BBS: TELESC.NET.BR Assunto: DAY1SVR: Day 1 Convective Outlook De: COD Weather Processor Data: Fri, 17 Apr 2026 12:40:47 +0000 ----------------------------------------------------------- ACUS01 KWNS 171240 SWODY1 SPC AC 171239 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 AM CDT Fri Apr 17 2026 Valid 171300Z - 181200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE UPPER AND MID MISSISSIPPI VALLEY SOUTHWESTWARD INTO KANSAS AND OKLAHOMA... ...SUMMARY... Numerous severe thunderstorms are likely this afternoon into tonight across parts of the Upper Midwest southward across the lower Missouri Valley into central Great Plains. Initially this may be accompanied by a risk for large to giant hail and a few strong tornadoes, before severe wind gusts 60 to 90 mph become the most prominent hazard by this evening. ...Synopsis... Surface analysis this morning depicts a front bisecting MN north to south to a low near the NE-IA-SD border, with the front extending southwestward into the central High Plains. Water-vapor imagery shows a prominent upper trough near the MT-ND border south-southwestward into eastern UT. A belt of increasingly strong southwesterly 500-mb flow will overspread a destabilizing warm sector today as the upper trough eventually reaches the Upper Midwest and central Great Plains late tonight. Concurrently, the aforementioned cyclone will develop northeast to Lake Superior as a warm front over IA advances northward into the western Great Lakes. Meanwhile, the cold front will sweep southeast reaching the central Great Lakes southwestward into the southern Great Plains by early Saturday. ...Upper and Mid Mississippi Valley... A northward expanding warm/moist sector on the nose of a 50+ kt southerly LLJ will continue to destabilize as large-scale ascent approaches from the west. A large-hail threat may develop this morning with developing convection across southern MN (see forthcoming MCD #472 for short-term details). Heating and advection of 60s deg F surface dewpoints beneath steep mid-level lapse rates will support the development of a moderately to very unstable airmass from IA-IL northward into the upper MS Valley to the east of the front and southeast of the low. Upwards of 1500-3000 J/kg MLCAPE is forecast immediately ahead of the front with strengthening flow aloft, strongly favoring organized storms, including supercells. Recent model guidance continues to show the development of discrete supercells later this afternoon ahead of the front over parts of central/northern WI near the low, and farther south in the vicinity of eastern IA into adjacent portions of WI/northwest IL. All hazards will be possible with this potential activity, including the possibility for an intense tornado. Large to giant hail will be possible with supercells. Other storms likely to evolve quickly into a band of severe thunderstorms will develop farther west and push east coincident with the front. Damaging wind gusts will tend to become more prevalent during the evening with linear storm modes. Some tornado risk may continue into the evening as maturing bands of storms yield a threat for bowing segments and embedded mesovortices, before this activity gradually diminishes late as it moves east into IN/Lower MI late. ...KS-OK eastward into the lower MO Valley... Continued moistening and heating of an airmass to the east of a dryline/cold front and associated triple point will lead to a very unstable airmass from OK into KS by early to mid afternoon. A capping inversion will likely inhibit storm development until mid afternoon near the front. Initial storm development will likely be supercellular near the triple point before a more extensive band of cellular storms develops along the boundary. Both a supercell and QLCS tornado risk is apparent given the appreciably large CAPE/shear. A coalescing of cold pools and intensification of a squall line with embedded surges and bowing segments may result in focused swaths of more intense severe gusts (i.e., locally 75-90 mph) from south-central and eastern KS into west-central MO. Farther south, a more conditional setup south of the triple point along the dryline is expected. Large to giant hail could accompany any mature/sustained supercell along with a tornado risk. Eventually the front will sweep southeastward with a convective line yielding a risk for wind/hail. ..Smith/Dean.. 04/17/2026 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: Capitol City Online (1:2320/107) ----------------------------------------------------------- [Voltar]