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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0254 PM CDT Sat Jul 27 2024

Valid 272000Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTH DAKOTA AND NORTHERN MINNESOTA...

...SUMMARY...
Scattered severe thunderstorms capable of producing both large hail
and damaging winds appear possible across portions of the northern
Plains vicinity, including parts of the Dakotas and northern
Minnesota, mainly this afternoon and evening.

...20z Update...
Scattered thunderstorm activity is ongoing across portions of
eastern North Dakota into Minnesota, where daytime heating has
yielded around 1500-2000 J/kg of MLCAPE. A belt of enhanced
mid-level southwesterly flow aloft is supporting 40-50 kts of deep
layer shear from far eastern ND into northern MN. Activity thus far
has been elevated, given mid-level capping. Some uncertainty exists
in whether more robust surface based storms can develop. Should
surface based storms develop, this environment may support potential
for damaging winds, large hail, and possibly a tornado later this
evening. Additional thunderstorm development may occur further west
near a cold front across the western/central Dakotas later this
evening. Confidence in exact coverage of additional development
remains low.

Water vapor imagery shows a shortwave advecting eastward across
western Colorado. This feature will be the focus of thunderstorm
development and potential for isolated strong to severe winds across
the High Plains later this afternoon/evening. See MCD#1715 for more
information. 

Overall, the current D1 Convective Outlook characterizes these
threats well with no changes needed with this update.

..Thornton.. 07/27/2024

.PREV DISCUSSION... /ISSUED 1126 AM CDT Sat Jul 27 2024/

...Northern Plains/Upper Midwest...
A closed upper low centered over northern Saskatchewan/Manitoba this
morning will move slowly eastward towards Hudson Bay through the
period. Across the northern Plains, a low-amplitude shortwave trough
over the Dakotas is forecast to advance northeastward into eastern
ND and northern MN through this evening. This feature should aid in
renewed convective development across this area later today. A cold
front/surface trough arcs southward from the primary surface low in
northern Saskatchewan/Manitoba into parts of eastern MT. Low-level
moisture remains more limited with westward extent across the
northern High Plains, with greater surface dewpoints (mid/upper 60s
to low 70s) present farther east in the Dakotas and northern MN.

Scattered thunderstorms should develop this afternoon along an
instability/moisture gradient across parts of northern MN as the
previously mentioned shortwave trough overspreads this region.
Ongoing weak/elevated thunderstorms in northeast SD may also persist
and gradually strengthen as they move northeastward into greater
instability this afternoon. Around 1500-2500 J/kg of MLCAPE is
forecast to be in place in a narrow corridor across northern MN and
vicinity by late afternoon, as daytime heating of the moist
low-level airmass continues to occur, and as modestly steepened
mid-level lapse rates overspread the warm sector. Around 35-50 kt of
southwesterly mid-level flow associated with the shortwave trough
should aid in similar values of deep-layer shear, which will promote
organized severe thunderstorm potential, including supercells. Large
hail and severe/damaging winds will be a threat with any robust
convection that can remain at least semi-discrete. Enough low-level
shear should also be present to support some threat for a tornado or
two. This activity will spread northeastward towards the
international border through the evening, before eventually moving
into Canada.

Additional convection may also develop along the weak cold
front/surface trough in the western/central Dakotas vicinity late
this afternoon and early evening. This potential still appears
somewhat more uncertain in the wake of the lead shortwave trough.
Even so, any thunderstorm clusters that can be sustained will be
capable of producing both large hail and damaging winds, given a
favorable thermodynamic environment and sufficient deep-layer shear.
This convection should eventually weaken by late evening into the
eastern Dakotas with the loss of daytime heating.

...Northern Great Basin into the Central Rockies/High Plains...
Multiple mid-level vorticity maxima will move east-northeastward
across the northern Great Basin and central Rockies/High Plains
today. Scattered to numerous thunderstorms should develop across
these regions this afternoon and evening while spreading generally
eastward. Even though low-level moisture will tend to remain fairly
limited, steepened low/mid-level lapse rates and modestly enhanced
mid-level flow should support an isolated threat for strong to
severe wind gusts with the more robust cores. Convection may have a
tendency to form into one or more loosely organized clusters through
this evening, especially across the central High Plains of eastern
WY/northeast CO into the NE Panhandle vicinity. Still, with
generally modest deep-layer shear, confidence in a more concentrated
corridor of severe winds remains too low to include a Slight Risk
across the central High Plains with this update.