Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 05 2023 08:09:19 FOUS30 KWBC 050809 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 407 AM EDT Mon Jun 05 2023 Day 1 Valid 12Z Mon Jun 05 2023 - 12Z Tue Jun 06 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN HIGH PLAINS... ....Southern Plains through the Northern Rockies... Not a lot of changes made to the previous Excessive Rainfall Outlook for this time period as the persistent, stagnant blocked flow persists across the nation. There will continue to be an axis of above average PW stretching from the Southern to Central High Plains, through the Central to Northern Rockies and into the Northern High Plains. Embedded in this high PW axis will be numerous vorts that will help enhance uvvs and convective activity. The last several days, areas of the Southern High Plains from northeast NM into the TX/OK Panhandle have seen some organization and locally heavy totals than other areas that have not seen as much overlap. For this reason, we continue to depict a slight risk area from northeast NM into Northwest TX where models again show potential for additional convection. There is a typical amount of model qpf spread but at least some consensus in the models for additional convection across areas that are more hydrologically sensitive given recent rains. The slight risk area fits well with where the latest HREF neighborhood probabilities are high for 1"+ rains and overlap with the above mentioned heavy rains over the past few days. HREF probabilities are also high for 1"+ amounts in spots through the marginal risk area, but do not have the consistent overlap with recent heavy rain areas of previous days as do sections of the Southern High Plains. ....Central California coast Range into the Sierra Nevada... A strong closed low offshore of Southern California will be swinging steadily northeastward to a position at the coast Monday afternoon at which time it is then expected to slow significantly. An increasingly upper difluent flow pattern to the north and northeast of this closed low will support increasing scattered convection Monday afternoon from the central California Coast Range, northeastward into the Sierra in a region where PW values will be rising to 1 to 2+ standard deviations above the mean.=20=20=20 The previous marginal risk area was expanded to the southwest from the Sierra to the Central California Coast Range where the latest HREF probabilities show some potential for hourly rainfall rates of .50-1" in this anomalous PW axis from Monday afternoon into evening. With stream flows remaining above average, isolated flash flooding possible. In addition, some of this heavy rain potential may occur across burn scar regions from the past several years. ....Upper Midwest... A marginal risk was maintained along and ahead of the strengthening frontal boundary forecast to stretch northwest to southeast from south central Canada into eastern portions of the Northern Plains and Upper MS Valley. With PW rising to 2+ standard deviations above the mean in an axis of MUCAPE values 1000-2000 J/kg in the vicinity of this front, locally heavy rainfall amounts are possible. The simulated radars from the latest CAM guidance suggests potential for slow moving cells in the vicinity of this front. With areas of higher than average stream flow as per the National Water Model from south central MN northwestward along the MN/ND border, isolated runoff issues possible from hourly rainfall rates of 1"+ with these slower moving cells. The marginal risk area agrees well with the latest CSU first guess fields which shows a marginal risk across eastern ND into northwestern MN. Oravec Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-wQ1teD2smcEKqFOLZRBk1qOljmtAwYGooWn2JC7cRP-= BwcMLudiZeujstt3AeePD80gEmYllbojxIBJng00iC4rs00$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-wQ1teD2smcEKqFOLZRBk1qOljmtAwYGooWn2JC7cRP-= BwcMLudiZeujstt3AeePD80gEmYllbojxIBJng00RZGJ2ZQ$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-wQ1teD2smcEKqFOLZRBk1qOljmtAwYGooWn2JC7cRP-= BwcMLudiZeujstt3AeePD80gEmYllbojxIBJng00trtAf8c$=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) .