ACUS02 KWNS 140556
SWODY2
SPC AC 140555

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1255 AM CDT Wed May 14 2025

Valid 151200Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF THE
UPPER MISSISSIPPI RIVER VALLEY AND WESTERN GREAT LAKES...

...SUMMARY...
Scattered severe thunderstorms are expected across parts of the
upper Mississippi River Valley and western Great Lakes region
Thursday afternoon and evening. More isolated severe thunderstorms
are expected through the lower Ohio River Valley, Ozarks Plateau,
and parts of the Mid-Atlantic.

...Synopsis...
The upper-level trough currently over the Intermountain
West/northern Rockies is forecast to eject into the upper MS River
Valley over the next 48 hours. As this occurs, a Pacific cold front
will rapidly push east into the MS Valley and Midwest as an intense
surface cyclone begins to occlude over the eastern Dakotas/western
MN. Scattered thunderstorms are expected to develop along the front
by early-afternoon with increasing coverage across the upper MS
Valley through early evening. Increasingly sparse, but severe,
thunderstorms are anticipated along the front across the Midwest
into the lower OH Valley and Ozarks/Texarkana regions through the
evening and overnight hours.

...Upper MS Valley and western Great Lakes...
04 UTC surface observations show upper 50s to low 60s dewpoints
already spreading northwest into the upper MS Valley as a surface
low begins to organized across the northern Plains. Confidence
remains high that dewpoints in the mid 60s should overspread much of
the region by mid-day Thursday and will contribute to regional
MLCAPE values upwards of 2000-2500 J/kg. Strong forcing for ascent
along the approaching front and within the left-exit region of a
50-60 knot mid-level jet will erode capping at the base of a stout
EML and promote thunderstorm development by early afternoon across
parts of central to southern MN. Elongated hodographs with
cross-boundary mean winds will promote organized, initially discrete/semi-discrete cells with an attendant severe wind and hail (potentially as large as 2 inches) threat. Veering winds through the
lowest 2 km will also support a tornado threat with early convection.

With time, persistent strong forcing along the front should promote
some degree of upscale growth/clustering, though supercells will
remain likely on the southern fringe of the line where capping will
remain stronger and favor more isolated convection. The potential
for somewhat longer-lived supercells may be maximized across
southeast WI into adjacent portions of IL, northern IN, and
southwest lower MI. Forecast soundings depict ESRH values on the
order of 200-300 m2/s2, suggesting a significant tornado threat
could materialize. Confidence in the coverage of such cells remains
limited, but trends will be monitored for the need for increased
tornado risk probabilities.

...Midwest and Ohio Valley...
Forecast guidance continues to show the best moisture return across
parts of IL, IN, and northern KY by Thursday afternoon. Dewpoints in
the upper 60s to low 70s under nearly 8 C/km mid-level lapse rates
will support a very unstable air mass with MLCAPE values approaching
4000 J/kg. Despite the very favorable buoyancy, capping at the base
of the EML is expected to limit storm coverage across this region.
Recent guidance has trended towards perhaps a slightly increased
coverage of thunderstorms compared to previous runs, but the overall
consensus among deterministic and CAM ensemble guidance is that
storm coverage should be sparse. Nonetheless, effective bulk shear
values on the order of 40-50 knots will promote supercells during
the late afternoon/evening hours with all hazards possible,
including the potential for significant hail/tornadoes.
Consideration was given for an expansion of the Enhanced risk area,
but limited confidence in convective coverage precluded such expansion.

...Texarkana to the Ozark Plateau...
Weaker forcing along the front and strong capping will likely limit thunderstorm coverage from the Texarkana region into the Ozark
Plateau during the afternoon/evening. Heading into the overnight
hours, increasing low-level isentropic ascent over the frontal
boundary will support thunderstorm development - especially across
the Ozarks into the mid-MS Valley. Strong deep-layer shear will
promote initial supercells, but storm propagation along the front
will likely promote clustering with time. Nonetheless, a severe
hail/wind threat will likely materialize within this corridor.

...Mid-Atlantic...
A moist, weakly capped air mass is expected to remain in place
across the Mid-Atlantic through Thursday afternoon. While lapse
rates will be modest after several days of convective overturning,
temperatures warming into the upper 70s/low 80s will promote
sufficient buoyancy for thunderstorm development. Upper ridging
moving into the region will likely limit thunderstorm coverage, but
convection developing along the Blue Ridge Mountains will mature in
an environment with increasing deep-layer shear. A few organized
cells appear possible with an attendant severe hail/wind threat.

..Moore.. 05/14/2025

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ACUS02 KWNS 170603
SWODY2
SPC AC 170602

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Sat May 17 2025

Valid 181200Z - 191200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
OKLAHOMA AND MUCH OF CENTRAL AND EASTERN KANSAS...

...SUMMARY...
Severe thunderstorms capable of all severe hazards are expected on
Sunday across portions of the central and southern Plains.

...Synopsis...
A mid-level shortwave trough will move from the Southwest into the
Central Plains on Sunday as the broader trough develops across the Intermountain West. By 00Z Monday, a ~992mb lee cyclone will develop
along the KS/CO border. A warm front will extend from this surface
low into northern Kansas/southern Nebraska by Sunday evening and
will remain mostly stationary across the Southeast. A dryline will
extend from central Kansas to the southern Plains.

...Kansas and northern Oklahoma...
A very moist airmass will be in place east of the dryline on Sunday
with low 70s dewpoints forecast across much of Texas, Oklahoma, and
southern Kansas ahead of the surface boundary. As temperatures warm,
strong to very strong instability is forecast to develop. As the
mid-level shortwave trough emerges across the Plains, synoptic-scale
ascent will combine with the increasing instability to decrease
inhibition across much of the dryline. Forecast guidance shows
limited convergence along the dryline in Oklahoma and Texas during
the day Sunday with the better convergence focused across Kansas.
Therefore, confidence is higher for storms across central and
southern Kansas and perhaps into northern Oklahoma.

Any storms which develop will be supercellular with a threat for
very large hail and tornadoes, particularly by later in the evening
as the low-level jet strengthens. While confidence is higher in
storms across the Enhanced risk area, storm evolution remains
unclear. 00Z CAM guidance has wide variations in the northeastward
progression of the surface warm front which will significantly
impact storm development on Sunday. A more discrete storm mode would
likely pose a greater very large hail and tornado threat, while more
widespread storm development would likely favor development into a
MCS which could pose a greater severe wind threat across eastern
Kansas and into Missouri.

Despite the uncertainties, the Enhanced (Level 3 of 5) risk seems
appropriately placed where severe storms are most likely. The 10%
tornado probabilities do not extend to the northern extent of the
Enhanced due to the aforementioned uncertainties in the warm frontal
position. However, elevated hail will remain a threat north of the
warm front.

...Oklahoma/Texas...
A dryline will be in place across western Oklahoma and north Texas
for much of the day Sunday. Convergence will be mostly weak along
the Oklahoma dryline for much of the day with better convergence
farther south in Texas, farther from the better upper-level forcing.
However, by the evening, convergence will increase somewhat which
could result in isolated supercell development as the low-level jet
intensifies during the evening. The environment across Oklahoma and
North Texas will be very volatile with a conditional threat for
intense supercells capable of very large hail and strong tornadoes.

...Northeast CO/Southwest Nebraska Vicinity...
By Sunday afternoon, low to mid 60s dewpoints will advect westward
around the surface low into northwest Kansas, northeast Colorado,
and southwest Nebraska. Moderate to strong instability is forecast
ahead of the dryline which will aid in supercell development by the
afternoon. A narrow corridor of instability will be the primary
limiting factor to the tornado threat in an otherwise very favorable
STP environment. It appears supercells will likely be north of the
boundary before maturing which will support a primary threat for
large hail. However, if a storm can rapidly mature as it develops
off the dryline, it could pose a tornado threat given the favorable
low-level shear across the region.

...Mid Mississippi Valley to the Southeast...
Isolated thunderstorms are possible along a stalled frontal zone
that will extend from the Mid-Mississippi Valley to the Southeast.
Moderate to strong instability will be in place within a moderately
sheared environment. Forcing will be weak along the front with
neutral to perhaps slightly rising heights aloft. However, forecast
soundings show minimal inhibition and therefore, isolated
development is possible. A greater severe threat could materialize
from a remnant MCV/MCS which will likely evolve from Day 1/Saturday
convection across north Texas. If this maintains along the frontal
zone into the late morning on Sunday, it could provide a focused
region of greater severe weather threat Sunday afternoon across
AL/GA.

..Bentley.. 05/17/2025

$$
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ACUS02 KWNS 180602
SWODY2
SPC AC 180600

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun May 18 2025

Valid 191200Z - 201200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE CENTRAL/SOUTHERN PLAINS INTO THE OZARKS....

...SUMMARY...
Severe storms with all severe weather hazards are expected from the central/southern Plains into the Ozarks on Monday.

...Synopsis...
A mid-level trough will shift from the Intermountain West into the
central Plains on Monday. A moderate to strong mid-level jet streak
will emerge along the southern periphery of this trough from the
Southwest into the central/southern Plains. A surface low in
Nebraska will gradually consolidate southward and deepen as the
mid-level jet emerges across the southern Plains. A sharp dryline
will be present from central Kansas to central Oklahoma and
north-central Texas. A warm front will extend from near Omaha to the
lower Ohio Valley and remain mostly stationary during the day.

...Central/Southern Plains into the Ozarks...
Thunderstorms will likely be ongoing along the warm front in the
northern Missouri border vicinity on Monday morning. Otherwise, a
mostly convection-free warm sector is expected to the south. Very
strong instability will develop along and east of the dryline with
convective temperatures likely reached by early afternoon. As large
scale ascent ahead of the approaching trough overspreads the
dryline, expect scattered supercells to develop along the dryline in
Kansas and Oklahoma. Very large to potentially giant hail will be
possible with these supercells initially. In addition, hodographs
will support tornadoes. The tornado threat will increase through the
afternoon and peak during the evening as the low-level jet
strengthens and low-level shear increases. However, by this time,
storm mode could be messy which is one factor precluding higher
probabilities at this time.

00Z CAM guidance shows a range of solutions including:

1. Earlier storms as the primary threat.

2. Delayed dryline initiation with a potential tornado outbreak type
solution across central/eastern Kansas and central/eastern Oklahoma.

3. A combination of both solutions.

The uncertainty in guidance at this time precludes a moderate risk,
but higher probabilities may be needed when a more favored solution
becomes more clear, especially if one of the higher-end scenarios
appears likely.

..Bentley.. 05/18/2025

$$
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