Mammoth Mountain Ski Patrol 2009-10 Storm
Summary - Sesame Snow Study Site 9,000' (2,743m) |
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Date |
New Snow |
Base Depth |
SWE |
Rain |
% Density |
Storm Snow |
Storm SWE |
Season Snow |
Season SWE |
Base Hi Temp |
Base Lo Temp |
Notes |
10/4/2009 |
3.5 |
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0.32 |
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9 |
3.5 |
0.32 |
3.5 |
0.32 |
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10/5/2009 |
6.0 |
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0.56 |
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9 |
9.5 |
0.88 |
9.5 |
0.88 |
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6.3” HS, 0.88” SWE 10/5.
Daily HS based on Mammoth Pass station. SWE divided between 2 days assuming
constant density. |
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10/13/2009 |
Trace |
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Trace |
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36 |
22 |
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10/14/2009 |
21.5 |
21.5 |
4.58 |
1.64 |
21 |
21.5 |
4.58 |
31.0 |
5.46 |
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4.58” SWE followed by 1.64” Rain. Runnels indicate heavy rain to at least
11k'. 21.5” HS was max before rain
began. |
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10/19/2009 |
0.0 |
~4.0 |
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0.06 |
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0.0 |
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Heavy rain in town would indicate greater total rainfall. |
10/20/2009 |
2.0 |
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0.46 |
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23 |
2.0 |
0.46 |
33.0 |
5.92 |
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10/27/2009 |
Trace |
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Trace |
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West winds
in excess of 100mph at Chair 1. |
10/28/2009 |
1.5 |
1.5 |
0.11 |
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6 |
1.5 |
0.11 |
34.5 |
6.03 |
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Despite cold T, SWE seems slightly low. No manual observation to verify automatic
measurements. NE wind up 100mph @ 11k' |
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for several days.
Starting zones presumed to be very stripped. |
11/12/2009 |
Trace |
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Trace |
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43 |
27 |
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11/13/2009 |
4.0 |
5.0 |
0.48 |
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12 |
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38.5 |
6.51 |
28 |
19 |
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11/28/2009 |
12.0 |
14.5 |
0.70 |
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6 |
12.0 |
0.70 |
50.5 |
7.21 |
34 |
19 |
Most of the snow fell after NE wrap around. |
11/29/2009 |
1.5 |
13.5 |
0.07 |
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5 |
13.5 |
0.77 |
52.0 |
7.28 |
20 |
14 |
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12/6/2009 |
Trace |
7.0 |
0.03 |
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Trace |
0.03 |
52.0 |
7.31 |
28 |
12 |
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12/7/2009 |
7.0 |
12.5 |
0.69 |
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10 |
7.0 |
0.72 |
59.0 |
8.00 |
15 |
12 |
Brief graupel at 7:30, ~2hrs prior to measurement. |
12/8/2009 |
5.5 |
18.5 |
0.48 |
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9 |
12.5 |
1.20 |
64.5 |
8.48 |
17 |
4 |
Strong SSW wind. |
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12/10/2009 |
Trace |
14.5 |
0.01 |
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Trace |
0.01 |
64.5 |
8.49 |
31 |
14 |
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12/11/2009 |
6.5 |
19.0 |
0.77 |
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12 |
6.5 |
0.78 |
71.0 |
9.26 |
31 |
23 |
Mostly needle snow forms in AM. |
12/12/2009 |
17.0 |
32.0 |
2.43 |
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14 |
23.5 |
3.21 |
88.0 |
11.69 |
26 |
23 |
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12/13/2009 |
33.5 |
54.0 |
4.21 |
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13 |
57.0 |
7.42 |
121.5 |
15.90 |
28 |
18 |
Graupel and some ice pellets late afternoon on 12/12. Precip gauge overwhelmed by snowfall. |
12/14/2009 |
3.5 |
52.5 |
0.61 |
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17 |
60.5 |
8.03 |
125.0 |
16.51 |
22 |
18 |
This storm almost doubled the season total snowfall and
SWE. 4-6mm surface hoar on Hemlock
Ridge. |
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Date |
New Snow |
Base Depth |
SWE |
Rain |
% Density |
Storm Snow |
Storm SWE |
Season Snow |
Season SWE |
Base Hi Temp |
Base Lo Temp |
Notes |
12/22/2009 |
9.5 |
49.0 |
1.19 |
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12 |
9.5 |
1.19 |
134.5 |
17.70 |
31 |
15 |
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12/23/2009 |
Trace |
47.5 |
0.01 |
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9.5 |
1.20 |
134.5 |
17.71 |
19 |
5 |
Extremely strong NE winds.
Top scoured down to rocks in some places. |
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12/27/2009 |
1.0 |
44.0 |
0.11 |
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11 |
1.0 |
0.11 |
135.5 |
17.82 |
40 |
19 |
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12/29/2009 |
5.0 |
47.5 |
0.41 |
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8 |
5.0 |
0.41 |
140.5 |
18.23 |
30 |
10 |
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12/30/2009 |
6.5 |
50.0 |
0.90 |
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13 |
11.5 |
1.31 |
147.0 |
19.13 |
26 |
19 |
Widespread small avalanche activity. |
12/31/2009 |
0.5 |
50.0 |
0.04 |
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8 |
12.0 |
1.35 |
147.5 |
19.17 |
31 |
13 |
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1/9/2010 |
1.0 |
42.0 |
0.07 |
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7 |
1.0 |
0.07 |
148.5 |
19.24 |
44 |
31 |
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1/10/2010 |
2.0 |
44.0 |
0.24 |
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12 |
3.0 |
0.31 |
150.5 |
19.48 |
44 |
28 |
2-4mm graupel on surface, ice crust on storm board. |
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1/12/2010 |
Trace |
43.0 |
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Trace |
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150.5 |
19.48 |
43 |
12 |
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1/13/2010 |
15.5 |
58.5 |
2.05 |
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13 |
15.5 |
2.05 |
166.0 |
21.53 |
43 |
23 |
12-16" avalanche results across most of lower
mountain. Strong NE wind following
storm scoured most starting zones. |
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1/18/2010 |
3.0 |
54.5 |
0.35 |
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11 |
3.0 |
0.35 |
169.0 |
21.88 |
29 |
22 |
6-10mm
crust of melt-freeze on snow surface. |
1/19/2010 |
25.5 |
73.0 |
2.69 |
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11 |
28.5 |
3.04 |
194.5 |
24.57 |
29 |
18 |
10" new snow overnight.
Many small releases PM of 1/18 on ski cuts, very few results AM of
1/19. |
1/20/2010 |
14.0 |
81.0 |
1.08 |
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8 |
42.5 |
4.12 |
208.5 |
25.65 |
29 |
15 |
Many 10-12" releases on ski cuts in AM. Hard rime ice on surface at top of Gravy
Chute (~10k') |
1/21/2010 |
20.5 |
92.0 |
1.71 |
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8 |
63.0 |
5.83 |
229.0 |
27.36 |
20 |
5 |
Strong SW winds PM 1/20.
4 to 6 hour clearing in storm AM 1/21.
New snowfall beginning again at 9:30. |
1/22/2010 |
23.5 |
107.0 |
2.00 |
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9 |
85.5 |
7.71 |
252.5 |
29.36 |
20 |
9 |
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1/23/2010 |
4.0 |
104.0 |
0.28 |
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7 |
90.5 |
8.11 |
256.5 |
29.64 |
16 |
12 |
Chair 23 opens late in day. |
1/24/2010 |
Trace |
98.0 |
0.06 |
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90.5 |
8.17 |
256.5 |
29.70 |
29 |
8 |
Top opens. |
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1/25/2010 |
1.5 |
95.0 |
0.25 |
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16 |
1.5 |
0.25 |
258.0 |
29.95 |
33 |
21 |
Very little new snow, but a great deal of wind drifting. |
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Date |
New Snow |
Base Depth |
SWE |
Rain |
% Density |
Storm Snow |
Storm SWE |
Season Snow |
Season SWE |
Base Hi Temp |
Base Lo Temp |
Notes |
1/26/2010 |
7.0 |
97.0 |
0.96 |
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13 |
7.0 |
0.96 |
265.0 |
30.91 |
37 |
22 |
Good clearing and top opened 1/25. |
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1/30/2010 |
2.5 |
89.0 |
0.16 |
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6 |
2.5 |
0.16 |
267.5 |
31.07 |
37 |
20 |
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1/31/2010 |
1.5 |
88.0 |
0.11 |
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7 |
4.0 |
0.27 |
269.0 |
31.18 |
24 |
9 |
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2/5/2010 |
10.0 |
88.0 |
1.31 |
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13 |
10.0 |
1.13 |
279.0 |
32.49 |
31 |
23 |
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2/6/2010 |
8.0 |
96.5 |
0.93 |
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12 |
18.0 |
2.24 |
287.0 |
33.42 |
28 |
24 |
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2/7/2010 |
4.0 |
97.0 |
0.32 |
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8 |
22.0 |
2.56 |
291.0 |
33.74 |
27 |
17 |
Moderate N wind scoured loading zones AM of 2/7. |
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2/9/2010 |
Trace |
93.0 |
0.01 |
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Trace |
0.01 |
291.0 |
33.75 |
32 |
18 |
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2/10/2010 |
5.5 |
97.0 |
0.43 |
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8 |
5.5 |
0.44 |
296.5 |
34.18 |
25 |
11 |
Strong NE wind overnight scoured loading zones. |
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2/20/2010 |
Trace |
82.0 |
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Trace |
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296.5 |
34.18 |
37 |
24 |
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2/21/2010 |
5.0 |
86.5 |
0.39 |
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8 |
5.0 |
0.39 |
301.5 |
34.57 |
25 |
17 |
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2/22/2010 |
12.0 |
98.0 |
1.00 |
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8 |
17.0 |
1.39 |
313.5 |
35.57 |
22 |
7 |
Strong NE wind in AM scoured upper loading zones. |
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2/24/2010 |
20.5 |
105.5 |
1.88 |
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9 |
20.5 |
1.88 |
334.0 |
37.45 |
33 |
20 |
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2/25/2010 |
9.5 |
112.0 |
1.21 |
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13 |
30.0 |
3.09 |
343.5 |
38.66 |
25 |
22 |
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2/27/2010 |
27.0 |
131.0 |
3.01 |
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11 |
27.0 |
3.01 |
370.5 |
41.67 |
34 |
23 |
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2/28/2010 |
4.5 |
130.0 |
0.37 |
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9 |
31.5 |
3.38 |
375.0 |
42.04 |
28 |
20 |
Strong NE wind scoured upper loading zones PM of 2/27. |
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Date |
New Snow |
Base Depth |
SWE |
Rain |
% Density |
Storm Snow |
Storm SWE |
Season Snow |
Season SWE |
Base Hi Temp |
Base Lo Temp |
Notes |
3/3/2010 |
6.0 |
124.0 |
0.77 |
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13 |
6.0 |
0.77 |
381.0 |
42.81 |
31 |
18 |
Top opened for approximately one hour, moderate skier
compaction. |
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3/4/2010 |
13.0 |
134.5 |
1.16 |
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9 |
13.0 |
1.16 |
394.0 |
43.97 |
25 |
11 |
Very heavy wind loading from SW wind. |
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3/9/2010 |
5.5 |
125.0 |
0.57 |
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10 |
5.5 |
0.57 |
399.5 |
44.54 |
24 |
2 |
Strong SW wind during majority of precip followed by moderate
NE winds. |
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3/10/2010 |
3.0 |
125.5 |
0.14 |
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5 |
3.0 |
0.14 |
402.5 |
44.68 |
26 |
9 |
Strong SW wind overnight. More wind transported snow than
snowfall. |
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3/13/2010 |
11.0 |
130.5 |
1.53 |
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14 |
11.0 |
1.53 |
413.5 |
46.21 |
34 |
17 |
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3/27/2010 |
1.5 |
104.0 |
0.09 |
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6 |
1.5 |
0.09 |
415.0 |
46.30 |
39 |
18 |
Storm preceded by two weeks of high pressure, with significant
melt-freeze. |
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3/30/2010 |
4.5 |
102.5 |
0.63 |
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15 |
4.5 |
0.63 |
419.5 |
46.93 |
44 |
27 |
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3/31/2010 |
15.5 |
114.5 |
1.51 |
|
10 |
20.0 |
2.14 |
435.0 |
48.44 |
27 |
17 |
Very strong SW winds in excess of 120mph at Top previous day. |
4/1/2010 |
3.0 |
117.5 |
0.26 |
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9 |
23.0 |
2.40 |
438.0 |
48.70 |
20 |
3 |
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4/2/2010 |
Trace |
115.0 |
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Trace |
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438.0 |
48.70 |
27 |
6 |
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4/3/2010 |
4.0 |
118.5 |
0.96 |
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24 |
4.0 |
0.96 |
442.0 |
49.66 |
30 |
21 |
Dense wind slabs. Very
little avalanche activity. |
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4/4/2010 |
0.5 |
117.0 |
0.08 |
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16 |
0.5 |
0.08 |
442.5 |
49.74 |
29 |
17 |
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4/5/2010 |
25.5 |
135.0 |
3.03 |
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12 |
25.5 |
3.03 |
468.0 |
52.77 |
25 |
16 |
100+
mph WSW to SW winds for several hours overnight at Top and Ch22
stations. |
4/6/2010 |
2.0 |
138.5 |
0.23 |
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12 |
27.5 |
3.26 |
470.0 |
53.00 |
20 |
13 |
Winds shifted to NW in AM of 4/6. |
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4/12/2010 |
19.5 |
134.5 |
1.98 |
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10 |
19.5 |
1.98 |
489.5 |
54.98 |
36 |
17 |
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4/13/2010 |
2.5 |
134.5 |
0.35 |
|
14 |
22.0 |
2.33 |
492.0 |
55.33 |
23 |
16 |
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4/20/2010 |
Trace |
112.5 |
0.04 |
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Trace |
0.04 |
492.0 |
55.37 |
51 |
31 |
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4/21/2010 |
7.0 |
123.5 |
0.70 |
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10 |
7.0 |
0.74 |
499.0 |
56.07 |
32 |
15 |
Brief clearing AM of 4/21. |
4/22/2010 |
2.5 |
123.5 |
0.16 |
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6 |
9.5 |
0.90 |
501.5 |
56.23 |
22 |
14 |
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4/23/2010 |
2.0 |
123.5 |
0.17 |
|
9 |
11.5 |
1.07 |
503.5 |
56.40 |
28 |
20 |
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All
observations are made in the morning, therefore all measurements are for new
snow during approximately the previous 24 hours. |
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Units
for Base Depth, New Snow, Storm Total, and Season Snowfall are in
inches. |
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SWE≡Snow
Water Equivalent, the amount of water produced from melting a known volume of
snow, measured in inches of H2O. |
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Units for 24
Hour Base Hi Temp and Base Lo Temp are degrees Fahrenheit. |
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HS=Height of
Snow |
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Line breaks
indicate clearing between storms, despite occasional consecutive days. |
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