CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
Matsuo Bashō
Ah spring, spring
How great is spring !
and so on…
ISSUED AT 08:15 THURSDAY APRIL 15
VALID FROM : THURSDAY APRIL 15 -- UNTIL : TUESDAY APRIL 20 2021
GENERAL SYNOPSIS
Surface high pressure toping towards 1036 over North Sea, is drifting slowly towards Norway without weakening until Saturday; relative surface low 1010-1015 almost stationary over the Mediterranean. • High up : altitude cut-off, Northwestern Alps, expected to crossing over our Region southward bound in the afternoon and overnight. • As a result : fair sunny weather this morning; then increasing instability over the hours, favouring cumulus cloud growth in still unseasonably cold atmosphere. • Variation on the same pattern likely each afternoon until Sunday, depending on altitude stream backing west, or even southwest.
TODAY - THURSDAY APRIL 15
SKY CONDITION : clear early in the morning, becoming partly cloudy - locally cloudy or mostly cloudy in the afternoon with well grown cumulus cloud above median altitude range slopes. Period of sunshine close to 60%.
PRECIPITATION : possible snow flurries over the slopes in the afternoon under some cumulus cloud.
WIND - ground level : calm -> variable light -> occasionally SW.
WIND - mid mountain : calm -> variable light -> calm.
WIND - high mountain : NW moderate to strong -> W light to moderate.
TEMPERATURE : low -5°C - high +10°C.
ISOTHERM 0°C : 900 -> 1500 -> 1300 m.
ISOTHERM -10°C : 2500 -> 2700 -> 2600 m.
OVERNIGHT
SKY CONDITION : evening cumulus cloud dispelling, yet cloud patches persistently running over from south - iso 0°C dropping towards 900 m.
PRECIPITATION : none.
WIND - aloft : W -> SW light to moderate.
TEMPERATURE : low -2°C.
FRIDAY APRIL 16
SKY CONDITION : partly cloudy to cloudy - bulky cumulus cloud growing above median altitude range slopes in the afternoon. Period of sunshine close to 60%.
PRECIPITATION : none.
WIND - aloft : SW light to moderate -> SSW light.
TEMPERATURE : low -3 °C - high +10°C.
SATURDAY APRIL 17
SKY CONDITION : clear, then partly cloudy - cumulus cloud growing above median altitude range slopes in the afternoon. Period of sunshine close to 80%.
PRECIPITATION : none.
WIND - aloft : NE light - occasionally light to moderate.
TEMPERATURE : dropping lows - rising highs.
EXTENDED OUTLOOK UNTIL TUESDAY APRIL 20 2021
Sunday : fairly sunny morning - locally mostly cloudy in the afternoon with cumulus cloud spreading while getting bulky - fairly strong northeast high up in the morning. Monday : partly sunny - locally cloudy in the afternoon with cumulus cloud spreading - northerly stream high up, fairly strong at times. Tuesday : uncertain - fair weather likely - cumulus cloud growing over the massifs in the afternoon - getting slightly milder.
Forecast reliability : fairly good until Saturday - uncertain thereafter.