SPC AC 140100
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Tue Oct 13 2026
Valid 140100Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL PLAINS INTO THE LOWER MISSOURI VALLEY...
...SUMMARY...
Scattered severe storms capable of large hail and severe gusts are
expected this evening into tonight over parts of the central and
southern Plains into the Lower Missouri Valley. Isolated large hail
may also occur in the southern Great Lakes.
...Southern and Central Plains...
The latest water vapor imagery shows an anticyclonic flow pattern in
place over the eastern two-thirds of the nation, with southwesterly
mid-level flow from the Desert Southwest into the southern and
central Plains. At the surface, a cold front is located from near
the Oklahoma Panhandle northeastward into north-central Missouri. A
1007 mb low is analyzed over the northeastern Texas Panhandle.
Low-convergence is maximized along the front over the central
Plains, where scattered thunderstorms are ongoing. The convergence
axis extends southward into the Low Rolling Plains of northwest
Texas, where a cluster of storms is also ongoing. Ahead of the
convergence axis, surface dewpoints are in upper 60s and lower 70s F
over much of the southern and central Plains, which is contributing
to moderate instability, with the RAP estimating MLCAPE mostly in
the 2000 to 2500 J/kg range.
In addition to the instability,the WSR-88D VWP at Wichita, KS has
0-6 km shear near 35 knots with 40 to 45 knots of southwesterly flow
in the mid-levels. Some directional shear is present in the boundary
layer. This environment will support a threat for supercells with
cells that remain discrete. Supercells will be capable of large
hail, severe wind gusts and perhaps a tornado or two. Severe wind
gusts are expected to become the primary severe threat as the
primary mode becomes linear, later this evening.
Further south into western Oklahoma and northwest Texas, the latest
WSR-88D VWP at Frederick has about 35 knots of 0-6 km shear. The RAP
also has steep mid-level lapse rates in the 7 to 7.5 C/km range.
This should support supercells with a potential for large hail and
severe wind gusts.
...Southern Great Lakes...
A minor shortwave trough appears to be moving into the western Great
Lakes early this evening. Ahead of this feature, thunderstorms have
developed over far southern Wisconsin. The storms will track
east-southeastward into the southern Great Lakes this evening into
the overnight. The RAP currently shows an axis of instability
analyzed from western Illinois northeastward into the southwestern
Great Lakes. Along and near this axis, RAP forecast soundings late
this evening have MUCAPE around 1500 J/kg with effective shear near
40 knots. This may be enough for an isolated large hail threat, with
the stronger elevated storms.
..Broyles.. 10/14/2026
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
SPC AC 131730
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Tue Oct 13 2026
Valid 141200Z - 151200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM WESTERN NORTH
TEXAS...ACROSS OKLAHOMA...TO THE WESTERN OZARK PLATEAU...
...SUMMARY...
Severe thunderstorms capable of mainly damaging wind gusts, isolated
hail and a tornado or two are possible across portions of the
southern Plains into the Ozark Plateau, and in the parts of the
upper Ohio Valley and Mid-Atlantic Wednesday afternoon and evening.
...Southern Plains to the Ozarks...
An upper low, initially over the Four Corners, is forecast move
eastward over the High Plains while southwesterly flow aloft
increases. A series of convectively enhanced vorticity maxima will
move along a cold front through the Mid-Atlantic, OH and mid-MS
Valleys, and into portions of the southern Plains. Western portions
of the front, modified by convection, may eventually stall and
perhaps retreat north Wed night in response to falling pressures
with a deepening lee low over eastern CO and the central Plains.
Scattered to numerous thunderstorms, in one or more clusters, are
likely to be ongoing from the mid MS valley into southern/eastern KS
and central OK at 12z Wed. The cold front will likely be reinforced
by the convection with the morning outflow potentially causing it to
sag slowly across central OK and the western Ozarks Plateau through
the day. To the south of the boundary, the air mass should remain
very moist (70s F dewpoints), with modest heating contributing to
weak to moderate diurnal destabilization. Large-scale ascent will
gradually increase as the upper low approaches, aiding in
thunderstorm redevelopment along the dryline across the TX
Panhandle/western OK, and within the broader warm sector by early
afternoon. Increasing deep-layer shear (40-50 kt) will be supportive
of a mix of organized supercells and lines/clusters. Damaging winds
are the most likely threat given modest low/mid-level lapse rates
and a mixed convective mode. However, isolated hail and perhaps a
tornado, are also possible with any more persistent supercells.
As the main upper low moves eastward into the evening/overnight, the
stalled surface front may gradually return northward as a warm front
across OK and KS. The air mass will remain very moist, aided by
further moisture advection associated with a developing 30-40 kt
low-level jet. As low-level warm air advection increases near the
boundary, storm redevelopment is possible through the
evening/overnight. Expanding low-level hodographs (ESRH 150-200
m2/s2) and the very moist PBL could support a tornado or two with
any supercells or linear clusters able to develop near the surface
low and warm front into early Thursday.
...OH Valley to the Mid Atlantic...
Daytime heating combined with boundary-layer dewpoints in the mid
60s to low 70s F is expected to contribute to pockets of moderate
instability with MLCAPE near 1000 J/kg by mid-late afternoon ahead
of the cold front. Thunderstorms ongoing over the mid MS valley, and
additional development from the aforementioned vorticity maxima, are
expected to increase in areal coverage along the front through the
afternoon. Steepening low-level lapse rates coupled with
strengthening west-southwesterly winds with height (yielding up to
35-40 kt of deep-layer shear) appear supportive of isolated damaging
wind gusts into evening.
..Lyons.. 10/13/2026
WUUS02 PTSDY2
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
SPC AC 131930
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 PM CDT Tue Oct 13 2026
Valid 151200Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID MISSISSIPPI VALLEY AND MIDWEST...
...SUMMARY...
Isolated severe storms are possible over portions of the mid-
Mississippi Valley and Midwest Thursday afternoon and evening.
...Mid MS Valley/Midwest...
The upper low ejecting over the central Plains is forecast to weaken
to a positive-tilt open wave as it continues eastward and merges
with a northern stream trough from southern Canada late Thursday.
The lee low over KS will continue eastward and strengthen as a
diffuse warm front lifts northward across the Mid MS and lower OH
Valleys. A cold front will trail the low, sweeping south and east
from the MO valley into the southern Plains.
Scattered to numerous thunderstorms are expected to be ongoing early
Thursday ahead of the low within a zone of low-level warm air
advection from the central Plains into the mid-MS Valley. A narrow
plume of upper 60s to low 70s F dewpoints will be advected
northeastward ahead of this activity across eastern IA/MO into
western IL. Modest clearing/heating of the air mass should support
weak destabilization with MLCAPE of 500-750 J/kg. This will allow
for intensification of the storms/new development through the
afternoon. Increasing ascent/vertical shear (EBWD 45-60 kt) will
support the potential for one or more organized clusters of storms
capable of damaging wind gusts through Thursday evening.
Farther southwest across OK/TX, a broken band of showers and storms
may still be ongoing ahead of the surging cold front Thursday
morning. Low-level flow should quickly veer as the front accelerates
favoring undercutting. Poor lapse rates, multiple rounds of prior
precipitation and rapidly decreasing surface moisture suggest only
weak buoyancy will be present. This should limit severe potential,
though a stray severe gust cannot be completely ruled out.
..Lyons.. 10/13/2026
WUUS03 PTSDY3
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
|
