SPC AC 010618
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0118 AM CDT Sun Aug 01 2021
Valid 031200Z - 041200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
A few strong storms may affect parts of the Carolinas and Oregon on
Tuesday, but severe potential appears limited.
A large area of mainly weak cyclonic flow aloft will persist over
the eastern CONUS on Tuesday, with an upper low over IN. An embedded
wave will move northward across the Mid Atlantic during the day,
with 35-40 kt midlevel winds. To the west, a ridge will remain over
the Great Basin, but heights will fall along the Pacific Coast as a
shortwave trough approaches late.
At the surface, a front will linger across the northern Gulf of
Mexico, curling northeastward across the coastal Carolinas.
Low-level moist advection is possible over the eastern Carolinas in
association with increasing southerly 850 mb winds, and this will
also enhance shear. However, models vary how far inland this will
Scattered showers and storms are likely to be ongoing throughout the
day over the eastern Carolinas given aforementioned moisture
advection. Heating may be severely limited, and destabilization
uncertain. If enough instability can develop, either by increasing
dewpoints or pockets of heating, a threat of marginally severe
storms could develop with 100-200 m2/s2 effective SRH, most likely
over far eastern NC. At this time, the threat is too conditional to
introduce a risk area.
A surface trough is forecast to develop over central/eastern WA and
OR during the day, where strong heating will occur. Lapse rates
aloft will also remain steep with around -10 C at 500 mb. Isolated
afternoon storms are expected as CIN is removed, primarily over
central OR. Forecast soundings depict inverted-v profiles, with
around 35 kt effective shear. This may favor a few cells capable of
marginal hail or isolated severe gusts. However, boundary-layer
moisture content will be questionable, thus will maintain general
thunder at this time.
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