Subj : MESO: Mesoscale Discussion 1506 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jul 12 2023 20:06:20 ACUS11 KWNS 122006 SWOMCD SPC MCD 122005=20 INZ000-ILZ000-WIZ000-122130- Mesoscale Discussion 1506 NWS Storm Prediction Center Norman OK 0305 PM CDT Wed Jul 12 2023 Areas affected...Northern Illinois and far southern Wisconsin Concerning...Severe potential...Tornado Watch likely=20 Valid 122005Z - 122130Z Probability of Watch Issuance...95 percent SUMMARY...A tornado watch is likely across northern Illinois and possibly southern Wisconsin by 21Z. DISCUSSION...The air mass is recovering rapidly across northern Illinois in the wake of the morning MCS. An EML, advecting eastward amid 40-50 knots of mid-level flow has cleared out cloud cover and allowed for surface heating across eastern Iowa and northwest Illinois. Temperatures in this area have warmed into the low 80s with dewpoints remaining steady, or even climbing slightly, into the low 70s. Temperatures remain in the 60s across northern Illinois, but expect this warm front to lift quickly northeast through the evening as a result of surface heating north of this front and strengthening low-level flow in response to the deepening surface cyclone across eastern Iowa. Additional heating, combined with cooling temperatures aloft ahead of the approaching shortwave trough should result in 1500 to 2000 J/kg MLCAPE by this evening across northern and northeast Illinois. This instability will be co-located with a strong, veering wind profile (sampled by the 20Z LOT VWP). Expect a similar wind profile (featuring 200+ m2/s2 0-500m SRH) to remain along the outflow boundary/composite front through the evening. Supercells are expected to form along this boundary as ascent increases ahead of a digging mid-level shortwave trough and within the left-exit region of the upper-level jet. Southerly winds ahead of the surface low will provide sufficient low-level streamwise vorticity for a tornado threat. However, any storms which remain along or slightly north/east of the boundary, where more backed surface winds will be present, should ingest much higher SRH and will pose a greater tornado threat and even the potential for a strong tornado. In addition, large hail and damaging wind gusts will be possible. A tornado watch is likely by 4pm to cover this threat. ...Bentley.. 07/12/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!9yYnkhGk3WdQwhTRXgulxwkX__Y4DCGvAaG1Bsi90GdnH_wbWZaGwtOSA1-kjmwLc-7squCFJ= mKjK_w9rwffItgZFMI$ for graphic product... ATTN...WFO...LOT...MKX...DVN... LAT...LON 40998855 41538984 41929004 42299010 42539006 42618930 42578790 42318761 41768749 41248754 40998855=20 =3D =3D =3D 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 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .