074
FXCN01 CWHF 190900
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 0930Z ON
FRIDAY 19 DEC
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KEY FORECAST POINTS:
- WINDS WILL CONTINUE TO INCREASE THROUGHOUT THE DAY REACHING
SOUTHERLY GALE TO STORM FORCE BY LATE TODAY.
- EXPECT PERIOD OF HEAVY RAIN AHEAD OF COLD FRONT TODAY.
- WEAKER SYSTEM AFFECTS THE REGION SUNDAY LEAVING COOLER AIR AND A
FEW FLURRIES OVER THE REGION IN ITS WAKE.
- UNCERTAINTY WITH THE TIMING OF A SYSTEM LATE ON THE 23RD.
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SHORT RANGE DISCUSSION FOR 0600Z 19 DEC TO 0400Z 21 DEC.
MODEL DISCUSSION: USED RDPS/HRPDS.
CONFIDENCE: GENERALLY HIGH.
COMMENTS/IMPACTS: AN INTENSIFYING LOW PRESSURE SYSTEM WILL TRACK
ACROSS QUEBEC TODAY WHILE THE ASSOCIATED COLD FRONTAL TROUGH TRACKS
THROUGH NOVA SCOTIA TODAY INTO TONIGHT. AHEAD OF THE TROUGH CLOUD
WILL THICKEN WITH PATCHY DRIZZLE DEVELOPING THIS MORNING BECOMING A
FEW SHOWERS THIS AFTERNOON THEN PERIODS OF RAIN, AT TIMES HEAVY BY
EARLY THIS EVENING. EXPECT 30 TO 45 MM OF RAIN, POSSIBLY MORE IN
THE HEAVIEST SHOWERS, BEFORE RAIN TAPERS OFF NEAR MIDNIGHT AS THE
COLD FRONT MOVES THROUGH. ADDITIONALLY, EXPECT SOUTHERLY WINDS TO
STRENGTHEN THROUGHOUT THE DAY BECOMING GALE FORCE THIS AFTERNOON
AND SUSTAINED STORM FORCE THIS EVENING. WINDS EASE SOMEWHAT AND
VEER TO THE SOUTHWEST NEAR MIDNIGHT IN THE WAKE OF THE COLD FRONT.
A CHANCE OF SHOWERS WILL CHANGE TO A CHANCE OF FLURRIES SATURDAY AS
TEMPERATURES GENERALLY DROP THROUGH THE MORNING, REMAIN STEADY
THROUGH THE AFTERNOON THEN DROP IN THE EVENING AGAIN. CLOUDS CLEAR
AND WINDS EASE FURTHER LATE SATURDAY AFTERNOON INTO THE EVENING AS
RIDGING BUILDS ACROSS NOVA SCOTIA. EXPECT INCREASING CLOUDINESS
DURING THE OVERNIGHT AHEAD OF THE NEXT, WEAKER, SYSTEM.
LONG RANGE DISCUSSION FOR 0400Z 21 DEC TO 0400Z 24 DEC.
MODEL DISCUSSION: USED GDPS THOUGH HEDGED TOWARDS GFS/ECMWF FOR
TUESDAY.
CONFIDENCE: GENERALLY HIGH BECOMING MEDIUM TO LOW TUESDAY.
COMMENTS/IMPACTS: AS NOTED ABOVE, ANOTHER SYSTEM BEGINS TO DEVELOP
AND APPROACH THE REGION SATURDAY NIGHT INTO SUNDAY, THOUGH MUCH
WEAKER. EXPECT A FEW SHOWERS TO DEVELOP SUNDAY AFTERNOON AS THE
COLD FROTNAL TROUGH MOVES THROUGH WITH STRONGER WINDS OUT AHEAD
BECOMING LIGHT WITHIN THE TROUGH LATE IN THE DAY. IN THE WAKE OF
THE SYSTEM, STRONGER NORTHERLY TO NORTHWEST WINDS DEVELOP. GDPS
DOES NOT STRENGTHEN WINDS AS MUCH AS OTHER MODELS WITH A SLIGHT DIP
IN THE PRESSURE PATTERN SO HAVE EDGED THE GDPS NORTH TO NORTHWEST
FLOW A BIT STRONGER IN THE WAKE OF THE SYSTEM MONDAY AND WENT MORE
POSITIVE WITH FLURRIES AS ALL MODELS SHOWER EXTENSIVE FLURRIES
MOVING ACROSS NOVA SCOTIA MONDAY. BY MONDAY NIGHT THE MODELS FALL
OUT OF AGREEMENT, ESPECIALLY TIME WISE. GFS/ECMWF BRING THE RIDGE
THROUGH NOVA SCOTIA TUESDAY MORNING INTO THE AFTERNOON THEN RIGHT
ON ITS HEELS, BRING THE NEXT LOW PRESSURE SYSTEM INTO NOVA SCOTIA
GIVING SNOW TO THE HALIFAX REGION BY END OF DAY. GDPS/ICON KEEP THE
RIDGE TO THE WEST OF NOVA SCOTIA WITH STILL A CHANCE OF FLURRIES
THROUGH SOME OF THE DAY. RIDGE MOVES THROUGH WITH THESE MODELS
OVERNIGHT THEN SNOW FROM THE NEXT SYSTEM NOT ARRIVING UNTIL
WEDNESDAY. HAVE A CHANCE OF FLURRIES ON TUESDAY AND MAINLY CLOUDY
CONDITIONS BUT SUNNY BREAKS ARE POSSIBLE IN EITHER SCENARIO THOUGH
NOT AT THE SAME TIME. CHANCE OF FLURRIES IS IN THE MORNING/EARLY
AFTERNOON ACCORDING TO THE GDPS/ICON WHILE A CHANCE OF SNOW LATE IN
THE DAY IS EXPECTED BY THE GFS/ECMWF AT THIS TIME. MUCH LOWER
CONFIDENCE ON TUESDAY FORECAST.
END/METOC-HFX
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