(All days are valid from 12 UTC - 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 210739
SPC AC 210739
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0239 AM CDT Wed Mar 21 2018
Valid 241200Z - 291200Z
Models have come into much better agreement for the D4-D8 period,
depicting an upper trough amplifying across the West and slowly
progressing across the southern Plains.
On Sunday/D5, a warm front will lift north across OK and into KS as
low pressure forms over the central High Plains. Indications are
that a leading shortwave trough will move across TX and OK
relatively early in the day, which may induce midday storm formation
in a warm advection regime from central OK into southwest MO. Thus,
while a dryline will exist across southwest KS into western OK,
additional diurnal development is uncertain. Conditionally, a few
severe storms cannot be ruled out given potentially 1000-1500 J/kg
MUCAPE beneath 40-50 kt southwesterly midlevel flow.
For Monday/D6, the upper flow across the Plains will become a bit
more meridional as the trough digs southward into northern Mexico. A
strengthening speed max aloft will emerge across the southern high
Plains late on Monday, with winds aloft roughly parallel to the
dryline which itself will be quasi-stationary. Areas of storms are
likely across much of west-central TX and OK, and a few could be
strong or severe with wind or hail. Instability looks to be marginal
for severe weather, but will also depend on how much early day
convection there is. Thus, will maintain a predictability too low
The same pattern will persist into Tuesday/D7, shifting east OK and
TX. By this time, heavy rain may become a concern, along with
isolated severe storms.
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