SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Mon May 19 2025
Valid 192000Z - 201200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS FAR NORTH
TEXAS...MUCH OF CENTRAL AND EASTERN OKLAHOMA...SOUTHEAST
KANSAS...NORTHWEST ARKANSAS...AND SOUTHWEST MISSOURI...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EAST
TENNESSEE INTO WESTERN SOUTH CAROLINA...
...SUMMARY...
Significant severe weather is likely from the central/southern
Plains into the the Ozarks today into tonight. All severe weather
hazards are expected, to include tornadoes (some potentially strong
to intense), very large hail, and severe winds.
...20Z Update...
A regional outbreak of severe thunderstorms is still anticipated
this afternoon and evening as a shortwave trough ejecting from the
central/southern High Plains into the central/southern Plains, where
a very moist and unstable airmass is in place. Recent surface
analysis shows low 70s dewpoints across much of central and eastern
OK, with mid 60s dewpoints as far north as southeast NE. Both the
18Z OUN and OAX soundings sampled cold mid-level temperatures and
associated steep mid-level lapse rates. Ample moisture beneath these
steep lapse rates is supporting very strong buoyancy. 18Z OUN
sounding reported MLCAPE over 3500 J/kg.
Storms that developed earlier this afternoon across central OK are
now moving into southeast KS. These storms have maintained their
elevated character thus far, but some transition to a more
surface-based character is possible as destabilization continues
downstream. More surface-based, cellular development has initiated
across south-central OK and adjacent far northeast OK. Airmass
downstream is favorable for storm maintenance as they track
east-northeastward. All severe hazards are possible with these
storms, including very large hail, strong wind gusts, and strong to
intense tornadoes.
Convergence along the dryline is modest now, but will likely
increase later this afternoon and evening. Expectation is for
another round of supercells capable of all hazards (i.e. very large
hail, strong wind gusts, and strong to intense tornadoes) moving
from southwest OK/far northwest TX into central/south-central OK and
adjacent north-central TX. Large-scale ascent will increase across
eastern KS and southeast NE as well, with thunderstorms capable of
all hazards expected across this region as well.
By this evening, there will likely be a nearly continuous line of
thunderstorms from southeast NE/southwest IA into north-central TX.
A mix of supercells and bowing segments will maintain the risk of
significant severe weather throughout the evening and tonight,
continuing into early tomorrow morning from the Mid-MS Valley into
the Arklatex.
Guidance has trended towards more favorable environmental conditions
for a greater severe risk across southeast MO tonight, Wind and
tornado probabilities were increased across this region as a result.
..Mosier.. 05/19/2025
.PREV DISCUSSION... /ISSUED 1130 AM CDT Mon May 19 2025/
A powerful upper trough over the southern Rockies will eject into
the Plains today, with an associated 70-80 knot mid level jet nosing
into OK. Meanwhile, the primary surface low will deepen over
northwest OK and a southerly low-level jet will strengthen across
the warm sector. The resulting synoptic pattern is very favorable
for significant severe weather over portions of OK/AR/MO/KS, with
the potential for strong tornadoes, very large hail, and widespread
damaging winds. However, the mesoscale details of the forecast
result in considerable uncertainty regarding the corridors of
greatest risk.
...Eastern OK/Western AR/Southwest MO...
A southern stream shortwave trough over TX will track northeastward
today. Large scale ascent ahead of this feature will weaken the cap
and likely lead to rather widespread convective development by early
afternoon over much eastern OK and western AR. Forecast soundings
in this area show a very unstable air mass and favorable low and
deep layer shear profiles for supercell development. All severe
hazards are possible, including strong tornadoes. Refer to MCD #874
for further details.
...North TX/Central OK/Eastern KS/southeast NE...
Behind the aforementioned convective development, a pronounced
dryline will become established from west-central OK into central
KS. Strong heating along and west of the dryline, combined with
dewpoints near 70f to the east, will result in extreme instability
and only a weak cap. Large-scale mid-level height falls/forcing for
ascent associated with the approaching upper trough over the
southern Rockies will lead to discrete/intense supercell development
by mid/late afternoon - potentially along the entire length from
north TX into KS. These storms will pose a risk of very large hail
and strong tornadoes through the early evening.
Farther north in northeast KS and southeast NE, the Pacific cold
front will impinge on the dryline, aiding convective development but
perhaps leading to more linear forcing. Nevertheless, large hail
and tornadoes will still be possible.
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