Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 12 2023 23:56:58 AWUS01 KWNH 122356 FFGMPD MTZ000-WYZ000-UTZ000-IDZ000-NVZ000-130400- Mesoscale Precipitation Discussion 0474 NWS Weather Prediction Center College Park MD 756 PM EDT Mon Jun 12 2023 Areas affected...eastern Idaho and western Wyoming Concerning...Heavy rainfall...Flash flooding possible Valid 130000Z - 130400Z Summary...Scattered slow moving showers and thunderstorms will persist into this evening before waning rapidly with loss of daytime instability. Storms moving only around 5 kts may create an additional 1" of rainfall in a few areas. Isolated flash flooding is possible. Discussion...The GOES-E visible imagery this afternoon shows widespread Cu/TCu with anvil/blow-off encompassing nearly all of the Inter-mountain West and Great Basin. Beneath these clouds, the regional radar mosaic indicates widespread slow moving showers and thunderstorms, but with little overall organization in a generally pulse and diurnally-driven environment. The satellite/radar imagery indicates clearly the broad cyclonic flow around a mid-level trough centered over UT/NV, with storms moving slowly from the E/NE across WY and ID. Although recently storms have shown some general weakening with reduced coverage, estimated rain rates from KSFX are still around 1.5"/hr, and these slow moving storms have produced FLASH responses as high as 200% of the QPE-FFG ratio. The general waning trend of both coverage and intensity should persist as these storms are diurnally forced by SBCAPE of 500-1500 J/kg with minimal bulk shear. However, weak shortwaves identified in WV imagery and via the SPC RAP could help organize and strengthen a few cells across western WY and eastern ID for the next few hours. While any cell could briefly tick up in intensity through the evening, the HRRR sub-hourly rainfall accumulation of more than 0.25"/15 minutes, reflecting hourly rain rates above 1"/hr, are generally confined to near these impulses. With storm motions likely continuing around just 5 kts, coincident with similar Corfidi vectors, these could produce a few instances of more than 1" of rainfall into tonight. The overall flash flood risk does appear isolated. However, these storms will be moving slowly atop extremely saturated soils noted by AHPS 7-day rainfall that is in many areas 300-600% of normal, leading to FFG that is just 0.5-1"/1hr. The HREF exceedance probabilities peak around 30% through the next few hours, indicating that any more intense rainfall could yield rapid runoff and isolated flash flooding, especially if it occurs atop some of the more sensitive terrain or burn scars. Weiss ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!6qnRHoFTr1Xm8OuaDe27Ghnu2oOg61i4V9U7EL5JC58lUPVnpaPbEYsW9Pai4L3eFfF8= vvbgFQSnBvEdIg_4W54RIu0$ for graphic product... ATTN...WFO...BOI...LKN...MSO...PIH...RIW...SLC...TFX... ATTN...RFC...CBRFC...MBRFC...NWRFC...NWC... LAT...LON 44561278 44461019 43970785 43620724 43090716=20 42380758 41670843 41380984 41491146 41831338=20 42041432 42741530 43371589 44111588 44381543=20 44501452=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) .