CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Matsuo Bashō
Heat shimmer
Rising from the shoulder
My paper robe
ISSUED AT 08:05 WEDNESDAY AUGUST 5
VALID FROM : WEDNESDAY AUGUST 5 ‑‑ UNTIL : MONDAY AUGUST 10 2020

GENERAL SYNOPSIS
The low pressure complex which crossed over the Alps on Monday and Tuesday morning is currently drifting towards Northwest Balkans. From now on, it’s mere effect is a gradually decreasing Bise wind high up. High ridge which already developed, Bay of Biscaye to Czech Republic (1016‑1020), will extend further northeast and then refocus towards 1025 over Southeast Balitic Sea. While being reinforced by subtropical originated altitude spur, that anticyclonic pattern will keep a kind of hot and stable air cupola over the area where temperature highs might climb above 30°C towards 1000 m each afternoon, Thursday to Saturday. • Moderate diurnal instability is expected to resuming by Sunday.
TODAY - WEDNESDAY AUGUST 5
Fair weather ‑ cool in the morning ‑ resuming quite hot in the afternoon
SKY CONDITION : clear ‑ momentarily partly cloudy due to some cumuls cloud above the massifs towards the middle of the afternoon. Period of sunshine close to 90%.
PRECIPITATION : none.
WIND - ground level : NE light ‑> calm ‑> thermal SW light to moderate ‑> calm.
WIND - mid mountain : NE light to moderate ‑> N light.
WIND - high mountain : NNE moderate ‑> N light to moderate.
TEMPERATURE : low +5°C - high +25°C - temperature inversion toward 1200 m early in the morning.
ISOTHERM 0°C : 4300 ‑> 4700 m.
ISOTHERM -10°C : 5900 ‑> 6100 m.
OVERNIGHT
Fair summer night ‑ clear skies ‑ cool in the Valley by dawn
SKY CONDITION : clear ‑ excellent radiation condition, though with iso 0°C towards 4600 m, probably setting a limit to snow‑surface re‑freezing towards 3900‑4000 m.
PRECIPITATION : none.
WIND - aloft : N light to moderate ‑> light.
TEMPERATURE : low +9°C - temperature inversion toward 1400 m.
THURSDAY AUGUST 6
Amazingly fair ‑ still pleasant cool in the morning ‑ sweltering heat in the afternoon
SKY CONDITION : clear ‑ tiny cumulus cloud here and there in the afternoon. Period of sunshine close to 100%.
PRECIPITATION : none.
WIND - aloft : N ‑> NNE light ‑ occasionally light to moderate.
TEMPERATURE : low +7 °C - high +30°C.
FRIDAY AUGUST 7
Amazingly fair weather ‑ cloudless ‑ scorching heat
SKY CONDITION : clear. Period of sunshine close to 100%.
PRECIPITATION : none.
WIND - aloft : N light ‑ occasionally light to moderate.
TEMPERATURE : rising slightly.
EXTENDED OUTLOOK UNTIL MONDAY AUGUST 10 2020

Saturday : fair weather, scorching heat (32°C). Sunday : typical summer weather with diurnal evolution ‑ scorching heat (31°C), somewhat sultry ‑ large cumulus cloud locally, with evening shower risk. Monday : typical summer weather ‑ highs dropping slightly (29°C), yet sultry with more convection than previously ‑ thundery shower risk later. • Light altitude stream with calms during the three days, mostly between northwest and southwest.

Forecast reliability : fairly good until Friday.

ReportsAs a reminder, today in Chamonix, the sun rises at 06:21:06 and goes down at 20:55:46.
45.55 N 6.51 E - Altitude 1020 m
August 5 - 08:00
Temperature +6°C
Relative humidity 90%
Wind 0 km/h
Sea level pressure 1017 hpa - rising slowly
Pressure at 1042 m 896 mb
Precipitation last 6h 0.0 mm
Skies clear
Visibility 80000 m
Altitude 3845 m
August 5 - 07:00
Temperature 0°C
Wind NE 15/30 km/h
Altitude 2250 m
August 5 - 07:00
Snow depth 0 cm
Wind 0 km/h
Gusts 15 km/h
Temperature +9°C