SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 AM CDT Thu Jul 28 2022
Valid 281300Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
FROM EASTERN NY TO NH AND MA...
...SUMMARY...
Occasional damaging gusts and marginally severe hail are expected
across parts of the Northeast this afternoon. Isolated wind damage
will also be possible from parts of the Mid-Atlantic to the Ozarks,
and marginally severe wind/hail may occur near the Front Range in
Colorado.
...Northeast this afternoon...
A deep midlevel low over ON will move slowly eastward toward western
QC, as embedded speed maxima translate eastward from the Great Lakes
to New England on its southern periphery. An associated/diffuse
surface cold front will likewise move eastward across the upper OH
Valley and lower Great Lakes by early tonight. Thunderstorm
development is expected by early afternoon along/ahead of the cold
front, and along a pre-frontal trough from eastern NY into eastern
PA, with the greater storm coverage expected from NY northward in
the zone of larger height falls.
Afternoon surface temperatures warming into the 80s in cloud breaks
and boundary-layer dewpoints in the upper 60s to lower 70s will
support MLCAPE of 1000-1500 J/kg. Midlevel lapse rates will be poor
(< 6.5 C/km), but long and relatively straight hodographs with 35-45
kt effective bulk shear will favor a mix of supercells and short
line segments capable of producing occasional damaging outflow gusts
this afternoon.
...Portions of the Mid-Atlantic to the Ozarks this afternoon...
Vertical shear will be weaker with southward extent away from NY,
though modestly enhanced midlevel flow may extend as far south and
northern VA. Cloud debris with morning convection will tend to slow
surface heating today from eastern KY into WV and western VA, with
the stronger buoyancy expected on the southern and eastern fringes
of the morning clouds. During the afternoon, widely scattered
thunderstorms could form in the zone of differential heating, and
the strongest storms could produce isolated wind damage with
downbursts. Wind profiles will be relatively weak in the low-mid
levels along the southern periphery of the early clouds/convection
from northern AR/southern MO to western TN. However, strong surface
heating and steep low-level lapse rates south of the clouds could
support a few multicell storms/clusters capable of producing
isolated strong/damaging outflow gusts near and just after peak
heating.
...Eastern CO and vicinity this afternoon/evening...
Outflow with overnight convection has moved southwestward to the
Front Range in CO. Some clouds will linger across the eastern
Plains of CO, and vertical shear will be weaker with less steep
midlevel lapse rates compared to Wednesday afternoon. Still,
boundary-layer dewpoints near 60 F, pockets of surface heating, and
low-level upslope flow should support the development of scattered
thunderstorm clusters this afternoon near the Front Range. The
strongest storms will pose a threat for marginally severe hail and
isolated strong-severe outflow gusts.
..Thompson/Gleason.. 07/28/2022
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