Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
218 ACUS03 KWNS 280730 SWODY3 SPC AC 280729 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Fri Jun 28 2024 Valid 301200Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN MT INTO WESTERN ND...AND ALSO FROM THE MID ATLANTIC INTO SOUTHERN/EASTERN NEW ENGLAND... ...SUMMARY... Scattered damaging winds are possible across parts of the Mid Atlantic and Northeast on Sunday. Hail and severe gusts will also be possible from eastern Montana into western North Dakota. ...Carolinas into the Northeast... A seasonably deep and positively tilted trough is forecast to move southeastward across the Northeast and Mid Atlantic on Sunday. A surface low will move from eastern Quebec into the Canadian Maritimes, as a trailing cold front moves across parts of the eastern CONUS. Weak midlevel lapse rates could limit prefrontal destabilization to some extent across parts of the Northeast/New England, but potentially strong diurnal heating and sufficient deep-layer shear could result in scattered strong storms capable of scattered damaging wind and possibly some hail during the afternoon/evening. Guidance continues to vary somewhat regarding timing of the front. A Slight Risk has been included from parts of the Mid Atlantic into New England, where organized damaging-wind potential appears most possible at this time. Some adjustments will likely be needed, depending on trends regarding timing of the front and prefrontal destabilization. Farther south, somewhat stronger destabilization will be possible into the Carolinas, within a very moist environment. Mid/upper-level flow will be weaker, but modest west-northwesterlies aloft could support some stronger cells/clusters capable of at least isolated damaging wind. ...Montana into the western Dakotas... A mid/upper-level trough is forecast to move from the Northwest across northern Rockies during the day on Sunday, with some influence of the trough expected to spread into the northern High Plains by Sunday evening. A surface low is expected to deepen across northern WY, with low-level moisture return expected east and north of the low into parts of Montana and the western Dakotas. At least modest diurnal destabilization will be possible from southwest into central MT, with moderate buoyancy potentially developing farther east into parts of eastern MT and the western Dakotas. Guidance still varies somewhat regarding timing of stronger ascent across the region, but storm development will be possible across western into central MT during the afternoon. These storms may move eastward with time, with other isolated development possible by early evening into eastern MT. Increasing deep-layer shear will support organized convection, and a few stronger clusters and/or supercells will be possible, with a threat of hail and severe gusts. An MCS may develop Sunday night and move into western/central ND, as a low-level jet nocturnally strengthens. The severity of any MCS will be more uncertain with eastward extent, due to increasing low-level stability. However, some threat for severe gusts could spread across western and possibly central ND. Storm development/coverage is more uncertain farther south, but with the environment expected to become conditionally favorable by late afternoon into the evening, a strong/severe storm or two will also be possible into western SD. ...CO Front Range into the central High Plains... In the wake of a cold frontal passage, low-level moisture will stream westward into the CO Front Range vicinity and adjacent central High Plains, with the western extension of the boundary expected to lift northward as a warm front through the day. Moderate destabilization will be possible during the afternoon, with potential for at least isolated storm development. Midlevel flow will likely remain weak to modest, but sufficient veering with height could support organized multicell clusters and perhaps a supercell or two, with a threat of hail and severe gusts. ...South-central Great Plains into the Southeast and TN Valley... A cold front is forecast to move into parts of the south-central Great Plains and Ozark vicinity Sunday morning, potentially accompanied by ongoing convection. Moderate to locally strong buoyancy may develop along/south the front during the afternoon, in areas that are not as influenced by early-day convection. Midlevel flow will likely remain weak, but may take on a more northerly component later in the day, which could provide sufficient deep-layer shear for briefly organized storms. Given the rather weakly sheared environment and uncertainty regarding the favored frontal corridor, no probabilities have been included for this regime at this time. ..Dean.. 06/28/2024 $$