207
FXCN01 CWHF 152010
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
WEDNESDAY 15 JULY
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KEY FORECAST POINTS:
- SLIGHT CHANCE OF SHOWERS OR THUNDERSHOWERS THIS EVENING THEN
CLEARING.
- SUNNY THURSDAY MORNING.
- MODERATE TO STRONG SOUTHWEST WINDS AND SHOWERS WITH A CHANCE OF
THUNDERSHOWERS THURSDAY AFTERNOON AND EVENING.
- RAIN ON SUNDAY.
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SHORT RANGE DISCUSSION FOR 1800Z 15 JULY TO 0300Z 17 JULY.
MODEL DISCUSSION: USED RDSP/HRDPS.
CONFIDENCE: MODERATE.
COMMENTS/IMPACTS: CONTINUES TO BE DIFFERENCES BETWEEN THE HRDPS AND
RDPS IN WHERE AND WHEN IT DEVELOPS SHOWERS AND THUNDERSHOWERS OVER
THE REGION DUE TO A WEAK TROUGH MOVING THROUGH. UPPER LEVEL SMOKE
OVER NOVA SCOTIA IMPACTING THE AMOUNT HEATING OVER THE REGION HAS
NOT HELPED MATTERS. ANY RESIDUAL SHOWERS OR THUNDERSHOWER THAT
DEVELOP LATE TODAY SHOULD DISSIPATE THIS EVENING. LIGHT TO MODERATE
WEST WINDS BECOME LIGHT NORTHWEST THIS EVENING IN BEHIND THE TROUGH.
ON THURSDAY ANOTHER TROUGH FORECAST TO DEVELOP OVER EASTERN QUEBEC
WILL DROP SOUTH THROUGH THE MARITIMES. MODERATE TO STRONG SOUTHWEST
WINDS DEVELOP THURSDAY AFTERNOON AHEAD OF THE TROUGH THEN DIMINISH
TO LIGHT TO MODERATE WESTERLY IN ITS WAKE IN THE EVENING. SUNNY
SKIES ARE EXPECTED TO START THE DAY. HOWEVER DAYTIME HEATING LEADS
TO CONVECTION WITH A CHANCE OF SHOWERS OR THUNDERSHOWERS IN THE
AFTERNOON AHEAD OF THE TROUGH MAINLY ALONG THE SPINE OF NOVA
SCOTIA. THEN MODELS ARE SHOWING A STRONG LIKELIHOOD OF SHOWERS AND
THUNDERSHOWERS IN THE EVENING AS THE TROUGH MOVES IN. SKIES CLEAR
IN THE EVENING IN BEHIND THE TROUGH.
LONG RANGE DISCUSSION FOR 0300Z 17 JULY TO 0300Z 20 JULY.
MODEL DISCUSSION: USED GDPS.
CONFIDENCE: GENERALLY HIGH.
COMMENTS/IMPACTS: NO CHANGE FROM THE PREVIOUS LONG RANGE
DISCUSSION...
THERE IS ACTUALLY MORE CONFIDENCE IN THE LONG RANGE FORECAST OVER
THE SHORT RANGE ONE THIS MORNING. THE MODELS ARE AGREEING ON A
SOLUTION, AND THAT HELPS, PLUS THE FEATURES BECOME BETTER ORGANIZED
IN THE LONG RANGE PERIOD.
FRIDAY SEES THE AREA IN A COOLER WESTERLY FLOW IN AN UNSTABLE
AIRMASS WITH A LARGE LOW PRESSURE SYSTEM IN LABRADOR. CUMULUS AND
STRATOCUMULUS DEVELOPMENT IS EXPECTED ON FRIDAY AS THE JULY SUN
HEATS THE UNSTABLE AIR.
ON SATURDAY, A RIDGE MOVES THROUGH IN THE MORNING AND CLOUD FROM A
DEVELOPING GREAT LAKES LOW SPILLS INTO THE REGION QUICKLY BEHIND
IT. A SOUTHWEST GRADIENT STRENGTHENS BEHIND THE RIDGE.
ON SUNDAY, THERE IS GOOD CONSENSUS THAT A RATHER ROBUST AREA OF
LOW PRESSURE WILL MOVE ACROSS NOVA SCOTIA. MODELS ARE SHOWING A
STRONG SOUTHEAST FLOW WITH RAIN. CURRENT RAINFALL AMOUNTS ARE
PROJECTED TO BE QUITE HIGH.. MORE THAN 25 MM AND POSSIBLY 50 OR
MORE.
END/METOC-HFX
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