Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 04 2023 04:26:24 AWUS01 KWNH 040426 FFGMPD SDZ000-NDZ000-041000- Mesoscale Precipitation Discussion 0632 NWS Weather Prediction Center College Park MD 1225 AM EDT Tue Jul 04 2023 Areas affected...southern ND into much of SD Concerning...Heavy rainfall...Flash flooding possible Valid 040424Z - 041000Z Summary...Convective development out ahead of a forward propagating line of thunderstorms may support areas of short term training and possible flash flooding across southern ND into a large portion of SD. Rainfall rates of 1-2 in/hr and storm totals near 3 inches may occur through 10Z. Discussion...04Z regional radar imagery showed a line of strong convection oriented roughly north to south along the western SD border, arcing southeastward to near Chadron, NE. Widely scattered thunderstorms were also noted well ahead of this line over portions of southern, central and eastern SD. The environment north of a quasi-stationary front (located east to west across southern SD) was characterized by 2000-3000 J/kg MUCAPE just ahead of the convective line in southwestern SD, lowering to 500-1000 J/kg in southeastern ND via the 04Z SPC mesoanalysis. Steep 700-500 mb lapse rates of 7.5 to near 9 C/km were present across the region and southerly 850 mb winds were increasing as noted by a 5-10 kt increase in the KLNX VAD wind over the past 2 hours, showing 30-35 kt at 04Z. Out ahead of the eastward propagating north-south line of convection in western SD and ahead of an approaching upper trough from the west, 850 mb winds are forecast by the RAP to increase to near 40 kt from the western SD/NE border into east-central SD by 07Z. Increasing divergence and diffluent flow aloft beneath overrunning low level flow atop the stationary front and subsequent increases in low level moisture into SD/ND should increase instability and reduce low level convective inhibition overnight. Additional development of thunderstorms is expected over SD, in advance of the forward propagating convective line to the west. Given fairly unidirectional flow from the west, there could be periods of training with 1-2 in/hr rainfall rates. These cells followed by the larger line of storms to the west and any immediate development of thunderstorms in advance of the line could support localized rainfall totals near 3 inches through 10Z. As a result, localized flash flooding will be possible. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6cPIqXdeGaTwgdmAxJGW8UUJxQKwZObdH0Avjx3OcldUCHhTPaEBDoCnba4V15Ul5T5m= -XMg5c3CawmH5HhCwOLK6Po$ for graphic product... ATTN...WFO...ABR...BIS...FGF...FSD...UNR... ATTN...RFC...MBRFC...NCRFC...NWC... LAT...LON 46840052 46719838 46119717 45209696 44319716=20 43629810 43250036 43270215 43830364 44870392=20 45910295=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) .