SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1232 AM CDT Fri Apr 15 2022
Valid 151200Z - 161200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
OKLAHOMA...ACROSS PORTIONS OF THE LOWER MS VALLEY INTO THE
MID-SOUTH...
...SUMMARY...
Isolated strong to severe thunderstorms are expected Friday evening
and night from central/eastern Oklahoma into the lower Mississippi
Valley and Mid-South. Large hail and damaging winds should be the
main threats where thunderstorms develop. A brief tornado can not be
ruled out across eastern Oklahoma into western Arkansas during the
evening.
...Northeast OK to Lower MS Valley/Mid-South...
Seasonally strong zonal flow is forecast to continue across much of
the CONUS Friday. Though several weak disturbances will traverse
lower latitudes, general height rises are expected through the
period. Latest satellite imagery and surface observations suggest
higher-PW air mass is surging north across the Edwards Plateau
toward the TX South Plains as LLJ is strengthening across this
region. This moisture increase will prove instrumental, along with
the remainder of strong daytime heating, for convective development
across northeast OK by early evening.
Latest model guidance suggests intense boundary-layer heating will
be noted west of the dryline from west TX into western OK. Forecast
soundings reflect this with dry-adiabatic lapse rates in the lowest
3km near/west of the dryline by 22z. As the low-level flow veers
across this region, deeper convergence should contribute to robust
convective initiation downstream over northeast OK shortly
thereafter. SBCAPE should be on the order of 1500 J/kg with this
early development, and wind profiles certainly favor organized
long-lived updrafts with surface-6km bulk shear values in excess of
50kt. Steep lapse rates, strong shear, and long hodographs all favor
large hail with this activity. Have introduced Sig Hail to this
portion of the outlook where surface-based supercells should
develop, then track/propagate southeast toward western AR. While
large hail will be the primary concern, locally damaging winds and
perhaps a brief tornado can not be ruled out.
Additionally, have expanded low severe probabilities across the
Ozark Plateau toward the MS Delta region of southeast MO/extreme
western KY. Current thinking is decidedly westerly component will
encourage elevated warm-advection supercells to spread a bit farther
downstream than earlier anticipated. Surface cold front will also
surge south across this region during the overnight period which
will aid thunderstorm activity along/north of the wind shift. Larger
complex of storms should sag south through sunrise.
..Darrow/Weinman.. 04/15/2022
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