Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0253 PM CDT Fri Aug 01 2025
Valid 012000Z - 021200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THERE IS A SLIGHT
RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE CENTRAL HIGH PLAINS
INTO WESTERN SOUTH DAKOTA...
...SUMMARY...
Scattered severe thunderstorms are possible across parts of the High
Plains this afternoon and evening. Large to very large hail, a
couple of tornadoes, and severe gusts are possible.
...20z Update...
The forecast largely remains on track. The primary update was to
introduce 5% tornado probabilities across portions of northwest SD
ahead of a pronounced MCV where initial stages of thunderstorm
development are noted in recent GOES/lightning data. Visible imagery
shows slowly building cumulus within the southeasterly flow regime
ahead of the MCV as temperatures warm into the mid/upper 70s.
Forecast soundings suggest this is adequate for surface-based
convection, and depict enlarging hodographs later this evening as
the nocturnal jet strengthens. While localized, this environment may
be somewhat more favorable for tornadoes compared to adjacent
portions of SD.
Elsewhere, minimal changes are required. 5% wind probabilities were
amended slightly across portions of the Carolinas to better reflect
recent thunderstorm development/trends. See the previous discussion
below as well as MCDs #1860-1862 for additional details.
..Moore.. 08/01/2025
.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 01 2025/
...High Plains...
Water-vapor imagery late this morning shows a few disturbances
undercutting an upper ridge currently over the High Plains/Alberta.
An MCV is slowly moving eastward near the MT/WY/SD/ND border, a more
pronounced upper trough will remain over the northern Rockies and
adjacent high plains of MT, and a more subtle disturbance will move
east-northeastward across the central Rockies.
A residual frontal zone draped generally south-north abutting the
higher terrain is providing a focus for richer moisture east of this
boundary over the High Plains. Surface dewpoints will likely range
from the mid 50s to the lower 60s across much of the Slight Risk. A
belt of slightly stronger westerly upper flow is forecast across the
central High Plains which will act to elongate hodographs.
Additionally, a plume of steep 700-500 mb lapse rates (7.5 to 9 deg
C/km) will contribute to MLCAPE 2000-3000 by mid-late afternoon.
The aforementioned low-amplitude disturbance over the central
Rockies coupled with low-level upslope flow/orographic effects will
result in initial thunderstorm development over the high terrain and
the Cheyenne Ridge.
The best overlap between buoyancy and shear is expected from western
SD into northeast CO/WY/NE Panhandle border region. Model ensemble
data suggest a few favored corridors for severe may result. The
most notable area may focus near the Cheyenne Ridge and adjacent
northeast CO where supercell potential appears greatest. Large to
very large hail and a tornado or two are possible with this activity
before gradually transitioning to primarily a risk for severe gusts.
One other area of interest is across northwest SD, where an MCV
moving slowly into the region could result in a focused area of
thunderstorms. Increased low-level convergence and low-level
vertical shear near this MCV could lead to a greater threat for all
severe hazards, including large hail and perhaps a brief tornado or
two.
...Carolinas into Georgia-Alabama-Mississippi...
A seasonably moist airmass was sampled by 12 UTC area raobs this
morning (near 16 g/kg lowest 100-mb mean mixing ratio).
Visible-satellite imagery shows extensive low cloud cover across
central and eastern NC near and behind the wind shift/cold front.
Farther west, initial cumulus field development is noted over the
southern Appalachians where strong heating is occurring and farther
south/southeast over the Piedmont and to the coastal plain. As
temperatures continue to warm through early afternoon, erosion of
convective inhibition will result in scattered storms favoring the
higher terrain and eventually near the wind shift. High PW (2
inches or greater) and diurnally steepened surface to 1.5 km lapse
rates will support a risk for wet microbursts with the more intense
water-loaded downdrafts. Localized gusts 50-65 mph are possible and
scattered pockets of wind damage may result.
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/TMFfxq
