Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Sep 03 2023 11:32:48 AWUS01 KWNH 031132 FFGMPD IDZ000-NVZ000-ORZ000-031630- Mesoscale Precipitation Discussion 1029 NWS Weather Prediction Center College Park MD 732 AM EDT Sun Sep 03 2023 Areas affected...Central & north-central NV...Far Southeast OR...Far Southwest ID... Concerning...Heavy rainfall...Flash flooding possible Valid 031130Z - 031630Z SUMMARY...Very slow eastward moving band with embedded more intense cells capable of 1-1.5"/hr rates within a repeating environment. Band will also track through areas recently affected by anomalous rainfall, suggesting spots of flash flooding are possible.=20 DISCUSSION...GOES-W WV suite depicts a compact vorticity center along the CA/OR border slowly lifting northward, likely to pivot in south-central OR over the next few hours. This wave within the larger parent deep closed low centered along the NW CA coast is accompanied by a buckle in the upper-level jet core resulting in enhanced diffluence/divergence over north-central to central NV.=20 This is coincident with surface front and tighter moisture gradient where above normal Tds range from upper 40s to upper 50s along the boundary/front. CIRA LPW also denotes an enhanced 850-700 as well as 700-500mb moisture pocket/wedge supporting near 1-1.2" total PWats across the area of concern which is well above normal and possibly near record values being 3.5-4 standard deviation above the mean. Given the confluent flow and divergence aloft, a broad shield of warm conveyor belt ascent is noted in GOES-W IR channels as=20 cirrus/stratus deck which is confirmed by RADAR with moderate rainfall within/under it likely with limited evaporation loss.=20 However, RAP analysis and model profiles suggest some weak but sufficient instability due to some weak lapse rates supporting 250-500 J/kg of MUCAPE. As such, and confirmed by recent GLM and ground based network lightning networks, there are embedded convective elements within the shield particularly over Churchill and Pershing into Lander counties, aligned with shallow but cooling IR tops. Given moisture, there are spots likely producing ..5-.75" in 15-30 minute as the lift northward in modestly fast fairly unidirectional steering flow. As such, a few cells may have time to repeat/train toward the north-northeast across central to north-central NV. While the height-falls are delayed by the buckle in the jet/northward track of the pivoting shortwave in S OR; there remains some slow eastward propagation of the conveyor belt so the repeating window is likely to be limited for a few hours. Though this also will result in the axis of showers/thunderstorms to move over areas recently saturated over the last day or two across Lander to W Elko counties, where FFG values are already naturally low, but likely have been reduced even further for the recent rain-fall. As such, with spots of 1-1.5" totals in short-duration (1-2 hrs) may be possible to induce localized flash flooding conditions particularly if falling along steeper slopes/terrain or recent burn scars along the Ranges of central NV.=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!-moOLZsobfoj0C_4KeBIrzNHyGu4U7zD9ymwK2qPI0RDlz5KtN6DJ7kBMpOHt8TOmG7w= cY-HxkTD7CglSKR05BRDeAA$ for graphic product... ATTN...WFO...BOI...LKN...REV...VEF... ATTN...RFC...CNRFC...NWRFC...NWC... LAT...LON 43401690 42411564 40861555 39001644 38511681=20 38231726 38221778 38501825 39181846 40781842=20 43051865=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) .