657
FXCN01 CWHF 122004
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
MONDAY 12 OCT
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KEY FORECAST POINTS:
- STRONG NORTHERLY WINDS DEVELOP THIS EVENING.
- MAINLY CLOUDY AND A LITTLE COOL TUESDAY BUT WITH LIGHTER WINDS.
- HEAVY RAIN EVENT SCHEDULED FOR WEDNESDAY.
- ANOTHER BLAST OF COOLER AIR TO END THE WEEK.
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SHORT RANGE DISCUSSION FOR 1800Z 12 OCT TO 0300Z 14 OCT.
MODEL DISCUSSION: USED RDPS / HRDPS
CONFIDENCE: MEDIUM
COMMENTS/IMPACTS: THE MODELS STRUGGLED A LITTLE BIT WITH THE SLOT OF
DRIER AIR OVER NEW BRUNSWICK AND TRIED TO BRING IT IN THE OPS AREA,
BUT THE LOW LEVEL MOISTURE AFTER THE RAIN HUNG ON WAY TOO LONG. A
COLD FRONT TO THE NORTH OF THE AIR AT ISSUE WILL DRIVE SOUTHWARD
QUICKLY THIS EVENING. STRONG AND GUSTY NORTHERLY WINDS ARE FORECAST
TO DEVELOP BEHIND IT. EMBEDDED INSTABILITY BEHIND THE SYSTEM IS
EXPECTED TO GENERATE A FEW SHOWERS ESPECIALLY IN THE ONSHORE AND
UPSLOPE AREAS OF NOVA SCOTIA, BUT THE LOCAL OPS AREA WILL BE
SOMEWHAT SPARED IN THE DOWNSLOPE WINDS. TOWARD MORNING, AS THE FLOW
WEAKENS WITH A SMALL WEDGIE OF RIDGE TRYING TO POKE IN, THERE COULD
BE A SUNNY BREAK OR TOO. HOWEVER, AS SOON AS THE SUN GETS GOING,
THE UNSTABLE AIRMASS IS EXPECTED TO GROWN CLOUDS PRETTY QUICKLY.
AS WELL, A NEW RAIN SYSTEM DEVELOPING IN THE GREAT LAKES
WILL PUSH ITS CLOUD SHIELD OVER THE TOP OF NOVA SCOTIA AS WELL.
CURRENT MODEL TRENDS SUGGEST ARRIVAL OF RAIN WILL OCCUR JUST AFTER
MIDNIGHT.
LONG RANGE DISCUSSION FOR 0300Z 14 OCT TO 0300Z 17 OCT.
MODEL DISCUSSION: USED GDPS
CONFIDENCE: HIGH
COMMENTS/IMPACTS: A VERY ACTIVE WEATHER PATTERN REMAINS IN EFFECT
FOR THE REST OF THE WEEK AS THERMAL CONTRASTS START DRIVING ROBUST
WEATHER SYSTEMS.
ON WEDNESDAY.. A SYSTEM FROM THE GREAT LAKES INTENSIFIES AS IT
TRACKS INTO THE MARITIMES. A BAND OF 25-50 MM OF RAIN MOVES ACROSS
THE PROVINCE DURING THE OVERNIGHT THROUGH EARLY AFTERNOON TIME
FRAME. SOUTHEAST WINDS RAMP UP DURING THE RAIN. THE LAST FEW MODEL
RUNS HAVE BEEN SHOWING A HIGH CHANCE OF GALE FORCE WINDS OR GUSTS
IN THE SOUTHEAST FLOW, BUT THIS MODEL RUN HAS BACKED OFF BY ABOUT 5
KNOTS, SO NOW THERE IS ONLY A THREAT OF LEVEL ONE WINDS. I WILL
LEAVE THIS BE BE REASSESSED FOR A POSSIBLE WARNING FOR THE
OVERNIGHT SHIFT.
BY THURSDAY, A BLAST OF COOL UNSTABLE HAS MOVED INTO THE REGION
BEHIND THAT AFORE MENTIONED SYSTEM. STRONG NORTHWEST WINDS WITH
SLOWLY IMPROVING CONDITIONS ARE EXPECTED FOR THIS DAY.
BY FRIDAY, A LARGE HIGH PRESSURE SYSTEM HAS TAKEN OVER THE
MARITIMES IN THE MORNING WITH LIGHT WINDS. HOWEVER, THIS TIME OF
YEAR IS DIFFICULT TO GET ABUNDANT AMOUNTS OF SUNSHINE INTO THE
REGION WITH COOL AIRMASSES IN PLACE OVER WARMER WATERS. LINGERING
LOW CLOUD COMBINED WITH HIGH CLOUDS SPILLING IN FROM THE NEXT GREAT
LAKES SYSTEM WILL LEAVE A GENERALLY CLOUDY LOCALLY. RAIN AND STRONG
SOUTHEAST WINDS WILL BE PUSHING IN LATER IN THE DAY.
END/METOC-HFX
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