CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Natsume Sôseki
Ask the breeze
Which leaf
First to fall will be
ISSUED AT 07:55 THURSDAY SEPTEMBER 21
VALID FROM : THURSDAY SEPTEMBER 21 ‑‑ UNTIL : TUESDAY SEPTEMBER 26 2017

GENERAL SYNOPSIS
High 1023 hpa focusing over Bavaria this morning, weakening slightly. Altitude high ridge, Maghreb to Southern British Isles, driving a dry and fairly mild northerly backing flow over the Alps. • Amazingly fair sunny weather this Thursday, autumnal cold in the morning, still summer‑like warmth in the afternoon. • This favorable pattern should be partly knocked over on Friday afternoon and Saturday, upon approach of a cold front linked to a deep low far south of Iceland. • That front will be disintegrating over Western France, causing cloud passings over the Western Alps, diurnal instability will make cumulus cloud grow larger over the high massifs, nothing more. • Temperature in the seasonal average all over the period.
TODAY - THURSDAY SEPTEMBER 21
Fair weather ‑ cold in the morning ‑ almost warm in the afternoon
SKY CONDITION : clear or partly cloudy ‑ thin high cloud at times ‑ some cumulus cloud over the slopes. Period of sunshine close to 95%.
PRECIPITATION : none.
WIND - ground level : NE light ‑> calm ‑ moderate thermal SW at times, early afternoon.
WIND - mid mountain : NE light to moderate ‑> variable light.
WIND - high mountain : N moderate ‑> light.
TEMPERATURE : low ‑1°C - high +19°C - temperature inversion toward 1200 m early in the morning.
ISOTHERM 0°C : 3600 ‑> 3700 ‑> 3600 m.
ISOTHERM -10°C : 5300 ‑> 5200 m.
OVERNIGHT
Partly cloudy ‑ cold in the valley ‑ milder in the mediant altitude range
SKY CONDITION : clear or partly cloudy ‑ thin high cloud crossing over from the west.
PRECIPITATION : none.
WIND - aloft : N ‑> W light.
TEMPERATURE : low +2°C - temperature inversion toward 1400 m.
FRIDAY SEPTEMBER 22
Fairly sunny ‑ chilly in the morning ‑ afternoon cloudy deterioration
SKY CONDITION : clear or partly cloudy ‑ high cloud coming in, fairly thick at times during the afternoon ‑ some cumulus cloud over the massifs. Period of sunshine close to 75%.
PRECIPITATION : none.
WIND - aloft : W light ‑ light to moderate at times.
TEMPERATURE : low +1 °C - high +20°C - temperature inversion toward 1200 m early in the morning.
SATURDAY SEPTEMBER 23
Uncertain ‑ sunny spells and cloud passings ‑ probably dry
SKY CONDITION : cloudy with sunny spells. Period of sunshine close to 60%.
PRECIPITATION : probably none.
WIND - aloft : NW light ‑> WNW light to moderate.
TEMPERATURE : rising lows.
EXTENDED OUTLOOK UNTIL TUESDAY SEPTEMBER 26 2017

Sunday : partly sunny ‑ dry ‑ warm in the afternoon. Monday : fairly sunny ‑ dry ‑ warm in the afternoon ‑ cloudy deterioration towards the evening. Tuesday : cloudy ‑ probably dry ‑ mild in the afternoon. Uncertain outlook for the three days.

Forecast reliability : fairly good until Friday ‑ poor thereafter.

ReportsAs a reminder, today in Chamonix, the sun rises at 07:20:15 and goes down at 19:29:47.
45.55 N 6.51 E - Altitude 1040 m
September 21 07:00
Temperature -1°C
Relative humidity 92%
Wind 0 km/h
Sea level pressure 1019 hpa - rising slowly
Pressure at 1042 m 903 mb
Precipitation last 6h 0.0 mm
Skies clear
Visibility 120000 m
Altitude 3845 m
September 21 07:00
Temperature -6°C
Wind NNE 35 km/h
Altitude 2250 m
September 21 06:00
Snow depth 3 cm
Wind 10 km/h
Gusts 15 km/h
Temperature +6°C