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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0742 AM CDT Tue Apr 19 2022

Valid 191300Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
THE SOUTHERN HIGH PLAINS...

...SUMMARY...
Isolated severe hail and strong-severe gusts may occur from
afternoon/evening thunderstorms over parts of the southern High
Plains.

...Synopsis...
A progressive, less-amplified mid/upper-level pattern is forecast
over most of the CONUS this period, behind a strong synoptic trough
and embedded cyclone that will move from the upper Great Lakes to
southeastern Canada and New England.  A series of northern-stream
perturbations will contribute enough cooling aloft and low/middle-
level instability to support general thunder potential over parts of
the Northwest.

Substantial mid/upper forcing will remain well-displaced from a
southward-shunted reservoir of low-level moisture over the western
Gulf and northeastern MX.  However, a weak perturbation initially
over NM should cross the southern High Plains around 18Z and reach
OK by 00Z, with a trailing vorticity lobe over the TX Panhandle
around 00Z, and another weak trough just upstream over NM.

At the surface, 11Z analysis showed a cold front extending from the
Atlantic south of New England across central/southern FL and the
north-central Gulf, beco*ing quasistationary west-northwestward over
parts of deep south TX and northern Coahuila.  Optimally high-
theta-e surface conditions will remain south of this boundary as it
moves slowly northward across southwest/central TX and beco*es
diffuse through the period.

...Southern High Plains...
Isolated severe thunderstorms may form and move eastward across the
region through early evening, offering large hail and damaging
gusts.  Convective coverage is uncertain, given the subtlety of
forecast forcing for ascent in the layer of buoyancy rooted above
the surface.  This makes the outlook very conditional; however,
forecast wind profiles support supercell potential with any
sustained convection that can develop this afternoon.  Isolated hail
also may be noted with earlier, elevated convection around midday,
immediately ahead of the leading perturbation.  However, weak
buoyancy should preclude an organized severe threat with that
activity.

With this area still separated from the moist Gulf boundary layer by
a few hundred miles today, the bulk of convective potential should
arise in a more-humid 700-850-mb layer that may beco*e minimally
inhibited, with MUCAPE in the 500-1000 J/kg range.  Forecast
soundings also suggest 45-60-kt effective-shear magnitudes for such
convection, even with lack of access to more-backed flow near the
surface.  Although the boundary layer likely will be capped for
convective development rooted there for most of the afternoon,
forecast soundings with several hours of diabatic heating suggest an
inverted-v/well-mixed thermodynamic profile below the EML's basal
inversion.  Enough heating may even occur on a localized basis for
initially elevated convection to beco*e surface-based, at least
briefly, before the nocturnal cooling stabilizes the near-surface
layer.  These factors also support potential for downdrafts to
produce strong/isolated severe gusts as they descend through the
boundary layer late this afternoon and early this evening.

..Edwards/Dean.. 04/19/2022