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FXCN01 CWHF 090810
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
WEDNESDAY 09 JULY
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KEY FORECAST POINTS:
- A LOW CONFIDENCE CLOUD FORECAST FOR TODAY AND THURSDAY.
- WINDS EXPECTED TO STAY UNDER 15 KNOTS FOR TODAY AND THURSDAY BUT
STAY GENERALLY ONSHORE.
- LOW CONFIDENCE FORECAST OF SHOWERS ON FRIDAY.
- IMPROVEMENT FOR SATURDAY AND SUNDAY.
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SHORT RANGE DISCUSSION FOR 0600Z 09 JULY TO 0300Z 11 JULY.
MODEL DISCUSSION: USED A BLEND OF THE MODELS
CONFIDENCE: MEDIUM-LOW.
COMMENTS/IMPACTS: SYNOPTICALLY THERE IS NOT MUCH TO HANG THE
FORECAST ON FOR THE NEXT TWO DAYS. GENERALLY THERE IS WEAK
TROUGHING SOUTH OF NS AND WEAK RIDGING TO THE NORTH. DRIER AIR IS
TRYING TO PUSH INTO HALIFAX FROM THE NORTH, BUT THERE IS A
STRUGGLE WITH THE ONSHORE WINDS AND THE ABUNDANT MOISTURE OVER
SOUTHERN NOVA SCOTIA. THE MODELS ARE STRUGGLING WITH THE
PREDICTION OF HOW FAR SOUTH THE CLOUD WILL PUSH AND CURRENT
SATELLITE IMAGERY IS NOT HELPING IN PREDICTING WHAT WILL HAPPEN.
THE PREDICTED TREND IS THAT THE DRIER AIR WILL WIN FOR A WHILE,
AND SOME SUN WILL BREAK THROUGH FOR TODAY.
TONIGHT, THE TROUGH FROM THE SOUTH NUDGES NORTHWARD AND MID CLOUD
SPILLS INTO THE REGION AND THEN THE LOW LEVELS MOISTEN UP
OVERNIGHT. HI RES MODELS ARE SHOWING STRATUS AND FOG REDEVELOPING
ALONG THE IMMEDIATE COAST AND THIS IS ENTIRELY PROBABLE.
ON THURSDAY, THE TROUGH CONTINUES ITS SLOW NORTHWARD PUSH. MODELS
ARE SHOWING CLOUD COVER FOR THE DAY NOW, AND THE HI RES EVEN HAS
SHOWERS PUSHING OVER THE MAINLAND LATER IN THE DAY. THE FORECAST
WILL BE FORCED TO BECOME MORE PESSIMISTIC AS A RESULT.
LONG RANGE DISCUSSION FOR 0300Z 11 JULY TO 0300Z 14 JULY.
MODEL DISCUSSION: USED A MODEL BLEND
CONFIDENCE: LOW-MEDIUM BUT IMPROVING ON THE WEEKEND.
COMMENTS/IMPACTS: A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF NS ON
FRIDAY. THE MODELS HAVE BEEN WAFFLING ON AND OFF ABOUT PUSHING RAIN
OVER NS. TONIGHT, THEY'RE ARE ABOUT HALF AND HALF. THERE IS A TROF
OVER NB AND THE MODELS ARE STRUGGLING WITH HOW MUCH TO LINK THE
MOISTURE FROM THESE TWO SYSTEM TOGETHER. IT SEEMS PRUDENT TO
MAKE THE SHOWER FORECAST MORE POSITIVE BASED ON THE LATEST MODEL
TRENDS.
ON SATURDAY, THE WEAK TROF LINGERS IN MAINE AND NB WHILE THE LOW
MOVES OFF TOWARD NEWFOUNDLAND. THIS ALLOWS A LIGHT NORTHWEST FLOW
OF SOMEWHAT DRIER AIR TO MOVE INTO THE OPS ZONE. BUT THE AIRMASS
REMAINS UNSTABLE, SO A CLOUD SUN MIX IS THE BEST FORECAST I CAN
OFFER AT THIS TIME. IT REMAINS UNSTABLE AS WELL, SO THERE IS A
CHANCE OF SHOWERS WITH THE CLOUDS.
ON SUNDAY, A SURFACE RIDGE STRENGTHENS OVER THE MARITIMES, SO MORE
SUNSHINE SHOULD FINALLY DEVELOP.
END/METOC-HFX
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