CHAMONIX VALLEY AND MONT-BLANC AREA WEATHER FORECAST
ISSUED AT 07:50 SUNDAY APRIL 30
VALID FROM : SUNDAY APRIL 30 ‑‑ UNTIL : FRIDAY MAY 5 2017
Deep through it
Fair weather interlude persisting today, thanks to a mobile high ridge, currently Norway to Eastern Alpine Range and keeping fairly high pressure field over Northern Italy up to Piedmont. • Low 988 hpa, southwest close to Ireland, causes at first a fœhn gradient with that italian high, then will shape an altitude cold trough which is expected to crossing over our Region overnight and on Monday morning, triggering a new winter‑like bad weather spell. • The most part of the linked precipitation will be moving away eastward by Monday afternoon. • While coming off that thalweg and stagnating over France, an altitude cold low will influence the weather over the Alps making it unsettled and often humid until Thursday, probably.
TODAY - SUNDAY APRIL 30
SKY CONDITION : clear or partly cloudy ‑ thin high cloud from the west until the middle of the afternoon ‑ becoming cloudy later. Period of sunshine close to 75%.
PRECIPITATION : none.
WIND - ground level : moderate fœhn by the NE.
WIND - mid mountain : mainly NE ‑ light to moderate ‑ more noticeable in line with the large glaciers.
WIND - high mountain : SW light to moderate ‑> moderate to strong.
TEMPERATURE : low +3°C - high +19°C.
ISOTHERM 0°C : 2500 ‑> 2300 ‑> 2600 m.
ISOTHERM -10°C : 4200 ‑> 4000 m.
SKY CONDITION : cloudy, then mostly cloudy in the first part of the night ‑ becoming overcast later.
PRECIPITATION : starting up towards the latter part of the night ‑ light to moderate ‑ rain‑snow limit towards 1800 m, dropping towards 1300 m by dawn ‑ expected snowfall towards 1800 m : 5‑10 cm.
WIND - aloft : SW ‑> S moderate to strong.
TEMPERATURE : low +1°C.
MONDAY MAY 1
SKY CONDITION : overcast in the morning ‑ becoming mostly cloudy to cloudy with fleeting sunny spells in the afternoon. Period of sunshine close to 25%.
PRECIPITATION : moderate and continuous early in the morning ‑ turning into shower ‑ rain‑snow limit dropping towards 1100 m ‑ expected snowfall towards 1800 m : 10‑15 cm.
WIND - aloft : S moderate to strong ‑> variable light ‑> WNW moderate.
TEMPERATURE : low +1 °C - high +6°C.
TUESDAY MAY 2
SKY CONDITION : cloudy with sunny spells in the morning ‑ becoming mostly cloudy in the afternoon. Period of sunshine close to 45%.
PRECIPITATION : showers in the afternoon ‑ rain‑snow limit towards 1500 m ‑ expected snowfall towards 1800 m : ± 5 cm.
WIND - aloft : WSW moderate to strong ‑> SW moderate.
TEMPERATURE : dropping lows ‑ rising highs.
EXTENDED OUTLOOK UNTIL FRIDAY MAY 5 2017
Wednesday : cloudy with sunny spells ‑ shower risk ‑ temperature matching seasonal average. Thursday : uncertain ‑ changeable and cooler ‑ cloud passings and sunny spells ‑ slight shower risk, increasing somewhat. Friday : uncertain ‑ partly sunny ‑ getting slightly milder ‑ mostly westerly altitude stream, possibly fairly strong at times.
Forecast reliability : fairly good until Monday ‑ poor thereafter.
Avalanche risk is considerable (3/5) above 2400 m.