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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.


Thursday, June 23, 2022

SPC Jun 23, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Thu Jun 23 2022 Valid 232000Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF KS/NE/SD/MN... ...SUMMARY... Scattered severe thunderstorms are most likely over parts of the central Great Plains and the central portions of Minnesota to South Dakota, mainly this evening. ...20Z Update... The 2% and 5% tornado areas have been expanded slightly southward across parts of north-central KS, based on the current position of the effective warm front, but otherwise no major changes have been made to the outlook. See MCD 1264 for more information regarding the threat across NV/UT, MCD 1265 for more details across KS/NE, and the previous outlook discussion below for details regarding the threats in MN/SD and MT. Isolated strong wind gusts will also be possible with storms across parts of AZ/NM, though deep-layer flow/shear is quite weak across this region, which should preclude a more organized severe wind risk. ..Dean.. 06/23/2022 .PREV DISCUSSION... /ISSUED 1130 AM CDT Thu Jun 23 2022/ ...Northern KS/southern NE... Low-level warm theta-e advection has maintained a swath of elevated convection centered on northeast to east-central KS, just northeast of the surface warm front. To the south and west of this activity, robust boundary-layer heating is underway, likely increasing baroclinicity across the front by late afternoon. A low-amplitude mid-level perturbation over the southern Rockies should be favorably timed to aid in scattered high-based convection developing along the lee trough in western KS to its intersection with the warm front near southwest NE. While morning guidance varies substantially with the overall thermodynamic environment, the 12Z HRW-NSSL/ARW and NAM-Nest all suggest potential for at least a couple long-lived supercells slowly spreading east-southeast from southwest NE across northern KS. Midlevel flow will not be strong, although speed shear into the upper levels will favor large hail growth. Hodographs will depend on the degree of low-level easterly flow component in the warm advection zone along and north of the warm front, which guidance also varies substantially on. Even so, an increase in a nocturnal southerly low-level jet will likely assist in potential for a small MCS this evening. Given the conditionally favorable setup, potential for sig hail and wind is apparent in addition to a tornadic supercell or two. ...Central portions of MN/SD... A weak surface trough, associated with a low-amplitude shortwave impulse over northern ON, will drift southeast across northeast to west-central MN, with a separate surface trough extending north from western KS/NE into central SD. An increase in low-level moisture from the south and southwest, combined with strong daytime heating and modest convergence along the troughs, should support isolated to scattered thunderstorm development during the late afternoon to early evening. While model moisture forecasts are likely overdone, and weak large-scale forcing for ascent limits confidence, steep mid-level lapse rates and adequate deep-layer shear will support conditional potential for a few supercells and multicell clustering. Most morning CAM guidance suggests a narrow corridor of cat 2/SLGT-risk caliber storms should form with a threat for large hail and damaging winds. ...Central/eastern MT... A mid-level closed low over southern BC will move eastward, with the primary jet crossing northern MT through tonight. Associated surface cold front will push east and provide a focus for isolated to scattered thunderstorm development across central to eastern MT during the late afternoon and evening. Low-level moisture will remain limited with boundary-layer dew points in the 40s, yielding MLCAPE to only around 500 J/kg. Still, inverted-v thermodynamic profiles and some increase in mid-level flow will support the threat for isolated severe gusts and small to marginally severe hail. ...Eastern NV/western UT... A low-amplitude shortwave trough over the Sierra NV will gradually progress east across parts of NV into western UT through tonight. Moderate forcing for ascent ahead of this trough, combined with daytime heating/mixing, will support scattered high-based thunderstorm development. Limited boundary-layer moisture will result in only meager MLCAPE and effective bulk shear will remain weak. But deeply mixed inverted-v thermodynamic profiles and DCAPE greater than 1000 J/kg will support a threat for isolated severe gusts. Read more CHECK UPDATE ZOOM GRAPHIC
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