LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Sat Jun 20 2026
Valid 201300Z - 211200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...
...SUMMARY...
Severe thunderstorms are likely across parts of the central Plains
mainly this afternoon and evening. Large to very large hail, severe
winds (some 75+ mph), and a few tornadoes are possible.
...Central Plains...
Recent surface observations show a front extending from the central
High Plains of eastern CO into KS, and continuing east-northeastward
into the mid MS Valley/Upper Midwest. Isolated/elevated
thunderstorms are ongoing this morning to the north of the front
across parts of central NE into north-central KS, likely aided by
weak low-level warm advection over the southern/central Plains.
While isolated hail may occur in the short-term with this activity
given weak MUCAPE and strong shear in the cloud-bearing layer,
current expectations are for a more robust severe threat to develop
across the central Plains later this afternoon and evening.
Initially high-based thunderstorms will likely form by early to mid
afternoon along/east of the higher terrain of eastern CO/southeast
WY in a weak low-level upslope flow regime, and as modest
large-scale ascent preceding an eastward-moving shortwave trough
overspreads the central Rockies/High Plains. Greater low-level
moisture (60s surface dewpoints) will be in place with eastward
extent across KS/NE, and these thunderstorms should gradually
strengthen as they move eastward. Deep-layer shear appears strong
enough to support supercells with an attendant threat for large
hail, with steep mid-level lapse rates and ample instability in the
hail-growth zone possibly supporting isolated very large hail (2+
inches).
While exact details of subsequent convective evolution remain
somewhat unclear, these initial supercells will probably tend to
interact/grow upscale in some form along and near the surface front
from late afternoon through the evening as a southerly low-level jet
strengthens over the central High Plains. An increasing threat for
at least scattered severe/damaging winds should be realized as one
or more bowing clusters spreads east-southeastward across NE/KS.
Isolated significant gusts (75+ mph) may occur with the more intense
portions of these clusters. Some risk for a few tornadoes should
also exist, mainly late this afternoon into the evening with either
persistent supercells or embedded within clusters as 0-1 km SRH
increases in tandem with the low-level jet. A severe wind threat may
continue through the overnight hours farther east across KS and
perhaps into parts of western MO.
...Northern Utah/Eastern Idaho into Western/Central Wyoming...
A weak mid-level shortwave trough over the northern Great Basin this
morning will continue to move eastward across the northern/central
Rockies today. Although low-level moisture is expected to remain
limited along/west of the higher terrain, steepened low/mid-level
lapse rates will exist with a very well-mixed boundary layer this
afternoon. Modestly enhanced mid-level flow will support
east-northeastward developing convection through the
afternoon/evening across parts of northern UT/eastern ID into
western/central WY. This activity may pose a threat for occasional
strong to severe winds, but the overall severe threat should tend to
remain isolated due to the weak instability forecast.
...Gulf Coast/Southeast...
Modest flow aloft (generally 25 kt or less) will exist today across
much of the Gulf Coast/Southeast, as a mid-level anticyclone remains
anchored over the Gulf. A very moist low-level airmass, with surface
dewpoints in the mid/upper 70s to low 80s, exists along/south of
convection ongoing from parts of coastal/east TX into the lower MS
Valley. Given the weak mid-level flow and related deep-layer shear,
overall thunderstorm organization and intensity should remain fairly
limited. Even so, occasional damaging winds could occur as the
loosely organized cluster spreads east-southeastward into a
destabilizing airmass across the lower MS Valley/central Gulf Coast
states through the afternoon.
...Western Pennsylvania...
Within west-northwesterly mid-level flow, low-topped thunderstorms
should develop/move across parts of western PA and vicinity this
afternoon. Instability will remain weak, but modestly enhanced flow
and steep low-level lapse rates may support occasional strong gusts
from convective downdrafts. The overall magnitude of the threat
still appears too limited for low severe wind probabilities.
..Gleason/Broyles.. 06/20/2026
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