Subj : MESO: Mesoscale Discussion 2180 To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Sep 23 2023 14:38:35 ACUS11 KWNS 231438 SWOMCD SPC MCD 231437=20 IAZ000-NEZ000-SDZ000-231630- Mesoscale Discussion 2180 NWS Storm Prediction Center Norman OK 0937 AM CDT Sat Sep 23 2023 Areas affected...Northeast/East-Central NE...Northwest/West-Central IA Concerning...Severe potential...Watch possible=20 Valid 231437Z - 231630Z Probability of Watch Issuance...40 percent SUMMARY...Isolated large hail and/or damaging gust are possible over the next few hours across northeast/east-central Nebraska and northwest/west-central Iowa. DISCUSSION...Organized convective line continues to push eastward/northeastward across northeast NE at around 30-35 kt. Based on a recent surface analysis, this line is just to the northeast of a surface low centered near GRI (in south-central NE). The warm frontal zone associated with this low is fairly diffuse, but some interaction between this warm front and the ongoing convective line has likely contributed to stronger gusts reaching the surface. OFK recently gusted to 53 kt and recent OAX radar imagery shows strengthening inbound velocities in Colfax and Stanton Counties. The downstream air mass is cool, moist, and modestly buoyant.=20 12Z OAX sounding sampled very steep mid-level lapse rates, supported by 500 mb temperatures around -13 to -14 deg C. These conditions are still in place, with a mesoanalysis estimating a pocket of 8 to 8.5 deg C 700 to 500 mb lapse rates ahead of the line. These lapse rates are supporting modest buoyancy, with recent mesoanalysis estimating MLCAPE around 1000 J/kg, most of which is above 700 mb. Strong vertical shear is in place as well, and the overall expectation is that the line will maintain its intensity for at least the next few hours as it continues northeastward.=20 Low-level stable layer will likely limit the amount and strength of the downdrafts reaching the surface. It is not entirely out of the question for additional strengthening of this line, which could intensify the rear-inflow jet enough for it to reach the surface. However, that appears to be a low-probability scenario at this point. Given the steep lapse rates, large hail appears possible within this line as well. Overall severe coverage will likely remain isolated, but convective trends will be monitored closely. ...Mosier/Guyer.. 09/23/2023 ....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!-b1B5lsT4X_QSoWoyc6f44HYXYasz4alSbh0pyNP2BpYWuBIhuS6hra1qhSMd1gUVMG8LkkRh= KNP6P4XSRgKLClBDao$ for graphic product... ATTN...WFO...DMX...FSD...OAX...GID... LAT...LON 42419744 42839701 42979554 42279499 41739498 41169568 41039734 42419744=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) .