CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 19:45 ON FRIDAY NOVEMBER 27, 2015
VALID FROM : FRIDAY NOVEMBER 27 2015 -- UNTIL : THURSDAY DECEMBER 03 2015
Ridge linking Azores high to Central Europe is currently weakening over France, allowing for a cold frontal trough, linked to the extended arctic low system, to insinuate up to the Alps towards the end of the night. Altitude stream will thus be increasing while backing west-northwest and a snowy spell is expected on Saturday. • Getting milder on Sunday with some hypothetical remaining precipitation changing to rain in a rising pressure field over the Western Alpine Range. • Fair condition thereafter, with the comeback of the high pressure african air mass high up, likely to cause unusual tepidity in the median altitude range, if related to seasonal average, at least until Thursday.
FRIDAY EVENING NOVEMBER 27 - AND OVERNIGHT
SKY CONDITION : clear in the first part of the night - increasing cloud of the median étage later.
PRECIPITATION : none.
WIND - ground level : SW -> variable light.
WIND - mid mountain : variable -> SW light.
WIND - high mountain : N -> WNW moderate.
TEMPERATURE : low -10°C.
ISOTHERM 0°C : 2000 -> 1500 m.
ISOTHERM -10°C : 3800 -> 3500 m.
Temperature inversion likely towards 1400 m.
ROAD CONDITION ••••• : @ 19:00, no traffic issue on salted roadways - driving locally difficult otherwise.
TOMORROW - SATURDAY NOVEMBER 28
SKY CONDITION : mostly cloudy - fleeting sunny spells towards the latter part of the night. period of sunshine close to 15%.
PRECIPITATION : light and scattered snow showers - slightly more frequent and moderate towards the middle of the day - ending in the afternoon - rain-snow limit towards 600 m, rising - expected snowfall towards 1000 m : 5-10 cm.
WIND - ground level : variable -> SW light.
WIND - mid mountain : SW -> WNW light.
WIND - high mountain : WNW moderate -> NW moderate to strong.
TEMPERATURE : low -8°C - high -1°C.
ISOTHERM 0°C : 1500 -> 900 m.
ISOTHERM -10°C : 3500 -> 3000 m.
SATURDAY TO SUNDAY NIGHT - NOVEMBER 28 TO 29
SKY CONDITION : cloudy with clear spells spreading out.
PRECIPITATION : probably none.
WIND - aloft : NW moderate to strong.
TEMPERATURE : low -8°C.
SUNDAY NOVEMBER 29
SKY CONDITION : mostly cloudy, then overcast. Period of sunshine close to 5%.
PRECIPITATION : probably scattered and very light - rain-snow limit rising up towards 1300 m - morning snow flurries changing to rain in the afternoon.
WIND - aloft : NW moderate to strong -> WNW strong.
TEMPERATURE : low -6 °C - high +3°C.
MONDAY NOVEMBER 30
SKY CONDITION : remaining cloud likely early in the morning - becoming clear or partly cloudy. Period of sunshine close to 75%.
PRECIPITATION : none.
WIND - aloft : WNW strong.
TEMPERATURE : low 0°C - high +6°C.
Still slightly uncertain.
EXTENDED OUTLOOK UNTIL THURSDAY DECEMBER 03
Tuesday : fairly sunny ‑ getting milder, especially high up. Wednesday and Thursday : sunny and mild, or even very mild in the median altitude range.
Forecast reliability : fairly good until Saturday ‑ poor thereafter.
Avalanche risk is considerable (3/5) above 2000 m.