P3.1
an analysis of a prolific tornado producing cyclic supercell
thunderstorm
in NUCKOLLS county nebraska, may 24, 2004
High Resolution Figures
Figure 1 Locations and tracks of 11
tornadoes associated with the Nuckolls County storm in Nebraska (source SPC, SeverePlot).
Figure 2 Tornado I (right, near
Deshler) at 2115 UTC. View towards the southwest. (Photo: John
Monteverdi).
Figure 3 Belleville, KS tornado at
2200 UTC. View towards the northwest.
(Photo: Thom Trimble).
Figure 3 Visible satellite imagery at 1932, 2002, 2012 and 2032 UTC showing
storm initiation near Hastings.
Figure 3 Subjective analysis of
(a) 1513 and (b) 1743 UTC 24 May 2004 surface data. Storm initiation area
shown as red box on b. Region with dew point temperatures 68F and greater shown on b.
Figure 4 (a) Base reflectivity, 0.5o
tilt,; (b) storm relative velocity, 0.5o
tilt,; and (c) base reflectivity, 3.4o tilt, (2051 UTC) from KUEX,
at approximate time of Ruskin tornado report (tornado G on Figs. 1 and 2 and
also shown in Fig. 5)
Figure 5 The first long-track
tornado (G on Fig. 1 and Table 1) associated with the Nuckolls County storm at
2058 UTC, near Ruskin, view to the southwest. (Photograph by Thom Trimble)
Figure 6 Base reflectivity (2105 UTC) from KUEX at 0.5o
and 3.4o degree tilts, illustrating BWER, as explained in text. T shows the position of the long-track
tornadoes near Hebron, seen in Fig. 2.
The KUEX radar was intersecting the storm at a range of 56.7 km and at
heights of 650 m (0.5o tilt) and 3366 m (3.4o degree tilt).
Figure 7 NCEP Reanalyses
NAM data, showing key 700 mb features 1800 UTC, 24 May
2004. (a) 700 mb heights d(m) and temperatures (C); (b) 700 mb heights (dm) and
vertical velocity (µbar s-1); (c) 1000-500 mb thickness (dm) and 700
mb absolute vorticity (10-5 s-1).
The KTOP (Topeka, KS) rawinsonde
ascent was closest to the Nuckolls County storm at 1800 UTC on 24 May. This ascent was deep in the warm air
south of the boundary, and showed the lid clearly (not shown) while the KOAX (Omaha, NE
–not shown) sounding was just north of the synoptic scale boundary and
away from the lid edge.
Figure 8 NCEP reanalysis of surface
based CAPE (colors) and CINH (black contours) in J/kg at 1800 UTC 43 May 2004.
Figure 9 1800 UTC 24 May 2004 proximity
sounding for Beatrice, Nebraska, obtained by combining (a) KTOP environmental
(red) and dew point (blue) lapse rates (from bottom of lid to surface) and (b)
KOAX environmental lapse rate (from top of lid) Inset is 1600 proximity
hodograph, shown in Fig. 12. Mandatory and significant level wind information
for KTOP and KOAX plotted at right.
Figure 10 Proximity Hodograph for the
Nuckolls County storm obtained from the 1600 UTC Fairbury (FBYN) profiler and
the KTOP wind profile at 1800 UTC, as explained in the text.