RSS Mesoscale Discussions from Storm Prediction Center
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1116 AM CDT Thu Jun 18 2026
Valid 181630Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NEW ENGLAND...THE MID-ATLANTIC REGION...AND FROM THE GULF COAST
STATE INTO THE CAROLINAS....
...SUMMARY...
Isolated to scattered severe thunderstorms are expected from
Kentucky and the central Appalachians to the Mid-Atlantic, with
primarily damaging wind gusts or marginal hail. Scattered severe
storms are possible from upstate New York into New England, with
damaging wind gusts and tornado potential. A few tornadoes may also
occur over parts of the middle Gulf Coast states, and scattered
storms may produce gusty winds or marginal hail from Oklahoma into
western North Texas.
...NY/New England...
A fast-moving low-topped squall line is tracking eastward across NY.
Low and mid level wind fields in this region are very strong,
contributing to occasional bowing structures and QLCS mesocyclones.
This activity will spread into VT/NH through the afternoon with a
continued risk of damaging winds and isolated tornadoes. Confidence
in severe storms farther south into southern New England is lower,
but at least isolated strong/damaging wind gusts are possible.
...KY into Mid Atlantic...
A remnant outflow boundary from overnight storms extends across KY
into southern VA. Strong heating along and south of the boundary
will likely result in renewed convection this afternoon, in a zone
of moderate westerly flow aloft and CAPE values around 2000 J/kg. A
few severe storms are expected in this corridor, with activity
moving into northern NC later today. Damaging winds are the main
risk.
...Gulf Coast into Carolinas...
The remnant circulation of Arthur is becoming more progressive with
time, and is accelerating eastward. As this occurs, the zone of
relatively strong southerly low-level winds will also shift across
AL into GA and eventually SC/NC tonight. Ample low-level moisture
and high theta-e values will coincide with the region of strong
shear, and CAM solutions suggest clusters of thunderstorms in this
area as well. This suggests at least some risk of damaging wind
gusts and tornadoes through the afternoon and night as the system
moves northeastward.
...TX/OK...
Scattered thunderstorms will occasional hail risk will slowly
diminish across northern OK this afternoon. Later today, new
thunderstorms are expected to develop in a hot and very unstable air
mass in vicinity of the surface low near ABI/SJT. These slow-moving
storms will have some damaging wind and hail risk through the
evening.
..Hart/Chalmers.. 06/18/2026
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1228 PM CDT Thu Jun 18 2026
Valid 191200Z - 201200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITHIN THE UPPER
MISSISSIPPI VALLEY...PARTS OF THE CENTRAL PLAINS...ARKLATEX INTO THE
SOUTHEAST AND COASTAL CAROLINAS...
...SUMMARY...
Isolated strong storms may produce gusty winds and hail across the
Upper Midwest and parts of the central Plains. Additional strong
thunderstorms may produce damaging wind gusts from north
Texas/southern Oklahoma through portions of the Gulf Coast states
and into the coastal Carolinas.
...Synopsis...
The primary upper-level trough is expected to move off the Northeast
coast on Friday. Another compact shortwave trough will move into the
northern Plains/Upper Midwest. A remnant tropical low will move into
the Carolinas. A stalled cold front will extend from the Carolinas
into the southern Plains with another weak cold front from the Upper
Midwest into the central High Plains.
...Coastal Carolinas...
With the remnants of a tropical low beginning to phase with the
upper trough in the east, a window of severe risk will occur during
the morning in the coastal regions of the Carolinas. Enhanced
low-level flow associated with the remnant circulation will promote
a risk for damaging winds and a brief tornado near the circulation
itself and along a pseudo warm front.
...Upper Mississippi Valley...
While moisture return is a bit uncertain, generally 50s F dewpoints
are expected to advect northward into the Upper Mississippi Valley.
A compact, moderately strong shortwave trough will likely promote
thunderstorm development during the afternoon along the surface
trough/weak cold front. The potent mid-level jet will bring 45-55 kt
of effective shear to the region. 500-1000 J/kg MLCAPE is expected
despite the limited moisture as temperatures aloft (-18 to -20 C at
500 mb) will accompany the trough. Isolated to widely scattered
supercells are possible. Isolated large hail and severe wind gusts
are possible.
...ArkLaTex into Southeast...
An MCV is anticipated along the Red River during the morning. This
feature, coupled with heating of a very moist (70+ F dewpoints)
airmass along and south of a stalled cold front will promote
scattered thunderstorms during the afternoon. Deep-layer shear will
be weak, particularly away from the cold front, and storm
organization will depend on the MCV or mesoscale clustering.
Damaging downburst winds are the main hazard with this activity.
Similar activity can be expected along the Atlantic sea breeze front
from near Jacksonville to the Space Coast.
...Northwest Kansas into central Nebraska...
Modest moisture return on the western flank of the surface high will
potentially allow thunderstorms to develop along the surface
trough/weak cold front. Surface convergence will be weak and
mid-level ascent will be nebulous at best. Coverage is likely to be
isolated if storms can form. Moderate mid-level winds will promote
40-50 kt of effective shear. Storm mode would likely be
supercellular with a risk of severe wind gusts and large hail.
...Northern Sierra/Northwest Nevada...
A modest upper-level low and mid-level moisture will promote widely
scattered to scattered thunderstorms within the northern Sierra.
Some of this activity may become marginally organized given stronger
mid-level winds. Small hail and strong outflow winds are possible.
Overall coverage of marginally severe activity still appears too low
for probabilities.
..Wendt.. 06/18/2026
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