Avalanche and weather report, Loveland and Berthoud passes, Colorado state highway, 1962-63 season

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Avalanche and Weather Report tor Loveland and Berthoud Passes

Colorado state Highway

1962-63

Season

It as a dry, warm fall until the middle of November when a small storm came and temperatures dropped to nearly zero. The storm left only

9

inches of snow on the ground, and it was the first of December before another small storm came. There was only one other small storm in December so that the snow depth on the ground January 3 was only

16

inches. There was very cold weather the last of December, and this, together with shallow snow depth, pranoted the formation of depth hoar. The morning of January 19 there was only 2 feet of snow on the level

yet the major avalanche cycle of th.e season started that day with Palicachin1. During the first half' of January, storms contained only 10 inches of new

snowfall and

0.73

inch of water equivalent. However, this was sufficient overload on the

16

inches of unstable .snow, much 01' which vas depth hoar to cause maD7 slides with rather small volume.

From Janusr.y

19

to Februar.y 2 there was nearlf one continuous

st~r.m

with extremeq cold temperatures up to January 29 when it suddenly

warmed up and new fal ) 1 ng snow became wet with high densities. Cb FebrU.ary' 1 it rained on both sides of the continental divide up to elevations of

10,000 feet which 1s very unusual. , During this period moisture equivalent amounted to

4.31

inches and

50

inches of new snow fel.! - over one-fourth of the season' s prec1pi tat1.on fell in

14

days. For this period there were

31

avalanches of which

16

were released by artillery fire. Considering the sto:rmy weather and large amount of snow to be removed f'ran the highway, this is a good record.

The large amount of high density snow at the end of the storm canpacted all slides that had not run. Due to its weight and ability to canpact and f'reeze, a firm base vas formed which in some cases was probabq a thin crust of ice and caused snow which tell on it to be unstable.

After Februar,y 2 the.highway patrol was able to artiticially release most slides. Stoms were smaller than usual. Temperatures were high and as a result the maximum depth of snow occurred the third of March

(57

inches) and fran that date the snow depth decreased to nearly zero when the station was closed ~ 1. One damp type avalanche occurred May

7

caning out. of Number

4

of the

7

sisters which pushed a loaded semitrailer oft the asphalt onto the shoul.der. No one was injured.

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. For the season total new snowfall was

175

inches with a moisture equivalent of' 13.08 inches which 1s much below the nonnal of' a little over 200 inches.

Snowfall for November, December, March, and April Y8.8 all below normal. '.rempe turea were e%t;rem.eq

low

tor ·Januar;" and

vtud

velocities were much higher

,ban

nomal

tor

thi8 .,' otttl)" . I " .

'

.---location of instruments at the loveland station beside the highway maintenance garage was as in previous ye s since 1953 with 8-inch standard rain gage bygrothermograph on a platform above the station and a recording Friez (175 B) rain gage with staff gage located across the road inside the big curve at the foot ot the pass. All instruments functioned satisfactorily this season. Mr. Williamson collected daily records except in February when' he hurt his hand, and Mr. ~e Watlins' weekly plotted these data so maintenance personnel could see what had

happened and anticipate changes in weather and road conditions.

Attached 1s a table listing the slides for this season showing location size, date and time of occurrence, together with highway closure time. Another table g1 ves size and type of release for all seasons since

1950.

It

will

be noted that for this season

57

percentof the slides were reJ.eased by artillery fire which is somewhat better than the average figure of

45

percent. Also included in this report is the

station sUDJDl8.1"1' listing monthly precipitation temperature, wind velocity and direction, and avalanche occurrence. The daily precipitation and

snow depth records for IDveland station, Berthoud Pass, and Climax B.A.O. station are ~cluded at the end of the report. , The meteorological chart

for the station,gives a visual picture of weather factors and avalanche occurrence.

The same gun crew headed by Maintenance Superintendent Pat Murray has

-worked together since the fall. of

1957

and their experience in avalanche forecasting and control, together with efficiency and firing accuracy, is retlected in the records of slides controlled. This season on.l.y 84

rounds

ot

ammunition were used, as it was an unusual.l1' low snowfall season and the number

ot

slides was below normal.

Recommendations

1. Consideration is being given to shooting every Friday whenever there is a possibility of getting any slides. This should help solve the problem of having slides tie up week-end traffic except when a large storm occurs over the week-end. This policy of shooting on Friday is favored. ' 2. The anemometer should be moved to the ridge above the Seven Sisters

to a location selected for it.- (This has been a recommendation for·5 years.) Records are ot very little value at the present location.

3.

Closure of loveland Pass during extreme stormy periods should be considered. Actually, 1 t became closed with stalled cars and trucks creat1D8 a traffic block 80 that snowplows cannot work etf1cientq •

.

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Borland