CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 07:50 SUNDAY DECEMBER 16
VALID FROM : SUNDAY DECEMBER 16 ‑‑ UNTIL : FRIDAY DECEMBER 21 2018
On my brush tip
A water drop
Powerful low pressure whirl, 968 hpa almost stationary southeast of Iceland, driving still rather strong west to northwest stream high up, Atlantic to Alps. Satellite low, 986 hpa Northwestern Scotland, moving north while filling. Warm sector of the linked disturbance, currently in the process of occlusion, is moving away over Switzerland, still triggering light and scattered showers; rain‑snow limit mostly towards 1800 m may be locally dropping below 1000 m, owing to stagnating cold air in the depths of valleys. Precipitation will be breaking off for a while towards noon, then will resume in the evening, light and scattered with snow limit down towards 700‑800 m towards the end of the night.
TODAY - SUNDAY DECEMBER 16
SKY CONDITION : overcast ‑ ceiling towards 2000‑2200 m ‑ low cloud and fog patches as well ‑ mostly cloudy at times, with fleeting sunny spell in the first part of the afternoon. Period of sunshine close to 10%.
PRECIPITATION : intermittent and light, breaking off towards the middle of the day ‑ shower resuming in the evening ‑ rain‑snow limit rising towards 1600 m later in the morning, then dropping again in the evening ‑ expected snowfall towards 1800 m : ± 5 cm.
WIND - ground level : SW light ‑> calm.
WIND - mid mountain : W moderate ‑> WSW light to moderate.
WIND - high mountain : W strong ‑> WSW moderate.
TEMPERATURE : low ‑1°C - high +5°C.
ISOTHERM 0°C : 1800 ‑> 2000 ‑> 1500 m.
ISOTHERM -10°C : 3600 ‑> 3300 m.
ROAD CONDITION ••••• : snow-covered roadways - black ice locally. (Sun. 05:30).
SKY CONDITION : mostly cloudy to overcast.
PRECIPITATION : light, probably continuous ‑ rain‑snow limit towards 1200 m, dropping towards 800 m by dawn ‑ expected snowfall towards 1800 m : 5‑10 cm.
WIND - aloft : WSW moderate ‑> NW light to moderate.
TEMPERATURE : low ‑1°C.
MONDAY DECEMBER 17
SKY CONDITION : mostly cloudy in the morning ‑ becoming cloudy with sunny spells over the afternoon hours. Period of sunshine close to 25%.
PRECIPITATION : light and scattered in the morning ‑ rain‑snow limit towards 800 m ‑ expected snowfall towards 1800 m : ± 5 cm ‑ dry afternoon.
WIND - aloft : NW light to moderate ‑> NNW moderate to strong.
TEMPERATURE : low ‑1 °C - high +1°C.
TUESDAY DECEMBER 18
SKY CONDITION : clear or partly cloudy ‑ thin high cloud from southwest making hazy sunshine in the afternoon. Period of sunshine close to 75%.
PRECIPITATION : none.
WIND - aloft : W moderate ‑ light to moderate at times.
TEMPERATURE : dropping low ‑ rising highs.
EXTENDED OUTLOOK UNTIL FRIDAY DECEMBER 21 2018
Wednesday : unsettled ‑ fœhn and intermittent light precipitation in turn ‑ rain‑snow limit towards 1200 m, dropping towards 600 m during the following night ‑ fairly strong southwest high up. Thursday and Friday : changeable, slightly unsettled, sunny spells and light snow shower ‑ mostly northwest high up, fairly strong at times.
Forecast reliability : fairly good until Monday.
Avalanche risk is high (4/5) above 1400 m :
France - Switzerland - Aosta Valley.