(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 230851
SPC AC 230851
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0351 AM CDT Fri Jun 23 2023
Valid 261200Z - 011200Z
...DISCUSSION...
...Monday/Day 4...
An upper-level low is forecast to move across the Great Lakes region
on Monday, as an associated trough moves into the upper Ohio Valley
and southern Appalachians. A moist airmass, with surface dewpoints
in the lower 70s F, will likely be in place from the Carolinas
north-northeastward into the Mid-Atlantic. Moderate instability is
forecast to develop across much of this moist airmass by afternoon.
Thunderstorms that form in the higher terrain will move
east-northeastward into the Appalachian foothills during the
afternoon. The instability combined with moderate deep-layer shear
and steep low-level lapse rates will likely result in a some severe
storms. Wind damage and hail are expected to be the primary threats.
...Tuesday/Day 5 and Wednesday/Day 6...
On Tuesday and Wednesday, a typical summertime ridge is forecast
across the Great Plains. An axis of moisture and instability is
expected to setup beneath the upper-level ridge. Isolated to
scattered thunderstorms appear likely to develop along and near the
instability axis during the afternoon and evening. Although a severe
threat will be possible in parts of the central and northern Plains
on both days, predictability remains low concerning the magnitude
and spacing of any potential severe threat.
...Thursday/Day 7 and Friday/Day 8...
The upper ridge is forecast to move eastward across the Great Lakes
on Thursday and Friday, as an upper-level trough moves southeastward
into the north-central states. Ahead of the trough, low-level
moisture and instability is forecast to be sufficient for isolated
severe thunderstorms each afternoon. The severe-threat potential
will depend upon the timing of the upper-level system, and
distribution of moisture and instability. At this time,
predictability concerning these factors appears to be low.
..Broyles.. 06/23/2023
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