CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Natsume Sôseki
Evening let it glow
Red my mountain
In a radiant window
ISSUED AT 09:30 TUESDAY OCTOBER 26 2021
VALID FROM : TUESDAY 26 -- SUNDAY OCTOBER 31 2021

GENERAL SYNOPSIS
After shallow thalweg crossing over early this morning, the high ridge resumes ruling, Azores (1027) to Pennine Alps (Sion, 1025) and further to the Sea of Azov, northeast of Crimea, (1034). Concomitant Atlantic subtropical air income high up, involving Ukraine. • Development toward more wintry weather pattern seemingly initiating this Tuesday, with that tiny and slow collapse of Alpine surface pressure field, then with the gradual break of altitude mild air inflow, still faltering at first though becoming actual between Sunday and Monday, as a more structured westerly disturbance will be crossing over. • The latter seems indeed likely to triggering about 25-30 mm precipitation until Monday evening.
TODAY - TUESDAY OCTOBER 26
Mainly cloudy by dawn, then improving swiftly - getting pleasantly milder towards noon
SKY CONDITION : mostly cloudy to cloudy early in the morning - then sunny outbreaks spreading over the hours. Period of sunshine close to 40%.
PRECIPITATION : none.
WIND - ground level : calm -> variable - NE very light.
WIND - mid mountain : NW -> NE very light - occasionally calm.
WIND - high mountain : NW -> NE moderate.
TEMPERATURE : low +3°C - high +14°C.
ISOTHERM 0°C : 2300 -> 2700 m.
ISOTHERM -10°C : 4000 -> 4400 m.
OVERNIGHT
Clear and windy high up - stratocumulus cloud layer likely in the valley
SKY CONDITION : clear in the first part of the night - stratocumulus cloud layer likely to infiltrating thereafter in the valley, between 800 and 1100 m - iso 0°C rising up towards 3000 m by dawn - radiation condition becoming good in the median to high altitude range, thus favouring snow surface re-freezing.
PRECIPITATION : none.
WIND - aloft : NE moderate -> ENE moderate to strong.
TEMPERATURE : low +3°C.
WEDNESDAY OCTOBER 27
Fair sunny after early morning low cloud dispelling - almost warm in the afternoon
SKY CONDITION : stratocumulusus cloud in the valley by dawn, dispelling fairly soon - else clear or partly cloudy. Period of sunshine close to 85%.
PRECIPITATION : none.
WIND - aloft : ENE -> E moderate to strong - occasionally moderate.
TEMPERATURE : low +2 °C - high +14°C.
THURSDAY OCTOBER 28
Fair weather - less risk of early low cloud - cold in the morning - very mild afternoon
SKY CONDITION : clear or partly cloudy - risk of low cloud layer likely to rising above 1100 m seems quite low, but cannot be overruled. Period of sunshine close to 90%.
PRECIPITATION : none.
WIND - aloft : SE -> SSE moderate.
TEMPERATURE : rising highs.
EXTENDED OUTLOOK UNTIL SUNDAY OCTOBER 31 2021

Friday : fair weather, soon fairly mild - foehn puffs in the afternoon, while SW will become fairly strong high up. Saturday : uncertain - foehn generated sunny spells until mi-afternoon - rainy deterioration later - morning mild and windy (NE) in the valley, and SW high up, both fairly strong. Sunday : very uncertain - foehn might keep blowing rather strong, thus delaying until evening the approach of the rainy cold front.

Forecast reliability : fairly good until Thursday.

ReportsAs a reminder, today in Chamonix, the sun rises at 08:06:43 and goes down at 18:25:56.
Chamonix - ville
45.55 N 6.51 E - Altitude 1020 m
October 26 08:00
Temperature +4.5°C
Relative humidity 91%
Wind 0 km/h
Sea level pressure 1023 hpa - rising slowly
Pressure at 1042 m 905 mb
Precipitation last 6h 0 mm
Skies mainly cloudy - clear above 4000 m
Visibility 8000 / 90000 m
Altitude 3845 m
October 26 07:00
Temperature -8.5°C
Wind W 15-40 km/h
Altitude 2250 m
October 26 07:00
Snow depth 0 cm
Wind 0 km/h
Gusts 9 km/h
Temperature -0.7°C