Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Thu Jun 08 2023 20:04:26 AWUS01 KWNH 082004 FFGMPD MTZ000-IDZ000-WAZ000-090015- Mesoscale Precipitation Discussion 0445 NWS Weather Prediction Center College Park MD 403 PM EDT Thu Jun 08 2023 Areas affected...northern MT into northern ID Concerning...Heavy rainfall...Flash flooding likely Valid 082002Z - 090015Z SUMMARY...Scattered thunderstorms are expected to increase across portions of northern MT through the afternoon eventually impacting northern ID. Rainfall rates of 1-2 in/hr are expected and flash flooding is considered likely although coverage of higher totals remains uncertain. DISCUSSION...1930Z visible satellite imagery showed ongoing convection across the Lewis Range in northwestern MT with breaks in cloud cover to the east up to and including an MCV noted over southern Blaine County. However TCu were actively building in the vicinity of the MCV where SPC mesoanalysis data showed MLCAPE of 1000-1500 J/kg. Very anomalous moisture was in place over northern MT (2 to 3+ standardized PW anomalies) along with surface dewpoints in the upper 50s to lower 60s. 10-20 kt of easterly flow was present at 700 mb, with an axis of confluence noted between MSO and BIL on VAD wind plots. Convective temperatures have been reached area wide and it appears coverage of thunderstorms will continue to increase through the afternoon. Expectations are for areas of flash flooding to develop across northern MT as convective coverage increase over the next couple of hours, with wet antecedent conditions playing a role in flash flood susceptibility. While wind speeds are not especially strong, easterly upslope flow into the Lewis Range will continue to support numerous thunderstorms with unidirectional flow supporting repeating and likely short term training of cells which will be capable of generating 1-2 in/hr rainfall rates, although some of that could fall on the sub-hourly scale. Farther east, given forcing associated with the approaching MCV and visible satellite trends, scattered thunderstorms are likely to increase with similar potential for repeating and short term training as the mesoscale circulation advances west. In addition, short term forecasts from the RAP support the axis of 700 mb confluence shifting northward into northwestern MT through 00Z which may aid with storm development. There could be a relative minimum in heavy rain due to downsloping immediatley west of the Lewis Range but into the ID Panhandle, thunderstorms are expected to increase as mid-level vorticity and related thunderstorms ongoing over southwestern MT advance WNW through 00Z. Sufficient heating is ongoing across this region which should support at least 500-1000 J/kg MLCAPE into the region late this afternoon/early evening. Otto ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!5kCX9Jek41uq1JQ_6vh78tFIPUMBc8jlwZ1uWxItKTRCG536dPXApE7fMsg-0rQno3vG= 1VKRyw18WtaRbaAAq8RTX2I$ for graphic product... ATTN...WFO...GGW...MSO...OTX...TFX... ATTN...RFC...MBRFC...NWRFC...NWC... LAT...LON 49131295 49110960 49010862 48350842 47390886=20 47211023 47311189 47211527 47421659 47961704=20 48901712 49121627=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) .