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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.


Friday, June 30, 2023

SPC Jun 30, 2023 1300 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1300Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0743 AM CDT Fri Jun 30 2023 Valid 301300Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS EASTWARD TO THE MID MS AND TN VALLEYS... ...SUMMARY... Occasional large hail and damaging gusts will be possible this afternoon into this evening across the central/southern High Plains, and from the mid Mississippi Valley into the Tennessee Valley. ...Central/southern High Plains this afternoon/evening... A midlevel shortwave trough will move eastward from the central Rockies to the High Plains this afternoon and continue into KS overnight. Lingering boundary-layer dewpoints in the low-mid 50s in the post-frontal environment, steep midlevel lapse rates and surface heating in cloud breaks (strongest in southeast CO) will result in moderate buoyancy (MLCAPE near 1500 J/kg) and weakening convective inhibition after 18z. The early arrival of the midlevel trough will support relatively early storm development near and just east of the Front Range, and storms will subsequently spread eastward over the plains. The moderate buoyancy and effective bulk shear near 40 kt (with relatively straight hodographs) will initially support a few supercells capable of producing large hail near 2 inches in diameter. Upscale growth into clusters/line segments appears likely through the afternoon, and the potential for occasional severe outflow gusts and isolated large hail will persist into early tonight as storms spread eastward into KS. Farther south, a weak surface trough/dryline will focus scattered thunderstorm development this afternoon across the southern High Plains. Deep-layer vertical shear will weaken gradually with southward extent into west central TX, which supports a mix of multicell clusters and transient supercells capable of producing isolated strong-severe outflow gusts and large hail this afternoon into this evening. ...Mid MS to TN Valley area through tonight... The composite outflow from yesterday's MCS is still fairly well defined from near I-70 in MO southeastward into western KY/TN, with a substantially cooler/drier air mass farther northeast in IL/IN this morning. Upstream storm clusters across southern IA/northern MO will pose some threat for wind damage and marginally severe hail this morning to near the MO/IA/IL border region, but the storms will likely weaken thereafter while encountering the diminished buoyancy toward IL. Other elevated storms are ongoing in a warm advection zone across eastern TN/KY, and some of this convection could persist while moving southward as the boundary layer destabilizes from west-to-east through the day. By afternoon, it appears that the primary focus for thunderstorm development will be the composite outflow boundary, from east of a weak surface wave in northwest MO continuing southeastward near Saint Louis and into western KY and TN. Vertical shear will be on the lower margins for sustained supercells, though continuing steep lapse rates and large buoyancy will favor storm clusters capable of producing damaging gusts and large hail. There is uncertainty regarding whether or not a cluster or two will grow upscale and persist into tonight, and how far east any such cluster (especially if it originates across northern MO) could move with an attendant threat for damaging winds. With no clear expectation for an additional overnight cluster farther east, have reduced the Slight risk area some across IN/southwest OH/northeast KY. ..Thompson/Gleason.. 06/30/2023 Read more CHECK UPDATE ZOOM GRAPHIC
SUNRISE AND SUNSET TIMES IN UTC (if you're not logged in to Google)
CHICAGO UTC-6 during CST (Central Standard Time, e.g., winter)
CHICAGO UTC-5 during CDT (Daylight Savings Time, e.g., summer)