Heavy Rainfall for Portions of the West and Southern Plains; Dangerous Heat for the Northwest

Monsoonal flow coinciding with a frontal boundary will focus more showers and thunderstorms across the central Great Basin, central Rockies, Southwest into the Southern Plains. Heavy rainfall may bring about instances of flash flooding. Meanwhile, record setting heat continues for the Pacific Northwest through Monday. Heat combining with dry conditions could allow for any fires to quickly spread. Read More >

February 4, 2006
Winter Weather Event Review
Section 6: Summary

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This was a very difficult warn verses no warn event. The forecasters were challenged with mixed signals leading up to the event. On the one hand the model trends showed an overall westward and warmer trend but also tended to linger precipitation longer when it was cold enough for snow. Also, HPC solutions trended back and forth and trended above warning criteria when Wilmington had to make the warn/no warn decision.

Some preliminary findings:

Although the model soundings and QPF showed the potential for warning criteria snowfall and lagged precipitation longer in the cold air the model signals (upper divergence, isentropic lift, favorable forcing) indicated that the accumulating snow would end quicker than the QPF indicated.
Conceptual models regarding path of the synoptic features and trends proved to be helpful in this case.
Boundary layer temperatures and precipitation type was crucial to the changeover and height of the freezing level was superior to thickness techniques.
The warm ground at the start of the event played a role in keeping snow accumulations down.
A surface low track along the spine of the Appalachian as initially indicated by the NAM solution is not a climatologically favored track.