CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 08:55 THURSDAY DECEMBER 3
VALID FROM : THURSDAY DECEMBER 3 ‑‑ UNTIL : TUESDAY DECEMBER 8 2020
And then not –
Fallen leaves –
Low system, gulf of Genoa to Northwest Balkans, still driving northerly flow over our Region this morning, which is currently getting dryer while decreasing. • Remaining fog patches and low cloud will dispel quite soon, then Atlantic low coming in and deepening towards 975 hpa over Northern England will make that northerly rotate back southwest and a possibly very tight foehn gradient appear between Savoie and Italian Piedmont, meaning a risk of strong winds in the valley overnight. • Cold front of the English low is then expected to crossing over the Alps on Friday, causing wintry unsettled weather, with probably moderate activity along the northern slopes of the bordering ridge, while heavy against Italian slopes.
TODAY - THURSDAY DECEMBER 3
SKY CONDITION : fog patches and stratus cloud toping towards 2200 m will be mostly dispelling this morning ‑ high cloud coming in from northwest will then make hazy sunshine in the afternoon ‑ that veil is expected to thickening noticeably in the evening. Period of sunshine close to 60%.
PRECIPITATION : none.
WIND - ground level : calm or SW light ‑> foehny NE in the evening.
WIND - mid mountain : NNE light ‑> calm ‑> SW moderate.
WIND - high mountain : N moderate ‑> W light to moderate ‑> WSW modéré to strong.
TEMPERATURE : low ‑4°C - high +3°C.
ISOTHERM 0°C : 700 ‑> 1600 ‑> 1400 m.
ISOTHERM -10°C : 3100 ‑> 3200 ‑> 3000 m.
ROAD CONDITION ••••• : roadways remain locally snow covered and slippery - no precipitation (Thursday, 05:30).
SKY CONDITION : skies becoming mostly cloudy, thickening high cloud ‑ simultaneously broken cloud income in the median altitude range with foehn generated clear outbreaks ‑ iso 0°C rising occasionally towards 1800 m.
PRECIPITATION : probably none on french slopes.
WIND - aloft : WSW modéré to strong ‑> SW severe gale ‑ strong foehn in the valley.
TEMPERATURE : low ‑3°C - temperature inversion toward 1500 m.
FRIDAY DECEMBER 4
SKY CONDITION : becoming quickly overcast early in the morning. Period of sunshine close to 5%.
PRECIPITATION : light to moderate snowfall fairly soon in the morning ‑ occasionally lighter towards the middle of the day ‑ rain‑snow limit towards 1000 m, dropping towards 700 m ‑ expected snowfall towards 1500 m : 20‑30 cm.
WIND - aloft : SW severe gale ‑> S moderate to strong ‑ strong foehn early in the morning, yet dropping soon.
TEMPERATURE : low ‑3 °C - high +2°C.
SATURDAY DECEMBER 5
SKY CONDITION : overcast, then mostly cloudy ‑ ceiling below 1500 m at times ‑ fleeting sunny spells likely. Period of sunshine close to 10%.
PRECIPITATION : some snow flurries still possible early in the morning ‑ rain‑snow limit towards 800 m ‑ else no precipitation.
WIND - aloft : SSW moderate to strong ‑> moderate.
TEMPERATURE : slightly dropping lows ‑ slightly rising highs.
EXTENDED OUTLOOK UNTIL TUESDAY DECEMBER 8 2020
Sunday : still unseasonably cold ‑ often cloudy ‑ fleeting sunny spells in the morning ‑ probably dry ‑ fairly strong SW high up. Monday : uncertain ‑ cloudy easterly backings ‑ bitter cold in the morning ‑ milder thanks to sunny spells in the afternoon. Tuesday : very uncertain ‑ gloomy and bitter cold ‑ some snow flurries later.
Forecast reliability : fairly good until Friday ‑ poor thereafter.