069
FXCN01 CWHF 300808
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
THURSDAY 30 APR
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KEY FORECAST POINTS:
- INCREASING MOIST EASTERLY FLOW GIVING PATCHY DRIZZLE AND MIST THIS
MORNING BECOMING EXTENSIVE DRIZZLE MIST AND FOG BY THIS EVENING.
- APPROACHING LOW PRESSURE SYSTEM GIVING RAIN, AT TIMES HEAVY, WITH
A RISK OF THUNDERSTORMS AND STRONG SOUTHEAST FLOW TONIGHT THROUGH
MUCH OF FRIDAY.
- FAIR WEATHER AND SPRING LIKE CONDITIONS EXPECTED TO DEVELOP
SATURDAY AND MONDAY....
- HOWEVER, INCREASING CONFIDENCE WITH LARGE AND INTENSE LOW PRESSURE
SYSTEM PASSING SOUTH OF THE REGION SUNDAY GIVING RAIN,
POTENTIALLY HEAVY, AND STRONG NORTHEAST WINDS.
===================================================================
SHORT RANGE DISCUSSION FOR 0600Z 30 APR TO 0300Z 02 MAY.
MODEL DISCUSSION: USED RDPS/HRDPS.
CONFIDENCE: GENERALLY HIGH, MEDIUM WITH PRECIPITATION AMOUNTS.
COMMENTS/IMPACTS: SIGNIFICANT LOW LEVEL MOISTURE REMAINS IN EASTERLY
FLOW OVER THE REGION GIVING EXTENSIVE STRATUS TODAY. EXPECT STRATUS
TO THICKEN UP GIVING A CHANCE OF DRIZZLE THIS MORNING BECOMING
PATCHY THIS AFTERNOON AND EXTENSIVE BY EARLY THIS AFTERNOON. AS
WELL, PATCHY MIST WILL BECOME EXTENSIVE THIS AFTERNOON WITH PATCHY
TO EXTENSIVE FOG DEVELOPING OVER THE REGION THIS AFTERNOON INTO
THIS EVENING. LOW PRESSURE SYSTEM DEVELOPING ALONG THE EASTERN US
SEABOARD WILL TRACK NEAR THE CAPE COD REGION LATE TODAY AND THROUGH
NOVA SCOTIA OVERNIGHT THROUGH FRIDAY. EXPECT AN INCREASING
SOUTHEAST FLOW TONIGHT WITH GUSTS IN THE LOW 30 KNOT RANGE OVER THE
APPROACHES. IT IS POSSIBLE THAT STRONGER GUSTS MAY MIX DOWN IN
HEAVY PRECIPITATION BUT IS NOT EXPECTED TO BE THE GENERAL FLOW
TONIGHT/FRIDAY MORNING. RAIN, AT TIMES HEAVY, WITH A RISK OF
THUNDERSTORMS, IS EXPECTED OVER THE REGION BEGINNING NEAR MIDNIGHT
THEN WILL TAPER TO PATCHY DRIZZLE OR SHOWERS FRIDAY AFTERNOON AND
END LATER IN THE DAY. THERE REMAINS QUITE THE SPREAD IN EXPECTED
PRECIPITATION TOTALS OVERNIGHT TONIGHT THROUGH FRIDAY. AN ADVISORY
IS LIKELY AND A RAINFALL WARNING IS POSSIBLE. THE LATEST 00Z RDPS
MODEL RUN HAS LOWERED PRECIPITATION TOTALS TO NEAR 30 MM. HOWEVER,
QUITE A FEW MODELS HAVE INCREASED AMOUNTS IN THE LATEST RUN WITH
ENSEMBLE MODELS STILL GIVING A GENERAL SPREAD OF 30 TO 60 MM.
LONG RANGE DISCUSSION FOR 0300Z 02 MAY TO 0300Z 05 MAY.
MODEL DISCUSSION: USED RDPS/GDPS.
CONFIDENCE: MEDIUM TO HIGH.
COMMENTS/IMPACTS: IN THE WAKE OF THE LOW PRESSURE SYSTEM FRIDAY,
DRIER NORTHWEST WINDS DEVELOP NEAR OR AFTER MIDNIGHT GIVING A
CLEARING TREND OVERNIGHT INTO EARLY SATURDAY MORNING. EXPECT
NORTHWEST WINDS TO BACK TO THE SOUTHWEST AND A MAINLY SUNNY DAY
WITH MID TEEN HIGH TEMPERATURES. ON SUNDAY.. AS NOTED IN PREVIOUS
DISCUSSIONS, A SIGNIFICANT LOW PRESSURE SYSTEM IS EXPECTED TO PASS
SOUTH OF NOVA SCOTIA GIVING RAIN AND STRONG EAST TO NORTHEAST
WINDS. WHILE THERE IS STILL A SPREAD IN THE TRACK/TIMING/INTENSITY
OF THIS SYSTEM, MODELS ARE IN MUCH BETTER AGREEMENT WITH RAIN
LIKELY TO DEVELOP LATE SUNDAY MORNING INTO THE AFTERNOON THEN TAPER
OFF OVERNIGHT INTO EARLY MONDAY MORNING. HIGHER RAINFALL AMOUNTS
AND STRONGER WINDS ARE EXPECTED IF THE MODEL TRACKS CLOSER TO THE
COAST AS THE GDPS WOULD SUGGEST. GFS STILL TRACKS THE SYSTEM
FURTHEST SOUTH THOUGH RECENT MODEL RUNS ARE MUCH CLOSER TO THE GDPS
GIVING RAIN AND MODERATE TO STRONG WINDS TO THE REGION. ICON AND
ECMWF CONTINUE TO LIE BETWEEN THE TWO MODEL SOLUTIONS. OF NOTE WITH
THIS SYSTEM, MOST MODELS INDICATE THAT THE INTENSE LOW WILL WRAP
COLDER AIR INTO THE NORTHWEST QUADRANT GIVING PATCHY RAIN MIXED
WITH SNOW TO SOME LOCATIONS. THIS MIX WILL BE BOTH TRACK AND
ELEVATION DEPENDENT. LASTLY, WINDS.. EXPECT STRONG TO GALE FORCE
NORTHEAST WINDS AHEAD OF THE LOW AND GUSTS TO GALES IN THE WAKE OF
THE SYSTEM SUNDAY NIGHT INTO MONDAY MORNING. MODELS ARE THEN QUICK
TO CLEAR SKIES LATE SUNDAY NIGHT INTO MONDAY MORNING GIVING A
FAIRLY SUNNY AFTERNOON, IF NOT MORNING AND ONCE AGAIN, HIGH
TEMPERATURES APPROACHING MID TEEN VALUES.
END/METOC-HFX
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