEMENT BY THE CANADIAN HURRICANE CENTRE
      ON THIS STORM.

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INTERMEDIATE TROPICAL CYCLONE INFORMATION STATEMENT ENDED FOR:
      NEWFOUNDLAND
      QUEBEC MARITIME.

      ALTHOUGH THE LINGERING EFFECTS OF ARTHUR ARE STILL OCCURRING
      OVER PARTS OF THESE REGIONS, THIS BULLETIN IS SERVING AS A
      SUMMARY REPORT FOR THE PRIMARY AFFECTED AREAS AROUND THE
      MARITIME PROVINCES.

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==DISCUSSION==

*** METEOROLOGICAL SUMMARY OF THE EVENT ***.

HURRICANE ARTHUR TRANSFORMED INTO A POTENT POST-TROPICAL STORM OVER 
THE MARITIME PROVINCES ON SATURDAY JULY 5 2014 CAUSING SIGNIFICANT 
TREE DAMAGE AND LIGHT TO MODERATE FLOODING FOR MANY AREAS. THE 
TRANSFORMATION WAS A RESULT OF THE MERGING OF THE HURRICANE WITH A 
COLD FRONT - SIMILAR TO HURRICANE IGOR IN NEWFOUNDLAND IN 2010 - BUT 
OBVIOUSLY FARTHER WEST AND NOT AS SEVERE.

THIS EVENT AS WELL AS OTHERS LIKE IGOR HIGHLIGHT THAT WHEN A 
HURRICANE BECOMES A POST-TROPICAL STORM IT IS NOT ALWAYS A 
'DOWNGRADE'.  IN FACT, WHEN THESE STORMS UNDERGO THE TRANSFORMATION 
TO POST-TROPICAL STATUS, THE AREA OF HIGH WINDS (AND RAIN) EXPANDS 
SIGNIFICANTLY EVEN THOUGH THE HIGHEST WINDS AND HEAVIEST RAINFALL 
INTENSITY IN THE STORM MAY DECREASE A BIT. AS A RESULT A WIDER AREA 
IS AFFECTED AND THE STORM'S TOTAL ENERGY ACTUALLY INCREASES IN MANY 
CASES.  IN THE CASE OF ARTHUR THE HIGHEST WINDS AT THE END OF ITS 
HURRICANE STATUS WERE ABOUT 120 KM/H AND DURING THE HOURS AFTER WE 
DECLARED IT POST-TROPICAL THE HIGHEST WINDS WERE STILL AROUND 110 
KM/H (WHICH WE SAW IN THE FORM OF GUSTS OVER LAND).

VIGOROUS HURRICANE TRANSFORMATIONS LIKE THIS HAVE STRONG WINDS NOT 
ONLY TO THE RIGHT OF WHERE THE STORM CENTRE (LOWEST PRESSURE) TRACKS 
BUT ALSO SLIGHTLY TO THE LEFT OF THE TRACK AS WE SAW DURING THIS 
STORM AND OTHERS SUCH AS IGOR OVER NEWFOUNDLAND IN 2010. THESE 
LEFT-OF-TRACK WINDS ARE USUALLY FROM THE NORTH, NORTHWEST OR WEST
AND ARE WHAT WE REFER TO IN METEOROLOGY AS A "STING JET". IT WAS
THIS SO-CALLED "STING JET" THAT CAUSED THE HIGH WINDS AT
FREDERICTON, ACROSS PARTS OF THE WESTERN HALF OF NOVA SCOTIA AND 
SPECIFICALLY THE ANNAPOLIS VALLEY. WE EMPHASIZED THESE WINDS IN
THE FORECAST BULLETINS AND DURING MEDIA INTERVIEWS. THIS IS NOT A
NEW PHENOMENON - BUT IS A TERM NOT OFTEN REFERRED-TO IN TRADITIONAL 
WEATHER FORECASTS.

WHAT WAS EXCEPTIONAL ABOUT THIS STORM WAS THE EXTENT OF THIS WIND 
FEATURE TO THE LEFT (NORTHWEST) OF THE STORM TRACK - IN FREDERICTON
- AND THE PEAK STRENGTH OF IT OVER THE ANNAPOLIS VALLEY WITH THE 
EXTREME GUST OF 138 KM/H AT THE GREENWOOD D.N.D. BASE. ALSO OF NOTE 
WITH THESE TYPES OF STORMS IS THAT THERE CAN BE VERY LITTLE RAIN AND 
EVEN SUNSHINE ON THE RIGHTHAND SIDE (USUALLY SOUTH) OF THE STORM 
CENTRE/TRACK. RAINFALL IS TYPICALLY VERY HEAVY NORTH (LEFT) OF THE 
STORM TRACK WHERE THE COLD FRONT ACTS AS A CONDUIT FOR THE MOISTURE 
FROM THE HURRICANE.

THE OFFICIAL STATUS OF ARTHUR AT LANDFALL WAS A NEAR 
HURRICANE-STRENGTH POST-TROPICAL STORM WITH MAXIMUM WINDS OF 60
KNOTS (110 KM/H). THE LANDFALL LOCATION OF THE CENTRE WAS IN THE 
VICINITY OF PORT MAITLAND / METEGHAN IN WESTERN NOVA SCOTIA.
THE CENTRAL PRESSURE AT LANDFALL WAS 980 MB (28.94").


FURTHER DETAILS:
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LISTING OF TOP WIND SPEEDS:

MAXIMUM GUSTS (KM/H):
---------------------------------------------

GREENWOOD, NS           138
BRIER ISLAND, NS        128
FIVE ISLANDS, NS        127*
YARMOUTH, NS            111
LUNENBURG, NS           108
CHARLOTTETOWN, NS       105
FREDERICTON, NB         100

THE GASPÉ REGION OF QUEBEC AND THE MAGDELAN ISLANDS WERE AFFECTED 
WITH HIGH WINDS AS WELL WITH GUSTS FROM 80 TO NEAR 100 KM/H. 
NEWFOUNDLAND IS STILL BEING AFFECTED AT THE TIME THIS BULLETIN WAS 
ISSUED.

LISTING OF TOP RAINFALL AMOUNTS:

TOTAL RAINFALL (MM):
---------------------------------------------

ST. STEPHEN, NB         143
NOONAN, NB              140
MILLVILLE, NB           127
MIRAMICHI, NB           122

MUCH LESS RAINFALL IN PRINCE EDWARD ISLAND AND NOVA SCOTIA. YARMOUTH 
HAD 52 MM AND WESTERN PEI HAD 27 MM (NORTH CAPE). GASPÉ RECORDED 67 
MM.

* VOLUNTEER WEATHER OBSERVER.

OFFSHORE WIND AND WAVES:

BUOY 44024      5.4 M
BUOY 44258      6.9 M (MOUTH HALIFAX HARBOUR)
BUOY 44150      9.0 M

END/FOGARTY