156
FXCN01 CWHF 070805
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 07 MAY
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KEY FORECAST POINTS:
- SHOWERS, AT TIMES HEAVY WITH A RISK OF THUNDERSHOWERS AND STRONG
GUSTY SOUTHERLY WINDS AHEAD AND ALONG A COLD FRONTAL TROUGH TODAY.
- UNSTABLE AIRMASS COMBINED WITH DAYTIME HEATING GIVING SCATTERED
SHOWERS AND ISOLATED THUNDERSHOWERS ACROSS THE MARITIMES FRIDAY.
- NEXT TROUGHING APPROACHES SATURDAY NIGHT GIVING SHOWERS AND
DRIZZLE INTO EARLY NEXT WEEK AS IT VERY SLOWLY TRACKS EASTWARDS.
- A SERIES OF IMPULSES WILL MOVE UP THIS TROUGH GIVING POTENTIALLY
HEAVIER SHOWERS/RAIN EARLY NEXT WEEK... WORTH WATCHING FOR
SIGNIFICANT RAINFALL AMOUNTS.
===================================================================
SHORT RANGE DISCUSSION FOR 0600Z 07 MAY TO 0300Z 09 MAY.
MODEL DISCUSSION: USED RDPS/HRDPS.
CONFIDENCE: HIGH TO MEDIUM.
COMMENTS/IMPACTS: SHOWERS, AT TIMES HEAVY TODAY, WITH A RISK OF
THUNDERSHOWERS WILL TAPER TO DRIZZLE WITH A FEW SHOWERS LATE TODAY
THEN END THIS EVENING. 25 TO 35 MM OF RAINFALL IS EXPECT WITH
LOCALIZED 50 MM IN HEAVIEST CONVECTION.. THOUGH EXPECTED EAST OF
HALIFAX REGION AT THIS TIME. PATCHY MIST AND FOG WILL BECOME
EXTENSIVE IN THE SOUTHERLY FLOW THIS MORNING THEN GRADUALLY BECOME
PATCHY ONCE AGAIN OVERNIGHT. MIST AND FOG WILL DISSIPATE EARLY
FRIDAY WITH STRATUS LIFTING INTO CU. AN UNSTABLE AIRMASS WITH WEAK
TROUGHING IN THE WAKE OF TODAY'S SYSTEM WILL GIVE SCATTERED SHOWERS
AND ISOLATED THUNDERSHOWERS ACROSS THE MARITIMES FRIDAY. CONVECTION
WILL DIMINISH AFTER SUNSET AND SKIES WILL GRADUALLY CLEAR AS WEAK
RIDGING BUILDS INTO THE REGION.
WINDS.. STRONG SOUTHERLY WINDS WILL AFFECT THE REGION WELL AHEAD OF
THE COLD FRONT THIS MORNING BEFORE EASING WITHIN THE TROUGH THEN
VEER TO A MORE WESTERLY FLOW LATE TODAY. CONFIDENCE LOWER IS
SUSTAINED GALES OCCURRING THOUGH GUSTS TO GALES ARE LIKELY IN SOME
OF THE HEAVIEST SHOWERS.
LONG RANGE DISCUSSION FOR 0300Z 09 MAY TO 0300Z 12 MAY.
MODEL DISCUSSION: USED RDPS/GDPS.
CONFIDENCE: MEDIUM.
COMMENTS/IMPACTS: AS RIDGING GIVES LIGHT FLOW AND CLEAR SKIES, LOCAL
MIST AND FOG WILL ONCE AGAIN DEVELOP LATE OVERNIGHT FRIDAY AND
DISSIPATE EARLY SATURDAY MORNING. WITH A PREVAILING SOUTHWEST FLOW,
EXPECT ANY DAYTIME HEATING CU/TCU TO BE PUSHED UP TO THE NORTHEAST
OF THE REGION GIVING A FAIRLY SUNNY DAY WITH SOME AFTERNOON
CLOUDINESS... MAINLY INLAND. CLOUD WILL BEING TO INCREASING AHEAD
OF THE NEXT APPROACHING TROUGH WITH A FEW SHOWERS DEVELOPING NEAR
MIDNIGHT. GFS IS A BIT SLOWER BUT DOES GIVE SOME OVERNIGHT SHOWERS.
THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK... THE BASE OF THE
TROUGH WILL MOVE OUT OF THE GREAT LAKES TO ALONG THE EASTERN
SEABOARD AND FINALLY INTO NOVA SCOTIA. ALL THE WHILE, EXPECT AN
UNSTABLE AIRMASS OVER THE REGION WITH A SERIES OF IMPULSE MOVING
THROUGH THE REGION AHEAD OF MAIN TROUGH LINE. SOUTHERLY WINDS WILL
CONTINUALLY DRAG MOISTURE INTO THE REGION THROUGHOUT THE PERIOD AS
WELL WITH DRIZZLE AND SHOWERS EXPECT SUNDAY.. MORE SHOWERS THAN
DRIZZLE MONDAY AS THE TROUGH GETS CLOSER WITH POTENTIALLY
SIGNIFICANT RAINFALL THEREAFTER. GFS AND ECMWF HAVE THE MAIN TROUGH
LINE A BIT FURTHER WEST SO NOT AS MUCH SHOWERS/PRECIPITATION ON
MONDAY COMPARED TO THE GDPS/ICON.
END/METOC-HFX
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