Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1236 AM CDT Sun May 03 2026
Valid 031200Z - 041200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
NORTHERN/CENTRAL MISSOURI INTO CENTRAL ILLINOIS...
...SUMMARY...
A few strong thunderstorms are possible across parts of
northern/central Missouri and central Illinois on Sunday.
...Synopsis...
A short-wave trough with a belt of enhanced northwesterly flow
within the broader eastern US trough will overspread the Missouri
Valley through this evening. A weak cold front will extend across
portions of the central Plains into the Missouri Valley. This
boundary will be the focus for potential isolated thunderstorm
development as the short-wave moves in across the region by the
evening.
...Northern/central Missouri into central Illinois...
Moisture quality continues to be a question within the Marginal Risk
area as previously stated in prior outlooks. Surface observations
show 50s dew points have made it as far north as the Red River in
southern Oklahoma as of late Saturday evening. There remains some
question just how far north (or deep) this moisture will be by late
afternoon across Missouri/Illinois. Most 00z guidance suggests that
50 F dew points will steadily spread into Missouri through the day
today. However, afternoon sounding profiles suggest this moisture to
be thin and potentially subject to mixing. Through the afternoon,
weak convergence along the front and a mid-level capping inversion
will likely prohibit convective development. As the short-wave
ascent arrives in the evening, 00z HREF guidance suggest that at
least isolated thunderstorms may develop (as seen in ensemble paint
balls >40z dBZ and in calibrated thunder chances around 40-50%).
Temperatures aloft will be rather cold (around -20 C at 500 mb).
Even upper 40s F dewpoints will result in around 1000 to perhaps
1500 J/kg MLCAPE by late afternoon/early evening. Given steepening
lapse rate profiles and cold temperatures aloft, potential for a few
instances of severe hail and strong to severe winds will be
possible.
...Northern California/southwest Oregon...
Convection is possible during the afternoon as mid-level
temperatures cool in close proximity to the upper low off the coast.
Filtered surface heating could allow for a few stronger storms to
develop. Small hail and gusty winds are possible. Anvil-level flow
will be quite weak which will likely lead to storms that are only
strong briefly. The overall severe potential appears low.
..Thornton/Lyons.. 05/03/2026
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