CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 08:35 SATURDAY OCTOBER 01 2022
VALID : SATURDAY OCTOBER 01 -- THURSDAY OCTOBER 06 2022
How many days of this ?
Azores high ridge is about to resume, 1026, NE Ponta Delgada, up to Alpine Range (Sallanches, 1018 - Sion, 1018 - Innsbruck, 1015 hpa), countered by polar air thalweg which is currently reaching the Mediterranean S of Provence, yet expected to be repelled up to Black Sea by Sunday morning owing to NE spread of a subtropical altitude ridge. • Being driven by powerful NW, resulting disturbance will cross over our Region this Saturday, triggering light pre-frontal shower as of mid-morning, then featuring organized precipitation spell in the afternoon with barrier effect against W and N slopes of the high massifs until the latter part of the night. • Finally, 10-15 mm water likely in the valley, with rain-snow limit rising up 2300 ‑> 2800 m in the initial warm sector. • Improving thereafter, towards a 4-5 days period of fair weather next week, rather warm each afternoon.
TODAY - SATURDAY OCTOBER 01
SKY CONDITION : fleeting sunny outbreak, then thick cloud layer coming in, altostratus then stratus - overcast as of the middle of the day - ceiling towards 1800 m, dropping. Period of sunshine close to 10%.
PRECIPITATION : slight shower risk, early morning - rainy deterioration over the hours - rain-snow limit towards 2700-2800 m - possible water amount in the valley : 6-8 mm.
WIND - ground level : calm -> SW light - locally light to moderate.
WIND - mid mountain : W light -> WNW moderate to strong.
WIND - high mountain : NW strong -> severe gale.
TEMPERATURE : low +6°C - high +11°C.
ISOTHERM 0°C : 2900 -> 3300 m.
ISOTHERM -10°C : 3800 -> 4200 m.
SKY CONDITION : overcast in the first part of the night, ceiling towards 1800 m - becoming mostly cloudy towards the latter part, fleeting clear outbreaks already possible high up - iso 0°C towards 3300 m.
PRECIPITATION : light to moderate in the first part of the night, then becoming scarce and finally ending by dawn - rain-snow limit dropping towards 2600 m - possible water amount in the valley : 4-7 mm.
WIND - aloft : NW severe gale -> WNW strong.
TEMPERATURE : low +8°C.
SUNDAY OCTOBER 02
SKY CONDITION : still locally cloudy in the first part of the morning, then clearing fairly widespread. Period of sunshine close to 65%.
PRECIPITATION : maybe some persistent drops by daybreak - else, none.
WIND - aloft : WNW strong -> severe gale -> NW moderate to strong.
TEMPERATURE : low +8 °C - high +17°C.
MONDAY OCTOBER 03
SKY CONDITION : some low cloud might remain early in the morning, then clearing swiftly and widespread. Period of sunshine close to 85%.
PRECIPITATION : none.
WIND - aloft : NW moderate to strong -> NNW moderate.
TEMPERATURE : dropping slightly.
EXTENDED OUTLOOK UNTIL THURSDAY OCTOBER 06
Tuesday : after possible low cloud dispelling, fair weather sustained by light NNW flow high up, or occasionally light to moderate. Wednesday : fair sunny weather - W high up, light to moderate. Thursday : uncertain - fair weather likely, not much wind high up, maybe SW, to be confirmed.
Forecast reliability : fairly good until Sunday - poor thereafter.