CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Masaoka Shiki
Summer rain
Drums at
The carp's head
ISSUED AT 19:40 ON WEDNESDAY JULY 18, 2018
VALID FROM : WEDNESDAY JULY 18 -- UNTIL : TUESDAY JULY 24 2018

GENERAL SYNOPSIS
Weak high ridge temporarily setting up, far northwest of Azores to North Sea. African originated altitude high pressure spur extending to Bavaria, shaping like a stable warmth dome over the Alps, temporarily as well. • Light westerly altitude stream and mildness in the median altitude range will make a pleasing night, even with some high cloud shading stars brightness at times. Fair and hot weather will continue on Thursday, yet with somewhat larger cumulus cloud over the slopes in the afternoon. • Withdrawal of the protective structure will make instability resume on Friday, while a tiny thermal low will deepen over Spain, then move northeast, driving a small thundery cold front which could trigger fairly heavy thunderstorms over the High Massifs during the night to Saturday, • Sultry atmosphere with thunderstorm still likely on Saturday, then becoming changeable and cooler with some light showers on Sunday. Probably improving as of Monday.
WEDNESDAY EVENING JULY 18 - AND OVERNIGHT
Fair weather - fairly mild in the median altitude range
SKY CONDITION : clear to partly cloudy - high cloud running over from the south or the southwest at times.
PRECIPITATION : none.
WIND - ground level : SW light -> calm.
WIND - mid mountain : SW light.
WIND - high mountain : WSW light to moderate -> SW -> WNW light.
TEMPERATURE : low +10°C.
ISOTHERM 0°C : 4100 -> 3900 -> 4000 m.
ISOTHERM -10°C : 5600 -> 5500 m.
Same weather in the bordering Valais and the Upper Aosta valley.
TOMORROW - THURSDAY JULY 19
Fair weather - becoming quickly hot - cumulus cloud growing over the massifs
SKY CONDITION : clear or partly cloudy in the morning - locally cloudy in the afternoon due to large cumulus cloud growth over the massifs. Period of sunshine close to 85%.
PRECIPITATION : none.
WIND - ground level : calm -> SW light to moderate -> light.
WIND - mid mountain : SW light -> light to moderate -> W light.
WIND - high mountain : WNW light -> W light to moderate.
TEMPERATURE : low +9°C - high +29°C.
ISOTHERM 0°C : 4000 -> 4100 m.
ISOTHERM -10°C : 5500 -> 5700 m.
Same weather in the bordering Valais and the Upper Aosta valley.
THURSDAY TO FRIDAY NIGHT - JULY 19 TO 20
Fair weather - mild in the median altitude range
SKY CONDITION  : clear.
PRECIPITATION : none.
WIND - aloft : W light to moderate -> WSW moderate.
TEMPERATURE : low +12°C.
Incertain.
FRIDAY JULY 20
Fairly sunny in the morning - becoming sultry - thunderstorm likely later
SKY CONDITION : clear, then partly cloudy in the morning - high cloud from the southwest - becoming cloudy or locally mostly cloudy in the afternoon. Period of sunshine close to 60%.
PRECIPITATION : thundery showers or thunderstorm towards the latter part of the afternoon, locally fairly heavy - rain-snow limit towards 3500 m, dropping.
WIND - aloft : WSW moderate - SW moderate to strong at times.
TEMPERATURE : low +10 °C - high +29°C.
Uncertain.
SATURDAY JULY 21
Often mainly cloudy ‑ frequent thundery showers ‑ getting cooler
SKY CONDITION : mostly cloudy to overcast - fleeting sunny spells likely towards the middle of the day. Period of sunshine close to J20%.
PRECIPITATION : frequent thundery showers, locally fairly heavy - rain-snow limit towards 3100 m, dropping towards 2700 m.
WIND - aloft : W moderate -> NW light to moderate.
TEMPERATURE : low +11°C - high +21°C.
Uncertain.
EXTENDED OUTLOOK UNTIL TUE. JULY 24

Sunday : uncertain ‑ starting up to improving ‑ cloudy and unseasonably cool, persisting afternoon shower risk. Monday : summer condition ‑ fairly sunny in the morning ‑ cumulus cloud over the massifs in the afternoon. Tuesday : summer condition ‑ fairly sunny in the morning ‑ large cumulus cloud over the massifs in the afternoon ‑ evening shower risk.

Forecast reliability : fairly good until Thursday ‑ poor thereafter.

ReportsAs a reminder, today in Chamonix, the sun rises at 06:00:09 and goes down at 21:17:26.
45.55 N 6.51 E - Altitude 1040 m
July 18 07:00
Temperature +8°C
Relative humidity 88%
Wind 0 km/h
Sea level pressure 1019 hpa - steady
Pressure at 1042 m 902 mb
Precipitation last 6h 0.0 mm
Skies clear
Visibility 65000 m
Altitude 3845 m
July 18 07:00
Temperature -1°C
Wind W 10 km/h
Altitude 2250 m
July 18 06:00
Snow depth 0 cm
Wind 5 km/h
Gusts 10 km/h
Temperature +8°C