Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 26 2023 19:53:52 ACUS01 KWNS 261953 SWODY1 SPC AC 261952 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Mon Jun 26 2023 Valid 262000Z - 271200Z ....THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE MID ATLANTIC... ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CAROLINAS INTO PARTS OF NEW YORK... ....SUMMARY... Scattered damaging winds are most likely from the Carolinas to parts of the Mid-Atlantic and Northeast States through this evening. Minor adjustments to the marginal risk line were made across western PA as the stronger activity should remain east where watches are ongoing. The marginal risk area was also removed from southern LA as activity tonight will be focused farther north. Otherwise, a large area of instability remains from NY into the Carolinas, with scattered severe storms producing damaging wind gusts expected. For more information see MCDs 1283 1284 1285. ...Jewell.. 06/26/2023 ..PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Jun 26 2023/ ....Carolinas to southern VA... The more favorable thermodynamic and kinematic environment will be across this portion of the broader severe threat in the East. In the wake of a couple MCVs progressing through the central portions of Carolinas and VA, nearly full insolation across the western portions of these states, coincident with moderately steep mid-level lapse rates around 7 C/km, will support moderate buoyancy with MLCAPE of 1500-2500 J/kg towards early evening. The most consistent signal for scattered thunderstorm development is across the higher terrain of western NC later this afternoon. While low-level shear will be weak, a belt of 35-45 kt 500-mb westerlies will support a few cells with mid-level updraft rotation, mainly early before convection tends to consolidate into one or more organized clusters. This will likely support multiple swaths of damaging winds, centered mainly on the Piedmont, before convection tends to gradually weaken across the coastal plain tonight. ....Mid-Atlantic/Northeast States... Mid-level westerlies should be weaker north of southern VA, and become increasingly meridional from PA northward, yielding a more marginal deep-layer shear environment relative to farther south. In addition, isolated to scattered thunderstorms are already ongoing across parts of NJ/NY/PA and this will tend to subdue greater destabilization with north and east extent. The primary severe threat within this region will likely emanate from a later afternoon round of thunderstorms that form over the higher terrain from central PA to western VA. Morning CAM guidance is more consistent with convection being maintained east across eastern PA/central MD and parts of the DE and Potomac Valleys where multicell clustering should support scattered damaging winds. An MCV over north-central VA and relative instability minimum in its vicinity may be suppressive to maintaining multicell clustering into the Delmarva region later today. ....Lee of the north-central Rockies and Black Hills... A narrow zone of moderate low-level moisture return is expected to persist over the central High Plains beneath a low-amplitude mid-level ridge. Isolated to scattered thunderstorms appear most likely to develop along the northern periphery of this confined buoyancy plume where steep mid-level lapse rates support MLCAPE of 1000-2000 J/kg. A belt of moderate westerly mid-level flow between strong jets over the Southwest and Mid-MS Valley should be adequate to support a few supercells. Significant severe hail will be the main threat initially, especially with potential for a long-track supercell. An attempt at clustering towards the Black Hills/NE Panhandle vicinity might occur as the High Plains low-level jet strengthens this evening, but the confined spatial extent of the buoyancy plume and nocturnal increase in MLCIN yields low confidence in maintaining severe coverage beyond an isolated threat tonight. ....Ark-La-Tex vicinity... In the wake of a decaying MCS over southeast LA (see MCD 1281 for near-term discussion), regenerative convection may yield an isolated severe hail threat for a few more hours, but convection should become more suppressed later this afternoon amid difluent low-level flow. A separate round of elevated convection is anticipated overnight with weak 850-700 warm theta-e advection. Isolated large hail may occur initially owing to the large elevated buoyancy, but deep-layer shear magnitude/orientation will tend to favor a predominant cluster mode which should serve to marginalize the overall severe hail threat and support isolated damaging winds. ....Southern High Plains... Isolated storm development is possible across the southern High Plains, within a hot and well-mixed environment. Any deep convection would pose a threat for microbursts and perhaps marginally severe hail, though storm longevity appears limited at this time within this weakly forced regime. $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .