SPC AC 021628

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1128 AM CDT Tue Jul 02 2024

   Valid 021630Z - 031200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   SOUTHERN/CENTRAL IOWA...NORTHERN MISSOURI...NORTHEAST KANSAS...AND
   SOUTHEAST NEBRASKA...

   ...SUMMARY...
   Scattered to numerous damaging thunderstorm winds, a few tornadoes,
   and occasional large hail appear most likely this afternoon and
   early evening over parts of southern/central Iowa, northern
   Missouri, and northeastern Kansas.

   ...Iowa/Missouri into Northeast Kansas and Vicinity...
   Elevated thunderstorms with a marginal/isolated hail threat are
   ongoing late this morning across eastern NE and southern IA in a
   low-level warm advection regime. This activity is also being aided
   by modest large-scale ascent associated with a subtle mid-level
   vorticity maximum moving eastward over the central Plains. The
   primary upper cyclone and related surface low will remain over
   central Canada today, with a cold front extending southward over the
   northern Plains/Upper Midwest and continuing southwestward into the
   central Plains. An effective warm front extends northeastward from a
   secondary surface low in north-central KS across northern MO into
   southern IA. This boundary will likely serve as a focus for severe
   thunderstorms this afternoon and evening as it attempts to lift
   further northward into IA.

   The 12Z sounding from TOP showed a very moist boundary layer, with
   precipitable water values through the column greater than 2 inches
   and somewhat steepened mid-level lapse rates. Robust daytime heating
   of this airmass along/south of the front will likely aid the
   development of moderate to strong instability by mid afternoon, even
   though mid-level temperature remain somewhat warm. A belt of
   stronger (40-55 kt) southwesterly mid-level flow associated with the
   subtle central Plains shortwave trough will likely overspread the
   frontal zone across IA and northern MO in the same time frame. With
   sufficient veering/strengthening of the wind field with height
   through mid-levels, around 35-50 kt of deep-layer shear is expected
   to promote organized convection, including the potential for both
   supercells and a bowing cluster.

   Thunderstorms should intensify by early to mid afternoon near the
   front across southeast NE/northeast KS into southern/central IA and
   perhaps northern MO. If this initial development can remain at least
   semi-discrete for a few hours, then sufficient low-level shear near
   the warm front would support a threat for a few tornadoes. Isolated
   severe hail may also occur with any sustained supercell. Otherwise,
   upscale growth into an MCS by mid to late afternoon appears likely
   given the mainly linear/frontal forcing and mid-level flow aligned
   mostly parallel to the surface front. Scattered to numerous damaging
   winds generally ranging 60-70 mph should become the primary severe
   hazard by late afternoon and early evening across IA and northern
   MO, but embedded QLCS circulations will also be possible. Convection
   should tend to weaken later this evening as it approaches the MS
   River and encounters a less unstable airmass.

   ...Southern/Central Plains...
   Additional convection should develop along the front with
   southwestward extent into KS and the southern/central High Plains.
   Given a well-mixed boundary layer and steepened low-level lapse
   rates with daytime heating, isolated to scattered severe/damaging
   winds should be the main threat with this activity. Modest low-level
   upslope flow in the post-frontal regime may encourage the
   development of isolated supercells across parts of southeast CO and
   vicinity. Occasional large hail and severe wind gusts may occur with
   any intense convection that can persist, but confidence in a small
   bowing cluster developing from this activity this evening remains
   low. Other occasionally strong to severe convection may develop
   southeastward from eastern WY into western NE this afternoon and
   evening. Weaker instability across this region should keep the
   overall severe threat rather isolated.

   ..Gleason/Thornton.. 07/02/2024

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