MD 0255 CONCERNING SEVERE POTENTIAL…TORNADO WATCH LIKELY FOR SOUTHEASTERN KS…NORTHEASTERN OK…NORTHWESTERN AR…AND SOUTHWEST INTO CENTRAL MO
Mesoscale Discussion 0255
NWS Storm Prediction Center Norman OK
0250 PM CST Mon Mar 06 2017
Areas affected...southeastern KS...northeastern OK...northwestern
AR...and southwest into central MO
Concerning...Severe potential...Tornado Watch likely
Valid 062050Z - 062215Z
Probability of Watch Issuance...95 percent
SUMMARY...Thunderstorms are forecast to develop during the 22-01 UTC
period. Initially, a couple of supercells are expected with an
attendant risk for 2+ inches diameter hail, a couple of tornadoes
(perhaps a strong tornado), and a damaging-wind risk forecast to
evolve as storms grow upscale later this evening.
DISCUSSION...Visible-satellite imagery shows a bubbling cumulus
field generally near and east of the I-35 corridor in OK and
extending into southeastern KS. Surface observations show the 60
degree F isodrosotherm steadily moving northward through
east-central and into northeastern OK during the past several hours.
GOES sounder and GPS PW data show PW values rising into the
1.00-1.10 inch range and this agrees with the latest RAP sounding
initialization. The RAP shows the lowest 100-mb mean mixing ratios
increasing into the 11-12 g/kg range from 10-11 g/kg during the next
several hours prior to convective overturning in the model.
Steep to very steep 700-500 mb lapse rates (near 8 degrees C/km) and
the increasing boundary-layer moisture are resulting in moderate
buoyancy (1500-2000 J/kg MLCAPE) across western half of the
discussion area. Enlarging hodographs this evening (300-500 m2/s2
0-1 km SRH) will become more favorable for low-level mesocyclone
development. The primary uncertainties regarding the tornado risk
involve the actual quality of low-level moisture and the vertical
wind profile exhibiting some veer-back-veer tendency. Nonetheless,
it seems likely a significant-hail threat will develop with initial
storms early in their convective lifecycle. The overall tornado
risk will probably be related to how quickly the convective mode
changes from quasi-discrete to linear. After the transition to a
linear mode occurs, severe gusts yielding a wind-damage hazard will
become increasingly possible, along with some lingering tornado risk
with the stronger storms.
..Smith/Grams.. 03/06/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...SGF...EAX...TSA...TOP...ICT...OUN...
LAT...LON 35489690 37989658 38459312 37919203 36679199 36049272
35549420 35489690
from SPC Mesoscale Discussions http://bit.ly/2muI97n
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