Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
422 ACUS02 KWNS 131725 SWODY2 SPC AC 131724 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1224 PM CDT Thu Jun 13 2024 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF CO/KS/NE AND THE NORTHEAST STATES... ...SUMMARY... Scattered severe storms with large hail and wind gusts of 60-80 mph will be possible from mid-afternoon through the evening on Friday along the Front Range to the central Great Plains. Scattered strong storms with sporadic damaging winds and isolated hail will be possible across the Northeast States during the afternoon to early evening. ...CO/KS/NE... Primary categorical change this cycle is to expand the level 2-SLGT risk southward into the more deeply mixed air with thunderstorms expected to develop off the Raton Mesa/Sangre de Cristo Mountains. This includes expansion of the significant severe wind highlight for gusts to around 80 mph. A southern-stream shortwave trough currently off the northern Baja CA coast will reach the Four Corners area by Friday afternoon and progress towards the central High Plains through early Saturday. This feature will likely dampen during the D2 period. The bulk of mid to upper-flow enhancement will be confined along the southern arc of the trough, near/ahead of substantial warming within the southwest quadrant of the trough. As such, the overall kinematic profile will be relatively modest by typical central High Plains standards. But the large-scale forcing for ascent attendant to the approaching trough will support scattered to widespread thunderstorm development during the afternoon off the higher terrain onto the adjacent plains. A quasi-stationary front, modulated by D1 convection, should be draped from the Ozark Plateau west-northwest into the central High Plains. Moderate uncertainty exists with regard to placement of the front in western KS/eastern CO by peak heating, with hot temperatures expected within the deeply mixed air mass to its south. A confined plume of enhanced low-level moisture will be present along and just north of the front emanating west-northwest from the Ozarks. This should support a corridor of MLCAPE from 1500-2500 J/kg amid initially steep mid-level lapse rates. Given the modest deep-layer shear profiles and pervasive convective coverage, a cluster mode should dominate as storms spread onto the High Plains. As they impinge on the greater buoyancy plume/frontal zone, a bowing structure or two may develop as a modestly organized QLCS moves east-northeast into western parts of KS/NE. Scattered severe wind swaths and some hail will be possible, peaking in the late afternoon to dusk. The north and east extent of the threat should slowly wane in both intensity/coverage Friday night. ...New England to the central Appalachians... A series of shortwave impulses embedded within a broader mid/upper trough over ON/QC and the Great Lakes will shift east across the Northeast States through Friday Night. One of these impulses should amplify somewhat as it tracks from the southern Great Plains into NY/PA. A surface cold front should extend from New England southwestward into the OH Valley on Friday afternoon, with a lee trough east of the Appalachians. Mid-level lapse rates will be relatively steeper with northern extent into New England and weaker with southern extent into the Mid-Atlantic States and the central Appalachians. However, deeper boundary-layer warming/mixing is anticipated with southern extent. A broad plume of modest buoyancy with MLCAPE of 500-1500 J/kg is anticipated. Scattered thunderstorms are expected along and ahead of the surface cold front during the afternoon. While the bulk of strong mid to upper-level southwesterly flow should lag behind the boundary and largely parallel it as well, vertical shear will be sufficient for organized cells capable of isolated severe hail and damaging winds across New England. With southern extent, strong gusts within multicell clusters should yield sporadic wind damage. The level 2-SLGT risk corridor in the Northeast represents the relatively more favorable potential for cells/clusters to produce scattered damaging winds and marginally severe hail. ..Grams.. 06/13/2024 $$