CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST


Matsuo Bashō
Even the longest day
Is not enough
For the skylark singing
ISSUED AT 08:30 THURSDAY JULY 16
VALID FROM : THURSDAY JULY 16 ‑‑ UNTIL : TUESDAY JULY 21 2020

GENERAL SYNOPSIS
Azores High has been refocusing (1030) halfway between the Archipelago and Ireland. Low trough Northern Norway ‑> Northern Balkans, which allows for an altitude cut‑off over Northeast Germany. Northwest to north stream in‑between, i.e. over a large western part of the Alpine Range, moderate and dry high up, yet light and humid in the median altitude range and the lower layers, and featuring moderate Bise gradient (‑4) between Savoie and Italian Piedmont • Humidity being stuck against northern slope gives thick millefeuille cloud layer (1500‑3600 m) which will rise and break under direct sunshine, yet without totally dispelling. • More pronounced evolution by Friday : fair sunny outbreaks towards the middle of the day while large cumulus cloud will rule again in the afternoon. • Resuming hot anticyclonic condition, Saturday to Monday.
TODAY - THURSDAY JULY 16
Mainly cloudy with some drizzle at first ‑ scattered sunny spells in the afternoon
SKY CONDITION : several superposed layers between 1500 and 3600 m early in the morning, yet clear high up ‑ that cloud millefeuille will rise and partly dispelling under direct sunshine, then sunny outbreak expected towards the middle of the day ‑ large cumulus cloud growing later. Period of sunshine close to 40%.
PRECIPITATION : local drizzle along the valley’s slopes in the morning.
WIND - ground level : calm ‑> SW light ‑> calm.
WIND - mid mountain : oscillating between NW & NNW ‑ light.
WIND - high mountain : NNW moderate.
TEMPERATURE : low +11°C - high +20°C.
ISOTHERM 0°C : 3800 ‑> 3700 ‑> 3900 m.
ISOTHERM -10°C : 5600 ‑> 5700 m.
OVERNIGHT
Low cloud patches resuming in the valley ‑ clear high up
SKY CONDITION : cloud patches will rebuild between 2000 and 3000 m ‑ good radiation above, yet snow surface refreezing should be restricted by iso 0°C rising towards 3900 m.
PRECIPITATION : none.
WIND - aloft : NNW moderate ‑> N light to moderate.
TEMPERATURE : low +12°C.
FRIDAY JULY 17
Improving slowly while getting warmer ‑ little Bise wind in the median altitude range
SKY CONDITION : often cloudy ‑ fair sunny sunny likely towards the middle of the day ‑ noticeable convection in the afternoon. Period of sunshine close to 60%.
PRECIPITATION : none.
WIND - aloft : N ‑> NNE light to moderate.
TEMPERATURE : low +11 °C - high +22°C.
SATURDAY JULY 18
Fair summer weather, resuming hot ‑ cumulus cloud over the massifs later
SKY CONDITION : clear to partly cloudy ‑ fair weather cumulus over the massifs in the afternoon. Period of sunshine close to 85%.
PRECIPITATION : none.
WIND - aloft : N ‑> NNW moderate ‑ occasionally light to moderate.
TEMPERATURE : slightly dropping lows ‑ noticeably rising highs.
EXTENDED OUTLOOK UNTIL TUESDAY JULY 21 2020

Sunday : fair weather, hot in the afternoon (26‑27). Monday : fair weather, hot in the afternoon (28‑29), getting sultry ‑ fairly strong west at times high up. Tuesday : uncertain ‑ while withdrawing south, altitude high ridge might allow for more pronounced diurnal evolution than previously ‑ sunny morning ‑ thundery shower risk later in the afternoon ‑ decreasing westerlies high up.

Forecast reliability : fairly good until Saturday.

ReportsAs a reminder, today in Chamonix, the sun rises at 05:58:41 and goes down at 21:18:42.
45.55 N 6.51 E - Altitude 1020 m
July 16 - 08:00
Temperature +13°C
Relative humidity 86%
Wind 0 km/h
Sea level pressure 1020 hpa - rising slowly
Pressure at 1042 m 898 mb
Precipitation last 6h 0.0 mm
Skies mostly cloudy - clear above 3700 m
Visibility 6000 m
Altitude 3845 m
July 16 - 07:00
Temperature -3°C
Wind NNW 20/35 km/h
Altitude 2250 m
July 16 - 07:00
Snow depth 0 cm
Wind 5 km/h
Gusts 10 km/h
Temperature +4°C