Over the past 26 years, the month of October has witnessed a
total of 5 tornadoes within the Texas and Oklahoma Panhandles. In
addition, of the nearly 600 tornadoes that ocurred during this time
period, only 1% of the tornadoes touched down between midnight and
1 AM. The statistics would indicate that the tornado on October
17th should not have happened, especially considering that it touched
down just after Midnight. So what caused this rare tornado? A number
of factors played out during the day and nightime hours that allowed
the thunderstorms to become tornadic.
Normal high temperatures for mid October are right around 72 degrees.
The high temperature on October 16th peaked in Amarillo at 78 degrees.
This allowed sufficient surface heating to take place. Plus, surface
winds were generally out of the south to southeast across the central
to eastern panhandles. Surface moisture was able to stream north
into the panhandles. The combination of the warm afternoon temperatures
and abundant low level moisture provided an unstable atmosphere
capable of supporting thunderstorm development. Also, the average
wind speed for the day was just over 20 mph. But this was just at
the surface. The winds above the surface were even stronger and
formed a low level jet...or an area of very fast moving air surrounded
by slower moving air. Furthermore, the wind direction was veering
with height. This means that winds near the ground were blowing
from the southeast while winds above the surface were coming out
of the west. This turning of the winds with height allowed the thunderstorms
to rotate. Finally, an upper level low pressure system was approaching
the panhandles from the west. This system brought short wave energy
that move over the panhandles and helped trigger the storms.
In other words, the atmosphere was primed for thunderstorms and
certainly appeared to support rotating storms which could lead to
tornadoes. When the storms began to form during the late evening
hours on October 16th, they quickly intensified and became severe.
The first storms moved into the southern Texas Panhandle (southern
Deaf Smith and Randall Counties) after 10 PM and began producing
large hail up to Golf Ball size in Amarillo around 11:30 PM. However,
the storm that impacted Amarillo was not the tornadic storm. The
tornadic storm moved into southern Randall county near midnight
and produced the tornado around 12:16 AM on October 17th. The results
from the storm survey rated the tornado as a very high end EF1 and
lasted for nearly 20 minutes. Please
click HERE to read the full damage survey from this tornado. |