CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Matsuo Bashō
On a mountain path
Something might charm you
A wild violet
ISSUED AT 18:50 ON TUESDAY AUGUST 26, 2014
VALID FROM : TUESDAY AUGUST 26 2014 -- UNTIL : MONDAY SEPTEMBER 01 2014

GENERAL SYNOPSIS
Strong westerly stream high up over the Northern Alps. Low 1004 hpa, English Channel, filling quickly. Linked disturbance drifting east, although possibly triggering isolated showers overnight, locally fairly heavy. Improving gradually sunny on Wednesday and Thursday while a fleeting high ridge is interfering from the north. Then, new low system expected over the British Isles, probably causing changeable condition over the area edging south of the unsettled Atlantic stream, from Friday until Sunday. Altitude cold drop possibly crossing over east of the area on Monday.
TUESDAY EVENING AUGUST 26 - AND OVERNIGHT
Starting up to improving - persistent strong wind high up
SKY CONDITION : mostly cloudy, then cloudy - clear spells spreading out, high up at first - persistent cloud patches along the slopes.
PRECIPITATION : isolated showers possible until the latter part of the night, locally fairly heavy - rain-snow limit towards 3000 m.
WIND - ground level : variable light.
WIND - mid mountain : SW -> W light.
WIND - high mountain : W -> WNW strong.
TEMPERATURE : low +10°C.
ISOTHERM 0°C : 3400 -> 3300 m.
ISOTHERM -10°C : 5400 m.
Sharper improvement over the Upper Aosta Valley.
TOMORROW - WEDNESDAY AUGUST 27
Partly sunny - getting milder, although still windy high up
SKY CONDITION : cloudy with sunny spells - persistent cloud patches along the slopes - becoming partly cloudy as time goes by in the afternoon. period of sunshine close to 65%.
PRECIPITATION : none.
WIND - ground level : variable light to moderate.
WIND - mid mountain : W light -> NW light to moderate.
WIND - high mountain : WNW strong -> moderate to strong.
TEMPERATURE : low +10°C - high +21°C.
ISOTHERM 0°C : 3300 -> 3900 m.
ISOTHERM -10°C : 5400 -> 5600 m.
Same kind of weather over the Upper Aosta Valley.
WEDNESDAY TO THURSDAY NIGHT - AUGUST 27 TO 28
Partly cloudy - somewhat mild, more noticeably high up
SKY CONDITION  : partly cloudy.
PRECIPITATION : none.
WIND - aloft : WNW moderate to strong -> moderate.
TEMPERATURE : low +8°C.
Uncertain.
THURSDAY AUGUST 28
Fine sunny weather - cool in the morning - warm in the afternoon
SKY CONDITION : clear or partly cloudy - afternoon cumulus cloud over the massifs. Period of sunshine close to 90%.
PRECIPITATION : none.
WIND - aloft : WNW moderate -> W light to moderate.
TEMPERATURE : low +8 °C - high +24°C.
Uncertain.
FRIDAY AUGUST 29
Hazy sunshine, becoming warm, then cloudy with thundery shower risk
SKY CONDITION : partly cloudy early in the morning - becoming cloudy - thickening high cloud - cumulus cloud growing fat in the afternoon - probably mostly cloudy towards the evening. Period of sunshine close to 60%.
PRECIPITATION : afternoon thundery shower risk - rain-snow limit towards 3400 m, dropping.
WIND - aloft : WSW -> W moderate.
TEMPERATURE : low +9°C - high +24°C.
Uncertain.
EXTENDED OUTLOOK UNTIL MONDAY SEPTEMBER 01 2014

Saturday : changeable ‑ sunny spells in the morning ‑ afternoon shower risk, mainly south of the massifs ‑ mild. Sunday : cloudy with sunny spells ‑ shower risk ‑ mild. Monday : diurnal instability - sunny morning - cloudy with shower risk in the afternoon. Outlook is still uncertain for the three days.

Forecast reliability : fairly good until Wednesday ‑ poor thereafter.

ReportsAs a reminder, today in Chamonix, the sun rises at 06:47:36 and goes down at 20:20:17.
45.55 N 6.51 E - Altitude 1040 m
27 August 08:00
Temperature +11°C
Relative humidity 100%
Wind 0 km/h
Sea level pressure 1016 hpa - rising
Pressure at 1042 m 899 mb
Precipitation last 6h 0.5 mm
Skies cloudy - low cloud - clear above 1500 m
Visibility 1000 m
Altitude 3845 m
27 August 08:00
Temperature -4°C
Wind SW 60 km/h
Altitude 2250 m
27 August 08:00
Snow depth 0 cm
Wind 40 km/h
Gusts 50 km/h
Temperature +6°C