SPC Jul 11, 2018 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook

Day 2 Outlook Image

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1225 PM CDT Wed Jul 11 2018

Valid 121200Z - 131200Z


Severe thunderstorms are possible from northern Nebraska into
western Wisconsin.

...NE to WI...

Mid-level heights will be weakly suppressed across the eastern
Dakotas and MN during the day2 period as primary 500mb speed max
ejects across northern MN into ON. This feature will contribute to a
front settling to a position from central MN...southwest into the NE
Panhandle by 13/00z. With a dominant upper high expected to remain
anchored over the Midwest the large-scale pattern will continue to
prove favorable for higher PW air mass to extend across the High
Plains, arcing into the upper Great Lakes region. Within this plume
of higher moisture it appears strong boundary layer heating will
contribute to the removal of inhibition for thunderstorm
development. Strongest heating is expected across NE where surface
temperatures climbing into the mid 90s should allow parcels to reach
their convective temperatures. Forecast soundings suggest
thunderstorm initiation could occur as early as 21z, especially near
the front where low-level convergence will be maximized. In the
absence of a large-scale feature for broader ascent, strong surface
heating and frontal forcing will be the primary mechanisms for an
elongated corridor of deep convection. SLGT Risk has been oriented
along this wind shift where the greatest concentration of storms are
expected. While damaging winds may be the greatest risk, some hail
could be noted with supercell structures despite the relatively warm
mid-level temperatures.


Northwesterly mid-level flow will persist across the eastern US
during the day2 period as anticyclone remains centered over the
Midwest. This flow regime should encourage a weak surface front to
sag south across the Carolinas during the day.  High PW air mass, on
the order of 1.75-2", will extend across this pre-frontal region
where scattered thunderstorms should readily develop during the heat
of the day. There is some concern that a few wet micro bursts could
evolve with this activity. Given the lack of large-scale ascent, in
the wake of mid-level short-wave trough, will not introduce 5%
severe probs for locally damaging winds; however, thermodynamic
profiles could support this type of event. Severe probs may be
introduced to this region during the day1 period if/when confidence
in this scenario is higher.

Tornado:   2%     - Marginal
Wind:     15%     - Slight
Hail:      5%     - Marginal

..Darrow.. 07/11/2018

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