099
FXCN01 CWHF 181955
FORECAST DISCUSSION FOR OPS AREA ALPHA AND THE ECHOES, CFB HALIFAX
PROPERTIES AND 12 WING SHEARWATER ISSUED BY AVIATION AND DEFENCE
SERVICES OF ENVIRONMENT AND CLIMATE CHANGE CANADA AT 2030Z ON
WEDNESDAY 18 JUNE
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KEY FORECAST POINTS:
- STRATUS CEILINGS, MIST AND FOG WILL DEVELOP IN EARNEST TONIGHT.
- NOT A GOOD FLYING OR SAILING DAY THURSDAY WITH LIGHT SOUTHERLY
WINDS, STRATUS, MIST AND FOG WITH PASSING SHOWERS EXPECTED.
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SHORT RANGE DISCUSSION FOR 1800Z 18 JUNE TO 0300Z 20 JUNE.
MODEL DISCUSSION: USED RDPS
CONFIDENCE: HIGH
COMMENTS/IMPACTS: A LIGHT SOUTHERLY FLOW AHEAD OF AN ELONGATED
SURFACE TROUGH MOVING INTO NEW ENGLAND WILL CONTINUE TO MOISTEN UP
THE LOWEST LEVELS TONIGHT. THE PLAN IS FOR STRATUS WITH MIST AND
FOG TO CONTINUE TO DEVELOP AND ENHANCE THIS EVENING AND MOVE
ONSHORE BY MIDNIGHT TONIGHT. THERE IS EMBEDDED MID LEVEL MOISTURE
AND INSTABILITY AHEAD OF THE TROUGH TONIGHT AND THURSDAY AND
OCCASIONAL SHOWERS ARE EXPECTED.. ESPECIALLY DURING PRIME TIME
CONVECTION HOURS - EARLY MORNING AND AFTERNOON. AN ISOLATED
THUNDERSTORM CANNOT BE RULED OUT - ESPECIALLY WITH THE AFTERNOON
DEVELOPMENT. THE MODELS ARE SHOWING SIGNS OF A WEAK SURFACE TROUGH
MOVING THROUGH THE AREA AROUND 00Z TOMORROW NIGHT, AND GETTING A
WIND SHIFT FROM SOUTH TO SOUTHWEST. THEY ARE ALSO SHOWING THAT LOW
LEVELS WINDS WILL INCREASE TO 20-25 KNOTS, BUT IT IS HUGELY STABLE,
SO A STRONG WIND ADVISORY DOES NOT LOOK NECESSARY AT THIS TIME FOR
THE PERIOD BEFORE MIDNIGHT.
LONG RANGE DISCUSSION FOR 0300Z 20 JUNE TO 0300Z 23 JUNE.
MODEL DISCUSSION: USED GDPS - IT HAS CHANGED FROM PREVIOUS 24 HR
SOLUTION, BUT FOR THE BETTER, AND MATCHES OTHER MODELS. GFS STILL
SHOWING SOMEWHAT DIFFERENT SOLUTION.
CONFIDENCE: MEDIUM.
COMMENTS/IMPACTS: ON FRIDAY, A RATHER INTENSE LOW TRACKS FROM THE
GREAT LAKES INTO NORTHERN NEW BRUNSWICK. A STRONG SOUTHWEST
GRADIENT DEVELOPS AHEAD OF THE FEATURE OVER THE OPS AREA - BUT THE
GDPS SOLUTION IS NOW CONSISTENT WITH THE FOREIGN GUIDANCE AND KEEPS
THE SHOWER / RAIN ACTIVITY TO MAINLY TO THE NORTH AND WEST OF THE
SYSTEM. STRATUS AND FOG WILL REMAIN A PROBLEM IN THE APPROACHES FOR
MOST OF THE DAY, BUT THIS WIND DIRECTION OFFERS IMPROVEMENT OVER
THE HARBOUR AND BASIN.
ON SATURDAY, A TROUGH FROM THE LOW GOES THROUGH OVERNIGHT AND
SHIFTS THE WINDS TO THE NORTHWEST. SKIES CLEAR OUT AS DRIER AIR
MOVS IN. THE GDPS IS SHOWING THE NORTHWEST WIND DROPPING OFF EARLY
WHILE THE GFS STILL KEEPS A STRONGER NORTHWEST GRADIENT INTACT. THE
GFS LOW IS ALSO CLOSER TO NOVA SCOTIA AND HENCE IT KEEPS BROKEN
STRATOCU CLOUDS OVER THE AREA LONGER THAN OUR MODEL WOULD SUGGEST.
A SUNDAY A FAST-MOVING CLIPPER SYSTEM MOVES SOUTHEASTWARD FROM
WESTERN QUEBEC TO THE GULF OF MAINE BY EVENING ALL THE WHILE
WEAKENING. A FAIRLY LARGE AREA OF SHOWERS WITH THE SYSTEM INITIALLY
FIZZLES AS IT REACHES WESTERN NOVA SCOTIA AND THE GDPS IS SHOWING
SHOWERS STAYING CONFINED TO THE SOUTH SHORE AND VALLEY. THIS IS A
SIMILAR SOLUTION TO WHAT THE ECMWF WAS SHOWING, THE GFS IS NOT
SHOWING THE STRENGTH OF THE FEATURE THE OTHER MODELS HAVE.
END/METOC-HFX
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