Avalanche Advisory: Sunday - Apr 14, 2019

THIS AVALANCHE ADVISORY EXPIRED ON April 16, 2019 @ 6:46 am
Avalanche Advisory published on April 14, 2019 @ 6:46 am
Issued by Steve Mace - ESAC

*Advisories will continue to be issued 4 days a week through April 21st. After the 21st, we will be issuing weekly snowpack summaries on Thursdays until May 9th. Danger ratings will no longer be formally issued as conditions can change over multiple day periods. *

* This Avalanche Advisory is in effect for Sunday, April 14th, and Monday, April 15th*

April 14-Transitional springtime conditions exist throughout the forecast area with heightened avalanche hazard in specific areas. Expect daytime warming on Sunday to increase the risk of Loose Wet avalanches at all elevations.  It will also be possible to find fresh sensitive wind slabs on specific terrain features on all aspects at mid and upper elevations. 

April 15-New snow coupled with moderate to strong SW winds will increase the avalanche hazard for Monday.  While it will still be possible to wind slabs on all aspects,  most concerning will be northerly and easterly aspects at mid and upper elevations where continued slab development is likely. You can also expect the risk of loose wet avalanches to increase at lower elevations with continued warm temperatures and rain expected below 8500'. Evaluate snow conditions and terrain carefully and avoid features of concern.

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Avalanche Problem 1: Loose Wet
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April 14 -Temperatures rose significantly on Saturday, and numerous loose wet avalanches were reported.  Similar temperatures are expected Sunday, with clear sunny skies. Couple this with the absence of a hard refreeze last night and we can expect Loose wet avalanches to be possible at all elevations. 

April 15 -Mostly cloudy skies will limit the solar gain on Monday and moderate winds may help to keep things cool. However, relatively warm overnight temperatures coupled with some strong green housing effects may lead to enough surface warming to make loose wet avalanches a greater concern. Be particularly cautious at lower elevations where precipitation may come in the form of rain.

Travel Advise -Increasing boot penetration, wet, sticky snow surfaces, and rollerballs are all signs of surface warming and may foreshadow larger point release avalanches.  Expect lower elevations to be more concerning than alpine terrain and be prepared for the danger to be low in the morning, rising throughout the day as the ambient air temperature increases.

Avalanche Problem 2: Wind Slab
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April 14 -Over the last 48 hrs we have seen the winds shift around the compass. The winds are expected to increase and shift to the southwest today with anticipated gusts around 60 mph on ridge tops. In addition, recent observations have found up to 10” of loose cold snow in some areas at higher elevations.   Be on the lookout for wind slabs on all aspects at mid and upper elevations. These wind slabs are likely to range from old and stubborn on more southerly aspects to fresh and sensitive on northerly and easterly aspects. It’s also worth keeping in mind that warm temperatures and clear skies today may make wind slabs on solar aspects more sensitive.

 April 15 –An oncoming storm should begin to impact the region Sunday evening and continue through Monday night.  Precipitation totals will likely be small, but they are sure to be higher at upper elevations. Moderate to strong southwest winds will continue to load northerly and easterly terrain at mid and upper elevations. Expect the size, distribution, and sensitivity on wind slabs to increase throughout the day on Monday as the storm makes its way through the area. 

Travel Advice -Problem areas will be specific to terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions.  Be particularly cautious in extreme terrain or on steep unsupported slopes where the consequences of an avalanche are elevated.  Surface clues such as blowing snow, recent cornice growth and uneven snow surfaces can help to identify and avoid areas of recent wind deposit.  

advisory discussion

Ski conditions have been quite good with surface conditions ranging from cold loose powder to supportable corn snow and a variety of melt-freeze crusts.  Unsettled spring weather continues to impact the area, and with each new batch of snow comes renewed avalanche concerns.  Even as more predictable spring conditions and relatively benign avalanche concerns become the norm, it is essential always to challenge our assumptions.  Keep an eye on changes in the weather and how this is affecting the snowpack, and always keep your options open. 

 I want to extend a big thank you to all those who continue to post their observations.  As we at ESAC wind down our operations for the spring, the observation page will continue to be a valuable source of information on snowpack and ski conditions. 

Weather and CURRENT CONDITIONS
weather summary

Expect another warm day Sunday with sunny skies and highs reaching into the mid 40’s at upper elevations. Clouds should begin to build this afternoon as another brief spring storm approaches the region.   Snow showers should begin Sunday night and build through the day on Monday with 2-6 inches expected above 8500’. Southwest winds are expected to be moderate Sunday increasing to strong by Monday. Temperatures are expected to drop below freezing at upper elevations Sunday night and another warm day is on tap for Monday with daytime highs expected in the mid to upper 30’s.

High pressure will return to the area late next week with very warm temperatures expected. There is a chance of more unsettled weather next weekend marked by scattered showers and increased winds. 

Two-Day Mountain Weather Forecast Produced in partnership with the Reno NWS
For 8,000 ft. to 10,000 ft.
Sunday Sunday Night Monday
Weather: Sunny then becoming partly cloudy. Mostly cloudy. Slight chance of showers in the evening. Chance of snow showers after midnight. Snow levels 8500 feet. Chance of precipitation is 20%. Mostly cloudy then becoming partly cloudy. Chance of showers. Snow levels 8500 feet. Chance of precipitation is 25%.
Temperatures: 43 to 53. deg. F. 28 to 34. deg. F. 39 to 49. deg. F.
Mid Slope Winds: Southwest 15 to 25 mph. Gusts up to 45 mph increasing to 60 mph in the afternoon. Southwest 15 to 25 mph with gusts to 60 mph. Southwest 15 to 25 mph with gusts to 60 mph.
Expected snowfall: 0 in. 80% probability up to 1 inch. 20% probability of 1 to 3 inches. | SWE = less than 0.10 inch. in. 70% probability up to 1 inch. 30% probability of 1 to 3 inches. | SWE = less than 0.10 inch. in.
Over 10,000 ft.
Sunday Sunday Night Monday
Weather: Sunny then becoming partly cloudy. Mostly cloudy. Chance of snow showers through the night. Snow levels 8500 feet. Chance of precipitation is 30%. Mostly cloudy. Chance of snow showers. Snow levels 9000 feet. Chance of precipitation is 35%.
Temperatures: 35 to 43. deg. F. 22 to 28. deg. F. 31 to 39. deg. F.
Ridge Top Winds: Southwest 25 to 40 mph with gusts to 60 mph. Southwest 30 to 45 mph with gusts to 65 mph. Southwest 30 to 45 mph with gusts to 65 mph.
Expected snowfall: 0 in. 80% probability up to 1 inch. 20% probability of 1 to 3 inches. | SWE = less than 0.10 inch. in. 70% probability up to 1 inch. 30% probability of 1 to 3 inches. | SWE = less than 0.10 inch. in.
Disclaimer
This Avalanche Advisory is designed to generally describe avalanche conditions where local variations always occur. This product only applies to backcountry areas located outside established ski area boundaries. The information in this Avalanche Advisory is provided by the Eastern Sierra Avalanche Center, who is solely responsible for its content.

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