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- Jan 12, 2018
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How much damage? You're desperate.On Friday afternoon at 415 pm a tornado touched down in western Spokane County near Fairchild Air Force Base.
A preliminary storm survey conducted by personnel at National Weather Service Spokane concluded that this tornado ranks as an F0 tornado on the Fujita Scale. The survey team observed shingles blow of roofs, some shallow rooted trees that were uprooted, and damage to two doors on a shed, all indicative of an F0 tornado with peak winds approaching 72 miles per hour.
Tornadoes in Washington are quite rare, with an average of only 1 tornado each year in the state. See http://www.erh.noaa.gov/er/cae/svrwx/tornadobystate.htm for details.
Here is a detailed explanation of the events:
After reviewing the radar data, it concludes that the tornado may have been produced by at least three separate processes acting in conjunction.The dominant one was the cyclonic line-end vortex on the northern end of the N/S "bowing" line segment. This vortex was within the pcpn band, not ahead of it as with classic supercell tornadoes (under updraft and rain-free cloud base). At the time of the tornado, a weak echo region was visible in this vortex.
Another process would be the merging of two separate storm clusters... the southern "bowing" line segment and the more E/W storm to the north (the storm the initial SVR was issued for). This merger could be analogous to a cold front-warm front occlusion...enhancing cyclonic vorticity and rapidly converting horizontal vorticity into vertical vorticity through vortex stretching by the updraft at the point of occlusion.
No tornadoes, eh. LOL