Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun May 28 2023 22:44:56 AWUS01 KWNH 282244 FFGMPD KSZ000-NEZ000-290300- Mesoscale Precipitation Discussion 0370 NWS Weather Prediction Center College Park MD 644 PM EDT Sun May 28 2023 Areas affected...Southern Nebraska...Northern Kansas... Concerning...Heavy rainfall...Flash flooding possible Valid 282245Z - 290300Z SUMMARY...Possible flash flooding, particularly near areas saturated over the last few days over SW NEB/NW KS. Upstream redevelopment/repeating and slow chaotic cell motions should allow for longer duration and potential for localized pockets of 2-4". DISCUSSION...GOES-E WV suite delineates a sharp mid-level boundary denoting the trailing edge of the mid to upper level shortwave exiting northward across NW NEB/SW SDak. This trails back toward a shortwave ridging in the low to mid-levels of confluent flow from Thomas/Sheridan to Furnas county. Sfc obs and VWP network suggest a bit of backed low level winds directed obliquely to this axis which appears to enhancing the congestous and developing CBs in the area and aligns with the best MLCAPE which is generally east of the deepest overall moisture. CIRA LPW also shows the nose of higher LPW values along this edge in the low levels, while some drying in the 7-500mb layer aids the instability. Still, moisture loading in the low levels is likely to provide ample rainfall production for rates of 1.5-1.75"/hr. Given this veering with height in the 800-600mb layer, mean cell motions are 10-15kts toward the NE but 500-1000 mb thickness shows localized ridging to promote weak upwind propagation vectors which may be even weaker in reality compared to RAP analysis given the chaotic mid-level flow regime. RADAR trends suggest weak outflow boundaries are trending westward but this should support any redevelopment along the outflow to track eastward crossings areas already affected by initial updrafts. As such, localized totals of 2-4" are possible across South-central to Southwest NEB into NW KS. Given this area was recently affected by significant rainfall, grounds are saturated and FFG values are <1.5"/hr and <2"/3hrs making flash flooding more probable across the western portions of the MPD area of concern. However, there remains sufficient uncertainty in cell motion speeds (given reliance on RAP field analysis) to declare flash flooding as possible.=20 Further southeast...South-Central NEB/North Central KS... Deeper moisture may allow for increased rainfall efficiency given total PWats nearing 1.5" and with 70-80% 700mb RH, less evaporative loss. Other factors supporting potential for localized flash flooding are increased convective development upstream (to the southwest) for repeating tracks. However, limiting factors are a more progressive northeast cell motion and stronger propagation vectors as the thickness fields are a bit tighter directing cell motions more eastward over time. Combine this with higher FFG values...flash flooding is still possible, but less likely and much more isolated in nature.=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!4Sjxktj54GCIgDr9DFqaW8tS1_hByetAAYmrbABGAR5QjlrVvqMltp8d7912BP_yh2OU= podBTy3HIR558JTijGk7Vp4$ for graphic product... ATTN...WFO...DDC...GID...GLD...ICT...LBF... ATTN...RFC...MBRFC...NWC... LAT...LON 41649959 41609888 41139819 40979804 40249795=20 39119811 38779912 39410015 39880078 40780049=20 41270052 41450019=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) .