Skip Navigation Linkswww.weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service Forecast Office   NWS logo - Click to go to the NWS homepage
WFO Greenville-Spartanburg, SC
 

Local forecast by
"City, St"
  

Tornadoes Strike Near Fallston

and Lincolnton on April 19, 2008

Patrick D. Moore
NOAA/National Weather Service
Greer, SC

Funnel cloud near Lawndale, NC, shortly before touching down near Fallston, on April 19, 2008

A funnel cloud was observed near Lawndale, North Carolina, shortly before a tornado touched down near Fallston on April 19, 2008. The image was provided by WSOC-TV Charlotte and taken by an unknown viewer. Used by permission.

Author's Note: The following report has not been subjected to the scientific peer review process.

1.  Introduction
An unusually small but well-organized thunderstorm developed over 
Cleveland County, North Carolina, during the evening of Saturday, 
April 19, 2008.  The storm produced two tornadoes as it moved 
across the eastern part of Cleveland County and the western part 
of Lincoln County.  The first tornado touched down at 805 pm EDT 
19 April (0005 UTC 20 April) near the Double Shoals community and 
lifted at 811 pm (0011 UTC) near Fallston.  Houses and trees were
damaged along Double Shoals Road and Fallston-Waco Road.  The 
second tornado touched down near the intersection of State Highways 
182 and 274 in southwest Lincoln County at 820 pm (0020 UTC) and 
produced an intermittent damage path that extended to the northwest 
side of Lincolnton.  The tornado damaged a chicken farm on Guy
Heavener Road, and trees and homes on Howard's Creek School Road 
and Betterbrook Lane.  The second tornado dissipated at 837 pm 
(0037 UTC).  Both tornadoes produced damage that was rated EF-1 on 
the Enhanced Fujita Scale.  A few reports of large hail were received 
as the storms moved across the northwest Piedmont of North Carolina, 
but overall the severe weather was relatively localized (Fig. 1).

[Note: all times hereafter will be referenced to Universal Time 
Coordinated (UTC), which is Eastern Daylight Time (EDT) plus four 
hours.]

Click here for a list of local storm reports for this event.
Severe thunderstorm and tornado reports for 19 April 2008
Figure 1.  Severe thunderstorm and tornado reports received by the 
Storm Prediction Center for the 24 hours ending 1200 UTC 20 April.
The events of 19 April 2008 were interesting in that the storms
developed in an environment that was initially thought to be not 
conducive to thunderstorms with vigorous updrafts, because of a
lack of instability and buoyancy.  In fact, several small 
thunderstorms developed and they exhibited many of the same
characteristics of storms that are classified as supercells
(Doswell and Burgess 1993).  Even more interesting was the absence
of cloud-to-ground lightning in the thunderstorm for 20 minutes 
prior to tornadogenesis and while the tornadoes were on the ground.
Similar characteristics were noted by Markowski and Straka (2000)
in a study of a miniature tornadic supercell thunderstorm event
in central Oklahoma.
2.  Synoptic Features and Pre-Storm Environment
A vertically stacked low pressure system was centered over Illinois 
on the morning of 19 April.  The 500 mb analysis at 1200 UTC showed 
a mid-level jet of 50 to 80 kt winds bringing colder temperatures 
around the bottom of the upper low and toward the Carolinas (Fig. 2).  
Meanwhile, a short wave trough manifested as a swirl in the water 
vapor satellite imagery over Missouri was expected to rotate across 
the Tennessee Valley and into the western Carolinas late in the day 
(Fig. 3).  Of note on the 850 mb analysis was the tongue of moisture
moving up from the northeastern Gulf of Mexico and stretching across 
Georgia (Fig. 4).  The moisture was moving northward ahead of an 
approaching cold front that stretched from a surface low located 
over northern Illinois, down across the Ohio and Tennessee valleys 
to the Florida Panhandle (Fig. 5).
Click here to view a 12 frame Java loop of water vapor imagery from 
1145 UTC to 2345 UTC.
500 mb analysis at 1200 UTC 19 April 2008
Figure 2.  SPC objective analysis of 500 mb geopotential height, 
temperature, and wind barbs at 1200 UTC 19 April.  Click to enlarge.
Water vapor imagery at 1145 UTC 19 April 2008
Figure 3.  GOES-12 water vapor imagery at 1145 UTC on 19 April.  
The warmer colors represent relatively dry air at mid-levels while 
the cooler or white shades represent moisture at mid levels.  
Click to enlarge.
850 mb analysis at 1200 UTC 19 April 2008
Figure 4.  SPC objective analysis of 850 mb geopotential height, 
temperature, dewpoint, and wind barbs at 1200 UTC 19 April.  
Click to enlarge.
Surface fronts and pressure analysis at 1200 UTC 19 April 2008
Figure 5.  Surface fronts and pressure analysis from the 
Hydrometeorological Prediction Center at 1200 UTC 19 April.
Click to enlarge.
The combination of strong winds at mid levels, dynamic forcing 
from the passage of the upper level short wave trough, and a 
conditionally unstable atmosphere ahead of the surface front was 
expected to support the formation of a few severe thunderstorms 
in the afternoon and evening.  However, the threat was not enough 
to warrant a Slight Risk on the updated Day 1 Convective Outlook 
issued at 1555 UTC by the Storm Prediction Center (SPC).  A 
relative lack of instability was the limiting factor, mainly due 
to extensive morning cloudiness ahead of the front and dewpoints 
only in the lower to middle 50s at around 1600 UTC.
The perceived threat of severe weather had not changed by the 
late afternoon.  The Day 1 Convective Outlook updated at 1934 UTC 
continued to indicate the possibility of isolated strong to severe 
thunderstorms.  Dewpoints climbed into the upper 50s and lower 60s 
in some locations immediately ahead of the front which was crossing 
the Appalachians at 2100 UTC (Fig. 6).  Cloud cover thinned across 
the North Carolina Foothills which allowed temperatures to reach 
the middle 60s (Fig. 7).  However, low levels of the atmosphere 
were only weakly buoyant with Convective Available Potential Energy 
(CAPE) under 500 J/kg. 
Regional surface fronts and pressure analysis at 2100 UTC 19 April 2008
Figure 6.  Regional surface fronts and pressure analysis at 2100 UTC 
19 April.  Observations are shown using the conventional station  
model.  Click to enlarge.
GOES-12 visible image at 2045 UTC 19 April 2008
Figure 7.  GOES-12 visible satellite image at 2045 UTC 19 April.
Click to enlarge.
By the early part of the evening, the front triggered a line of 
showers and thunderstorms across the central Appalachians and 
northwest North Carolina (Fig. 8).  Meanwhile, an isolated 
thunderstorm had formed over the southern Foothills of North 
Carolina.  By all measures, buoyancy and instability ahead of 
the front were weak at 2300 UTC (Fig. 9).  However, east of the 
mountains the effective bulk shear surpassed 40 kt (Fig. 10) and 
Storm Relative Helicity (SRH) was nearly 150 m2/s2 (Fig. 11).  
Both values were in the range that supported the development of 
supercell thunderstorms.  An upper air sounding released into the 
pre-convective environment near Greensboro, North Carolina (GSO), 
around 2300 UTC showed similar low values of CAPE and high values 
of SRH and shear (Fig. 12).
Regional  mosaic of radar reflectivity at 2300 UTC 19 April 2008
Figure 8.  Regional radar reflectivity mosaic at 2300 UTC 19 April 2008.  
Click to enlarge.
Most unstable CAPE at 2300 UTC 19 April 2008
Figure 9.  SPC objective analysis of most unstable CAPE (contours) 
and lifted parcel level (shaded) at 2300 UTC on 19 April 2008.  
Click to enlarge.
Effective bulk shear at 2300 UTC 19 April 2008
Figure 10.  SPC objective analysis of effective bulk shear (contours 
and barbs) at 2300 UTC 19 April 2008.  Click to enlarge.
0-1 km SRH at 2300 UTC 19 April 2008
Figure 11.  SPC objective analysis of SRH in the 0-1 km layer 
(contours) and storm motion (barbs) at 2300 UTC on 19 April 2008.  
Click to enlarge.
Upper air sounding from Greensboro, NC, at 0000 UTC 20 April 2008
Figure 12.  Skew T - log P diagram (upper left) and hodograph (upper 
right) of upper air sounding taken at GSO at 0000 UTC on 20 April 2008.  
A table of convective parameters and indices is shown at the bottom.  
Click to enlarge.
3.  Radar observations
Convective initiation occurred around 2130 UTC just to the 
northwest of the National Weather Service office located at 
the Greenville - Spartanburg Airport (GSP). The showers moved 
northeast over the next hour and gradually organized into a 
thunderstorm over southern Rutherford County, North Carolina, 
by 2300 UTC.  The thunderstorm crossed into west central 
Cleveland County around 2338 UTC, as seen by the Weather
Surveillance Radar at KGSP (referred to as the KGSP radar) 
(Fig. 13).  At this time the storm produced a cloud-to-ground 
lightning strike, which would be its last for the next hour.
Click here to view a 22 frame loop of composite reflectivity 
from the KGSP radar from 2135 UTC to 2328 UTC.
KGSP composite reflectivity at 2338 UTC 19 April 2008
Figure 13.  KGSP composite radar reflectivity at 2338 UTC on 
19 April 2008.  Intensity of precipitation is given by the color
table at the lower right.  Click to enlarge.
The thunderstorm organized rapidly over the next ten minutes. 
Cyclonic rotation was evident in the storm relative velocity 
observed on the southern flank of the storm on the lowest
elevation scan from the KGSP radar at 2348 UTC (Fig. 14).  The 
corresponding reflectivity image from that time showed an 
appendage on the southwest flank of the storm (Fig. 15), but 
interpretation of the data was difficult because of the small 
size of the cell (about 8 miles in diameter) and the resolution 
of the radar beam.  The reflectivity appendage was more apparent 
when the data were viewed using the GR2Analyst software package, 
which smoothed the data (Fig. 16a).  Consideration of the lowest 
four elevation scans from KGSP at that time revealed a weak echo 
region underneath a suspended high reflectivity core, indicative 
of an inflow of unstable air feeding an updraft (Fig. 16).  A 
cross-section through the high reflectivity core shows the 
shallow nature of the cell (Fig. 17).  The sounding in figure 12 
showed the freezing level just above 9,000 feet.  The high 
reflectivity (i.e. greater than 40 dbZ) in the Cleveland County 
storm extended only to about 15,000 feet.  This is well below 
the rule of thumb forecasters often use to identify cells that 
could produce cloud-to-ground lightning, which is 40 dbZ radar 
echoes 10,000 feet above the freezing level.
KGSP storm relative motion 0.5 degree scan at 2348 UTC 19 April 2008
Figure 14.  KGSP storm relative motion on the 0.5 degree scan at 
2348 UTC 19 April 2008.  The warmer colors represent motion away 
from the radar and the cooler colors represent motion toward the 
radar, which is located off the lower left corner of the image. 
Click to enlarge.
KGSP base reflectivity 0.5 degree scan at 2348 UTC 19 April 2008
Figure 15.  KGSP base reflectivity on the 0.5 degree scan at 
2348 UTC 19 April 2008.  The color table depicts the intensity of 
the precipitation. Click to enlarge.
KGSP base reflectivity at 0.5 deg, 1.5 deg, 2.4 deg, and 3.4 deg scans at 2348 UTC 19 April 2008
Figure 16.  KGSP base reflectivity at 0.5 degrees (a), 1.5 degrees (b), 
2.4 degrees (c), and 3.4 degrees (d) at 2348 UTC on 19 April 2008.  
The color bar depicts the precipitation intensity.  The white arrow 
in (a) shows the location of an inflow notch to the right of the 
reflectivity appendage.  The line in (d) denotes the location of the
vertical cross section in Figure 17.  Images created using GR2Analyst.  
Click to enlarge.
KGSP base reflectivity vertical cross section at 2348 UTC 19 April 2008
Figure 17.  KGSP base reflectivity vertical cross section at 2348 UTC 
on 19 April 2008.  The cross section was cut along the line shown in 
Figure 16 (d).  Image created with GR2Analyst.  Click to enlarge.
The rotational velocity, defined as the average of the absolute
value of the maximum inbound and maximum outbound velocity, 
remained around 20 kts for the next 20 minutes (Fig. 18), which 
is considered weak to minimal strength at a distance of 40 to 
50 nautical miles.  In the mean time, the first tornado touched 
down in Cleveland County near the Double Shoals community at 
0005 UTC on 20 April.  A significant increase in rotation, in 
this case taken as a 50 percent increase in rotational velocity, 
did not occur until the 0012 UTC scan (Fig. 19), by which time 
the first tornado had already lifted near Fallston. 
Observed rotational velocity from KGSP radar
Figure 18.  KGSP rotational velocity from 2313 UTC 19 April to 
0047 UTC 20 April.  The distance to the radar was approximately 
30 to 60 nautical miles during the time period.  The times that 
tornadoes were on the ground are indicated by the pink bars.
KGSP storm relative motion 0.5 degree scan at 0012 UTC 20 April 2008
Figure 19.  As in Figure 14, except for 0012 UTC on 20 April 2008.  
Click to enlarge.
The location of the Double Shoals - Fallston tornado was nearly 
equidistant from the KGSP radar and the Terminal Doppler Weather 
Radar north of the Charlotte - Douglas International Airport 
(referred to as the TCLT radar).  However, the TCLT radar did not 
offer any additional meaningful clues in the minutes leading up
to the Double Shoals - Fallston tornado, in spite of the better 
resolution of the data.  Rotational velocities were also in the 
weak to minimal mesocyclone range through approximately 0006 UTC 
(Fig. 20).  A significant increase in strength did not occur 
until the tornado was already on the ground.
Observed rotational velocity from TCLT radar
Figure 20.  As in Figure 19, except for the TCLT radar.  The 
distance from the storm to the radar was approximately 20 to 
45 nautical miles during the time period.  Range folded scans 
were indicated by a zero velocity.
A Tornado Warning was issued at 0015 UTC for northeastern 
Cleveland County and western Lincoln County based on the upward 
trend of the rotation observed on both the KGSP and TCLT radars.  
Although the rotation weakened over the next few minutes, a 
second tornado touched down in the southwestern corner of 
Lincoln County at 0020 UTC, near the intersection of State 
Highways 182 and 274.  This tornado had an intermittent path 
along the ground that lasted for 17 minutes before it finally 
lifted on the west side of Lincolnton.  The radar presentation 
at low levels was not as impressive as earlier, but the storm 
gradually gained strenth during the lifetime of the Western 
Lincoln tornado, as evidenced by the higher reflectivity in the 
core of the storm and its greater vertical extent at 0033 UTC 
(Figs. 21 and 22).
KGSP base reflectivity at 0.5 deg, 1.3 deg, 2.4 deg, and 3.1 deg scans at 0033 UTC 20 April 2008
Figure 21.  As in Figure 16, except at 0033 UTC on 20 April 2008. 
The line in (d) denotes the location of the vertical cross section 
in Figure 22.  Click to enlarge.
KGSP base reflectivity vertical cross section at 0033 UTC 20 April 2008
Figure 22.  KGSP base reflectivity vertical cross section at 0033 UTC 
on 20 April 2008.  The cross section was cut along the line shown in 
Figure 21 (d).  Click to enlarge.
The thunderstorm that produced the Double Shoals - Fallston and 
Western Lincoln tornadoes continued on a northeast path across 
the northwest Piedmont of North Carolina.  No additional reports
of tornadoes or wind damage were received, but penny to nickel 
sized hail was reported across Iredell, Rowan, and Davie counties.  
A similar thunderstorm developed behind and just to the south of 
the track of the first storm.  In many ways, the radar presentation 
of the second storm was more impressive, but this storm did not 
produce any severe weather.
Click here to view a 26 frame Java loop of 0.5 degree base 
reflectivity from the KGSP radar from 2338 UTC 19 April to 
0130 UTC 20 April.
Click here to view a 26 frame Java loop of 0.5 degree storm 
relative motion from the KGSP radar from 2338 UTC 19 April to 
0130 UTC 20 April.
4.  Summary 
The thunderstorm responsible for the two tornadoes across Cleveland
and Lincoln counties displayed several characteristics associated
with supercell storms.  It had a low level reflectivity appendage
and inflow notch, a weak echo region, and a mesocyclone through at
least half the depth of the storm that persisted for over one hour.
An amateur cellular phone video also showed a wall cloud feature.
That it was a miniature supercell made radar interpretation more
challenging.  While the mesocyclone was regarded as weak to 
minimal, it was possible that it might have been small enough to
prevent proper sampling by the radars.  This supercell was another
example of how the traditional mesocyclone strength nomogram 
(Andra 1997) might be misleading when applied to situations other 
than the classic Southern Plains supercell.  The rotational shear
nomogram of Falk and Parker (1998) (Fig. 23) shows promise in that 
regard.  The horizontal shear peaked at 0.012 s-1 at 2353 UTC, 
about ten minutes prior to the Double Shoals - Fallston tornado, 
which fell in the "tornado possible" category on the nomogram.
Rotational shear nomogram of Falk and Parker (1998)
Figure 23.  The rotational shear nomogram of Falk and Parker (1998).  
Click to enlarge.
The high reflectivity core did not extend high enough above the 
freezing level to allow the storm to produce cloud-to-ground 
lightning until after the last tornado lifted.  While unusual,
other examples of low cloud-to-ground flash rates in tornadic
supercells have been noted (Markowski and Straka 2000, McCaul
et. al. 2002, Perez et. al. 1997).  In the end, the presence of
cloud-to-ground lightning is not a requirement or a reliable 
precursor to tornado formation, especially in a thunderstorm with 
supercell characteristics.
Selected images of damage from the Double Shoals - Fallston 
tornado and the west Lincolnton tornado.  Images were taken by 
Vince DiCarlo (NWS) during a storm survey.  Click to enlarge.
References
Andra, Jr., D. L., 1997:  The origin and evolution of the WSR-88D
     mesocyclone recognition nomogram.  Preprints, 28th Conf. on
     Radar Meteorology,  Austin, TX,  Amer. Meteor. Soc., 364-365.


Doswell, C. A., and D. W. Burgess, 1993:  Tornadoes and tornadic 
     storms:  A review of conceptual models.  The Tornado:  Its 
     Structure, Dynamics, Prediction, and Hazards, Geophys. Monogr., 
     No. 79, Amer. Geophys. Union, 161-172.

Falk, K., and W. Parker, 1998:  Rotational shear nomogram for 
     tornadoes.  Preprints, 19th Conf. on Severe Local Storms,
     Minneapolis, MN, Amer. Meteor. Soc., 733-735.

Markowski, P. M., and J. W. Straka, 2000:  Some observations of 
     rotating updrafts in a low-buoyancy, highly sheared environment.  
     Mon. Wea. Rev., 128, 449-461.
	 
McCaul, E. W., Jr., D. E. Buechler, S. Hodanish, and S. J. Goodman, 
     2002:  The Almena, Kansas, tornadic storm of 3 June 1999:  A 
     long-lived supercell with very little cloud-to-ground lightning.  
     Mon. Wea. Rev., 130, 407-415.

Perez, A. H., L. J. Wicker, and R. E. Orville, 1997:  Characteristics
     of cloud-to-ground lightning associated with violent tornadoes.
     Wea. Forecasting, 12, 428-437.
Acknowledgements
Thanks are given to Steve Udelson and Lindsay Varner of WSOC-TV
in Charlotte, who supplied the images of the funnel cloud over 
Cleveland County.  The upper air analyses, mesoscale analyses, and
sounding were obtained from the Storm Prediction Center.  The
surface analyses were obtained from the Hydrometeorological
Prediction Center.  Radar mosaics and satellite imagery were 
obtained from the University Corporation for Atmospheric Research.
Radar data images were created using the Java Nexrad viewer from
the National Climatic Data Center and the GR2Analyst software
package. 


Local Climate Water & Weather Topics:
Current Hazards, Current Conditions, Radar, Satellite, Climate, Weather Safety, Contact Us

National Weather Service
Weather Forecast Office Greenville-Spartanburg
GSP International Airport
1549 GSP Drive
Greer, SC 29651
(864) 848-3859
Questions or Comments? Send us email
Page last modified: August 26, 2011

Disclaimer
Information Quality
Credits
Glossary
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities