Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jul 13 2024 22:14:03 AWUS01 KWNH 132213 FFGMPD WIZ000-MNZ000-IAZ000-140315- Mesoscale Precipitation Discussion 0615 NWS Weather Prediction Center College Park MD 613 PM EDT Sat Jul 13 2024 Areas affected...Southern WI...Southeast MN...Northeast IA... Concerning...Heavy rainfall...Flash flooding possible Valid 132215Z - 140315Z SUMMARY...Increasing moisture flux may support short-term rates of 2-2.5"/hr; though flanking line of cells has some potential for longer term training and slower cell motions to allow for increased totals of 2-4" and result in possible flash flooding. DISCUSSION...GOES-E WV depicts a potent shortwave crossing Lake Superior that has resulted in deeper layer convergence along the leading edge of height-falls across central WI. Deep layer flow along has aligned with rear-inflow jet resulting in increasing forward propagation and deep bulk shear. As a result, recent high moisture flux into a developing rotating updraft supported 2.5-3" of rain in an hour near Wausau, WI; though this is likely to be the abnormality due to that burst of isallobaric inflow.=20 Still, the environment remains very favorable for deep layer moisture flux from southerly to south-southwesterly surface to boundary layer flow with Tds in the low to mid 70s; while deeper mid-level moisture is being advected on strengthening southwesterly 850mb flow where Tds are in the low to mid 60s and winds are 20kts. Total moisture is about 1.8" slow increasing.=20 So rates of 2-2.5"/hr are likely to become more common and given FFG values of 1.5-2"/hr in the region may be enough for spotty low-end flash flooding incidents even with faster forward progression. Further west, stronger low level capping is in place across NW/north-central IA and SW MN; but high theta-E air across the area has made the region highly unstable with CAPE values over 4000 J/kg. The gradient is tight across SE MN though values of 2500-3500 J/kg exist at the interface of the cooling influence of the shortwave aloft. Combined with isentropic ascent along an effective low level boundary from the initial convection in the Mississippi River Valley, the flanking line is starting to develop discrete cells that will have the potential for consolidating.=20 With supportive WAA of 15-20kts orthogonal to the southeasterly low level flow near the flanking line; stronger moisture flux convergence should support cells capable of similar rates. Unlike cells further east, the orientation of the line is fairly parallel to the deep layer flow and may support repeating/training across SE MN, into NE IA/SW WI over the next few hours. Spots of 2-3, isolated 4" are possible and may result in a broader areal extent of possible flash flooding (relative to further east). Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5qs48ng0WMjyirWfYfKfE1aQoHX0NO4vVhVC5mdpbMscY6CmYPtZwKIlDsQzkC3CssiP= 9-w338IZmmhGsIkeI1H6-ts$ for graphic product... ATTN...WFO...ARX...GRB...MKX...MPX... ATTN...RFC...NCRFC...NWC... LAT...LON 45178880 45138802 44368754 43768755 42988811=20 42698907 42809088 43139224 43699338 44199421=20 44619437 44969392 44729338 44609278 44579173=20 44649080 44918995=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .