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Day 3 Outlook 0830Z Probablistic 0830Z
Current Day 3 Outlook 0730z
Categorical Day3 0830Z Outlook
  

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 Forecast Discussion

    
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ACUS03 KWNS 220726
SWODY3
SPC AC 220725

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0225 AM CDT Sun Jul 22 2018

Valid 241200Z - 251200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE TUESDAY
AFTERNOON AND EVENING ACROSS PARTS OF THE WESTERN INTO CENTRAL
DAKOTAS AND WESTERN NEBRASKA...

...SUMMARY...
Strong thunderstorms may impact parts of the western into central
Dakotas and western Nebraska late Tuesday afternoon and evening,
accompanied by at least some risk for severe wind and hail.

...Synopsis...
Highest mid-level heights may gradually shift westward across
Arizona during this period.  Otherwise, models indicate little
appreciable change to a prominent subtropical high encompassing all
but the northern tier of the western into central United States. 
Downstream troughing east of the Mississippi Valley into the
Atlantic Seaboard may also change little, with an elongated embedded
cyclonic circulation lingering over the eastern Gulf States.  But
guidance suggests that broad troughing within the mid-latitude
westerlies may begin to dig across the central Canadian/U.S. border
area.  Within seasonably strong northwesterly flow between this
feature and the northern periphery of the subtropical high, a
perturbation may emerge from the northern Rockies and dig across the
northern Plains by late Tuesday night.

...Western/central Dakotas and western Nebraska..
Models indicate at least modest steepening of lower/mid tropospheric
lapse rates associated with the eastward advection of elevated mixed
layer air into the northern High Plains by Tuesday afternoon.  In
association with a developing surface low to the lee of the northern
Rockies, boundary layer moistening is expected to contribute to an
axis of weak to moderate destabilization with insolation.  This
probably will take place beneath 30-50 kt northwesterly 700-500 mb
flow, which may contribute to an environment conducive to organized
convection, including supercells, posing a risk for severe wind and
hail.  Enough spread exists within the various model output
concerning the synoptic and sub-synoptic details and magnitude of
destabilization to preclude a categorical slight risk at this time,
but it is possible that this could change in subsequent outlooks for
this time period.

..Kerr.. 07/22/2018

$$