CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 09:15 SATURDAY JULY 20
VALID FROM : SATURDAY JULY 20 ‑‑ UNTIL : THURSDAY JULY 25 2019
Summertime in the mountains
Straw sandals I am
Bowing to – and leave
Azores High ridge has been withdrawing west, leaving a loose gradient pressure area over Central Europe and the Alpine Range. • Low 998 hpa, Southern Scotland, driving blur cold front from northwest towards our Region in a moderate southwest to westerly stream high up. • Last, thermal low over Spain, driving humid mediterranean puffs northward, thus shaping rainy‑thundery limit just ahead of that cold front. • This unsettled system as a whole loses much of it’s activity while moving east; it is however likely to triggering some isolated thundery showers in the afternoon and later, and should be kept under close watch. • Scorching heat spell to be expected, Monday‑Thursday, with surface Azores High ridge and African altitude high ridge once more resuming simultaneously.
TODAY - SATURDAY JULY 20
SKY CONDITION : clear in the morning, becoming cloudy with sunny spells ‑ thick high cloud passing and cumulus large cloud growing over the massifs in the afternoon. Period of sunshine close to 65%.
PRECIPITATION : thundery shower risk in the afternoon ‑ rain‑snow limit towards 3700 m.
WIND - ground level : calm ‑> SW light ‑ light to moderate thermal increase early afternoon.
WIND - mid mountain : SW ‑> WSW light to moderate ‑ occasionally moderate.
WIND - high mountain : WSW ‑> W moderate ‑ occasionally moderate to strong in the evening.
TEMPERATURE : low +12°C - high +28°C.
ISOTHERM 0°C : 4100 ‑> 3900 m.
ISOTHERM -10°C : 5800 ‑> 5700 ‑> 5800 m.
SKY CONDITION : cloudy or mostly cloudy at times.
PRECIPITATION : isolated or scattered shower, randomly breaking out, with possible local thunderstorm ‑ rain‑snow limit towards 3700 m.
WIND - aloft : WSW ‑> W moderate ‑ occasionally moderate to strong.
TEMPERATURE : low +14°C.
SUNDAY JULY 21
SKY CONDITION : mostly cloudy, then quickly cloudy with sunny spells ‑ becoming clear or partly cloudy in the afternoon ‑ persistent cumulus cloud over the massifs. Period of sunshine close to 70%.
PRECIPITATION : probably none.
WIND - aloft : W ‑> WNW moderate.
TEMPERATURE : low +13 °C - high +30°C.
MONDAY JULY 22
SKY CONDITION : clear or partly cloudy ‑ some cumulus cloud in the afternoon. Period of sunshine close to 80%.
PRECIPITATION : none.
WIND - aloft : variable light.
TEMPERATURE : rising.
EXTENDED OUTLOOK UNTIL THURSDAY JULY 25 2019
Tuesday : fair and outstandingly hot‑ very light winds high up. Wednesday and Thursday : sunny morning ‑ large cumulus cloud locally in the afternoon, yet without triggering any precipitation ‑ highs about 8 to 10°C above seasonal averages.
Forecast reliability : uncertain.