A Light Snow Pack

February 25, 2010

Snow Water @ 3600' west of Mt. Hood

Snow Water @ 5,400' on Mt. Hood

Here are two images showing the poor state of the snowpack up in the Cascades. Friday is Snow Survey Day when the local media gets escorted up to a snow survey site on Mt. Hood by the NRCS. Those are the folks that maintain all the SNOTEL sites in the mountains. If you’ve lived in the Western USA long, you know that we have generally dry summers. The eastern USA is drier in the winter, but moist in the summer; the opposite is true out here. That means we rely on winter snow in the mountains as our “reservoirs” of water to get us through the dry season. So how are we doing? The January survey wasn’t good due to a dry and mild month. Very little changed this month; in fact we are down slightly in most spots during the last 30 days or so.  As a result we can expect low runoff from our rivers this spring.  There have most definitely been years in the past where we get a good dumping of mountain snow in later March or even early-mid April, but nothing of the sort appears likely through at least the first week of March according to the long-range models.

Some interesting things to point out on the charts (click for a closer view).  The light blue lines indicate the average snowpack through the winter.  The green is last winter.  The dark blue is this winter so far.  Notice the difference this winter between the higher elevation sites and lower sites.  Even though it’s a lower than average year up high, the snowpack has continued to slowly increase.  Compare that to the lower elevation spot (3600′ north of ZigZag).  See how the snowpack hasn’t changed in months?  Small snowfalls have been offset by some warm rains which melt the snow.  Also notice the very wet and cool March last year which dumped snow up in the Cascades.  I have a feeling that won’t be the case (as already mentioned) through at least the first half of the month.

As mentioned in yesterday’s post, and even more pronounced on the maps tonight, the split-flow pattern continues next week.  In fact I don’t see all that much rain next week.  I also see the 00z GFS has 850mb temps at/above -1 C degrees all the way through ten days!  No snow below 3,000′ in sight…

I’ll be off for tomorrow, so no posts until Monday.

Chief Meteorologist Mark Nelsen