SPC AC 031944

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0244 PM CDT Wed Jul 03 2024

   Valid 032000Z - 041200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
   NORTHERN/CENTRAL PLAINS...AND THE OZARKS INTO THE OHIO VALLEY...

   ...SUMMARY...
   Scattered severe thunderstorms appear possible through evening
   across parts of the northern/central High Plains, and from the
   Ozarks into the Ohio Valley. The most favorable corridor for
   isolated very large hail and significant severe wind gusts is
   centered on the central High Plains.

   ...20z Update...

   Severe probabilities remain unchanged from the previous outlook.
   Severe storms are possible into this evening from portions of the
   central High Plains to the Ozarks and lower Ohio Valley. See Severe
   Thunderstorm Watch 501 and MCD 1520 regarding short term discussions
   on severe potential in the central High Plains, MCD 1522 for the
   northern High Plains, and MCD 1521 for the Ozarks vicinity.

   ..Leitman.. 07/03/2024

   .PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Jul 03 2024/

   ...Synopsis...
   An upper trough will continue moving eastward across Ontario and the
   Great Lakes today, while an upper high remains centered over the
   Southeast. Farther west, a separate mid-level shortwave trough will
   advance east-southeastward from the northern Rockies to the
   northern/central High Plains through tonight. Multiple convectively
   augmented mid-level vorticity maxima will move generally
   east-northeastward across the central Plains into the mid MS and OH
   Valleys. At the surface, a cold front extends from the OH Valley
   southwestward to the southern Plains. Weak lee cyclogenesis is
   forecast to occur across the central High Plains through late this
   afternoon, and modest low-level moisture return is anticipated to
   the north of the front and east of a weak surface lee trough across
   parts of the northern/central Plains.

   ...Northern/Central Plains...
   Morning clouds and lingering convection across parts of the central
   Plains will hamper the development of instability today, especially
   with eastward extent into NE/KS. Even so, pockets of filtered
   daytime heating will occur across the northern/central High Plains
   along and east of the surface lee trough. With steepened mid-level
   lapse rates present over eastern CO/WY into western SD/NE, a narrow
   zone of moderate instability is forecast to be in place prior to
   robust convective initiation this afternoon. Initial development
   should occur along the length of the lee trough from parts of
   western NE into eastern CO. A somewhat separate area of convection
   may also develop from northeastern WY to the Black Hills, as
   large-scale ascent preceding the mid-level shortwave trough
   overspreads this region.

   Modest low-level east-southeasterly flow will quickly veer to
   westerly at mid/upper levels, with some strengthening and hodograph
   elongation. Corresponding strong deep-layer shear will support
   supercells initially, with attendant threat for large hail. Given
   relatively cool temperatures aloft and the presence of steep
   mid-level lapse rates, isolated very large hail greater than 2
   inches in diameter appears possible. A small zone with favorable
   overlap of moderate instability, strong deep-layer shear, and
   sufficient low-level shear remains apparent over parts of the NE
   Panhandle into northwest NE. This area may have a locally greater
   threat for a couple of tornadoes with any supercells that can
   persist late this afternoon into the early evening, assuming the
   boundary layer does not become too well mixed. Otherwise, upscale
   growth/clustering appears probable this evening as convective
   outflows aggregate into the central Plains. Severe/damaging winds
   should become the main threat as this occurs, with isolated
   significant gusts up to 75 mph possible if a more consolidated
   bow/MCS can develop. Confidence in this occurring still remains
   somewhat low, but the best chance for a more concentrated corridor
   of severe winds remains across parts of eastern CO into southwest NE
   and northwest KS this evening.

   ...Ozarks to the Ohio Valley...
   A rather moist low-level airmass remains present along/south of the
   front today, with surface dewpoints generally in the low to mid 70s,
   and precipitable water values around 1.75-2.2 inches. A fair amount
   of convective cloud debris is present along/near the front across
   the mid MS Valley. This will tend to slow diurnal destabilization to
   some extent across this area. Mid-level lapse rates are also
   expected to remain poor. Still, moderate to locally strong
   instability and steepened low-level lapse rates are forecast to
   develop through peak afternoon heating along/south of the front,
   which will extend from the Ozarks northeastward into parts of the OH
   Valley.

   Low-level winds are expected to remain generally weak, but a modest
   increase in southwesterly winds at mid levels should foster
   sufficient deep-layer shear to support some updraft organization.
   Mainly multicell clusters should develop this afternoon, focused
   along the front. Some of this activity may produce scattered
   damaging winds through early evening before eventually weakening.
   Morning guidance shows a greater concentration of thunderstorms with
   clustering potential across the Ozarks into the mid MS Valley.

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