Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Aug 13 2024 15:39:23 AWUS01 KWNH 131539 FFGMPD COZ000-WYZ000-UTZ000-132130- Mesoscale Precipitation Discussion 0875 NWS Weather Prediction Center College Park MD 1138 AM EDT Tue Aug 13 2024 Areas affected...Utah...Western & Central Colorado...Southern Wyoming... Concerning...Heavy rainfall...Flash flooding possible Valid 131540Z - 132130Z SUMMARY...Enhanced thunderstorm activity with rates up to 1.5"/hr and widely scattered totals up to 2" with potential training/repeating cells across hard ground conditions may pose widely scattered flash flooding incidents this afternoon into evening. DISCUSSION...Favorable synoptic set-up for increased convective activity this afternoon. A shortwave along the southeast side of polar trough over the Northwest, is moving quickly through the Upper Snake River into Southeast ID, though the deeper westerly trough axis can be tracked through central UT attm. A compact shortwave in the southern stream is rotating northward along the central NM/AZ border along the western periphery of the synoptic ridge, providing a downstream dPVA environment of increased activity/wedge deformation zone across SE UT into central CO in combination with the northern stream trough. This synoptic ascent has resulted in scattered weak convection but increased cloud coverage across E UT, W CO, but breaks in the clouds are trying to bring up insolation for overall deeper anomalous moisture fields across the Four Corners states.=20 CIRA LPW shows the surge of enhanced moisture along the AZ/NM line within the 700-6500 layer, lifting into the aforementioned deformation zone, while 850-700mb layer shows enhanced moisture trapped into the valleys of E UT/NW AZ, denoting the anomalous nature (resulting in PW values of 1-1.25 in SE UT). Even post mid-level trof, sfc to 700mb moisture continues to stream northward out of the low deserts into the Colorado River Valley and western UT low valleys. Like yesterday, Tds in the upper 50s and low 60s exist along/ahead of the range, though an effective dry line is starting to press east through eastern NV, though ELY/ENV remain in the 50s, 05U and even LSV have dropped into the 20s and 40s respectively. So increased clearer insolation over deeper moisture along/ahead of surface density/convergence boundary should help to activate stronger thunderstorms again along and west of the central UT mountain ranges, especially as the boundary is expected to advance westward in the wake of the upper-level trough passage. So rates of 1-1.5"/hr (stronger further west in W UT) are becoming increasingly probable with stronger convective cells over the next few hours, starting to peak in the 20-21z time frame. Cloud cover over along and just east of the mid-level trough may diminishing overall coverage in E UT for a short-term, but given stronger forcing/deeper moisture, should become similarly intense with time. Deep layer flow is fairly unidirectional across the area of concern from the southwest to west and may support some repeating cells to occur, more likely east of the UT/CO line given longer duration in the deeper moisture/forcing axis. This may allow for localized spots of 1-2" totals through 21z and may result in widely scattered incidents of flash flooding this afternoon.=20=20 Flash flooding conditions will be greater in proximity to burn scars in the region or intersecting slot canyons. Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-InnVfZ5nSxDDJcktFknHmyRkrO-cA-coDP9Rluov8fTUrxakStr784VC3U8PrQvdhUF= LxOUSDpBueDoTG7B87k3jCE$ for graphic product... ATTN...WFO...BOU...CYS...GJT...PUB...RIW...SLC... ATTN...RFC...ABRFC...CBRFC...MBRFC...WGRFC...NWC... LAT...LON 41981142 41980844 41860690 40850537 39670459=20 38580496 37570587 37090690 37080842 37070966=20 37031096 37071305 37411385 38561399 40781398=20 41641315=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 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .