577
FXCN01 CWHF 010805
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 0830Z ON
FRIDAY 01 MAY
===================================================================
KEY FORECAST POINTS:
- RAIN AT TIMES HEAVY, WITH A SLIGHT RISK OF THUNDERSTORMS,
TAPERING TO DRIZZLE THIS AFTERNOON THEN ENDING.
- SLOW TO CLEAR OVERNIGHT WITH LINGERING PATCHY MIST AND FOG INTO
EARLY SATURDAY MORNING THEN SUNNY.
- MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH SIGNIFICANT
SYSTEM TRACKING NEAR HALIFAX SUNDAY GIVING RAIN AND STRONG WINDS.
- CLEARING MONDAY IN THE WAKE OF THE SYSTEM THEN INCREASING
CLOUD/WINDS TUESDAY AHEAD OF AN APPROACHING TROUGH.
===================================================================
SHORT RANGE DISCUSSION FOR 0600Z 01 MAY TO 0300Z 03 MAY.
MODEL DISCUSSION: USED RDPS/HRDPS.
CONFIDENCE: GENERALLY HIGH.
COMMENTS/IMPACTS: RAIN, AT TIMES HEAVY, WITH A SLIGHT RISK OF
THUNDERSTORMS WILL CONTINUE TO IMPACT THE REGION THROUGH THIS
MORNING BEFORE TAPERING TO DRIZZLE THIS AFTERNOON THEN ENDING THIS
EVENING. SLIGHTLY LOWER CONFIDENCE WITH EXACT RAINFALL AMOUNTS
EXPECTED OVER THE REGION AS SECOND HEAVY BAND IS FORECAST TO
DEVELOP BEHIND THE BAND CURRENTLY AFFECTING THE REGION EARLY THIS
MORNING. TOTAL RAINFALL AMOUNTS OF 30 TO 40 MM ARE GENERALLY
EXPECTED BUT WITH EMBEDDED CONVECTION, THOSE AMOUNTS CAN BE
SIGNIFICANTLY DIFFERENT ACROSS THE HARBOUR AND BASIN. EXPECT LOW
CLOUDS AND VISIBILITIES IN MIST AND FOG THROUGHOUT THE DAY BEFORE
CONDITIONS BEGIN TO IMPROVE AFTER MIDNIGHT. PATCHY MIST AND FOG
WILL LINGER OVERNIGHT BEFORE CLEARING SATURDAY MORNING AS RIDGING
GIVES A FAIRLY SUNNY DAY TO THE REGION WITH LOW TO MID TEEN HIGH
TEMPERATURES. LATE IN THE DAY.. MID AND HIGH CLOUD WILL BEGIN TO
MOVE INTO THE REGION AHEAD OF THE NEXT SYSTEM.
LONG RANGE DISCUSSION FOR 0300Z 03 MAY TO 0300Z 06 MAY.
MODEL DISCUSSION: USED GDPS/GFS WITH SUPPORT FROM ICON/ECMWF.
CONFIDENCE: GENERALLY HIGH.
COMMENTS/IMPACTS: MODELS ARE IN MUCH BETTER AGREEMENT WITH THE
DEVELOPMENT AND TRACK OF THE LOW PRESSURE SYSTEM AFFECTING THE
REGION SUNDAY. CONTINUED INCREASING CLOUDINESS IS EXPECTED SATURDAY
NIGHT WITH RAIN, LIKELY AT TIMES HEAVY, MOVING INTO THE REGION IN
THE MORNING. RAIN WILL TAPER TO DRIZZLE/SHOWERS SUNDAY EVENING INTO
THE OVERNIGHT IN THE WAKE OF THE SYSTEM AND END GENERALLY
OVERNIGHT. EXPECT STRONG EASTERLY WINDS, WITH POSSIBLE STORM FORCE
GUSTS, AHEAD OF THE LOW DURING THE DAY. MOST MODELS HAVE THE LOW
MOVING THROUGH THE HARBOUR/BASIN OR JUST SOUTH OF THE APPROACHES,
GIVING A COUPLE HOURS OF A LULL IN THE WINDS BEFORE PICKING BACK UP
TO STRONG WEST/NORTHWEST IN THE WAKE OF THE SYSTEM BY EVENING.
GIVEN THE 3 WINDS ALREADY IN THE DAY 3 FORECAST, HAVE NO ADDED THE
LULL BUT IT IS LIKELY BETWEEN THE WINDS SHIFTING FROM EAST TO
WEST/NORTHWEST. LASTLY WITH THIS SYSTEM, MODELS CONTINUE TO
INDICATE COLD AIR WRAPPING INTO THE SYSTEM TO THE NORTH AND
NORTHWEST. GENERALLY, THE HARBOUR/BASIN/APPROACHES ARE FORECAST TO
REMAIN A RAIN BUT THERE IS A CHANCE OF SNOW MIXING IN WITH THE RAIN
FURTHER INLAND. AS WELL, THE GFS AND ECMWF HAVE THE RAIN/SNOW MIX
AWEFULLY CLOSE TO BEDFORD BASIN. THIS WILL NEED TO BE WATCHED WITH
THE STORM.
ON MONDAY.. CLOUD WITH A CHANCE OF SHOWERS EARLY IN THE WAKE OF THE
DEPARTING LOW PRESSURE SYSTEM WILL GIVE WAY TO CLEARING SKIES AS
RIDGING MOVES ACROSS THE REGION. EXPECT A MIX OF SUN AND CLOUD,
POSSIBLY BECOMING INCREASING CLOUDINESS LATE AS A TROUGH BEGINS TO
APPROACH THE REGION FROM THE WEST. WITH A STRONG HIGH OFF TO THE
SOUTHEAST AND WELL TO THE WEST, EXPECT AN INCREASING SOUTHWEST FLOW
THROUGHOUT THE DAY. ONCE AGAIN, MODELS ARE ALL IN GOOD AGREEMENT
THROUGH DAY 5 NOW SO CONFIDENCE IS HIGHER WITH THE OVERALL
FORECAST. WITH SUNNIER SKIES AND WEST TO SOUTHWEST FLOW, EXPECT LOW
TO MID TEEN HIGHS OVER THE REGION ONCE AGAIN TO START THE WEEK.
END/METOC-HFX
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