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SPC Apr 21, 2022 2000 UTC Day 1 Convective Outlook

SPC Apr 21, 2022 2000 UTC Day 1 Convective Outlook

[html]SPC 2000Z Day 1 Outlook
     
Day 1 Outlook Image

Day 1 Convective Outlook 
NWS Storm Prediction Center Norman OK
0246 PM CDT Thu Apr 21 2022

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS NORTHWEST
OKLAHOMA AND SOUTH-CENTRAL KANSAS AND NORTHERN KANSAS INTO FAR
SOUTHEAST NEBRASKA...

...SUMMARY...
Large, damaging hail, severe gusts, and perhaps a tornado are
possible with any thunderstorms that can develop over parts of
northwestern Oklahoma to south-central Kansas. Large hail is also
possible across parts of north-central Kansas into far southeast
Nebraska this evening into tonight.

...20Z Update...
Surface analysis reveals a sharp warm front extending from southeast
KS across southwest MO. Thunderstorms have initiated to the north of
this boundary and these isolated thunderstorms may pose a threat for
mainly hail over the next couple of hours. Hail probabilities were
extending southeastward to cover this threat.

Otherwise, the forecast remains on track with afternoon/evening
initiation possible near the triple point over the central OK/KS
border vicinity.

Additional elevated thunderstorm development is still expected
tonight across northern KS and southeast NE, with some hail
possible.

..Mosier.. 04/21/2022

.PREV DISCUSSION... /ISSUED 1129 AM CDT Thu Apr 21 2022/

...Synopsis...
Latest water-vapor imagery continues to show an upper-level trough
beginning to deepen across the eastern Pacific off the West Coast.
Broad height rises are noted across the central CONUS, leading to a
general amplification of the synoptic upper-level regime. At the
surface, a weakening low is analyzed over the TX Panhandle with a
warm front draped to the east/northeast across northern OK into
northwest AR. This warm front is expected to lift to the north into
the central Plains by 12 UTC Friday in response to a deepening low
over the northern Rockies. A dryline currently draped southward from
the TX Panhandle low will largely remain in place this afternoon
before retreating west overnight as moisture advection continues.
Thunderstorm chances this afternoon and overnight will primarily be
focused along the dryline and warm front.

...Northwest OK/southern KS...
Despite clearing across western OK, the inversion noted in the 12
UTC OUN sounding remains apparent in visible imagery across the
region. This inhibition is expected to linger through the late
afternoon as the warm front lifts north. The dryline across western
OK and the eastern TX Panhandle will likely extend northward into
the afternoon in tandem with the weakening surface low. Convective
initiation is possible late this afternoon in the vicinity of the
surface low and the dryline/warm front intersection where lift will
be locally maximized. The probability of initiation remains somewhat
low given the lack of stronger synoptic ascent (which is supported
by recent CAM solutions), but if convection can occur it will mature
in a favorable supercell environment. Storms will initially support
a large hail/damaging wind threat with an increasing tornado threat
after 00 UTC as the nocturnal low-level jet strengthens. Open
warm-sector convection and/or surface-based convection along the
warm front appears possible given weak capping by late afternoon and
would develop in a similar supercell environment, but this threat is
highly conditional and probability appears low.

...Northern KS/southeast NE...
Isentropic ascent over the warm frontal boundary is expected to
intensify through the day and into the overnight hours in response
to the deepening low across the northern Rockies/northern High
Plains. Elevated thunderstorms developing within the warm frontal
zone this evening/tonight will beco*e increasingly displaced to the
cool side of the boundary overnight given storm motions to the
northeast. However, strong shear within the MUCAPE layer will
maintain the potential for organized cells with an attendant hail
threat. This threat appears most likely across northern KS into
southern NE where the potential for discrete storm modes is highest.


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Source: SPC Apr 21, 2022 2000 UTC Day 1 Convective Outlook (http://ht**://www.spc.noaa.gov/products/outlook/day1otlk_2000.html)