CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 08:50 MONDAY SEPTEMBER 23
VALID FROM : MONDAY SEPTEMBER 23 ‑‑ UNTIL : SATURDAY SEPTEMBER 28 2019
Ask the breeze
First to fall will be
Classic autumnal weather pattern this week after disturbance passing that left about 15‑20 mm water in the valley last night, and currently moves further east. Atlantic circulation finally resumed towards British Isles latitude. Two low pressure systems will come after each other, the first one being former hurricane Umberto, which will reach Ireland on Tuesday, then a larger extension system whose center is expected over Scotland by Friday. Linked disturbances will marginally affect the Alps; however, westerlies will be blowing strong high up. • For now, high pressure push from southwest, going along with colder yet drier air inflow from northwest high up, will allow for relative improvement until Tuesday morning.
TODAY - MONDAY SEPTEMBER 23
SKY CONDITION : overcast early in the morning, then mostly cloudy with fleeting sunny spells before the middle of the day ‑ improving further in the afternoon ‑ partly cloudy in the evening. Period of sunshine close to 45%.
PRECIPITATION : probably none.
WIND - ground level : calm or SW light.
WIND - mid mountain : W ‑> NNW light.
WIND - high mountain : WSW moderate ‑> NW moderate to strong.
TEMPERATURE : low +11°C - high +16°C.
ISOTHERM 0°C : 2700 ‑> 3200 m.
ISOTHERM -10°C : 4700 ‑> 5400 m.
SKY CONDITION : partly cloudy ‑ thin high cloud at times ‑ good radiation condition in areas sheltered from wind.
PRECIPITATION : none.
WIND - aloft : NW moderate to strong ‑> W strong.
TEMPERATURE : low +8°C.
TUESDAY SEPTEMBER 24
SKY CONDITION : hazy sunshine early in the morning ‑ becoming mostly cloudy with fleeting sunny spells. Period of sunshine close to 25%.
PRECIPITATION : shower passing towards the middle of the day ‑ rain‑snow limit towards 3300 m, dropping ‑ less than 5 mm water in the valley.
WIND - aloft : W strong ‑> strong to gale force.
TEMPERATURE : low +5 °C - high +15°C.
WEDNESDAY SEPTEMBER 25
SKY CONDITION : overcast mostly in the morning ‑ becoming mostly cloudy ‑ occasionally cloudy with sunny spells towards the middle of the day. Period of sunshine close to 35%.
PRECIPITATION : remaining shower likely early in the morning ‑ shower risk increasing slightly towards the end of the afternoon ‑ rain‑snow limit towards 2400 m.
WIND - aloft : W strong ‑> NW moderate to strong.
TEMPERATURE : slight rising lows ‑ slightly dropping highs.
EXTENDED OUTLOOK UNTIL SATURDAY SEPTEMBER 28 2019
Thursday : changeable ‑ sunny spells and cloud passings ‑ slight shower risk. Friday : fair sunny spells ‑ almost warm ‑ evening shower risk ‑ southwest, then west fairly strong high up. Saturday : cloudy ‑ sunny spells, more widespread in the morning ‑ fairly strong west high up.
Forecast reliability : fairly good until Wednesday.