(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.
Forecast Discussion
ZCZC SPCSWOD48 ALL
ACUS48 KWNS 280859
SPC AC 280859
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0359 AM CDT Sun Apr 28 2024
Valid 011200Z - 061200Z
...DISCUSSION...
...D4/Wednesday - Central and southern Plains...
Extended-range guidance generally depicts a broad upper-level trough
gradually moving eastward across the western CONUS on Wednesday,
though differences remain regarding the amplitude of this trough.
Downstream of the trough, a surface low is forecast to deepen across
the south-central High Plains, with rich low-level moisture
streaming northward along/east of a developing dryline and south of
a northward-moving warm front. Moderate to strong buoyancy may
develop across the warm sector Wednesday afternoon, and scattered
thunderstorm development will be possible along/east of the dryline
and also near the warm front.
While mid/upper-level flow is currently forecast to remain rather
modest, deep-layer shear may be sufficient to support some organized
convection. With most extended-range guidance depicting scattered
thunderstorm development during the afternoon and evening within a
relatively favorable environment, a 15% area has been added for
parts of the central/southern Plains, where confidence in an
organized severe threat is currently highest.
Some guidance suggests the threat could extend into parts of
southwest and deep south TX, in advance of a low-amplitude
subtropical shortwave trough, though uncertainty remains rather high
regarding this potential.
...D5/Thursday - Central and southern Plains into the MS Valley...
A continuation of severe potential is expected into Thursday across
parts of the central/southern Plains and potentially into the
mid/upper MS Valley, with moderate to locally strong instability
expected again during the afternoon across the warm sector of a
northeastward-moving cyclone. However, predictability begins to
decrease at this forecast range regarding timing of a cold front
that is forecast to move southeastward and potentially provide a
focus for thunderstorm development during the afternoon and evening.
...D6/Friday - D8/Sunday...
A notable increase in spread amongst extended-range guidance is
noted by D6/Friday into the weekend. In general, a cold front will
likely continue moving southeastward before stalling across parts of
southern Plains into the Southeast. Rich low-level moisture and
stronger instability may be maintained across parts of TX, but
organized severe potential in that area remains very uncertain at
this time.
..Dean.. 04/28/2024
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