Areas affected…portions of southwest and south-central
Nebraska…central and northwest Kansas and east-central Colorado
Concerning…Severe potential…Watch likely
Valid 242055Z – 242300Z
Probability of Watch Issuance…80 percent
SUMMARY…Thunderstorms are expected to develop and increase in
intensity after 4 to 5 pm CDT with large hail and damaging winds
likely, and a tornado or two possible. Trends are being monitored
and a watch is likely prior to 6 pm CDT/23Z.
DISCUSSION…A gradually-deepening cumulus field was noted on
visible satellite imagery across western portions of the KS/NE
border at 2045Z. This area is on the southern periphery of a
mid-level convectively-enhanced vortex, and in advance of a compact
upstream impulse over northeast CO/NE Panhandle. Low-level moisture
advection beneath steepening mid-level lapse rates have contributed
to MLCAPE of 1500-2000 J/kg, and with additional diurnal heating
some further increase in surface-based instability is likely.
Mid-level northwesterly flow should increase slightly through this
evening, resulting in effective shear averaging 35-45 kts.
Thunderstorms are expected to develop over northern/western portions
of the discussion area over the next few hours in the presence of
negligible CINH and weakly confluent low-level flow. Initial mode
will include supercells, with large hail, possibly significant, and
damaging winds the primary threats. Notable low-level
veering/curved hodographs in RAP forecast soundings, primarily
across the KS portion of the discussion area, suggests some
potential for low-level rotation and perhaps one or two tornadoes
with more discrete storms in the first couple of hours after
initiation. With time, upscale growth is anticipated as a cold pool
organizes and the convective complex moves southeast this evening
aided by modestly increasing low-level warm advection. Damaging
winds should become the dominant threat, with large hail remaining
possible with the strongest updrafts.
Trends are being monitored and a watch is likely prior to 23Z.
…Please see www.spc.noaa.gov for graphic product…
LAT…LON 40270164 40610078 40710029 40679983 40339925 39989870
39369837 38839833 38379842 37779894 37690023 38740226
39140235 39740226 40270164