Subj : MESO: Mesoscale Discussion 0456 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Apr 04 2023 18:50:02 ACUS11 KWNS 041849 SWOMCD SPC MCD 041849=20 ILZ000-IAZ000-MOZ000-042045- Mesoscale Discussion 0456 NWS Storm Prediction Center Norman OK 0149 PM CDT Tue Apr 04 2023 Areas affected...portions of central/southern IA...northwest IL and northern MO Concerning...Severe potential...Tornado Watch likely=20 Valid 041849Z - 042045Z Probability of Watch Issuance...95 percent SUMMARY...Supercell thunderstorms are expected to develop by 22z/5 pm CDT and shift east across central/southern Iowa, northern Missouri and northwest Illinois through the evening. These storms will be capable of producing very large hail, tornadoes (some strong) and damaging gusts. A tornado watch will likely be issued in the next couple of hours. DISCUSSION...Northward transport of low-level moisture continues early this afternoon. Dewpoints across southern IL/northern MO into northwest IL have increased 8 degrees F over the past 3 hours. Strong heating to the south of a warm front has resulting in temperatures into the low/mid 80s F amid low/mid 60s F surface dewpoints. Some midlevel dry air is evident in forecast and observed soundings, and may result in some mixing of boundary-layer moisture. Forecast guidance suggest an increasing low-level jet will nose into the eastern IA/northwest IL later this afternoon and support open warm sector storms near the warm front. Additional storms are expected to develop near the surface low, southward along the eastward-advancing dryline/cold front. While mixing may result in somewhat higher LCLs, very steep midlevel lapse rates and strong vertical shear will support supercells capable of very large hail (greater than 3 inch in diameter) and damaging gusts. Furthermore, forecast soundings indicated favorable low-level shear and 0-1 km SRH increasing to around 250 m2/s2, supporting tornado potential.=20 Increasing cumulus is noted in latest visible satellite imagery both along the warm front and ahead of the dryline as of 1830z. A couple of elevated cells have even started to develop southward into west-central MO. While capping remains over the region, this may be an indication of some increased forcing beginning to impinge on the area. Continued low-level warm/moist advection beneath the cap, coupled with heating and gradual increasing ascent should result in greater convective initiation/coverage by around 22z. A tornado watch will be likely in the next couple of hours. ...Leitman/Hart.. 04/04/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!__dsoVCaTjl8-LIbFJVp3jNKBG-3y4qbhUSwqDOaAX1YU9aMC8iIpc-2fycOVUxkVSV3j42ag= 27v6OotqtJVNvQmVpU$ for graphic product... ATTN...WFO...LOT...ILX...LSX...DVN...DMX...EAX...OAX... LAT...LON 40968971 40519005 39839169 39319293 38929393 38989427 39369458 40639506 40819498 41119483 42089412 42449367 42519276 42499100 42259013 41678956 40968971=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) .