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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

Saturday, July 16, 2022

SPC Jul 16, 2022 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Sat Jul 16 2022 Valid 181200Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHEAST MONTANA...NORTHERN HALF OF NORTH DAKOTA...NORTHWEST MINNESOTA... ...SUMMARY... Widely scattered severe thunderstorms are possible from northeast Montana eastward through North Dakota and into northwest Minnesota on Monday and Monday night. ...Synopsis... A mid-level anticyclone will remain centered over the central-southern Rockies, as a potent mid-level low/trough moves east, cresting the ridge over the northern Rockies into the northern Great Plains. A surface low initially over MT and downstream of the mid-level wave, will develop eastward and deepen as it moves into ND Monday night. A frontal zone will become draped generally from west to east near the 48th parallel. Farther east, a mid-level trough will move from the Lower Great Lakes through much of New England. A surface low will develop northeastward from Lake Erie towards the mouth of the St. Lawrence River. ...Montana/ND/MN... The aforementioned strong mid-level disturbance will move into the northern High Plains during the day. Strong flow with a westerly component will likely contribute to drying in the immediate lee of the higher terrain. Nonetheless, model guidance varies somewhat and isolated thunderstorms may occur across much of central MT during the afternoon. A more likely scenario entails initial storms developing near/north of the low within a corridor of low-level moisture. Steep lapse rates and strengthening mid- to high-level flow (effective shear increasing to 50 kt by early evening) will favor storm organization. Supercells capable of mainly a hail risk may eventually coalesce into a cluster of storms during the evening with a hail/wind threat accompanying this activity. A strengthening LLJ during the evening and associated warm-air advection near the west-east boundary will aid in additional storms perhaps during the evening and especially into the overnight over ND/MN. The risk for hail/wind may persist through the end of the day-3 period over ND/MN. ...Southern New England... A likely messy/complicated scenario seemingly exists for isolated severe on Monday across parts of the Northeast. Showers/thunderstorms will likely increase in coverage during the day over NY/PA within a relatively moist airmass featuring dewpoints in the 60s to lower 70s. Planar model guidance implies and forecast soundings show weak lapse rates which will likely limit buoyancy. However, greater buoyancy will probably develop over southern New England (richer moisture) and will be more favorably displaced to the east from early-day shower/storm activity. However, strengthening low- to mid-level flow will act to enlarge hodographs. Although details are nebulous, it is plausible that some storm-scale rotation potential exists given the moist/sheared environment. This activity will likely diminish during the evening due to convective overturning and diurnal heat loss. ..Smith.. 07/16/2022 Read more CHECK UPDATE ZOOM GRAPHIC