252 AWUS01 KWNH 091944 FFGMPD MOZ000-IAZ000-KSZ000-NEZ000-100030- Mesoscale Precipitation Discussion 0956 NWS Weather Prediction Center College Park MD 343 PM EDT Tue Oct 09 2018 Areas affected...Northeast Kansas, Northwest Missouri, Southern Iowa Concerning...Heavy rainfall...Flash flooding possible Valid 091941Z - 100030Z Summary...Thunderstorms and heavy rain bands were beginning to expand in coverage from eastern Kansas, into northwest Missouri and southern Iowa early this afternoon. As areas of heavy rain become more widespread, the risk of flash flooding should increase. Chances of flash flooding would be highest from the Kansas City Metro Area northeast along the I-35 corridor, an area that has received several inches of rain in the past couple days already. Discussion...Regional radars show a squall line becoming increasingly well-defined, arcing across far southeast Kansas as of 1930Z, and pushing rapidly off to the NNE or NE (depending on the exact portion of the line). GOES-16 IR channels also showed cooling cloud tops, and there were some CG lightning strikes showing up in NLDN in the past hour or two. All these signs are indicative of a strengthening band of convection in a region of mid-upper level PVA. The low-level inflow area over Missouri (southeasterly winds) was moderately unstable with RAP analysis showing MLCAPE values reaching 1000 j/kg. The combination of this increasing instability and precipitable water values around 1.6 inches should yield heavy rain rates in the strongest convection, reaching 1-2 in/hr in narrow swaths where individual cell motions prolong the heavy rain longest. Ahead of the squall line, additional scattered convection was developing over northwest Missouri and southern Iowa. This was likely due to increasing low-level WAA and northward moisture flux associated with a strong LLJ lifting north with the low-level cyclone over Kansas. This may create some training patterns over parts of the outlined area, with corridors of up to around 2 inches of rain. Flash flood guidance was reduced across the region due to recent heavy rainfall, particularly from far eastern Kansas, into the Kansas City Metro Area, and up the I-35 corridor to near the IA-MO border. In that specific area, 3-hr FFG is less than 1.5 inches, certainly achievable given the atmospheric ingredients in place. The negating factor could be the relatively fast storm motions. Therefore, the flash flood threat will hinge on the ability for convection to be channeled into training patterns for an hour or two in a particular area, and/or the antecedent conditions being especially favorable for additional flooding. Lamers ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...DMX...EAX...ICT...OAX...SGF...TOP... ATTN...RFC...ABRFC...MBRFC...NCRFC... LAT...LON 41829311 41229244 40199317 39359375 38149453 37749531 38409587 40109565 41419469