SPC AC 011956

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0256 PM CDT Mon Jul 01 2024

   Valid 012000Z - 021200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
   NORTHERN PLAINS...

   ...SUMMARY...
   Severe thunderstorms should occur this afternoon and tonight across
   parts of the northern/central Plains, especially portions of
   Nebraska and the Dakotas. Scattered severe/damaging winds, large
   hail, and a few tornadoes all appear possible.

   ...20Z Updated...
   A small general thunderstorm area was added to account for ongoing
   convection over southern New England. This area is beneath the upper
   trough, with steep lapse rates, and little inhibition. Continued
   heating will support a few hours of shallow non-severe convection
   through late afternoon.

   The Marginal Risk area was reduced over parts of the southeast, as
   much of the area is subsident. Any change of locally strong gusts
   should be relegated to areas where upper 70s F dewpoints can
   counteract the relatively warm temperatures aloft.

   ...Northern/Central Plains...
   The severe risk area remains on track, with storms now developing
   along the front over the northern High Plains as the upper trough
   continues east. For more information see MCD 1503.

   To the south, an impressive temperature gradient exists along the
   warm front near the KS/NE border, with convection beginning to
   develop over northwest KS and eastern CO where temperatures are hot.
   Warming should spread north with the warm front later today into NE,
   with increasing storm coverage over time. Any cell within the narrow
   frontal zone may become supercellular, potentially thriving upon
   both enhanced low-level shear and surface based warmth.

   For more information, see forthcoming MCD 1504.

   ..Jewell.. 07/01/2024

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Mon Jul 01 2024/

   ...Northern/Central Plains...
   A notable upper trough across the northern Rockies will advance
   eastward today over the northern/central Plains. Related low-level
   mass response will encourage multiple surface lows to slowly deepen
   across the northern/central High Plains. An occluded/cold front will
   move eastward across the western/central Dakotas through this
   evening, while a warm front attempts to lift northward across
   northern KS into NE. Current expectations are for robust convection
   to develop along both the front in the western Dakotas, and the
   higher terrain of WY/CO as large-scale ascent associated with the
   upper trough overspreads the warm sector. Low-level moisture will
   remain more limited with northward extent into the Dakotas. But,
   sufficient instability in a narrow corridor, along with strong
   deep-layer shear, is still anticipated. Initial supercells over
   western ND/SD should pose a threat for large hail, before convection
   quickly grows upscale into a bowing cluster towards central ND/SD
   with a greater threat for severe/damaging winds. With sufficient
   ambient near-surface vorticity along the front, a brief tornado or
   two also appears possible with initially more cellular development.
   This activity should weaken with eastward extent tonight as it
   encounters much weaker instability towards the MN border.

   Initially high-based convection over central CO may pose an isolated
   threat for severe wind gusts as it moves into eastern CO/western KS
   and encounters a very well mixed boundary layer. The Marginal Risk
   has been expanded westward and southward a bit in CO to account for
   this potential. Otherwise, thunderstorms should eventually develop
   and strengthen by late this afternoon along/east of a surface low
   centered over northeast CO. Deep-layer shear will be strong enough
   to support supercells, but convective mode may quickly become messy
   as activity moves eastward along/near the northward-advancing warm
   front in NE. Large hail may occur with any sustained supercell, and
   sufficient low-level shear will be present along/near the warm front
   to support a threat for a few tornadoes. Even so, a more
   clustery/linear mode may become dominant fairly soon after initial
   development. This would support a greater threat for severe/damaging
   winds, and perhaps isolated gusts up to about 75 mph. Regardless of
   continued uncertainty over what the dominant convective mode will
   be, the severe threat will likely persist into eastern NE/western IA
   this evening and tonight before thunderstorms eventually weaken.

   ...Southeast...
   Scattered to numerous thunderstorms should develop this afternoon
   along and south of a cold front draped east to west across parts of
   the Southeast. Although mid-level flow and related deep-layer shear
   will remain modest, steepened low-level lapse rates though daytime
   heating and plentiful low-level moisture will easily support
   moderate to strong instability. Occasional strong to damaging winds
   may occur with the more robust cores and loosely organized clusters
   as they move generally southward through the early evening before
   eventually weakening.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z