SPC Jun 14, 2025 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0750 AM CDT Sat Jun 14 2025

Valid 141300Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered severe thunderstorms capable of producing large hail and
damaging wind gusts will be possible across parts of the northern
and central High Plains this afternoon and evening. Isolated strong
to severe thunderstorms may also occur today across parts of the
southern Plains into the Ozarks, and over portions of the southern
Mid-Atlantic.

...Northern/Central Plains into the Upper Midwest...
Compared to yesterday, mid-level heights are generally forecast to
remain neutral or even rise slightly today as upper ridging
gradually builds over the southern/central Rockies. Even so,
modestly enhanced southwesterly mid-level flow will persist over the
northern Rockies and adjacent High Plains. A seasonably moist
low-level airmass will remain over the northern/central High Plains
today, with steep mid-level lapse rates also present. Daytime
heating of this airmass should foster moderate to locally strong
MLCAPE by mid to late afternoon. High-based thunderstorms should
once again develop over the higher terrain of the northern/central
Rockies by late afternoon, before spreading eastward over the High
Plains this evening. Even though low-level winds are forecast to
remain generally modest, veering and gradual strengthening of the
flow with height through mid/upper levels should support around
35-50 kt of deep-layer shear (stronger across the northern High
Plains). Supercells that become established will have mainly a large
to very large (2+ inch diameter) hail threat, with any eventual
clusters posing more of a severe wind risk with eastward extent
through the evening.

A separate area of strong to isolated severe thunderstorms is also
apparent across parts of the Upper Midwest (IA vicinity) along/near
a surface boundary. While deep-layer shear will likely remain weak,
moderate instability may still support occasional hail and gusty
downdraft winds with any of the more robust cores that can develop
this afternoon and early evening.

...Southern Plains into the Ozarks...
Ongoing convective clusters and cells this morning across southern
KS and northern OK are being aided by weak southwesterly low-level
warm/moist advection. With generally weak deep-layer shear present,
the overall severe threat has remained generally isolated (reference
Mesoscale Discussion 1283 for additional details on the short-term
severe risk across south-central KS/northern OK). Still, steep lapse
rates aloft (per area 12Z soundings) are contributing to substantial
MUCAPE, which may support an isolated threat for hail and severe
wind gusts through the morning hours as these thunderstorms spread
generally east-southeastward along an instability gradient/surface
front. It remains unclear how far east the ongoing cluster in
southern KS may persist, with some guidance suggesting it may
restrengthen into parts of western/central AR this afternoon. Have
therefore expanded the Marginal Risk for severe/damaging winds
eastward across this area.

Considerable uncertainty remains regarding the potential for
additional convection to develop along/near the trailing outflow
from this morning activity across northern/central OK into
south-central KS and vicinity. It appears likely that moderate to
strong instability will be in place by late afternoon as diurnal
heating of a very moist low-level airmass occurs along and south of
the outflow boundary. But, large-scale ascent and deep-layer shear
will remain weak for much of the day, with modest low-level warm
advection forecast to gradually strengthen through the evening
hours. Any thunderstorms which can develop in this rather favorable
thermodynamic environment could pose an isolated threat for severe
hail and damaging winds. But, confidence in a more focused corridor
of severe potential remains too low to include greater severe
hail/wind probabilities at this time. Isolated strong to severe
thunderstorms may also develop this afternoon/evening across parts
of the southern High Plains along/east of a surface lee
trough/dryline, although forcing aloft will remain nebulous beneath
upper ridging.

...Southern Mid-Atlantic...
A weak mid/upper-level trough will move eastward across the
Southeast and OH Valley today, eventually reaching the southern
Mid-Atlantic by late tonight. A stalled surface boundary is located
across parts of northern VA into MD and the Delmarva Peninsula this
morning. This boundary is expected to move little through the day,
and will likely serve as a focus for convection later this
afternoon.

Current expectations are for thunderstorms to initially develop
around 20-22Z over the higher terrain of the Blue Ridge, and
subsequently spread east-southeastward across the I-95 corridor in
VA/DC/MD through the early evening. Various NAM/RAP forecast
soundings suggest that even with poor lapse rates aloft, sufficient
instability and modest deep-layer shear should be present
along/south of the surface boundary to support some updraft
organization. Occasional severe/damaging winds up to 60 mph and
perhaps some marginally severe hail will be possible with the
stronger cores through the evening, until they eventually weaken
with the loss of daytime heating.

..Gleason/Kerr.. 06/14/2025

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