(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 270844
SPC AC 270844
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0344 AM CDT Sat Jul 27 2024
Valid 301200Z - 041200Z
...DISCUSSION...
A ridge over the central CONUS will break down toward the middle of
next week which will likely result in some severe weather from the
northern Plains to the Ohio Valley D4/Tuesday and D5/Wednesday.
Toward the end of the week and into next weekend, a strong
upper-level ridge will build across the western CONUS with somewhat
lower severe weather concerns across the CONUS.
...Day4/Tue - Northern Plains to the Midwest...
A broad reservoir of 70F dewpoints are expected to exist from the
Canadian border into the Midwest and Ohio Valley on Tuesday. This
will result in an extended corridor of very unstable conditions
along and south of a frontal zone. Some moderate (30-35 knot)
mid-level northwesterly flow is expected along this frontal zone.
This pattern may support one or more severe MCSs on Tuesday.
However, a lack of a focused/strong low-level jet and weak,
mesoscale, mid-level shortwave troughs make predictability
challenging at this range. Therefore, no probabilities are warranted
at this time.
...D5/Wed - Midwest to the Ohio Valley and central Appalachians...
A diffuse frontal zone with strong instability will likely exist
from the Midwest to Ohio Valley and central Appalachians on
Wednesday. Some threat for severe MCS development will be likely
across this corridor, but the lack of a clear forcing mechanism
precludes probabilities at this time. The upper-level ridge centered
across the central CONUS will start to break down Wednesday night.
This should result in moderate forcing for ascent amid a very
unstable airmass. Therefore, some overnight severe weather threat
may exist in the Upper Midwest, particularly across southern
Minnesota where there is moderate agreement between the GFS and
ECMWF for the best upper-level forcing. If this ridge break down can
occur 6-12 hours earlier and the stronger forcing could coincide
with peak heating, a greater severe weather threat may evolve across
portions of the Upper Midwest.
..Bentley.. 07/27/2024
CLICK TO GET WUUS48 PTSD48 PRODUCT
weather.gov 
@NWSSPC
