Mesoscale Discussion 0492
NWS Storm Prediction Center Norman OK
1204 PM CDT Sat Apr 18 2026

Areas affected...portions of Edwards Plateau and Texas Hill Country

Concerning...Severe potential...Watch unlikely 

Valid 181704Z - 181900Z

Probability of Watch Issuance...5 percent

SUMMARY...Isolated large hail and occasional strong wind gusts are
possible across portions of Texas Hill Country and the Concho Valley
this afternoon/evening. Watch issuance appears unlikely at this
time.

DISCUSSION...Isolated thunderstorms have developed across the
southwestern portions of Edwards Plateau over the past hour, well
north of a southward-moving surface cold front. RAP forecast
soundings and latest mesoanalysis depict 500-1000+ J/kg MUCAPE with
lifted parcel levels atop the frontal inversion, which will continue
to favor robust updrafts with elevated convection. Coincident strong
mid/upper level flow (evident within the SJT VAD profile) is
contributing to 50-60 kts of effective bulk shear, sufficient for
elevated supercells. With modestly steep mid-level lapse rates and
elongated hodographs (noted via mesoanalysis and recent ACARS
profiles from SAT), isolated large hail will be possible with the
strongest storms. While convection will remain elevated, occasional
strong wind gusts may be possible with stronger downdrafts. Watch
issuance appears unlikely at this time given the expectation for the
threat coverage/magnitude to remain limited.

..Chalmers/Hart.. 04/18/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FWD...EWX...SJT...

LAT...LON   31630043 31869978 31999887 31959826 31739766 31249734
            30719749 30409800 30119863 29899966 29880025 29970070
            30180105 30370121 30660121 30960104 31310078 31630043 

MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN

Mesoscale Discussion 0491
NWS Storm Prediction Center Norman OK
1138 AM CDT Sat Apr 18 2026

Areas affected...northern Kentucky into eastern Ohio and western
Pennsylvania

Concerning...Severe potential...Watch possible 

Valid 181638Z - 181915Z

Probability of Watch Issuance...40 percent

SUMMARY...Storms may strengthen through the afternoon with potential
for strong to severe winds and some instances of hail.

DISCUSSION...Remnant shower activity is ongoing across portions of
the Ohio Valley from northern Kentucky into central Ohio. Ahead of
this activity, temperatures are warming into the upper 70s to 80s
amid broken mid-level cloud cover with increasing cumulus observed
in visible satellite. Dew points are largely in the mid to upper
50s, with a better plume of 60s dew points across northern Kentucky.
The cold front remains further west, extending from northern
Arkansas into central Indiana/northwestern Ohio.

Guidance suggests that some strengthening of activity along the
leading edge of the shower activity may be possible into the
afternoon. Though MLCAPE remains marginal, with around 250 J/kg
ahead of the ongoing activity in northern Kentucky, steep low to
mid-level lapse rates (7-8 degrees C/km), and strong deep layer
shear (around 40-50 kts) may support a few more organized storms to
develop. Should that occur, strong to severe winds and marginally
severe hail may be possible. Confidence in the exact evolution of
thunderstorm activity remains low but trends will be monitored.

..Thornton/Hart.. 04/18/2026

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PBZ...RLX...CLE...JKL...ILN...LMK...

LAT...LON   37488411 37818446 39408365 40748245 41248198 41458150
            41528118 41498085 41468062 41368029 41288008 41187991
            41007974 40927968 40597957 39428014 39078052 38778086
            38328134 38118159 37728235 37328333 37488411 

MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0732 AM CDT Sat Apr 18 2026

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
UPPER OHIO VALLEY TO THE APPALACHIANS...

...SUMMARY...
Scattered strong to severe thunderstorms capable mainly of damaging
winds will be possible today across the upper Ohio Valley and
central Appalachians.

...Synopsis...
Water-vapor imagery this morning shows a large-scale upper trough
over the Upper Midwest into the south-central Plains.  An elongated
mid-level vorticity lobe and associated speed max will quickly move
eastward across the Midwest today and reach the Lower Great Lakes
and upper OH Valley late tonight.  Farther south, a belt of strong
west-southwesterly flow associated with a subtropical jet will
reside over TX. 

A cold front extending from a low near James Bay southward through
the Great Lakes and into TX will continue to push east and southeast
through the period.  Convective outflow over the OH Valley to the
east of the front will eventually be overtaken by the front later
today as a band of showers/thunderstorms develops over the upper OH
Valley by early afternoon.  

...OH Valley into the Appalachians...
Some heating combined with a gradually moistening airmass (55-60 deg
F surface dewpoints) will result in weak destabilization by midday
as convective development ensues near the preceding outflow/wind
shift and front.  Ample mid to high-level flow will aid in some
potential for storm organization, mainly in the form of a few
stronger cells and linear bands.  Widely scattered strong to severe
gusts capable of wind damage will likely be the primary hazard, but
an isolated risk for hail or a brief tornado is possible with the
strongest cells.  This activity will likely weaken by early evening
as it encounters a slightly drier and less unstable airmass with
east extent.  

...Central Texas...
Scattered showers and elevated thunderstorms are expected throughout
much of the day as the cold front rapidly undercuts a moist and
unstable air mass.  The 12 UTC Del Rio, TX raob shows an 8.2 deg
C/km 700-500 mb lapse rate.  Forecast soundings show MUCAPE parcels
rooted in the 850-700 mb layer, with effective deep-layer shear of
50-60 kt.  Although an isolated risk for large hail appears to be
the main hazard with the stronger cells, there has been some
indication that a localized risk for severe gusts could accompany
the strongest cores.  For short-term details regarding a risk for
hail/wind with a few stronger thunderstorms this morning extending
from the Concho Valley east-northeast towards DFW, reference MCD
#490.

..Smith/Dean.. 04/18/2026

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1103 AM CDT Sat Apr 18 2026

Valid 181630Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
ACROSS PARTS OF THE UPPER OHIO VALLEY AND LOWER GREAT LAKES
REGION....

...SUMMARY...
Widely scattered strong to severe thunderstorms capable mainly of
damaging winds will be possible today across the Upper Ohio Valley
and Lower Great Lakes.

...Upper OH Valley...
Latest surface analysis shows a cold front pushing eastward across
western OH, associated with a band of widespread clouds and light
precipitation.  Mostly clear skies are present ahead of the front,
where temperatures are warming through the 70s.  This will lead to a
corridor of marginal afternoon instability and the potential for
scattered thunderstorm intensification along the front.  Forecast
soundings show strong mid-level winds and steep low-level lapse
rates, supportive of strong downdrafts in any vigorous convection. 
However, CAM guidance is consistent in showing very few
organized/strong storms through the day.  Will maintain the SLGT
risk for the conditional risk of a few damaging wind events, but
with limited confidence.

...TX...
Isolated intense thunderstorms have been ongoing this morning in the
post-frontal regime across central TX.  These storms have produced
hail and gusty winds for several hours.  It appears likely that this
scenario will shift eastward and weaken early this afternoon as the
primary upper jet moves into AR and away from the region, but will
maintain the MRGL risk area for a few more hours and extend it into
parts of AR/LA.

..Hart/Chalmers.. 04/18/2026