CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 07:50 SATURDAY JULY 22
VALID FROM : SATURDAY JULY 22 ‑‑ UNTIL : THURSDAY JULY 27 2017
Young green leaves
Flash in the sun
Surface pressure field featuring median value with loose gradient, Mediterranean to Alps. • Low 999 hpa, Ireland, filling slowly while drifting east, then southeast. • Resulting southwesterly stream is warm, humid and unstable. • Sunny this Saturday morning, then thundery activity will resume in the afternoon, possibly causing heavy thunderstorm passing, locally, towards the evening. • Further outlook remains uncertain in detail, but global evolution should lead to a fairly active cold front passing on Monday, likely to causing gloomy condition, moreover unseasonably cool.
TODAY - SATURDAY JULY 22
SKY CONDITION : remaining cloud patches sticking to summits by dawn ‑ becoming partly cloudy ‑ increasing cloud over the massifs in the afternoon leading to overcast skies later. Period of sunshine close to 55%.
PRECIPITATION : thundery shower or thunderstomr towards the end of the afternoon, locally fairly heavy ‑ rain‑snow limit towards 3600 m, dropping.
WIND - ground level : SW light ‑ light to moderate at times towards the middle of the day.
WIND - mid mountain : SW light to moderate ‑ moderate at times.
WIND - high mountain : SW moderate to strong.
TEMPERATURE : low +11°C - high +24°C.
ISOTHERM 0°C : 3900 m.
ISOTHERM -10°C : 5600 ‑> 5500 m.
SKY CONDITION : mostly cloudy to overcast ‑ becoming cloudy with clear spells later.
PRECIPITATION : thunderstorm breaking out randomly will continue to quickly crossing over the Region from the southwest until the middle of the night at least ‑ rain‑snow limit dropping towards 3300 m.
WIND - aloft : SW moderate to strong ‑> WSW strong.
TEMPERATURE : low +11°C.
SUNDAY JULY 23
SKY CONDITION : cloudy with sunny spells ‑ spreading for a short while towards noon ‑ at times mostly cloudy in the afternoon. Period of sunshine close to 50%.
PRECIPITATION : probably none.
WIND - aloft : WSW strong ‑> W moderate to strong.
TEMPERATURE : low +11 °C - high +23°C.
MONDAY JULY 24
SKY CONDITION : mostly cloudy to overcast ‑ few fleeting sunny spells likely. Period of sunshine close to 20%.
PRECIPITATION : intermittent, light to moderate ‑ rain‑snow limit towards 3000 m, dropping suddenly towards 2400 m in the middle of the day.
WIND - aloft : W moderate ‑> WNW moderate to strong.
TEMPERATURE : +10+17.
EXTENDED OUTLOOK UNTIL THURSDAY JULY 27 2017
Tuesday : often mainly cloudy with some showers ‑ fleeting sunny spells ‑ cooler than average ‑ fairly strong NW high up at times. Wednesday : partly sunny ‑ cumulus cloud growing over the massifs in the afternoon ‑ getting slightly milder. Thursday : changeable ‑ fair sunny spells, then mainly cloudy with shower risk ‑ strong W high up at times. Very uncertain.
Forecast reliability : poor.