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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.

Sunday, July 3, 2022

SPC Jul 3, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun Jul 03 2022 Valid 032000Z - 041200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF CENTRAL/EASTERN MONTANA AND SOUTHWEST NORTH DAKOTA... ...SUMMARY... The most concentrated corridor of severe storms, including potential for significant severe wind/hail and a few tornadoes, is forecast across parts of Montana into southwest North Dakota through this evening. ...20Z Update... Prior forecast reasoning remains largely on track. Only minor adjustments were made based on current observations. See MCD #1340 and #1341 for short-term details on the northern Rockies and northern High Plains, respectively. ..Wendt.. 07/03/2022 .PREV DISCUSSION... /ISSUED 1121 AM CDT Sun Jul 03 2022/ ...MT to western ND... Primary mid-level low just off the OR coast is embedded within a broader Pacific Coast trough. Multiple waves of ascent are evident downstream of this trough, with the ones most impactful for severe potential across southwest MT this morning and the next across southwest ID. Guidance differs on the degree of intensification of convection with the initial wave, while greater consistency exists on convective evolution emanating out of the latter one. With easterly low-level winds to the north of the effective surface front beneath 35-45 kt mid-level southwesterlies, enlarged and elongated hodographs will be favorable for several supercells, a few of which could become long-tracked. Primary uncertainty is how quickly storm-scale consolidation/upscale growth will occur. Supercell bow-echo evolution does appear probable as convection rides along the surface front given a deeply mixed thermodynamic environment to its south. A forward-propagating MCS is increasingly likely this evening as low-level winds and convergence strengthen across eastern MT. The full spectrum of severe threats is expected with significant large hail most likely from mid-afternoon to early evening, and significant severe wind potential centered on this evening. The tornado threat is more nebulous and convective mode dependent, but will be conditionally favored in a west/east-oriented corridor north of the front. ...Northern/central Great Plains... While most of the region will remain under the influence of low-amplitude mid-level ridging, a broad plume of moderate to large buoyancy is expected at peak heating with relative maxima centered near northwest SD and the KS/NE border. Remnant outflow boundaries, the lee trough over the High Plains, and the warm front across ND and the Red River Valley should all focus scattered to widespread thunderstorms from late afternoon into tonight. Stronger deep-layer shear will generally be confined to the ND/Red River Valley regime within the belt of enhanced mid-level westerlies, suggesting that supercell potential farther south will be tied to mesoscale boundaries with broader multicell clustering tending to dominate. While all severe hazards are possible, wind should become the overall primary threat, especially this evening into tonight as multiple MCSs spread east. ...Carolinas... Scattered thunderstorms are expected across much of the Southeast, but potential for loosely organized multicell clustering is most apparent across NC into parts of SC. The latter will be supported by the presence of differential heating across a southward-sagging cold front and the fringe influence of a trough over QC maintaining 15-20 kt mid-level westerlies. With 2000-2500 J/kg of MLCAPE along the coastal plain, strong to locally severe gusts will be possible in wet microbursts through early evening. Read more CHECK UPDATE ZOOM GRAPHIC