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SPC Jun 21, 2024 1730 UTC Day 2 Convective Outlook

1 year 1 month ago

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Fri Jun 21 2024 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR ADJACENT PORTIONS OF MISSOURI...IOWA...ILLINOIS...AND WISCONSIN... ...SUMMARY... Severe storms will be possible across the upper Mississippi Valley and upper Midwest on Saturday. Damaging wind, isolated hail, and a tornado or two are all possible. ...East-central Great Plains into the upper Midwest... A convectively augmented mid-level disturbance will move east across WI into MI during the morning into the early afternoon. Showers/thunderstorms will likely accompany this feature with some strong to severe risk possible, especially on a localized basis over the northern half of Lower MI as some heating contributes to destabilization. In the wake of morning convection, moderate to locally strong buoyancy is expected to develop from eastern KS/southeast NE northeastward into parts of southern WI/northern IL, along/south of an outflow-reinforced front. Scattered to numerous thunderstorms are expected to develop along the front by late afternoon into the evening from northern MO to the Lake MI vicinity. Effective shear generally in the 30-40 kt range will support a few organized cells/clusters. Relatively strong heating and large PW will support strong/damaging gusts as the most likely hazard. Warm 500-mb temperatures (-6 to -8 deg C) will tend to limit the overall magnitude of buoyancy and the potential hail risk with the stronger cells. A tornado or two will also be possible, in the presence of moderate low-level southwesterly flow and modestly enhanced SRH. Farther east, intensification of morning convection and/or afternoon redevelopment will be possible across parts of Lower MI. While instability will be weaker compared to areas father west, somewhat enhanced low/midlevel flow will support a threat for isolated damaging wind and possibly a brief tornado. ...South-central AZ... Model forecast soundings show seasonally high PW across the Sonoran Desert on Saturday. Intense surface heating will result in surface temperatures quickly rising into the 100s across the lower desert with mainly 50s deg F dewpoints. Very steep 0-3 km lapse rates and weak buoyancy will probably lead to isolated thunderstorm development initially in orographically favored locations. Existing storms' cold pools may potentially interact and promote additional storms during the evening. The environment in which these pulse-like thunderstorms develop will support large evaporative potential with the downdrafts. The more water-laden cores will possibly yield a risk for severe gusts (60-75 mph) before this activity diminishes in the 03-05z period. ...Parts of the Northeast... Model guidance continues to indicate widely scattered thunderstorms will be possible across parts of the Northeast during the afternoon and evening, within a warm, moderately unstable, and weakly capped environment along/south of a cold front draped across parts of New England. Isolated strong to locally severe gusts (50-60 mph) are possible with the stronger storms. ...Parts of ND... No change in thinking from the previous forecast. A mid/upper-level shortwave trough will move across parts of SK/MB on Saturday, with some influence of this shortwave expected to extend into parts of ND. Isolated to widely scattered thunderstorm development will be possible during the afternoon/evening, with moderate buoyancy and sufficient deep-layer shear supporting potential for a few organized storms capable of isolated hail and strong/severe gusts. ..Smith.. 06/21/2024 Read more