ACUS01 KWNS 171237
SWODY1
SPC AC 171235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Thu Jul 17 2025

Valid 171300Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHEAST AND NORTHERN HIGH PLAINS...

...SUMMARY...
Scattered damaging winds and a brief tornado are possible across
northern New England this afternoon. Isolated/sporadic damaging
winds may also occur across a broad swath of the
Northeast/Mid-Atlantic to the southern High Plains. A confined
corridor of large hail and severe gusts appears possible from
north-central Montana to southwest North Dakota this evening.

...Northeast...
The Slight Risk has been maintained across this region with no
changes. A shortwave trough will move northeastward from the Upper
Great Lakes to the Ontario/Quebec border vicinity by this evening. A
broad swath of enhanced 850-700 mb west-southwesterly winds is
forecast from PA/NJ northward into New England. Further weakening of
already poor mid-level lapse rates is anticipated across parts of
southern NY into southern New England. This may tend to limit
convective coverage across the northern Mid-Atlantic to southern New
England vicinity. But, farther north and in closer proximity to
ascent associated with the approaching mid-level shortwave trough,
scattered robust convection is anticipated this afternoon along the
Quebec border across northern New England. Sufficient instability
and deep-layer shear are forecast across this region to support a
mix of multicells and perhaps marginal supercells. Given the
enhanced low/mid-level flow, scattered damaging winds should be the
main threat with this activity as it moves generally
east-northeastward through the early evening, before eventually
weakening as it approaches the coast. Enough low-level hodograph
enlargement/curvature may also be present to support some risk for a
tornado or two.

...Mid-Atlantic to the Southern High Plains...
Extensive convection is ongoing this morning across
south-central/southeast KS into MO. This activity should generally
remain sub-severe, but it will help reinforce a front that is
expected to gradually sag southward and eventually stall across the
mid MS Valley to southern Plains today. Scattered to numerous
thunderstorms are expected to develop west of the Appalachians along
this boundary later this afternoon as diurnal heating occurs.
Moderate to strong instability amid steepened low-level rates
along/south of the outflow/front should support sporadic wet
microbursts. Isolated hail will be possible with thunderstorms in
the post-frontal upslope flow regime across parts of the southern
High Plains. But, modest deep-layer shear and warm temperatures
aloft across all these regions should temper the overall
intensity/coverage of severe convection. Isolated damaging winds may
also occur with thunderstorms that develop east of the central
Appalachians this afternoon, even though coverage should be somewhat less.

...Northern Plains...
A narrow corridor of supercell potential remains evident across
north-central MT to southwest ND, mainly this evening. A positively
tilted mid-level shortwave trough over the southern Canadian Rockies
will progress eastward along the international border with MT/ND
today. Mid to late afternoon convective initiation should occur over
parts of southwest Alberta in association with this feature. A
confined plume of weak buoyancy ahead of this activity should
initially temper updraft intensity as it spreads east-southeastward
into north-central MT by late afternoon. But, favorably timed
strengthening of a 500-mb westerly jet over MT will aid in hodograph
elongation at mid/upper levels this evening. This could support a
long-lived supercell or two during the evening, impinging on the
nose of moderate instability that should be present across southeast
MT. Large hail should be the main threat with these supercells if
they can be maintained. An isolated hail/wind risk may persist along
the ND/SD border vicinity overnight.

..Gleason/Bentley.. 07/17/2025

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