Non-Mesocyclonic Tornadic Environments
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JOHN UTECH
1. Introduction
Over the last few years a tremendous amount of research has been focused on mesocyclonic tornadogenisis. Focusing
on many parameters, which have followed a standard for many broadcast and operational meteorologists. The terms
land spout, waterspout and gustnados seem to have fallen into a category of non-supercell
tornadoes (Caruso, Davies 1). However, it is also very important to keep in mind that
the general public does not define a difference between land spout, waterspout or gustnado. The
vast majority of the general public strongly believes that, “If it is spinning and debris is
visible, it’s a Tornado!” Keeping this in mind, this paper is for the purpose of increasing
the awareness of tornados that can occur in a non-mesocyclonic environment for future broadcast
and operation meteorologists. When these types of tornados occur, many meteorologists have been
caught by surprise and have to quickly find reasons that tornado watches or warnings were never
issued. This paper is designed to increase awareness of the future broadcast and operation
meteorologist of this type of weather event. Items covered below will include the
geographical locations including an area of focus, the parameters that will need to be
closely watched, how to apply the parameters into ones forecast, the negative impacts
if a meteorologist chooses to ignore those parameters and finally a solution and the benefits
from increasing ones awareness of the non-mesocyclonic tornado.
2. Geographical Location
What geographical location are “non-mesocyclonic tornados” found? Different research and observations have
placed these events from parts of South Dakota, south to central Texas, but for the purpose of this paper
the area of focus will be contained to south central Kansas including the City of Wellington. This area
is located within the region termed “Tornado Alley”. It should also be noted that the majority of these
events coincide with timing of tornado season in the central plains, that being at anytime, but not
limited to, between the months of April through June for the State of Kansas (NSSL 1). This paper will
examine an event that occurred outside the normal “peak season” in south central Kansas.
3. Parameters
After examining several case studies there appears to be a few common ingredients in the atmospheric
environment to be favorable for formation of a non-mesocyclonic tornado. According to research by
meteorologist Jon Davies (Davies 2), a forecaster should be aware of the following parameters:
A stationary front or a very slow moving boundary with a very small temperature gradient, or even a wind shift boundary.
A surface heat axis intersecting the boundary,
A deep moisture sounding,
Low surface based CAPE below 3000m but, just above the LCL
Higher that expected LCL, above 2000m, followed very closely by a LFC elevation
Steep lapse rates in the lower 2 to 3km
And very small CIN readings
Some of the above parameters are displayed on the skew-t chart (Figure 1). If one does not look for the
above parameters, it would be easy to only see a “loaded gun” sounding and unknowingly ignore other parts
of the sounding. It should also be noted that research has shown that an area of overlapping of steep
low level lapse rates >7 C/km-1 and 0-3 km MLCAPE. > 30 J/KG-1, in Figure 2, should not be ignored. In
addition to the above parameters it appears that these non-mesocyclonic tornados can form in the early
updraft stage of a larger mesocyclonic storms life cycle as indicated in the radar image shown
in Figure 3. It is interesting, as if one examines closely in Figure 3, a small southbound
outflow boundary moving into the area of overlapping steep lapse rate and 0-3km MLCAPE. This
“boundary” appeared to be the focus of sudden increased vorticity. It did produce tornado
that caused F2 damage south of Wellington, Kansas. (CRH-1) Observers of the tornado
commented that it formed on the ground first and then ascended into the high cloud base
with a full condensation as shown in Figure 4. In addition, there was not an indication
of a mesocyclone on radar before or during the time of the event; however, there was
a severe thunderstorm watch in effect for the area as well as a tornado warning. The
warning, according to WCM Chance Hayes (National weather service forecast office in
Wichita, Kansas) was issued due to the very dedicated spotter network in the area.
4. Forecast Challenge
Forecasting a non-mesocyclonic tornado should not be stressful. Instead, a forecaster needs to just be
aware of the possibility that one could occur and occur very quickly. If the forecaster is aware of
the possibility of a tornado, outside the standard mesocyclonic environment, the chances of a
“surprise” tornado can be greatly reduced. Many times this can be challenging as the larger
synoptic setup can easily draw the forecasters total attention. But the Impact on not being
aware of the possibility if a non-mesocyclonic tornado could take place would be catastrophic!
5. Negative Impacts
For broadcast meteorologists the result would be lack of confidence from the public. This could also
involve the station as a whole. The possible loss of advertisers income, the damage to the stations
reputation and even the dismissal of the “on-air meteorologist” involved is not out of the question.
For the operational meteorologist the negative impacts could also be far reaching. Negative impacts
could include lack of respect and confidence from the local and state media, emergency management
personnel and storm spotters. Then residents of the damaged areas will be heard on newscasts
across the state and nation stating “we had no warning!”
6. Solutions and Conclusion
The solution is actually simple. To prevent the possible negative impacts, stated above, this paper offers
some simple precautions to the broadcast and operational meteorologists. Take some time to increase
ones awareness of the non-mesocyclonic tornado parameters. Make use of available data to look
closer at all data on a skew-T chart as well as surface and model graphics. For the broadcast
meteorologist this can be translated into simply making the viewer aware that there is a
possibility of a tornado in an area of concern. For the operational meteorologist, this
awareness will allow the information to be passed along to emergency management personnel
in the area as well as their spotters being prepared as well as the broadcast meteorologist
and their viewers. To conclude, ones awareness is a giant step to prevent
being “surprised” by a tornado in a non-mesocyclonic environment.
Figure 1
http://members.cox.net/jondavies2/nonmesotor_casestudies/nonmesotor_casestudies.htm
Figure 2
http://www.nwas.org/ej/cardav/figure1.html
Figure 3
http://members.cox.net/jondavies2/nonmesotor_casestudies/nonmesotor_casestudies.htm
Figure 4
http://members.cox.net/jondavies2/nonmesotor_casestudies/082704wellingtontor1_rrenfro(c).jpg
References:
-NSSL 1: http://www.nssl.noaa.gov/users/brooks/public_html/tornado/#state
-CRH 1: http://www.crh.noaa.gov/ict/newsletter/Fall2004.php#Section01
-Davies 1: Meteorologist Jon Davies Brief; Case Studies of Non mesocyclone Tornadoes in Small SRH and or High LCL Environments
http://members.cox.net/jondavies2/nonmesotor_casestudies/nonmesotor_casestudies.htm
-Davies 2: Tornados Associated with small SRH or High LCL Environments
http://members.cox.net/jondavies2/4thSSSS.pdf
-Caruso, Davies 1: Tornadoes in Non-mesocyclone Environments with Pre-existing Vertical Vorticity along Convergence Boundaries
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