SPC 1300Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0645 AM CST Sat Jan 30 2021

Valid 301300Z - 311200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM NORTHEAST OK AND SOUTHEAST KS INTO SOUTHWEST MO AND NORTHWEST
AR...

...SUMMARY...
Isolated severe thunderstorms will be possible this afternoon and
early evening from northeast Oklahoma into southwest Missouri,
including parts of southeast Kansas and northwest Arkansas.

...OK/KS/MO/AR this afternoon...
A well-defined midlevel trough over the TX Panhandle this morning
will continue east-northeastward over OK/KS today and MO/AR this
evening, before slowing over the lower OH Valley tonight as the
larger-scale pattern begins to amplify upstream (pronounced height
rises over Intermountain West).  An associated surface cyclone will
likewise develop eastward along the KS/OK border today, reaching
southwest MO this evening and southern IL late tonight.  Low-level
moisture return within the warm sector of the cyclone has been muted
by ongoing air mass modification over the Gulf of Mexico in the wake
of a prior frontal intrusion.  However, midlevel moistening and
lapse rates have been sufficient to support clusters of elevated
thunderstorms (rooted near 700 mb) this morning in the zone of
ascent preceding the midlevel trough.

The swath of elevated thunderstorms will likely persist into the day
across OK/KS and overspread MO/AR this afternoon.  In the wake of
the elevated convection, a zone of surface heating along a dryline 
will overlap a narrow corridor of boundary-layer dewpoints of 50-55
F from southeast KS across northeast OK, from roughly midday into
the afternoon.  Destabilization in this narrow corridor could be
sufficient for surface-based convection to develop near and
immediately south of the surface cyclone.  Steep low-midlevel lapse
rates and 500 mb temperatures of -20 C and colder should allow
MLCAPE of 250-500 J/kg, with a brief window of opportunity for
low-topped supercells within the left-exit region of the midlevel
jet.  Isolated damaging gusts and large hail, as well as an isolated
tornado, will be possible this afternoon with peak buoyancy, before
diminishing rapidly this evening with eastward extent and the onset
of nocturnal cooling.

..Thompson/Broyles.. 01/30/2021

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