Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jun 06 2023 08:07:37 FOUS30 KWBC 060807 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 406 AM EDT Tue Jun 06 2023 Day 1 Valid 12Z Tue Jun 06 2023 - 12Z Wed Jun 07 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE FRONT RANGE OF THE ROCKIES THROUGH THE SOUTHERN HIGH PLAINS... ....Southern High Plains through the Northern Rockies... Only some minor changes made to the previous Excessive Rainfall Outlook risk areas stretching from the Southern High Plains, through the Southern to Central Rockies, Central High Plains into the Northern Rockies and Northern High Plains. With no big changes anticipated to the large scale blocking flow regime that has been supporting widespread scattered convection across these regions over the past several days, anticipate another day of widespread locally heavy convective rainfall amounts from embedded vorts in the persistent axis of above average PW values, 1 to 2 standard deviations above the mean, across these regions. With recent rainfall totals well above average across much of the region, the flash flooding threat will persist given elevated soil moisture and stream flows. No changes made to the primary threat region denoted by the slight risk stretching from the front range of the Rockies into the Southern High Plains. HREF neighborhood probabilities continue fairly high for 1"+ totals in the slight risk area, decreasing for 2 and 3"+ totals but still showing the most geographic clustering across these regions. A small slight risk area was added in the vicinity of south central Montana where there are high HREF probabilities for 1, 2 and 3"+ totals that overlap a region that has seen rainfall anomalies of 300-400% of normal over the past week. ....Upper Midwest and Northern Plains... The stationary frontal boundary stretching along the MN/ND border into southern MN/northern IA region will be the focus for scattered convection Tuesday afternoon in an axis of PW values 1-2 standard deviations above the mean and mu cape values 500-1000 j/kg+. Simulated hi res radars show potential for slow moving, but fairly widely scattered activity. This is reflected in the HREF probabilities that are rather blotchy for 1, 2 and 3"+ amounts. The HREF EAS probabilities are very low for the 1 & 2 inch thresholds, mostly less than 5%, and 0% for 3" totals, reflecting the hi res guidance consensus or lack there of for organized complexes. Considered taking the marginal risk area out given current forecasts, but kept it in as the new CSU first guess field continued to show a marginal risk. ....Central California through the Northern Great Basin... The strong closed low along the south central CA coastal region is expected to move little during the upcoming day 1 period. With PW values expected to remain well above average, 2+ standard deviations above the mean, in a region of strong upper difluence to the north and northeast of this closed low, isolated heavy rainfall totals are possible from the Central CA Coast Range, through the Sierra, Northern CA and portions of the Great Basin.=20 Isolated flash flooding possible across areas of persistent high stream flow and recent burn scars. ....Central Gulf Coast... A very moist and unstable airmass to continue along the Central Gulf Coast day 1, with PW values 1.5-1.75"+ and MUCAPE values 1500-2000 J/kg. A weak mid to upper level flow passing just offshore of the Central Gulf coast will support another day of scattered convection in this moist unstable airmass. The region from the Upper TX coast to southern LA has been drier than normal over the past few weeks, so believe any potential runoff issues will be confined to urban areas. HREF probabilities are high for 1 and 2"+ amounts along the immediate Upper TX coast, southern LA into southern MS. 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!-1LqWFrpTMjzMLVQzONaUVA5CSgf5KauS2iW8tzR_Qek= jfl5P0MAzPDp8hEuLjZG3fcmDWicNua6CNUPXt939T8rcNY$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-1LqWFrpTMjzMLVQzONaUVA5CSgf5KauS2iW8tzR_Qek= jfl5P0MAzPDp8hEuLjZG3fcmDWicNua6CNUPXt93nOyS6Kg$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-1LqWFrpTMjzMLVQzONaUVA5CSgf5KauS2iW8tzR_Qek= jfl5P0MAzPDp8hEuLjZG3fcmDWicNua6CNUPXt93_mUTh5A$=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) .