Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
570 ACUS02 KWNS 291723 SWODY2 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 $$