Current Synoptics and Conditions
Firstly a comparison of where we are now, compared to what was suggested in previous blogs. The synoptic pattern is generally very similar to what was suggested on Tuesday, however more of the Alps has a feed from the SW as opposed to the South East. There has been a snow topup in parts of the Western Alps, but not to the extent forecast on Tuesday.
A bit of a change in the weather pattern in the upcoming week. Initially continuing dry and settled with a Tropical Maritime airmass. However gradually over the weekend, the airmass changes to more of a Returning Polar Maritime airmass, bringing cooler and rather unsettled conditions. This combination of colder and unsettled weather does considerably increase the chance of some much needed snow over the Alps. However winds will still be from the South West, so some lower resorts will see rain as opposed to snow, detail on this will always be tricky to nail.
Monday - Wednesday
By now the cooler unsettled conditions are in place, so possibly a snowy period of weather, more especially for the higher slopes (as ever).
Thursday and Friday
The general pattern is still the same, but perhaps a little bit milder, and some uncertainty this far out.
Alps Temperatures and Rainfall
For Saturday a split in the weather, for most of the Alps, W to SW winds, 850Hpa temps +2c to +5c, FL 1200m to 1500m generally, however for the S Germany, NE Switzerland and NW Austria border area 2100m
However much colder in Eastern Austria with S to SE winds -7c (SE) to +0c (Central Austria), FL 0m (NE Austria) to 600m (Central Austria)
For Sunday SW winds again for France, Switzerland and western parts of both Germany and Italy. 850Hpa temps -3c (N and E) to +2c (South West) , FL 1200m to 1600m generally
While SE winds for Austria and Eastern parts of both Germany and Italy 850Hpa temps -9c (N and E) to +3c (South West) , FL Sea level over much of Eastern Austria to 1600m further west.
Heavy precipitation for France and Western Switzerland to start the day, this push east during the afternoon and evening to cover Switzerland fringing other areas later, this continuing to edge east into Austria for Sunday but decaying as it does so. Snow levels 1800m approx to start, steadily dropping down to 1000m during the afternoon and evening, staying around 1000m on Sunday.
Monday - Wednesday
For Monday again a split in the weather, for most of the Alps, W to SW winds, 850Hpa temps +0c to +3c, FL 1200m to 1500m generally
However remaining much colder in the far East of Austria with S to SE winds -5c (NE) to -1c (Central Austria), FL 0m (NE Austria) to 900m (Central Austria) to 1500m (Western Austria)
A similar pattern on Tuesday, but slightly milder for Eastern Austria.
For Wednesday the west to south west flow is set to becoming established across the Alps with 850Hpa temps -1c to +1c, FL 1000m to 1400m generally
In terms of precipitation, another front pushing in for early Monday, giving heavy precipitation for Western areas, moving east slowly through the day to effect Austria later, the heaviest of the precipitation always
for western areas, with snow generally above 1300m, but at lower levels to around 1000m at times.
Thursday and Friday
Towards the end of the week, the Alps looks like being on the edge of the cold/mild divide, so apart from it perhaps turning milder at least some of the time, with 850HPa temps well above zero, very difficult to give much detail at this stage.
At this stage further areas of precipitation seems likely, again the heaviest most likely to be over western parts of the Alps, perhaps not making it to Austria. the Snow level is a bit more difficult to pinpoint, but Mostly snow above 1800m, and to much lower levels at times.
This shows that there is a risk of 100mm of rain equivalent over France and W Switzerland, 50-100mm for E Switzerland, 25-50mm for W Austria, and 5-25mm for E Austria.
If this was all snow this would give, up to 1m of snow over France and W Switzerland, 50cm-1m for E Switzerland, 25-50cm for W Austria, and 5-25cm for E Austria. However these often tend to overstate precipitation amounts.
So in summary a change to the weather pattern for the Alps, heavy snowfalls are expected for higher parts of the Alps say over 1800m, moderate snowfalls are expected above around 1500m while areas above 1200m are more likely to see a mix of rain, sleet and snow. Western areas are likely to see the heaviest precipitation, but conversely drier further east, but any precipitation is likely to fall as snow to lower levels to that further west.