Mesoscale Discussion 1903

Issued

Oct 26, 2021, 4:51 PM CDT (21:51 UTC)

Expired

Oct 26, 2021, 6:15 PM CDT

In force

84 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch likely

Chance of a watch

95%

The Dodge City radar (KDDC), 60 km from the middle of the area, began a volume at 21:57 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

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• Tornado Watch 536Oct 26, 6:15 PM CDT

320 
ACUS11 KWNS 262152
SWOMCD
SPC MCD 262151 
OKZ000-KSZ000-NEZ000-TXZ000-262315-

Mesoscale Discussion 1903
NWS Storm Prediction Center Norman OK
0451 PM CDT Tue Oct 26 2021

Areas affected...portions of southwest Nebraska into central Kansas
and northwest Oklahoma

Concerning...Severe potential...Watch likely 

Valid 262151Z - 262315Z

Probability of Watch Issuance...95 percent

SUMMARY...The potential for severe thunderstorms is increasing
within the warm sector, ahead of the cold front/dryline. Damaging
gusts appear to be the main threats though a couple tornadoes and
instances of large hail are also possible. A WW issuance is expected
by 23Z.

DISCUSSION...Latest METAR observations depict the gradual eastward
movement of the dryline and cold front across the central Plains
given the approach of a deepening surface low and couple mid-level
trough. Convective inhibition continues to erode as the boundary
layer mixes and surface temperatures exceed 80F and dewpoints
approach the mid 60s F. 8-8.5 C/km mid-level lapse rates are
overspreading the warm/moist low level airmass, contributing to
1500-2000 J/kg MLCAPE. Simultaneously, intensifying southerly
low-level flow with the approaching upper trough will contribute to
intensifying deep-layer and low-level shear, with up to 50 kts of
effective bulk shear and 400 m2/s2 effective SRH expected to develop
ahead of the dryline in the next few hours, when convective
initiation will occur. 

Meridional/unidirectional tropospheric wind profiles and strong
forcing for ascent ahead of a merging dryline/cold front suggests
that transient supercell structures will develop and rapidly merge
into line segments/squalls. The well-mixed boundary layer and up to
50 kt 850 mb flow suggests that strong to severe gusts should easily
reach the surface within and in advance of any well-developed storm
cores/line segments. Occasional bouts of large hail are also
expected given the 8+ C/km mid-level lapse rates. Though modest,
some low-level directional shear is evident in RAP forecast
soundings, suggesting that the more persistent supercells or
dominant storms embedded within the squall may acquire occasional,
strong low-level rotation, with at least a couple tornadoes
possible. However, the degree of tornado potential will be largely
dependent on the number of discrete/dominant storms that can form
and how long they persist, which remains uncertain. Nonetheless,
organized severe storms are expected in the next few hours, and a WW
will be issued to address this threat.

..Squitieri/Hart.. 10/26/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...ICT...OUN...GID...LBF...DDC...GLD...AMA...

LAT...LON   35769974 36430009 37160018 38090035 39100060 40290093
            40840079 41110059 41200025 40849966 40159898 39439854
            38429798 37499781 36879785 36309814 35839841 35559897
            35589944 35769974

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The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.