CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 19:40 ON MONDAY APRIL 27, 2015
VALID FROM : MONDAY APRIL 27 2015 -- UNTIL : SUNDAY MAY 03 2015
Of a pilchard eye
Extended low system, North of Faroes to Genoa Gulf, currently driving a southeasterly altitude stream over the Western Alps, mild, humid and unsettled. Valley was sheltered from precipitation by the resulting fœhn wind effect until this evening. Southern part of that low system is drifting east, followed by a maritime polar air inflow. Cold front will therefore be crossing over during the night, triggering snowfall well below 1500 m and causing the altitude stream to veer northwest. Improving on Tuesday and Wednesday, before a new unsettled period from Thursday afternoon until Sunday at least.
MONDAY EVENING APRIL 27 - AND OVERNIGHT
SKY CONDITION : overcast.
PRECIPITATION : isolated showers at first - becoming frequent and fairly heavy towards the middle of the night - then light and scattered later - rain-snow limit dropping towards 1300 m - expected snowfall towards 2500 m : 25-35 cm.
WIND - ground level : variable light - at times moderate towards the middle of the night.
WIND - mid mountain : SE light to moderate -> NNW moderate.
WIND - high mountain : variable faible -> WNW faible à modéré.
TEMPERATURE : low +3°C.
ISOTHERM 0°C : 2300 -> 1600 m.
ISOTHERM -10°C : 4100 -> 3600 m.
Amount of precipitation and snow level are uncertain.
ROAD CONDITION ••••• : @ 18:30, dry roadways; becoming wet during the night - snowfall risk later.
TOMORROW - TUESDAY APRIL 28
SKY CONDITION : probably still mostly cloudy early in the morning - low cloud - becoming cloudy with fair sunny spells. period of sunshine close to 40%.
PRECIPITATION : remaining light shower likely early in the morning - rain-snow limit towards 1300 m.
WIND - ground level : calm.
WIND - mid mountain : NNW moderate -> N light.
WIND - high mountain : WNW light to moderate -> moderate.
TEMPERATURE : low +3°C - high +12°C.
ISOTHERM 0°C : 1600 -> 2000 m.
ISOTHERM -10°C : 3600 -> 3300 -> 3800 m.
TUESDAY TO WEDNESDAY NIGHT - APRIL 28 TO 29
SKY CONDITION : clear or partly cloudy - high cloud coming in from the southwest towards the latter part of the night.
PRECIPITATION : none.
WIND - aloft : NW -> SW moderate.
TEMPERATURE : low 0°C.
WEDNESDAY APRIL 29
SKY CONDITION : parly cloudy until noon - high cloud crossing over - becoming cloudy due to cumulus cloud growth. Period of sunshine close to 60%.
PRECIPITATION : evening shower slight risk.
WIND - aloft : SW moderate.
TEMPERATURE : low 0 °C - high +15°C.
THURSDAY APRIL 30
SKY CONDITION : cloudy to mostly cloudy in the morning - becoming overcast in the afternoon. Period of sunshine close to 30%.
PRECIPITATION : showers becoming frequent and fairly heavy during the afternoon - rain-snow limit between 1800 et 2000 m.
WIND - aloft : WNW -> W moderate to strong - strong at times.
TEMPERATURE : low +3°C - high +14°C.
EXTENDED OUTLOOK UNTIL SUNDAY MAY 03 2015
Friday : changeable and cooler - sunny spells and showers. Saturday : cloudy with sunny spells and probably without precipitation ‑ getting slightly milder. Sunday : very unsettled - fairly heavy precipitation early in the morning and towards the evening - fleeting sunny spells in-between. Fairly strong wind high up during the three days, mainly west.
Forecast reliability : poor.