523
FXCN01 CWHF 090815
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
SUNDAY 09 AUG
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KEY FORECAST POINTS:
- SIGNIFICANT LOW LEVEL MOISTURE GIVING STRATUS MIST AND FOG
BECOMING PATCHY THEN DISSIPATING MONDAY.
- BROAD TROUGH OVER REGION CONTINUING TO GIVE UNSTABLE AIRMASS
LEADING TO SHOWERS AND THE RISK OF THUNDERSTORMS INTO THIS
EVENING BEFORE RIDGING GIVES FAIR WEATHER ON MONDAY.
- TROUGH/LOW MOVING THROUGH TUESDAY GIVING A FEW SHOWERS, LIKELY
RISK OF THUNDERSTORMS.
- FAIR WEATHER WEDNESDAY INTO THURSDAY BEFORE NEXT TROUGH BRING
SHOWERS THURSDAY AFTERNOON.
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SHORT RANGE DISCUSSION FOR 0600Z 09 AUG TO 0300Z 11 AUG.
MODEL DISCUSSION: USED RDPS/HRDPS.
CONFIDENCE: GENERALLY HIGH, LOWER WITH LOCATION OF THUNDERSTORMS
TODAY.
COMMENTS/IMPACTS: SIGNIFICANT LOW LEVEL MOISTURE GIVING EXTENSIVE
STRATUS MIST AND FOG OVER NOVA SCOTIA THIS MORNING. BROAD TROUGHING
GIVING AN UNSTABLE AIRMASS WITH ISOLATED SHOWERS AND THUNDERSTORMS
EVEN EARLY THIS MORNING. AS DAYTIME HEATING BURNS OFF THE STRATUS
MIST AND FOG THIS MORNING, IT WILL CREATE MORE UNSTABLE CONDITIONS.
GIVEN THE ONGOING CONVECTION... MODELS MAY BE UNDER-DOING THE
CONVECTION OVER NOVA SCOTIA THIS AFTERNOON. DYNAMICALLY, CONVECTION
WILL BE SUPPORTED BY A WEAKENING COLD FRONTAL TROUGH LIFTING TO THE
NORTHEAST. AT THIS TIME.. NEW BRUNSWICK WILL LIKELY SEE THE BULK OF
AFTERNOON CONVECTION THOUGH SCATTERED SHOWERS WITH ISOLATED
THUNDERSTORMS ARE FORECAST OVER NOVA SCOTIA. HRDPS DEVELOPS
CONVECTION OVER THE HALIFAX REGION NEAR 1400 LOCAL AND AFFECT THE
REGION INTO DINNER TIME. RDPS HAS LESS INTENSE CONVECTION GIVING A
FEW LIGHT SHOWERS AROUND THE HALIFAX REGION THIS AFTERNOON INTO
THIS EVENING. AT THIS TIME, HRDPS SEEMS TO HAVE A BETTER HANDLE ON
THE CONVECTION SO LEANING TOWARDS THAT FORECAST. AS CONVECTION
DISSIPATES SOMEWHAT AFTER SUNSET AND MOVES OFF TO THE EAST, LOW
LEVEL MOISTURE WILL REMAIN OVER THE REGION THOUGH MORE PATCHY.
EXPECT SOME STRATUS AND MIST TO DEVELOP THIS EVENING THOUGH AS THE
FLOW SHIFTS TO THE WEST/NORTHWEST OVERNIGHT, EXPECT CONDITIONS TO
IMPROVE INTO MONDAY MORNING. MAINLY SUNNY CONDITIONS MONDAY
MORNING AS RIDGING MOVES IN THEN A BIT OF CU DEVELOPING IN THE
AFTERNOON LEADING TO A MIX OF SUN AND CLOUD. CLOUD MOVES INTO THE
REGION IN THE EVENING AHEAD OF TUESDAYS TROUGH/LOW.
LONG RANGE DISCUSSION FOR 0300Z 11 AUG TO 0300Z 14 AUG.
MODEL DISCUSSION: USED RDPS/GDPS.
CONFIDENCE: GENERALLY HIGH.
COMMENTS/IMPACTS: NEXT LOW/TROUGH WILL MOVE INTO THE REGION TUESDAY
GIVING A FEW SHOWERS. RDPS/GDPS NOW DEVELOPING A CLOSED LOW AND
GIVING A BIT MORE SHOWER ACTIVITY, AND LIKELY THUNDERSTORMS, TO THE
REGION ON TUESDAY. HAVE GONE MORE POSITIVE WITH THE SHOWER
FORECAST, ADDING OCCASIONAL SHOWERS. A DRYER/PARTIALLY CLEARING
WEST/NORTHWEST FLOW DEVELOPS LATE IN THE DAY TO GIVE IMPROVING
CONDITIONS. EXPECT A MIX OF SUN AND CLOUD THOUGH AS THE DAY GOES
ON, MORE SUN IS LIKELY WITH WEAK RIDGING MOVING THROUGH. ISOLATED
SHOWERS STILL POSSIBLE OVER NOVA SCOTIA BUT LIKELY TO THE EAST OF
HALIFAX. AN ORGANIZING TROUGH/LOW MOVES IN FROM THE WEST GIVING
INCREASING CLOUDINESS WITH LIKELY SHOWERS DEVELOPING AT SOME POINT
IN THE DAY. MODELS ALL SHOW THE GENERAL SAME PATTERN THOUGH WITH
DIFFERENT INTENSITIES AND SLIGHTLY DIFFERENT TIMINGS. THAT SAID..
ANOTHER ROUND OF SHOWERS/THUNDERSTORMS MOVING THROUGH IS EXPECTED.
GDPS APPEARS THE WEAKEST WITH THE THOUGH INITIALLY SO HAVE BUMPED
UP THE WINDS A BIT COMPARED TO GDPS FORECAST AND BACKED THEM MORE
TO THE SOUTH.
END/METOC-HFX
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