103
FXCN01 CWHF 182044
KEY FORECAST POINTS:
-A QUICK MOVING LOW TO BRING RAIN AND POOR CONDITIONS THURSDAY
MORNING BEFORE IMPROVING IN THE AFTERNOON.
-A MORE SIGNIFICANT SYSTEM GIVING SNOW, AT TIMES HEAVY, BEGINNING
LATE FRIDAY EVENING INTO SATURDAY, BEFORE TAPERING TO FLURRIES LATE
SATURDAY AFTERNOON.
-PRECIPITATION TYPING A POSSIBLE ISSUE FOR SATURDAY MORNING WITH ICE
PELLETS LIKELY AND POSSIBLE RAIN FOR A SHORT TIME ALONG THE
IMMEDIATE COAST.
SHORT RANGE DISCUSSION FOR OPS AREA ALPHA AND THE ECHOES, CFB HALIFAX
PROPERTIES AND 12 WING SHEARWATER
PERIOD OF COVERAGE: 1800Z 18 DEC TO 0400Z 20 DEC.
MODEL DISCUSSION: MODEL GUIDANCE IN GOOD AGREEMENT FOR THIS PERIOD.
CONFIDENCE: HIGH.
COMMENTS/IMPACTS: A LOW PRESSURE SYSTEM WILL ADVANCE FROM THE WEST
OVERNIGHT GIVING INCREASING CLOUDINESS. RAIN IS EXPECTED TO DEVELOP
NEAR DAWN AND THEN TAPER OFF NEAR NOON ON THURSDAY WITH RAINFALL
AMOUNTS NEAR 10 MM. CONDITIONS WILL DETERIORATE IN RAIN WITH MIST
AND FOG PATCHES IN A LIGHT SOUTHERLY FLOW. CONDITIONS WILL GRADUALLY
IMPROVE THURSDAY AFTERNOON IN THE WAKE OF THE SYSTEM AS A MODERATE
TO STRONG NORTHWEST FLOW DEVELOPS WITH FOG AND MIST DISIPATING
LONG RANGE DISCUSSION FOR OPS AREA ALPHA AND THE ECHOES, CFB HALIFAX
PROPERTIES AND 12 WING SHEARWATER
PERIOD OF COVERAGE: 0400Z 20 DEC TO 0400Z 23 DEC.
MODEL DISCUSSION:
CONFIDENCE: MODERATE.
COMMENTS/IMPACTS: NO SIGNIFICANT CHANGE FROM THE PREVIOUS FORECAST
DISCUSSION...
RIDGING KEEPING A FAIRLY CLOUDY NORTH TO NORTHEAST
FLOW OVER THE REGION AS THE COLD AIRMASS CONTINUES TO PICK UP
MOISTURE FROM THE GULF OF ST.LAWRENCE. AT THE SAME TIME, A SYSTEM
THAT DEVELOPS SOUTH OF CAPE HATTERAS LATE THURSDAY WILL CONTINUE TO
STRENGTHEN AS IT MOVES UP TOWARDS THE REGION SPILLING CIRRUS AND
MID CLOUD INTO THE REGION BY AFTERNOON. MOST MODELS INDICATE SNOW
WILL MOVE INTO THE REGION BETWEEN FRIDAY EVENING AND NEAR MIDNIGHT,
BECOMING POSSIBLY HEAVY OVERNIGHT INTO SATURDAY MORNING. HOW CLOSE
THE LOW PASSES TO THE ATLANTIC COAST OF NOVA SCOTIA WILL DETERMINE
THE PRECIPITATION TYPING OF THIS SYSTEM. THE EXTENDED RDPS, INTO
EARLY SATURDAY MORNING, HAS THE CLOSEST LOW, CHANGING SNOW TO RAIN
OVER THE APPROACHES. MOST OTHER GUIDANCE KEEPS THE PRECIPITATION AS
SNOW OR MIXES ICE PELLETS WITH SNOW DURING THE MORNING BEFORE
TAPERING OFF TO A FEW LIGHT FLURRIES AS THE SYSTEM MOVES OFF TO THE
NORTHEAST. ADDITIONALLY, WHILE A MODERATE TO STRONG NORTHEAST FLOW
IS EXPECTED, THE GFS IS A BIT STRONGER GIVING NEAR GALES OVER THE
APPROACHES AHEAD OF THE SYSTEM EARLY SATURDAY AND IN THE NORTHWEST
FLOW IN THE WAKE OF THE SYSTEM LATE IN THE DAY. PRECIPITATION
TYPING, AMOUNTS AND TIMING ANY POSSIBLE CHANGE OVERS WILL BE AN
ISSUE AS THE SYSTEM APPROACHES FRIDAY NIGHT INTO SATURDAY. MODERATE
TO STRONG NORTH TO NORTHWEST WINDS WILL USHER IN A COLDER AIRMASS
WHERE TEMPERATURES ARE GENERALLY EXPECTED TO FALL ALL DAY SUNDAY.
WITH THE COLD AIR MOVING IN OVER WARMER SURROUNDING WATERS, EXPECT
A MAINLY CLOUDY DAY WITH A CHANCE OF FLURRIES SUNDAY.
END/METOC-HFX
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