Avalanche Report for Southern Cairngorms
Avalanche Hazard Forecast
FOR PERIOD 18:00 Sun 14/04/2019 TO 18:00 Mon 15/04/2019
Forecast Snow Stability & Avalanche Hazard
Daily avalanche reports have ended for this season. Please refer to SAIS homepage https://www.sais.gov.uk for current general snowpack and mountain information. The SAIS team would like to thank you for all your support over the last winter and wish you a good summer. See you next winter!
Forecast Weather Influences
Observed Avalanche Hazard -
Observed Weather Influences
Observed Snow Stability and Avalanche Hazard
Spring snow cover.
We started this period with complete snow cover above 650 metres. Throughout the Southern Cairngorms new snow cover was light with the main Cairngorms holding much deeper amounts. There was a return to milder temps with rain late on Friday 5th April. By the end of the weekend most of the superficial snow had gone, leaving only older deeper snow patches on various aspects. Over the last three days the snow cover has been subject to typical Spring weather and is now firm, well bonded and stable.Winters Return.
Last week there was a definite feel of 'Spring conditions'. However, there was a change in the weather pattern with cooler air and precipitation moving over us from the NE and E. Snow started falling on the 1st April, with the heaviest snowfall occurring to low levels on the 3rd of April. The winds were very strong from the N then NE during this period but have since moderated and veered to the East. Currently deepest amounts are on S through W to N aspects. Forecast to become warmer tomorrow.A mild week.
It has been a mild and mostly dry week with the snow cover thawing and diminishing at all levels. The well consolidated snow cover is very patchy, deepest areas are to be found in gullies and around corrie rims mainly on North-East to South-East aspects above 950 metres.Wintry start/mild end.
A Wintry start to the week with snowfall, strong winds and some avalanche activity. By Tuesday 19th there was a return to milder temperatures and a gentle thaw has been in progress since then. Surface layers became wet but drier snow with moderately bonded layers was to be found in deep accumulations at higher elevations. Large unstable cornices developed around parts of Lochnagar providing a significant hazard. Currently greatest accumulations are found on NE to SE aspects, patchy elsewhere.A stormy week.
There has been snowfall most days this week which generally has been accompanied by very strong winds. Wind directions were variable, as a result the snowpack distribution improved with deepest accumulations in wind sheltered features but generally remaining shallow in many locations. The snowline currently starts around 700 metres with overall stability improving in fluctuating freezing levels.Winters return.
There was a return to Wintry conditions last Sunday with some snowfall on most days leaving a thin cover from around 800 metres. Wednesday saw the heaviest showers, with greatest amounts forecast for the Northern side of our boundary. Strong winds from various directions has redistributed deposits into wind sheltered locations on many aspects. Fluctuating freezing levels have helped consolidate accumulations but there is now little snow below 800 metres.Spring conditions.
Generally, it has been a very warm and sunny week. The patchy snow cover continues to to thaw but is well consolidated and stable throughout. There is little snow left, greatest amounts are mainly restricted to gullies and around corrie rims in high North to East facing Corries.Thawing snow.
It has been a mild week with the freezing level above the summits and occasional rain. Remaining snow continues to thaw but is well consolidated. Greatest amounts are to be found in higher corries where some easier gullies are just about complete but elsewhere is mainly snow free.A week of change.
We started this week with full Winter conditions, although the snow was generally not deep. With the freezing level well above the summits and heavy rain at times, it has not taken long for snow cover to become patchy. Currently, most aspects above 950 metres still hold soft but stable snow in sheltered areas with most other areas becoming snow free.Thin cover with localised weakness.
It was a very cold and calm start to this period. This was followed by strong winds from various directions and occasional snowfall. Overall stability was improved by melt-freeze conditions in the last couple of days. Most of the snow cover is bridged by an icy layer but weaker layers are still to be found in some locations. These areas are very localised. Generally cover remain thin, currently thawing under 800 metres.Mild start/cold finish.
After a mild start to this period, Sunday 27th Jan saw a return to wintry conditions with snowfall and strong Northerly winds leaving new accumulations only in the most sheltered of locations and deeper deposits in sheltered glens and forests. Limited snowfall and redistribution of existing snow has left a thin covering of unconsolidated snow on most aspects and isolated areas of windslab above 800 metres, mainly E to S aspects.It has remained cold, weaknesses are persisting within the windslab.A cold week.
It has been a cold week, mostly dry but occasional strong winds led to some drifting and redistribution of existing deposits. There is a light covering of snow from low levels with only a few deeper areas in sheltered locations. Areas of unstable windslab developed, mainly in N to E facing corries above 900 metres. These areas were very localised and generally avoidable.Wintry conditions.
A generally mild week with some precipitation and freezing level fluctuations giving a dusting of snow at times. On the 16th there was a return to cooler conditions with moderate snow fall at all levels helping the overall wintry appearance of the hills. At higher elevations strong winds and subsequent drifting has led to deep pockets forming in sheltered locations on South-East and South aspects. Snow cover is very shallow elsewhere.Snow patches.
Over the last week, fluctuations in the freezing levels and a dusting of snow have made little difference to the current conditions. The slowly diminishing patchy snow cover remains well bonded and is generally restricted to features such as gully lines, around corrie rims and sheltered hollows above 950 metres.Patchy firm snow.
The start of this period was mild and often wet leaving a much depleted and patchy snow cover. The New Year saw a return to much cooler conditions with remaining snow becoming very firm and often icy. Snow is generally restricted to West through North to North-East aspects above 950 metres.Very patchy.
At the start of this period we had good snow cover although often shallow on plateau and exposed areas. It became much milder on Christmas Eve with the freezing levels lifting way above the summits. The snow cover has continued to thaw since then becoming well bonded but very patchy and mostly restricted to West through North to North-East aspects above 900 metres. Many areas are snow free and bare.Patchy snow cover.
It has been a mixed week for weather. There was significant new snowfall down to low levels leaving a general covering and deep accumulations in many sheltered locations. However Storm Deirdre followed with a savage thaw but the cooler temperatures after this have helped stabilise remaining snow. Many gullies are still incomplete but most Corries hold snow and there are significant patches on higher plateau areas.Updated Thursday 20th December
Updated Thursday 20th December
This period started with avalanches noted in rising temperatures on the 6th April on SW and S aspects. On the 7th, as the mild conditions took hold, further slab avalanches were noted on multiple aspects, mainly all failing on a weak layer that was first recorded on the 30th March. The snowpack continues to thaw and stabilise with the odd cornice collapse occurring. Currently the snow cover is good above 900 metres, patchy at low levels and stable throughout.
It has remained cold throughout this week. Moderately bonded windslab was present on mainly NW to NE aspects, the exception was the 30th March, when snow fell as graupel the previous evening, introducing a weak layer and a slightly more unstable snowpack. This layer has persisted in the snowpack since then. Snowfall was moderate on the 1st April, but becoming heavy on the evening of the 2nd April. Currently, this has left deeper unstable accumulations on the South-East to South-West aspects.
It was a mild start to this period, helping trigger some avalanche activity but ultimately consolidating and stabilising the snowpack. This was followed by a return to cooler conditions and some more snowfall, although this tended to be light. As we reached the 29th, the snowpack was firm and icy with some limited softer deposits in places. Although there has been some snow loss during this week, the hills are still in full Winter condition with good cover on most aspects above 850 metres.
The area started this period under full Winter conditions, new accumulations forming in the strong winds and existing instabilities persisting at depth in the cold snow. Extensive areas of hard ice also developed on wind exposed slopes. Monday and Tuesday were sunny with milder conditions creeping into the area thereafter. There has been some snow loss, particularly at lower levels with the hard ice melting out exposing the ground on higher levels. However, general cover remains good.
The week started with an active period of avalanche activity due to snowfall and strong winds loading already marginal slopes, where instability had been maintained by persistently cold air temperatures. Mid-week saw a gradual improvement in the situation with slightly milder temperatures encouraging the consolidation process, producing a generally stable snowpack throughout. We end the week with a forecast of heavy snow on severe gale force winds.
It has been an epic week with very cold temperatures, persistent Easterly airflow and heavy snowfall at all levels on strong winds. The end of the week has seen some respite with much less extreme weather, improved visibility and the opportunity to get a better overall view. Whilst consolidation is slowly taking place areas of concern still exist at higher elevations. Cornicing is a prevalent feature at present.
Currently, like most other areas, there is a very cold Easterly airflow affecting the area. Initially the snowpack was hard and firm with weaker layers noted at depth. Heavy snow showers started on the evening of the 27th and there has been frequent and occasional heavy snowfall since then. Currently, mountain travel is challenging and serious with deep, unstable accumulations developing mainly on South-West to North-West aspects. East aspects remain hard and scoured.
After an active week in terms of avalanche activity due to new snow instability and then thaw conditions at all levels, the snowpack has now refrozen developing a strong crust. Conditions are currently stable.
The defining week off the winter so far with daily snow showers. The wind has been the dominant feature, redistributing snow around the aspects, creating some deep drifts. Very cold temperatures at the start of the week developed faceted crystals that were problematic however slightly less cold temperatures and deeper snowpacks have reduced the steep temperature gradient that produced this situation. Recent snow is consolidating but further snowfall on strong winds is forecast.
With a generally showery airflow there has been a gradual improvement in the snow cover. Cold air temperatures have maintained a moderately well bonded snowpack. Recent very cold air temperatures have caused the development of less well bonded grains, with a deep seated weakness located in an otherwise well bonded snowpack today.
It has been a very windy week, with multiple gusts over 100 mph being recorded at The Cairnwell weather station. There has also been some snowfall on most days with the heaviest on Tuesday overnight, leaving deep unstable windslab, mainly on N to E aspects. On Thursday there was a change in the winds to the NE and NNE leading to a redistribution of existing deposits. Many areas on the hill are scoured, icy or bare with only very sheltered features holding deeper deposits.
At the start of the week there was good snow cover from low levels with instabilities found mainly on North to East aspects above 850 metres. Thaw conditions prevailed Monday and Tuesday resulting in significant snow loss before becoming cooler on Wednesday and moderate snowfall above 600m. At the end of this period snow cover is starting to become firm and stable with localised windslab present on steep terrain on North-East and East aspects above 800 metres.
There was a return to Wintry conditions on the 15th, becoming much cooler at all levels. Snowfall was heaviest on the 17th with significant amounts of drifting in the strong winds. Snow cover has again become much more widespread. Areas of windslab have developed in lee locations and are particularly unstable where they overlie older snow-ice. Cornices are developing with exposed areas becoming very icy. Likely to remain cold and unsettled for at least a few more days yet.
Some light precipitation at the start of the week with areas of moderately bonded windslab present. Consolidation has gradually taken place through the week aided by gently fluctuating temperatures. The snowpack is now generally well bonded and stable.
With snow showers and significant drifting in strong changeable winds, general snow cover continued to improve on most aspects with deep drifts in many lee locations. Unstable windslab also developed, particularly on NW through N to E aspects above 800 metres. A slight fluctuation in the freezing level in the last two days has helped stabilise most deposits but isolated areas of windslab still persist in sheltered steep terrain features on most aspects.
There was a return to cooler conditions with snow showers and strong winds from the North-West. There is now a thin cover of light and dry snow above 600 metres. Deeper unstable accumulations have developed only in very sheltered locations with weaknesses persisting mainly due to cold temperatures. These areas are very localised and restricted to steep sheltered terrain. The older patchy snow is very firm.
No significant issues to report. Limited patchy snow cover is well bonded and stable.
The Weekly Snowpack Summary for Southern Cairngorms will be updated on Thursday 21st December 2017
This week has predominately had the freezing level above the summits with strong sunshine on many of the days. The snow cover has been thawing with remaining snow now becoming restricted to North to East Corries above 950 metres with patches elsewhere. This period finished with some rainfall. Although this softened surface layers the remaining snow is well consolidated.
Light snowfall and redistributed deposits have led to a localised Moderate hazard throughout this period. Mainly windslab was to be found on North-East to South-East aspects above 900 metres but recent strong NE winds led to new generally shallow localised accumulations developing on other aspects. By 23rd there had been an improvement in stability of these deposits with the overall hazard becoming Low. Older snow is very icy with serious run outs.
The week started with some windslab persisting above 900m but then gentle thaw conditions became established with the hazard level gradually reducing to become low by the middle of the week. This theme continued with the snowpack slowly thawing and becoming patchy on all aspects but with greatest cover remaining above 1000 metres. The week ends with a forecast of cooler conditions and some limited light snowfall.
It's been a wintry week on the hills. It started with generally avoidable areas of windslab but midweek there was a good fall of snow on gale force winds. This led to a more extensive cover on the hills and deeper areas of windslab. A period of consolidation helped, with the hazard level lifting to around 1000m, before some more heavier snowfall in more gale force winds. North to East aspects are mostly affected and debris was noted at the bottom of some Lochnagar gullies, on Thursday.
The week started with snow to valley level and deep drifts in the mountains courtesy of Storm Doris. The weather then followed the well established cycle of storm/thaw and stripped the full snow cover back up to 900m. The week has ended with some very cold and often sunny weather with localised windslab being redistributed into sheltered locations on various aspects. Full winter conditions above 900m. Forecasters are tentatively suggesting that there will be some snowfall at the weekend.
Thaw conditions and a diminishing snowpack have been the dominant feature of the week, however there were a couple of melt/freeze cycles in there as well. The remaining patchy snow had stripped back to high altitude sheltered locations such as corrie rims above 950 metres. However Storm Doris at the end of the week has produced a good covering of snow down to valley level: Strengthening winds are now forming deep drifted accumulations in sheltered locations.
It has been wintry for most of the week. Changeable strong winds and snowfall led to deep deposits forming on South-East through North to North-East aspects from low levels. Weaknesses that developed during last week in deeper deposits were maintained by the cooler temperatures. However, during the later half of this week, it has become gradually milder, subjecting the snowpack to a gentle thaw and improving stability. By the 16th February the majority of the snowpack was well bonded.
All change! Starting with mild and wet weather and a thawing, extremely patchy snowpack the week has gradually become colder with increasingly heavy falls of snow. Some gale force winds have caused significant drifting but also snowfall on light winds have improved the general all round cover. Significant amounts of unstable windslab are now present on West through North to North-East aspects. Full winter conditions have returned.
The start of this week was cold with very light snowfall at higher levels. There was slightly heavier snowfall on the 29th/30th/31st leading to localised moderately bonded deposits developing in sheltered locations. However this was followed by milder conditions and rain at all levels. Currently the snow cover is very patchy with greatest amounts on North-East through East to South aspects above 950 metres. Light snow is forecast overnight on the 2nd February.
It has been a dry week, with only a trace of snow. Most days have been cold which has helped slow the snow loss down. The patchy snow is firm but continues to slowly recede with greatest amounts on North-East through East to South aspects above 950 metres. Elsewhere is mostly bare.
This period started with windslab developing in lee locations on South-East and South aspects, accumulations starting to become deep in places. However milder conditions returned and superficial cover melted quickly leaving a patchy snowpack which has continued to slowly thaw but has remained well bonded. Greatest amounts are to be found on North-East through East to South aspects above 900 metres.
There was a welcome return to wintry weather on the 10th January onwards with light snow showers and winds from the West every day. Winds have been very strong regularly into the 90+mph. Snow amounts have been low, often the showers didn't quite make it to us over in the East. Greatest amounts are mainly in very sheltered areas on NE to SE aspects above 850 metres with a covering of light superficial snow from valley level. We have been forecast heavier snow for Thursday evening.
The variable conditions continued, with snow showers on Northerly winds over Hogmanay and New Years day followed by a rise in the freezing level to above the summits. The snow cover slowly thawed during this period and was subject to another freeze at the end of this week. The patchy snow cover has consolidated well and is now firm and well bonded with the more extensive areas found on North through East to South-East aspects above 900 metres.
This week has been dominated by the variable weather conditions: Stormy conditions with very strong winds and frequent snow showers, separated by very mild conditions with +6 degrees centigrade on the mountains on Christmas day. During the snow showers, heavy drifting produced rapid build up of unstable windslab but only in very sheltered locations. Milder conditions at the end of the week thawed the superficial snow leaving patchy cover on mainly sheltered N through E to SE aspects above 900m.
The period started with dry, warm conditions and very little sign of Winter. But on 20th snow showers started, these were initially light but becoming heavier over the next two days leaving light cover to valley level. Winds have been very strong and localised areas of soft windslab developed in wind sheltered locations mainly on North to East aspects.
It has been a week of gently fluctuating temperatures with the freezing level rising and lowering around the summit levels. The snowpack has been generally well bonded and stable but snow showers have produced localised accumulations on various aspects. Generally these have been shallow in nature but occasionally slightly deeper deposits have formed in steeper, sheltered locations. The highest mountains and plateau areas have good cover above 900 metres: At present this is firm and icy.
There was an unstable start to this period with avalanches overnight on the 1st. After this there was light snowfall most days but the freezing levels fluctuated with snow to various levels. New accumulations tended to be shallow with some isolated deeper areas. Stability of new snow remained reasonably good with only surface instabilities noted on steep terrain. The older snow was generally soft but remained stable throughout the period. Glide cracks are developing in many locations.
At the start of the week there was a stable Spring snowpack. On Saturday 26th there was snow on the higher summits but heavy rain at most other levels, with a number of cornice collapses. After this most days saw new light snowfall to around 650 metres with a blanket of new snow over most aspects. This has generally bonded well to older hard snow-ice with new localised accumulations forming mainly on NW to NE aspects above 900 metres, often at the top of Corries.
The snowpack has been diminishing all week, often soft at lower levels but remaining generally well bonded on all aspects. Overnight on the 23rd, freezing levels dropped and there was some new snowfall above 800 metres. Accumulations were generally very light with isolated deeper pockets on N to E aspects. These were not significant enough to alter the avalanche hazard which remained Low. Creep lines continue to widen in older deep accumulations on steep convex slopes.
Unsettled conditions at the start of the week with unstable windslab on NE to SE aspects. A thaw on the 11th produced widespread avalanche activity. The mild weather continued through the week with gradually improving stability in a diminishing snowpack. High pressure at the end of the week has produced some glorious weather with the generally stable snow thawing during the day and refreezing at night. Cornice collapse and rock fall has been a feature of the week.
The week started with unstable windslab on East through South to West aspects. Avalanche debris on some of these aspects was noted towards the end of the week. On the 7th the dry, light snow was redistributed onto North to South-East aspects. Accumulations on these aspects are deep in places. A strong Northerly airflow on the 9th lead to further redistribution with avalanche activity noted on a SW aspect. On the10th the freezing levels started to rise and are forecast to be above the summits.
This week was dominated by high pressure with cold and dry conditions. Weaknesses persisted deeper within the snowpack but an overnight thaw on the 1st March, with some avalanche activity, helped stabilise conditions, particularly as freezing levels dropped again. There was heavy snowfall on the 2nd March with new windslab building on NE to SE aspects. These light, dry deposits will be easily re-distributed in stronger winds over the next couple of days. Expected to remain wintry into next week.
It has been an unsettled period with very windy weather for most of the week. Snowfall and drifting on the 19th led to avalanche activity being observed on a NE aspect. There was a quick melt/freeze cycle on the 20th with cornice collapse occurring. Further snow showers and very strong winds continued the cycle building windslab in sheltered locations on NE through E to S aspects, leaving the West and North-West aspects scoured and very icy. The week ended with high pressure building.
Generally a cold week, starting with strong winds and drifting. Heaviest snowfall occurred overnight on the 13th with a number of natural avalanches reported on West aspects. Storm force winds on the 16th Feb re-distributed softer deposits again. There was also a brief thaw later that night which has helped stabilise the snowpack when freezing levels dropped. Currently many areas are firm but some with deeper weakness and shallow windslab developing in sheltered areas.
It has been cold all week with new snow falling mainly on the 6th and 7th. Strong, changeable winds has led to a lot of redistribution with unstable windslab developing on most aspects during the week. Generally, stability is slowly improving, many areas becoming scoured and icy and windslab becoming restricted to sheltered steep terrain. Currently new accumulations are forecast to develop on South to South-West aspects.
It has been a very unsettled week with freeze cycles and a mix of snow and rain, which in general has helped consolidate most of the snow cover. Localised unstable windslab was generally restricted to steep, sheltered terrain on North through East to South East aspects above 800 metres. Winds were very strong and often variable with Storm Henry stripping most of the softer snow from the hill. Remaining cover is scoured and icy and currently subject to another thaw freeze cycle.
Thaw conditions for the first part of the week, severely diminishing cover below 700 metres. Generally had become stable, apart from isolated instabilities on steep terrain. Tuesday to Thursday were cooler with new snowfall and improved cover from 600 metres. However, strong winds have led to new windslab developing, mainly on N through East to South-East aspects above 800 metres, with some deep drifts at lower levels. Fluctuation in the freezing level is forecast with a mix of rain and snow.
This period started with significant Northerly winds after which it was calm with light snow and overall cover remained excellent. Weaker layers were noted on steep terrain on most aspects but were supported by harder denser snow above them. There was a temperature gradient in the cold, dry snow for most of the week and developing facets were noted. Strong winds today with deep unstable windslab developing on Northerly aspects. Currently rising freezing level with rain due later
Frequent snow showers gradually eased to give light snow and then dry days. Winds travelled all the way through the directions and have been variable in speed. The freezing level has gradually lowered to become very cold at the end of the week. The outcome of these influences is near full snow cover on all aspects down to 600 metres. Consolidation has been delayed by the very cold temperatures and deposits have remained available for redistribution in the variable winds. Instability persists.
Persistent precipitation all week, generally falling as snow from around 600 metres and accompanied by a strong Easterly airflow, has led to significant quantities of windslab on the hills. Stability remains poor on steeper slopes but there has been some consolidation elsewhere within the snowpack. Visibility has been poor with one avalanche noted at around 750 metres.
The week started well with cooler temperatures and some new snowfall but then ended with thaw conditions and finally Storm Frank. Heavy rain and mild temperatures significantly depleted the snowpack leaving patchy areas in the the most sheltered locations at higher elevations only. These snow patches are currently refrozen and very firm.
It has been mainly mild, wet and windy. At the start of the week there were limited patches of soft, wet snow in the higher gullies lines or around corrie rims. Towards the end of the week the temperatures lowered and produced some some showers giving a more wintery appearance and some isolated accumulations of deeper snow. However an overnight thaw at the end of the period has reduced the cover back to patchy areas in sheltered locations on mainly North to East aspects from 900 metres.
The week started with fairly significant thaw conditions (plus 8.1 degrees at 880m) rapidly reducing the snow cover. A return to cooler conditions with some precipitation gave a more wintery appearance in the middle of the week. However we end the week with all the superficial snow having thawed and patchy cover mostly above 900m on mainly NW through NE to SE aspects. Greatest amounts are present in the high North and East facing corries with some large cornice remnants still present.
It has been a dry and mild week and apart from the first two days, sunny and clear. Last weeks deep accumulations were soon gone in the warm temperatures, over +12 degrees recorded at 1000 m on Sunday. Surface instabilities, cornice collapse, rock and ice fall were commonplace but nothing significant has been observed despite the clear conditions. Cover is much depleted, patchy on all aspects with wet ground at all levels, burns and rivers flowing well but not full.
It has been an unsettled week, initially with new localised marginally stable accumulations developing over older snow. Heavy snow mid-week, down to valley level, buried already poorly bonded snow leaving weaker layers at depth with the hazard also becoming more widespread. A number of smaller avalanches occurred. Currently there is reasonable cover above 800 metres with deeper accumulations on NE to SE aspects. The freezing level is forecast to rise over the weekend.
Mostly a sunny week with spring like conditions. Fluctuating freezing levels ensured older snow remained stable, becoming very firm and icy at times. Snow cover is patchy, some burn lines but mostly North to East facing corries hold greatest amounts. More significant snowfall arrived on Wednesday night. Many locations where accumulations developed were bare ground but where it overlies old snow it had not bonded well on steeper terrain. Snow under 900 metres had started to thaw by afternoon.
Generally the snowpack has been well bonded with at times pockets of snow developing in wind sheltered locations, however these were not deep nor extensive. The last couple of days have been very mild with with the snow now thawing at all levels. Overall stability remains good but one avalanche and full depth avalanche was noted on an East aspect starting around 1000 metres.
During the first half of the week the snowpack diminished in the milder conditions. Cooler conditions with some snowfall in the second half of the week refroze the old snow and produced some windslab accumulations in sheltered locations. Currently, any shallow snow cover is thawing in the rain as the freezing level has just risen over the summits. The remaining snow is patchy and generally found above 900 metres, with deepest amounts present in the North and East facing corries.
It's been a mixed week for snowfall and freezing levels giving a series of thaw-freeze cycles, all accompanied with strong SW to NW winds . New accumulations were often light with the heaviest snowfall of the week on the 3rd. The 4th was a sunny and later calmer day with surface instabilities on sunny aspects. Snow cover has started to diminish and is largely soft and moist. E aspects have good cover with W and exposed ridges heavily scoured.
We started this period post thaw with many areas becoming patchy and a firm and well bonded snowpack. Significant snowfall arrived on the 22nd and 23rd with new unstable accumulations developing on N to SE aspects and plenty of lying snow for the changeable winds to redistribute. Visiting Lochnagar post storm there were 2 sets of crown walls but not really any other debris. We finish this period with an overnight thaw on the 25th and cooler temperatures refreezing the snowpack.
There has been limited new snowfall this week with a general depletion of snow cover at lower elevations occurring throughout the period. Thaw conditions became established at all elevations overnight Tuesday into Wednesday which resulted in significant snow loss, especially in exposed locations. The end of the period has brought a rapid return to cooler conditions with the remaining snowpack becoming firm and well bonded.
The last week has been dominated by cold nights with dry and sunny days. Generally the snowpack has been consolidating slowly, despite the occasional appearance of surface hoar and in shaded areas at higher altitudes, facets. The temperatures within the snow have been getting warmer particularly on the Southerly aspects. In many locations the snow is very icy and we are forecast heavy snowfall, however some of this will end up on aspects that currently have little snow.
A stormy start to the week with heavy snow and very strong winds resulted in both wind scoured slopes and heavily drifted areas. Cold temperatures and subsequent drifting maintained a slow rate of consolidation with instability persisting. The end of the week has seen lighter winds and a gradually rise in the freezing level leading to a consolidating snowpack. At present snow is encountered from valley level, with heather, ice, neve and deep drifts all present.
Initially, windslab was mostly stabilised by a couple of brief thaws around the weekend, which were not too severe, although there was loss of superficial snow. Monday onwards has seen a series of snow showers, high amounts of drifting and much cooler temperatures with weak layers developing in new accumulations. Snow-ice exposed to the wind is very firm with exposed aspects and ridges scoured and icy.
Storms eased at the start of the week leaving a good cover of cold, dry snow which had fallen on strong variable winds. In many open locations the snow was very hard packed and started to consolidate, with instabilities restricted to steep terrain. There was a reasonably strong temperature gradient within the snowpack for much of the week, with a hint of facets starting to develop. We ended this period with a much cloudier and slightly milder day.
The start of the week brought new snow showers and fluctuating temperatures. There has been more significant new snow in the last 48 hours with a massive improvement in cover, with accumulations becoming deeper from valley level. Milder temperatures overnight helped consolidate deposits at lower levels but we finish the week with deep, unstable snow at higher elevations.
This week has been dominated by a couple of severe thaws which left the snow cover restricted to mainly NE to SE aspects above 900 metres. Any new snowfall was not really significant and was generally short lived in the fluctuating temperatures. Another cooler period on the overnight of the 7th has left older snow very hard and icy with some heavier snowfall and drifting leading to deeper accumulations forming in wind sheltered locations on North to East aspects above 800 metres.
Very cold conditions at the start of the period maintained a slow consolidation rate for the recently formed but localised windslab. Elsewhere the snow cover tended to be superficial. Towards the end of the period, with slightly warmer temperatures, the localised areas of windslab had stabilised. Significantly warmer temperatures and rain on 01/01/15 has depleted snow amounts to very patchy cover at all elevations. Note: Colder temperatures and snow showers forecast for 02/01/15.
After an unsettled period of stormy weather there was a significant thaw last weekend which depleted the snow cover considerably. Snow showers on Wednesday settling above 500 metres have improved the cover slightly with some drifting.
In early December strong winds, mostly from the West, accompanied by snow showers led to unstable windslab developing in some locations. The recent mild temperatures have helped consolidate the snowpack but with some snow loss particularly at lower levels. A couple of minor avalanches were reported, one apparently triggered by a ski-tourer.
The snow has continued to slowly thaw but has remained well bonded throughout the week. Snow cover is patchy, more extensive areas above 850 metres with burn lines and gullies holding most. Glide cracks continue to develop, particularly round corrie rims where there is still deep snow.
With the freezing levels above the summits and no significant precipitation the snowpack has been slowly thawing and consolidating for the last week. Snow cover is still reasonable above 750 metres but the ground is starting to break through in some locations. Many cornices have gone but steep poor quality snow often bars the exits of gullies.
Snowfall and drifting led to new unstable accumulations forming earlier in the week but overall stability was improved by fluctuating temperatures. Most of the snowpack has become moist but well bonded with some areas of moderately bonded snow mostly but not exclusively restricted to NW to E facing corries. More cornices have collapsed but there are still many left.
The snowpack has continued to thaw with significant snow loss, particularly under 800 metres. Although soft, cover has remained well bonded for most of this period. Glide cracks have been growing in some locations with cornice collapse, rock and ice fall also observed. There is a return to wintery conditions with snowfall today and a drop in the freezing level.
We started this period with some avalanche activity and collapsing cornices but the last few days have seen a settled period both from the weather and the snow. Currently the snowpack surface layers have refrozen but there are much softer layers deeper within the snow. There are also plenty of old cornices that can fall and act as a trigger.
As well as a reasonable amount of new snow, we've had a few thaw freeze cycles resulting in a quite a few avalanches throughout the area. Weaker layers have developed deeper within the snowpack and were exposed where triggered by cornice collapse. Otherwise stability continues to improve.
The most significant event this week was Sunday's thaw. There was a lot of rain which helped trigger multiple avalanches throughout the area. Since then stability has generally improved, as there has has not been too much new snow but there has been reasonable amounts of drifting every day. New pockets of windslab have developed on NW,N,NE and E aspects at higher altitudes and in some places are poorly bonded. Cornices continue to re-develop.
It was a slightly calmer week which was mostly cloudy. There was less snowfall than on previous days and we had rain on a couple of occasions. A number of crown walls or avalanche debris have been reported with the likely trigger being cornices, some of which are very big. Currently after last nights thaw snow cover is mostly wet and soft but had already started to re-freeze this afternoon above 800 metres. Cover remains good on most aspects from 600 m, deepest on W through N to E.
We have had significantly more snow but less so in the latter half of the week. Stability is slowly improving but the winds have been variable, leaving localised windslab in many sheltered locations from 600 metres and deeper areas on NW,N and NE aspects above 800 metres.
Very strong S/SE winds and snowfall, heavy at times has resulted in substantial accumulations above 750 metres, mostly on W through N to E aspects. Extensive areas of moderately bonded windslab was to be found in sheltered locations. There have been a number of avalanches, but due to the high winds and poor visibility it has been not practical to visit and record details yet. Recent quick thaws to summit level have helped stability with some snow loss at lower altitudes.
We have continued to have significant snowfall at times as well as brief thaws to summit level. In the latter half of the week we had a slight change with snowfall from the East. The winds have moved much of the snow around and as a result we have a mix of ice,deep drifts and windslab on many aspects, mainly above 800 metres. Currently there are very deep accumulations on West to Northerly aspects which have weaker layers and are sitting on hard icy bases.
This week has been windy with snow showers throughout. Although there is very little snow below 800 metres, above 850 metres or so there is good cover. Windslab has been mostly on NW through to E aspects all week with avalanche debris noted on some of these aspects. Fluctuating temperatures has helped with consolidation but instabilities were persisting in many locations.
From around 750 metres there has been a well bonded and stable snowpack for most of the week. Towards the end of the week there have been two periods of fresh snowfall that were followed by a rapid thaw and subsequent refreeze of the snowpack.
A number of thaw freeze cycles, which were slowly stabilising the snowpack, was followed by a more substantial thaw. This left a moist soft snowpack at all levels which was then frozen as the freezing level dropped again. Currently we have good firm cover above 850 metres on most aspects.
It has been an unsettled period with strong winds mostly from a SW,S and SE direction and a mix of snow showers and rain. Areas of windslab developed on mainly W through N to E aspects above 900 metres. Stability has been improved due to a number of thaw-freeze cycles but some weaknesses persisted in deeper deposits on steep terrain. Generally there is now good cover above 800 metres which is icy in come locations.
A complicated week with snowfall, very strong variable winds and a quick melt freeze cycle. Windward slopes are scored whilst lee slopes have filled in with sheltered locations holding deeper snow. Another weather event is imminent with conditions changing daily.
There wasn't really too much to get excited about up until 24 hours ago. The last storm on Wednesday evening gave us a good amount of snowfall at most levels. The winds with this snow were very strong, 100 mph recorded on Cairnwell. So anything exposed is wind blasted, anything sheltered has reasonable depth of snow. Lower parts of gullies are still quite bare but at least the upper parts are starting to fill in.