793
FXCN01 CWHF 141957
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 14 SEP
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KEY FORECAST POINTS:
- CLOUD FROM LINGERING TROUGH PASSING THROUGH CLEARING THIS EVENING.
- FAIR WEATHER TONIGHT THROUGH THURSDAY UNDER RIDGING.
- FRONTAL TROUGH TRACKING THROUGH GIVING SHOWERS, POSSIBLY BEGINNING
THURSDAY NIGHT, THEN ENDING FRIDAY AND POSSIBLY CLEARING.
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SHORT RANGE DISCUSSION FOR 1800Z 14 SEP TO 0300Z 16 SEP.
MODEL DISCUSSION: USED HRDPS/RDPS.
CONFIDENCE: HIGH.
COMMENTS/IMPACTS: A LINGERING TROUGH, IN THE WAKE OF A FRONTAL
SYSTEM THAT AFFECTED THE REGION LATE LAST NIGHT, IS GIVING SOME MID
AND HIGH CLOUD TO THE REGION EARLY THIS EVENING. AS THE TROUGH
PUSHES TO THE EAST, CLOUDS WILL CLEAR AND WINDS WILL VEER THROUGH
THE NORTHWEST TO THE NORTH, INCREASING FROM LIGHT TO MODERATE TO
MODERATE TO STRONG AT TIMES. RIDGING WILL BUILD INTO THE REGION
FROM THE WEST THROUGHOUT THE DAY TUESDAY GIVING MAINLY SUNNY SKIES
AS WELL AS WINDS EASING THROUGH THE MORNING AND BECOMING LIGHT IN
THE AFTERNOON.
LONG RANGE DISCUSSION FOR 0300Z 16 SEP TO 0300Z 19 SEP.
MODEL DISCUSSION: USED RDPS/GDPS.
CONFIDENCE: GENERALLY HIGH.
COMMENTS/IMPACTS: RIDGING OVER THE REGION WEDNESDAY BECOMES SQUEEZED
AND STALLED OVER THE LOCAL REGION BETWEEN A QUASI-STATIONARY
FRONTAL BOUNDARY TO THE SOUTH AND A MORE INTENSE LOW PRESSURE
SYSTEM TRACKING ACROSS NORTHERN QUEBEC. EXPECT MAINLY SUNNY SKIES
WEDNESDAY UNDER THIS RIDGING. WITH THE TRAILING COLD FRONT FROM THE
QUEBEC LOW LIFTING WELL TO THE NORTHEAST OF THE REGION, A NEW RIDGE
BUILDS IN FROM THE NORTHWEST, CONTINUING TO GIVE FAIRLY DRY AIR.
HOWEVER, A BIT MORE CLOUD WILL SPILL INTO THIS SECOND RIDGE FROM
THE WEST AS AN AREA OF LOW PRESSURE/TROUGH ORGANIZES OVER THE LOWER
GREAT LAKES. AS A LOW MOVES OVER JAMES BAY AND ACROSS CENTRAL
QUEBEC LATE THURSDAY INTO FRIDAY, THE ORGANIZING AREA OF LOW
PRESSURE/TROUGH OVER THE LOWER GREAT LAKES WILL FEED UP INTO THE
COLD FRONTAL TROUGH OF THIS SYSTEM THEN TRACK ACROSS NOVA SCOTIA.
THIS IS A MORE SIGNIFICANT CHANGE FROM PREVIOUS DISCUSSION AS A
LINE OF SHOWERS IS LIKELY TO MOVE INTO THE REGION LATE
OVERNIGHT/EARLY FRIDAY MORNING THEN BLAST OFF TO THE EAST AND
POSSIBLY CLEAR IN BEHIND THE SYSTEM. GDPS IS THE SLOWEST WITH ONSET
AND SLOWEST WITH ENDING THE SHOWERS THEN CLEARING BUT THE GENERAL
TREND IS THERE WITH SHOWERS DEVELOPING, ENDING THEN SKIES CLEARING.
GFS/ECMWF WOULD HAVE SHOWERS DEVELOPING OVERNIGHT, ENDING EARLY IN
THE AFTERNOON THEN SKIES CLEARING/SUNNY BY MID TO LATE AFTERNOON.
AT THIS TIME, HAVE ONLY ADJUSTED THE FORECAST TO INDICATE SHOWERS
ON FRIDAY AND A VEERING WINDS FROM SOUTHWEST TO NORTHWEST AS THE
COLD FRONT SLIDES THROUGH. AS THE SYSTEM BECOMES BETTER ORGANIZED
IN NUMERICAL GUIDANCE, STRONGER WINDS MAY BE ADDED TO THE FORECAST
AHEAD AND IN THE WAKE OF THE SYSTEM.
END/METOC-HFX
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