CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Yosa Buson
Morning sun
Jumped out
Of a pilchard eye
ISSUED AT 19:40 ON MONDAY APRIL 27, 2015
VALID FROM : MONDAY APRIL 27 2015 -- UNTIL : SUNDAY MAY 03 2015

GENERAL SYNOPSIS
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
Becoming rainy - getting colder - snow likely towards 1300 m
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.morelive precipitation radar over the Alps
TOMORROW - TUESDAY APRIL 28
Improving - sunny spells spreading out - almost cold in the morning
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.
Uncertain.
TUESDAY TO WEDNESDAY NIGHT - APRIL 28 TO 29
Clear and cold - becoming slightly hazy later
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.
Uncertain.
WEDNESDAY APRIL 29
Cold and hazy morning sun, then getting comfortably milder ‑ increasing cloud later
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.
Uncertain.
THURSDAY APRIL 30
Disturbance coming in ‑ shower becoming frequent ‑ strong wind high up later
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.
Very uncertain.
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.

ReportsAs a reminder, today in Chamonix, the sun rises at 06:25:27 and goes down at 20:34:49.
45.55 N 6.51 E - Altitude 1040 m
27 April 07:00
Temperature +9°C
Relative humidity 80%
Wind 0 km/h
Sea level pressure 1003 hpa - falling slowly
Pressure at 1042 m 884 mb
Precipitation last 6h 0.0 mm
Skies cloudy
Visibility 25000 m
Altitude 3845 m
27 April 07:00
Temperature -8°C
Wind S 50 km/h
Altitude 2250 m
27 April 06:00
Snow depth 75 cm
Wind 20 km/h
Gusts -- km/h
Temperature +3°C