LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1245 AM CDT Tue Jul 04 2023
Valid 041200Z - 051200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL GREAT PLAINS...
...SUMMARY...
Greatest potential for scattered severe thunderstorms is over the
central Great Plains beginning late afternoon Tuesday into Tuesday
night. Severe thunderstorm gusts will be the primary hazard.
...Central Great Plains to the upper MS Valley...
Northern Rockies upper trough is forecast to advance into the
northern Plains later today, then into the upper MS Valley late in
the period. Weak height falls will be noted as far south as the
central Plains which will result in notable surface pressure rises
across the high Plains. Latest model guidance suggests a strong cold
front will surge across WY/western NE by 18z. This boundary will
advance into the TX Panhandle by 05/12z, arcing across northwestern
OK-eastern KS into WI.
Early this morning, a well-organized MCS has evolved across the
western Dakotas/northwestern NE. This activity has matured ahead of
a weak short-wave trough that is forecast to progress into the upper
MS Valley by 18z, then into northwestern ON/upper Great Lakes by
late afternoon. Models may be a bit slow with the forward
propagation of the MCS as it propagates across the northern Plains
prior to daybreak. Current thinking is boundary-layer heating should
contribute to moderate-strong buoyancy ahead of the remnants of this
MCS. Scattered thunderstorms should easily develop by mid afternoon
as CINH weakens with temperatures warming into the mid 80s. Modest
deep-layer flow will be more than adequate for sustaining organized
updrafts, including clusters and a few line segments. Damaging winds
and hail can be expected with this activity.
Farther south across the central Great Plains, pre-frontal wind
shift will orient itself southwest-northeast ahead of the primary
cold front across western KS into south-central NE. Latest data
suggests strong boundary-layer heating will be noted across the
central High Plains such that convective temperatures should be
breached by 22-23z as temperatures soar into the upper 90s just
ahead of the pre-frontal wind shift. Forecast soundings exhibit
large surface temp/dew point spreads (40F) within the initiation
corridor. Scattered high-based convection is expected to evolve
within an environment that will be modestly sheared with deep
southwesterly flow. Severe winds should be the primary concern with
thunderstorms that grow upscale along a corridor from northwestern
KS into south-central NE.
Isolated strong/severe thunderstorms are also expected to develop
over the higher terrain of southern WY then propagate southeast
within a post-frontal environment characterized by strengthening
westerly flow at 500mb. Forecast soundings suggest supercells should
be the dominant storm mode across southern WY into northeast CO.
Large hail and damaging winds should be the primary concern.
..Darrow/Weinman.. 07/04/2023
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