Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1239 AM CDT Sat May 09 2026
Valid 091200Z - 101200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN WESTERN AND
CENTRAL OKLAHOMA INTO NORTHWEST TEXAS...
...SUMMARY...
Widely scattered severe thunderstorms capable of large to very large
hail, locally damaging wind gusts, and perhaps a few tornadoes are
possible in parts of western into central Oklahoma Saturday
afternoon and evening. Sparser large hail and damaging wind
occurrences are possible across the Gulf Coast states, the northern
and central High Plains, the Great Lakes, and possibly mid-Atlantic.
...Synopsis...
A broad, cyclonic flow regime is forecast across much of the CONUS
east of the Rockies through the forecast period. A number of
embedded vorticity maxima moving through that large-scale pattern
will potentially aid in strong to severe storm development. The
first of which will track from the northern Rockies into the central
High Plains by Saturday evening. A stronger disturbance will be
attended by mid/upper-level jet streaks while progressing through
the Great Lakes region on Saturday. Additional, weaker disturbances
will traverse the Gulf Coast states and mid-Atlantic region.
At the surface, a cold front associated with the Great Lakes
disturbance will sweep east across that region during the day with
the trailing extension of the front advancing south into central
High Plains. An area of low pressure is forecast to develop along
the front in northwest KS Saturday afternoon with a pre-frontal
trough/dryline extending south from the low through the eastern
OK/TX Panhandles into west-central TX. Elsewhere, a front stretching
from south TX through the shelf waters of the northern Gulf into
north FL as of late evening will attempt to lift north as a warm
front. The advance of the boundary across the central and eastern
Gulf Coast may be impeded by early-day thunderstorms moving through
those areas.
...Western and Central Oklahoma into Northwest Texas...
The cold front that has pushed into the southern Plains this evening
is expected to wash out with initially modest moisture return
expected ahead of the trough/dryline with dewpoints increasing
through the 50s Saturday afternoon over the far eastern OK/TX
Panhandles into western OK. The moisture increase combined with
steep low/mid-level lapse rates will support an initially narrow
axis of 1000-1500 J/kg MLCAPE by mid/late afternoon.
While large-scale forcing for ascent will remain negligible through
the peak of the diurnal heating cycle, strong heating west of the
dryline and resultant deepening circulations along it are expected
to yield isolated to widely scattered, high-based storms by late
afternoon into early evening. 40-50 kt of effective bulk shear will
support supercell storm modes with large to very large hail being
the predominant hazard.
Considerable strengthening of the low-level jet is forecast across
western and central OK Saturday evening, which will enhance
low-level shear and the influx of greater, boundary-layer moisture
content. There is some model variability in the degree of evening
moistening that occurs, with the RAP remaining notably drier than
the NAM. Should the NAM scenario be closer to correct, tornado
potential would increase during the evening with any sustained
supercells from western into central OK. An 5% unconditional
probability and conditional-intensity group 1 have been added to
account for that possibility.
...Gulf Coast...
Clusters of thunderstorms or a quasi-linear MCS is expected to be
ongoing at 12z Saturday over the lower MS Valley, aided by a
low-level warm/moist advection regime. Forecast soundings suggest
that activity may be slightly elevated atop a shallow, near-surface
inversion and rooted within a moist environment with MUCAPE upwards
of 1500 J/kg. The 00z convection-allowing models suggest that
activity will continue south/southeast and potentially become more
surface-based across the central and eastern Gulf Coast from late
morning into afternoon. Generally weak low/mid-level lapse rates are
expected to limit updraft intensity, despite the presence of 40-50
kt effective bulk shear. Nonetheless, the potential will exist for
marginally severe hail and locally strong to severe wind gusts,
especially if a cold pool can organize.
...Great Lakes...
The pre-frontal air mass is not expected to be overly moist on
Saturday with dewpoints largely in the upper 40s to low 50s.
However, steepening low/mid-level lapse rates are expected to yield
a modestly unstable air mass by afternoon with MLCAPE of around 500
J/kg. The destabilization process will coincide with gradually
veering low-level winds, which will tend to limit the magnitude of
low-level and deep-layer shear.
Forcing for ascent associated with the short-wave trough mentioned
in the synopsis coupled with convergence/lift along the front are
expected to foster a broken band of thunderstorms initially across
eastern lower MI by early afternoon. Additional storms are expected
to form farther south along the front in northern OH with the
convective band rapidly moving east into portions of western NY and
northwest PA by late afternoon or early evening. Cold temperatures
aloft will favor isolated occurrences of marginally severe hail.
Locally strong wind gusts will also be possible during the afternoon
and early evening hours.
...Central Wyoming into southwest Nebraska and Northwest Kansas...
Increasing height falls/forcing for ascent preceding the short-wave
trough moving out of the northern Rockies will overspread a
steep-lapse-rate, but limited-moisture environment Saturday
afternoon, fostering the development of widely scattered, high-based
storms. The presence of 30-40 kt of effective bulk shear will
support some storm organization with the potential for isolated
occurrences of large hail and locally damaging winds during the
afternoon and evening hours.
...Mid-Atlantic States...
A couple weak disturbances traversing the lower Great Lakes and
central Appalachians are expected to contribute an area of showers
across portions of PA and southern NY into New England Saturday
morning into early afternoon. Weak destabilization on the southern
fringe of that cloud canopy may support isolated thunderstorm
development during the afternoon from the DE River Valley into parts
of MD amidst a weakly unstable environment with MLCAPE of only a few
hundred J/kg. Both low-level and deep-layer shear will be relatively
strong, and the potential will exist for isolated severe weather, on
the condition that sufficient instability develops to sustain
surface-based thunderstorms.
..Mead/Weinman.. 05/09/2026
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