Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1111 AM CDT Mon Jun 15 2026
Valid 151630Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTHERN HIGH PLAINS AND UPPER MIDWEST...
...SUMMARY...
Isolated large hail and severe thunderstorm winds may occur across
the southern High Plains and Dakotas/Upper Midwest this afternoon
and evening.
...Southern High Plains...
Northwesterly flow aloft will support a sharpening lee trough across
the southern High Plains today, with lee cyclogenesis yielding a
surface low over southeast CO by the late afternoon. Mass response
to the deepening lee trough and developing surface low will result
in moist low-level southeasterly/southerly flow across much of the
southern High Plains. This moistening will help offset mixing via
diurnal heating, keeping dewpoints in the 50s through the afternoon.
Steep mid-level lapse rates will be in place as well, with the
combination of low-level moisture and steep mid-level lapse rates
supporting airmass destabilization and moderate buoyancy by this
afternoon.
Thunderstorm development is initially expected over the high terrain
of south-central CO and central NM during the afternoon. Moderate
deep-layer westerly flow will take these storms into the lower
elevations of the southern High Plains during the late afternoon and
evening. Moderate buoyancy combined with 30 to 40 kt of effective
shear will support the potential for a few supercells and sustained
multicells, with potential consolidation into small organizing
southeastward-moving clusters. Hail is possible early in the
convective cycle, with a trend towards more damaging gusts within
any forward-propagating clusters during the late afternoon and
evening.
...Dakotas/Minnesota...
Morning satellite imagery shows a well-defined shortwave trough
dropping southeastward into the northern Plains within the western
periphery of a broad upper trough that extends over much of the
central and eastern CONUS. Surface moisture will be limited ahead of
this wave, but low to mid-level moisture attendant to the shortwave
and cold temperatures aloft will still support modest buoyancy
across the region this afternoon. This buoyancy coupled with ascent
from the shortwave will result in isolated to widely scattered
high-based thunderstorms. Additionally, strengthening
west-northwesterly flow attendant to the shortwave could yield some
strong/locally severe wind gusts this afternoon through around
sunset.
...Gulf Coast/Coastal Southeast...
A very moist airmass is in place in the vicinity of a weak frontal
zone that extends from the TX Coast northeastward through the
central Gulf Coast and southern GA. Numerous to widespread showers
and thunderstorms are anticipated across much of this region. The
airmass is weakly sheared, favoring a slow-moving, disorganized
storm evolution with heavy rain as the primary risk (as noted in the
Day 1 WPC Excessive Rainfall Outlook). However, a few damaging gusts
from water-loaded downbursts are still possible. Overall coverage is
expected to remain less than 5%.
..Mosier/Chalmers.. 06/15/2026
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