CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 19:00 ON FRIDAY NOVEMBER 24, 2017
VALID FROM : FRIDAY NOVEMBER 24 -- UNTIL : THURSDAY NOVEMBER 30 2017
In the winter sun
I d'like to leave
Low 969 hpa Southeastern Norwegian Sea, almost stationary, deepening somewhat further overnight, then starting up to filling on Saturday. It is driving a powerful unsettled southwesterly stream, west of Portugal to Finland. • The eastward progress of the cold front waving in that stream is slowed down by a moderately tight fœhn gradient. Which disturbance will finally cross over the High Massifs on Saturday morning, triggering snowfall below 1000 m by the middle of the day. It will be followed by a fairly inactive northwesterly tail on Sunday. • Sustained Bise pattern will help clearing skies on Monday. • Unsettled southwesterly expected to resuming as soon as Tuesday.
FRIDAY EVENING NOVEMBER 24 - AND OVERNIGHT
SKY CONDITION : cloudy to mostly cloudy at first - becoming overcast.
PRECIPITATION : isolated showers likely to running over from the southwest - continuous rain expected to starting up by dawn.
WIND - ground level : mainly SW - light - fœhn wind puffs, SE at times, in the upper part of the valley.
WIND - mid mountain : SW moderate -> strong.
WIND - high mountain : WSW moderate to strong -> strong.
TEMPERATURE : low +2°C.
ISOTHERM 0°C : 2400 -> 2300 m.
ISOTHERM -10°C : 4200 -> 4000 m.
Rain beginning sooner along the Italian Slopes.
ROAD CONDITION ••••• : @ 19:00, dry roadways. Disturbance coming in from the west. Shower risk.
TOMORROW - SATURDAY NOVEMBER 25
SKY CONDITION : mostly cloudy to overcast - fleeting sunny spell towards the latter part of the afternoon. Period of sunshine close to 10%.
PRECIPITATION : continuous and moderate in the morning - turning into showers during the afternoon - rain-snow limit towards 2000 m at first, dropping quickly towards 900 m towards the middle of the day - expected snowfall towards 1800 m : 20-30 cm, windblown.
WIND - ground level : SW light - moderate at times later in the morning.
WIND - mid mountain : SW strong -> WSW moderate -> WNW light.
WIND - high mountain : WSW -> W strong - gale force at times towards the middle of the day.
TEMPERATURE : low -1°C - high +4°C.
ISOTHERM 0°C : 2300 -> 1100 m.
ISOTHERM -10°C : 4000 -> 2600 m.
Same weather in the bordering Valais. Precipitation ending sooner in the Aosta Valley.
SATURDAY TO SUNDAY NIGHT - NOVEMBER 25 TO 26
SKY CONDITION : mostly cloudy, then probably overcast due to barrier effect against the northern slopes.
PRECIPITATION : shower becoming scattered - rain-snow limit dropping towards 700 m at times.
WIND - aloft : W -> NNW strong.
TEMPERATURE : low -5°C.
SUNDAY NOVEMBER 26
SKY CONDITION : mostly cloudy to overcast due to the barrier effect - sunny spells possibly spreading during the afternoon. Period of sunshine close to 30%.
PRECIPITATION : scattered snow showers - not much.
WIND - aloft : NNW strong -> moderate at times.
TEMPERATURE : low -5 °C - high 0°C.
MONDAY NOVEMBER 27
SKY CONDITION : clear or partly cloudy - some fog patches sticking to the slopes. Period of sunshine close to 70%.
PRECIPITATION : none.
WIND - aloft : NNW moderate.
TEMPERATURE : low -8°C - high 0°C.
EXTENDED OUTLOOK UNTIL THU. NOVEMBER 30
Tuesday : new disturbance coming in ‑ sleet showers at times ‑ strong WSW high up. Wednesday : mostly cloudy ‑ snow showers ‑ fairly strong SW high up in the morning. Thursday : very uncertain ‑ mainly cloudy, very cold - probably dry - fairly strong bise wind high up after the previous disturbance's crossing.
Forecast reliability : fairly good until Saturday ‑ poor thereafter.