SPC Apr 20, 2022 1630 UTC Day 1 Convective Outlook
[html]SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1117 AM CDT Wed Apr 20 2022
Valid 201630Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING OVER PARTS OF EASTERN OKLAHOMA AND THE VICINITY...
...SUMMARY...
The greatest severe-weather threat for today and this evening
appears to be over portions of central/eastern Oklahoma into the
western Ozarks region, where up to a few supercells with hail,
isolated severe gusts and a tornado are possible.
...Eastern OK and Vicinity...
Water vapor imagery shows a shortwave trough moving into western KS.
Ahead of this trough, strong heating is occurring west of the
surface dryline over OK, helping to mix it eastward. By mid/late
afternoon, the dryline will extend from a low in southeast KS into
east-central OK, with a very moist/unstable air mass present in the
warm sector. A capping inversion is also evident in forecast
soundings and in the numerous wave clouds present in visible
satellite imagery.
The confidence/coverage of convective initiation remains the main
forecast problem today. 12z model guidance continues to show a
diversity of solutions, ranging from several storms along the
dryline from southeast KS into southern OK, to virtually no storms.
Forecast soundings along the dryline show considerable low-level and
deep-layer shear that would be favorable for discrete supercell
development capable of very large hail, damaging winds, and a
tornado or two. Soundings also show a persistent but weak cap.
Therefore, will maintain the ongoing MRGL/SLGT areas with no
changes. However, will add a 5% tornado risk area given the
conditional risk if a storm or two can form. The primary risk
should be in the 22-03z window, before diurnal cooling strengthens
inhibition again.
...Western OR...
A shortwave trough off the coast of southwest OR will rotate
northeastward later today and affect the Cascades and coastal areas.
12z CAM solutions suggest a rather co*pact system with a focused
low-level jet tracking northward across the region late this
afternoon and evening. Enhanced low-level shear/forcing may be
sufficient for a few rotating showers or thunderstorms capable of
gusty winds or a brief tornado spin-up. Instability will be quite
weak, and it is uncertain whether updrafts will be strong enough to
take advantage of the low-level wind fields.
..Hart/Moore.. 04/20/2022
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Source: SPC Apr 20, 2022 1630 UTC Day 1 Convective Outlook (http://ht**://www.spc.noaa.gov/products/outlook/day1otlk_1630.html)