SPC Jun 18, 2025 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1230 PM CDT Wed Jun 18 2025

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CAROLINA
PIEDMONT INTO PARTS OF THE MID ATLANTIC AND NEW ENGLAND...

...SUMMARY...
Strong to potentially severe thunderstorms are forecast on Thursday
from parts of New England into the Mid Atlantic and Carolinas.

...Synopsis...
A positively tilted mid-level shortwave trough will move from the
Great Lakes to the Northeast on Thursday. Mid-level flow will
strengthen east of this trough from the Mid-Atlantic to the
Northeast. A surface low will deepen as it moves from the eastern
Great Lakes to northern Maine during the period. A cold front will
extend southwest from this surface low and will begin from the
eastern Great Lakes to the Mid-Mississippi Valley Thursday morning
and near or off the Atlantic Coast by 12Z Friday. 

...New England into the Mid-Atlantic/Southeast...
Strong heating is expected across a broad, moist warm sector with
dewpoints in the upper 60s to low 70s east of the Appalachians by
Thursday afternoon. This will result in moderate to potentially
strong instability across much of the East Coast. The best chance
for more organized storms will be from central Virginia northward
where stronger shear will be present beneath 50 knot mid-level flow.
A zone of potentially greater severe weather probabilities may be
present across the Mid-Atlantic where the greatest instability/shear
are expected to overlap. It appears the cold front will lag well
behind with the majority of convection developing along a
pre-frontal trough during the afternoon. Without the stronger
frontal forcing, some concerns about convective coverage/intensity
exist, precluding higher probabilities at this time. 

South of this area, mid-level flow will not be as strong. Therefore,
more modest shear will limit greater storm organization.
Nonetheless, modest (25 knot) shear will support some multicell
storms capable of damaging wind gusts across North Carolina. Even
weaker shear will be present across the southeast where strong
instability is expected. Storms are not expected to be as organized
here, but the strong instability and moist environment could support
some water-loaded downdrafts capable of damaging wind gusts. 

...Southern Montana...
Weak midlevel height falls are still expected across parts of
western MT Thursday afternoon/evening, in response to the
approaching mid/upper-level trough. Low-level moisture will remain
limited, but strong diurnal heating will support high-based storm
development. Steep low-level lapse rates and relatively strong
midlevel flow will result in potential for isolated severe gusts
during the afternoon and evening as convection spreads eastward.

...Upper Midwest...
Low-level warm advection related to the southeastward-moving
midlevel shortwave trough may aid in storm development on Thursday
from northern MN into parts of WI and upper MI. Moderate instability
and sufficient deep-layer shear will support potential for a few
stronger cells/clusters capable of producing large hail and damaging
wind. Additional strong to locally severe storms may redevelop later
Thursday night across parts of this region, in response to a
nocturnally strengthening low-level jet.

...Northern Plains...
Diurnal heating of an increasingly moist airmass will result in
moderate to strong buoyancy across parts of the northern Plains by
Thursday afternoon. Deep-layer shear will be sufficient for
organized storms, but diurnal storm development remains highly
uncertain amid background midlevel height rises associated with a
building ridge. Development of a storm or two cannot be ruled out
through evening near a surface trough/weak dryline. Elevated storm
coverage may increase somewhat Thursday night in response to a
strengthening low-level jet, which could pose a threat of hail and
localized strong gusts.

...Central High Plains...
Moderate to strong buoyancy will develop across the central High
Plains amid strong surface heating. Shear will not be as strong this
far south, but a dryline/surface trough may provide sufficient
forcing for a few high-based storms Thursday afternoon/early
evening.

..Bentley.. 06/18/2025

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