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Re: Recent snows in Washington DC area and building collapses

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   Drew,
     Out here 70 miles west of Washington D.C., the design ground snow load is 35 psf - to "varies locally" in the Allegheny Mountains. The ground snow load diminishes to 30 psf in the lower elevations east of Bull Run Mountain (Catoctin Mountain in Maryland) and to 25 psf east of Washington.
     We had a lot of snow - depending on specific local history and history of this storm, it was second or third deepest on record, maybe the deepest some places, and for the first six hours or so, the snow was rather dense. It got fluffier as the storm continued. Then we had another 6" to 18" a few days later and that drifted, a lot.
      Parts of the area have had more snow this winter than ever before on record, and most of the rest of us are within a few inches of the record (locally we're about 2" shy of the 1917 record).
      If there is more Sunday night, as predicted, then the design load may be lower than it should be, but there are not usually 3-4 storms from the Gulf of Mexico in a winter. Usually it's none or one, and the rest of our snow is from Alberta, not known for it's ability to put a lot of moisture in the air.
     And we had a large rainstorm before the first snow in December from the Gulf and another with nearly 2" of water a few weeks ago. Had it been 10 degrees colder, this winter would have already broken all records.
   Hope this is not too anecdotal for you.
   Jim Getaz
   Winchester, Virginia