Source: US National Oceanic and Atmospheric Administration
SPC AC 031628
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Sat May 03 2025
Valid 031630Z – 041200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CAROLINAS INTO THE MID-ATLANTIC AND NEW ENGLAND…
…SUMMARY…
Scattered strong to severe thunderstorms are possible this afternoon
and evening from parts of the Carolinas into the Mid-Atlantic and
Northeast. A more isolated severe threat may develop across the
Southeast, and also across parts of the Great Basin and far west
Texas.
…Carolinas into the Mid-Atlantic and New England…
Generally upper 50s to low 60s surface dewpoints are present
along/east of the higher terrain of the Blue Ridge/Appalachians from
parts of the Carolinas northeastward into the Mid-Atlantic and
southern New England. Even with mid-level lapse rates remaining
fairly modest, around 500-1000 J/kg of MLCAPE is forecast to develop
this afternoon in a narrow corridor across these regions with
additional filtered daytime heating. Large-scale ascent associated
with a slow-moving upper trough over the mid MS Valley will
gradually overspread the destabilizing warm sector in the next few
hours. This ascent, along with orographic lift over the higher
terrain, should aid in the development of scattered strong to severe
thunderstorms this afternoon and evening.
Around 30-40 kt of deep-layer shear should be present, which will
support a mix of multicells and marginal supercells. Scattered
damaging winds should be the main threat with the multiple clusters
that develop as they spread northeastward through the evening, but
some hail may also occur with any sustained supercell. Greater
confidence exists in overall thunderstorm coverage and intensity
across parts of the Mid-Atlantic into southern New England, where
the Slight Risk has been maintained with minimal changes. The
tornado threat remains less clear across these regions, but some
modest enhancement to the southwesterly low-level flow could aid in
occasional low-level updraft rotation.
…Southeast…
12Z soundings across the central Gulf Coast states show that
convection that occurred yesterday into the overnight/early morning
hours generally stabilized the environment this morning. Widespread
cloudiness evident in visible satellite imagery late this morning
should tend to delay/hinder robust destabilization this afternoon
along/ahead of the southeastward-advancing synoptic cold front,
which lends considerable uncertainty to the overall intensity of
renewed convection along/ahead of the front later today. Still,
mid-level winds and related deep-layer shear are forecast to
gradually strengthen through the afternoon/evening as the upper
trough over the mid MS/lower OH Valley develops slowly eastward.
This should support some threat for organized convection, and
isolated damaging winds may occur with any clusters that can form.
With continued concerns regarding the degree of instability
developing this afternoon, confidence remains too low to include
greater severe wind probabilities at this time.
…Great Basin…
Modestly enhanced southerly mid-level flow will overspread parts of
the western and northern Great Basin as an upper trough moves
eastward over the western CONUS through the afternoon/evening. While
boundary-layer moisture is expected to remain very limited,
increasing mid-level moisture and diurnal destabilization should aid
in weak MLCAPE developing by this afternoon. Scattered thunderstorms
are forecast to develop and spread northward, with an isolated
threat for severe winds given steepened low-level lapse rates and a
very well mixed boundary layer. Small hail may also occur with the
strongest cores.
…Far West Texas…
Even though large-scale ascent should remain weak/nebulous across
far west TX and vicinity today, isolated supercell development still
appears possible in a modest post-frontal/low-level upslope flow
regime. Both low-level winds and MLCAPE are expected to remain
modest, but strengthening westerly winds with height in mid/upper
levels should support around 30-40 kt of deep-layer shear and some
updraft organization. Based on latest guidance trends showing a
supercell or two developing this afternoon/evening, have introduced
a Marginal Risk for hail across parts of far west TX and vicinity.
..Gleason/Squitieri.. 05/03/2025
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