The First Snowstorm of the Winter of 2006-2007
Snowstorms of This Winter-Click here Snowstorms of Past Winters-Click here
Obs. Num. Time of Observation JANUARY
21     2007
Total Frozen Precip. Inches Total Melted Precip. Inches Temp. F Remarks for the Time Period
   0      1227 hrs.    0.0   0.00  28.5 F   Snow started as VERY fine snow particles that were more like frozen drizzle; no crystals visible in the snow. The snow then stopped after about 5 minutes and started again at 1245.
   1      1330 hrs.   0.2  Trace  25.6   At 1315 the ground started to become white and a few patches of white on the street. The snow flakes now have some broken crystals mixed in with icy particles and snow crystals that are fragments of broken crystals with moderate riming.
   2      1430 hrs.   0.4  0.03  25.2   The low dew point temperature and dry air this morning has added to the evaporative cooling and the temperature decrease of 3.3 degrees since the onset of the snow. The dew point temperature has been rising and the air temperature decrease should almost stop by the end of the next hour. The snow rate is now light and our street is already getting white. A few very small snow crystals now but many are broken crystals mixed in with icy particles with moderate riming.
   3      1530 hrs.    0.7   0.06  25.3   The snow rate is light but a fairly constant rate and our street is now white. The snow crystals are about the same as last hour with no aggregates of crystals making for very small flakes.
   4      1630 hrs.    0.9   0.08   24.9   The snow crystals are broken with light riming mixed in with some very small icy particles and no aggregates. This was the first time today that a few thin very small six-sided plate crystals were observed.
   5      1730 hrs.   1.1   0.12  24.7   Snow in a standing precipitation gauge has been melted to check accuracy of tripping bucket gauges. Liquid precipitation amounts have been corrected this hour on the table by melting snow in standing precipitation gauges. About ten minutes after the last report the first snow flake aggregates were observed. There are still a few thin very small six-sided plate crystals observed. Also some small aggregate flakes continue to occur during the past hour and a moderate snowfall rate started at about 1720.
   6      1800 hrs.   1.7  0.17  24.9   The snowfall rate has increased to a moderate rate this past half hour with larger aggregate flakes. The western edge of moderate snow is now near the western edge of Fairfax County.
   7      1830 hrs.   1.8  0.19  25.2  The snowfall rate decreased shortly after the 1800 reading and sleet started around 1820. The BIG news is that we now have sleet that will cause packing of the snow and reduce snowfall totals!
   8      2000 hrs.   1.7   0.23   26.2   The snow is over but a light frozen drizzle and liquid drizzle freezing on contact is currently occurring. The snow has settled to 1.7 inches and has developed a crust. This will be the last report on this snow.