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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.

Wednesday, July 14, 2021

SPC Jul 14, 2021 0600 UTC Day 1 Convective Outlook

SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Wed Jul 14 2021 Valid 141200Z - 151200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER MIDWEST... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE ENH AND ACROSS PARTS OF THE NORTHEAST... ...SUMMARY... Damaging winds, along with some hail threat, are expected with thunderstorms across the upper Midwest later this afternoon and evening. Isolated damaging winds are also possible across parts of the Northeast. ...Upper Midwest... MT short-wave trough is digging southeast in line with 00z model guidance. This feature is partly responsible for ongoing convection across the High Plains of western SD/NE early this morning. Latest radar data suggests slow upscale growth continues and a larger MCS may ultimately evolve over central SD/NE which should propagate to near the mid MO River Valley by sunrise. Latest model guidance suggests this cluster of storms may continue through the morning into the early afternoon as focused LLJ translates across IA into western WI. It's uncertain how much convective feedback the 00z NAM incorporates into the development of a surface low that tracks from south-central NE into southeast MN by late afternoon. However, if a sharp baroclinic zone evolves, a corridor of greater instability/shear will exist across portions of IA into southern WI such that more substantial, organized convection is possible. If the early-day MCS is dominant then the primary concern for organized severe will be along the leading edge of the larger complex. This activity will spread toward lake MI by late afternoon. Trailing flank of the MCS should extend southwest across IA where frontal interaction may encourage organized severe. The main severe threat with the MCS should be damaging winds, although hail may also be noted with convection that evolves within the more buoyant air mass later in the day. If supercells can develop there is also some threat for tornadoes given the forecast shear; however, much uncertainty exists regarding the MCS and potential storm mode. ...Northeast... Have opted to increase severe probabilities across a small portion of the Northeast later today. Modest mid-level flow (30kt at 500mb) is forecast to extend across eastern PA into southern New England ahead of a weak short-wave trough. Latest guidance suggests strong boundary-layer heating will also extend into the lower Hudson Valley. This should allow scattered robust storms to evolve over this portion of NY with subsequent movement expected across western MA into southern NH. Isolated damaging winds are the primary concern. ..Darrow/Wendt.. 07/14/2021 Read more LIVE: