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FXCN01 CWHF 090811
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
MONDAY 09 MAR
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KEY FORECAST POINTS:
- CLEARING EXPECTED THIS MORNING.
- STRATUS AND FOG PATCHES RETURN TONIGHT.
- CLEARING AGAIN TUESDAY MORNING WITH MID TEMPERATURES.
- WETNESS AND WIND EXPECTED WEDNESDAY AND THURSDAY.
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SHORT RANGE DISCUSSION FOR 0600Z 09 MAR TO 0300Z 11 MAR.
MODEL DISCUSSION: USED RDPS, BUT NOTED HRDPS DISCREPANCY
CONFIDENCE: MEDIUM
COMMENTS/IMPACTS: A WEAK RIDGE OF HIGH PRESSURE IS FORECAST TO CROSS
NOVA SCOTIA THIS MORNING. IT WILL BRING WITH IT A SHOT OF DRIER LOW
LEVELS, THE PROG TEPHIS AND THE RDPS BOTH SHOW STRONG CLEARING
SIGNALS. THE HRDPS DOES NOT, AND WAITS TILL MID DAY TO LOSE THE LOW
LEVEL MOISTURE. CURRENT SATELLITE TRENDS DO NOT SUPPORT THIS. A
BRIEF PUSH OF MODERATE WESTERLY WINDS WILL BECOME SOUTHWEST THIS
AFTERNOON AND THAT FLOW INCREASES TO STRONG TONIGHT. HOWEVER, THAT
STRONGER FLOW WILL COMPETE WITH A DEVELOPING LOW LEVEL INVERSION.
ALSO, STRATUS WITH PATCHY MIST AND FOG IS SHOWN BY ALL THE MODELS
FOR TONIGHT.
BY TUESDAY MORNING, A NEW PUSH OF DRIER AIR IS EXPECTED TO PUSH
THE STRATUS OFFSHORE. THE RDPS IS MORE AGGRESSIVE WITH THE CLEARING
WHEN COMPARED WITH THE HRDPS. CONFIDENCE IS LOW ON HOW MUCH TO
CLEAR OUT THE OPERATIONS AREA FOR TOMORROW. BY THE END OF THE DAY,
A NEW PUSH OF MOISTURE FROM THE SOUTH IS FORECAST TO PUSH THE
STRATUS BACK INTO THE REGION.
LONG RANGE DISCUSSION FOR 0300Z 11 MAR TO 0300Z 14 MAR.
MODEL DISCUSSION: USED GDPS.
CONFIDENCE: MEDIUM.
COMMENTS/IMPACTS: ON WEDNESDAY, A FRONTAL TROUGH OF LOW PRESSURE
STARTS TO GET ORGANIZED OVER THE GREAT LAKES AND STRETCHES TOWARD
THE MARITIMES. A PRECIPITATION SHIELD SPREADS EASTWARD NORTH OF THE
TROUGH . MEANWHILE FOG AND STRATUS OVER THE COASTAL REGIONS OF NOVA
SCOTIA WILL START TO ERODE AS A NORTHEAST FLOW DEVELOPS. THE FLOW
INCREASES TO A STRONG EAST DURING THE DAY, AND THE LOW LEVEL
MOISTURE WILL PUSH IN ONCE AGAIN LATER IN THE DAY AND MODELS ARE
SHOWING AN EXTENSIVE FIELD OF DRIZZLE DEVELOPING. WITH EVENING
TEMPERATURES DROPPING CLOSE TO ZERO, AND FLOW OF ZERO DEGREE WATER,
THERE WILL BE RISK OF FREEZING DRIZZLE OVERNIGHT.
BY THURSDAY MORNING, THE FLOW HAS BECOMING MORE SOUTHERLY AND WILL
BE STRENGTHENING DURING THE DAY. THE AIRMASS WILL BECOME LADEN WITH
SHOWERS AS THE DRIZZLE CONTINUES. TEMPERATURES WILL CLIMB.
A SHARP COLD FRONT GOES THROUGH OVERNIGHT, WITH A SHOT OF HEAVY
RAIN TURNING BRIEFLY TO SNOW BEFORE TAPERING TO FLURRIES IN THE
MORNING AS TEMPERATURES FALL IN A STRONG WESTERLY FLOW. MODELS ARE
SHOWING DRIER AIR IN PLACE BY AFTERNOON WITH DEVELOPING SUNSHINE.
IT WILL REMAIN A COOL TO COLD DAY.
END/METOC-HFX
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