SPC AC 291721

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1221 PM CDT Sat Jun 29 2024

   Valid 301200Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF THE
   NORTHEAST AND MID ATLANTIC...AND FROM PARTS OF MONTANA INTO NORTH
   DAKOTA...

   ...SUMMARY...
   Scattered damaging winds will be possible across parts of the
   Northeast and Mid-Atlantic States on Sunday. Hail and damaging winds
   may also occur from eastern Montana into western North Dakota.

   ...Synopsis...
   An upper trough will proceed eastward from the upper Great Lakes
   into the Northeast, with a primary midlevel speed max sweeping
   across northern New England during the day. Behind this initial
   feature, a positive tile wave will push southeastward toward the Mid
   Atlantic, with most of the height falls occurring late. A surface
   low will likely be over Maine, with a trough/wind shift extending
   southwestward across eastern PA/NJ, VA/Delmarva, and into the
   Carolinas.

   Behind that trough, high pressure will be centered over the upper MS
   valley, with an east-west oriented boundary sinking south across the
   OH/TN Valleys, becoming stationary over the central Plains.
   Southeast surface winds will maintain moisture into the central and
   northern High Plains, in advance of a shortwave trough moving across
   the Great Basin and northern Rockies. This system will induce low
   pressure over southern MT into northern WY, with increasing ascent
   into that area late in the day.

   ...Much of the Northeast and Mid Atlantic...
   The initial midlevel wave will move across NY and into northern New
   England, providing strong mid and high level wind fields/shear.
   Instability by midday over this area will gradually increase, with
   an environment favoring a few supercells developing across northern
   New England. Hail and perhaps a couple tornadoes will be possible
   near the surface low into Maine and where the air mass can recover
   sufficiently from the southwest.

   Farther south, scattered rain and storms will be ongoing along the
   length of the front early in the day across PA/WV/KY, with the
   primary ramp up in intensity occurring after 18Z and as the
   convection crosses int MD/VA. At that time, heating of the moist air
   mass will maximize instability with over 3000 J/kg MUCAPE possible.
   Low-level wind fields will be rather weak, but modest westerlies and
   the progressive trough will keep storms moving, while the
   uncapped/warmed boundary layer favors widespread outflow winds, some
   damaging and locally severe.

   ...MT into ND...
   Relatively cool southeast winds will maintain stable conditions for
   much of the day, but by late afternoon/early evening the air mass
   near the surface low should become heat and uncapped, with storms
   forming from southwest into central MT initially. Ascent with the
   developing cold front and progressive upper wave should then aid
   further storm development during the evening across much of eastern
   MT, with storms into ND after 03Z. It is expected that sufficient
   cold pools will develop to maintain at least isolated strong to
   severe storms despite potential capping. Damaging gusts should be
   the primary severe mode.

   ..Jewell.. 06/29/2024

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