Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
129 ACUS02 KWNS 050557 SWODY2 SPC AC 050555 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Sat Jul 05 2025 Valid 061200Z - 071200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Storms may produce severe wind and hail along the central High Plains tomorrow (Sunday). A few instances of 2+ inch diameter hail and 75+ mph wind gusts are possible. ...Synopsis... Mainly zonal upper flow will become established over the northern CONUS, with multiple embedded impulses poised to traverse the zonal flow through the day tomorrow (Sunday). The best chance for strong storms will be associated with mid-level impulses impinging on the High Plains and New England Sunday afternoon. Ample moisture and associated instability will precede the impulses, that combined with adequate vertical wind shear, will support storm organization, some of which could be severe. ...Maine... A belt of 50 kt westerly 500 mb flow will overspread southeast Quebec into Maine Sunday afternoon with the overhead passage of a mid-level impulse. Surface lee troughing over Maine will serve as an impetus for thunderstorm initiation during the afternoon, when surface temperatures/dewpoints in the low 80s/upper 60s F will boost MLCAPE to over 1000 J/kg. Modestly curved, sizeable low-level hodographs suggest that multicells and supercells will be the main storm mode, possibly accompanied by damaging gusts. ...Central and Southern High Plains... Low-level upslope flow will encourage the northwestward advection of 60s F surface dewpoints into the higher terrain of the High Plains Sunday afternoon, beneath 8-9 C/km 700-500 mb lapse rates. Moderate to strong instability will manifest, with over 3000 J/kg MLCAPE possible. Storms will initiate over the higher terrain, amid straight hodographs, contributing to splitting supercell potential. By evening, the southeasterly surface flow will be overspread by a strengthening southerly low-level jet, with flow quickly veering to westerly in the 700-500 mb layer. This directional shear will support curved low-level hodographs with continued supercell potential, before storms merge into an MCS by evening. While in the supercell phase, a few instances of severe hail (perhaps an instance or two of 2+ inch diameter hail) are possible, along with severe gusts and perhaps a tornado. By the time storms merge into an MCS, severe gusts will become the primary threat, and a few gusts exceeding 75 mph will be possible. Higher severe probabilities may be needed if confidence increases in a longer-lived, severe-wind producing MCS developing. Farther south into the southern High Plains, storm coverage should be relatively less, with multicells becoming outflow dominant more quickly given weaker vertical wind shear compared to the central High Plains. Nonetheless, an instance or two of hail is possible, along with severe gusts, especially with multicellular cold-pool mergers. ...Coastal Carolinas... A tropical storm is forecast to make landfall along the Carolina coastline at the start of the Day 2 period/12Z Sunday (please see the National Hurricane Center`s advisories for more information on the progression of Tropical Depression 3). A deeply moist troposphere will accompany the land-falling TC, with MLCAPE approaching the 750-1000 J/kg range. Nonetheless, the vertical wind fields associated with this land-falling tropical storm are expected to quickly weaken, along with vertical wind shear. As such, while the risk for a brief tornado is technically non-zero, confidence in any robust tornado coverage is too low for the introduction of 2 percent or greater tornado probabilities at this time. ..Squitieri.. 07/05/2025 $$