Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Fri Jun 27 2025 15:29:43 AWUS01 KWNH 271529 FFGMPD GAZ000-TNZ000-KYZ000-ALZ000-MSZ000-272100- Mesoscale Precipitation Discussion 0526 NWS Weather Prediction Center College Park MD 1129 AM EDT Fri Jun 27 2025 Areas affected...Middle TN...Northern AL...South-central KY...Adj Northeast MS & Northwest GA... Concerning...Heavy rainfall...Flash flooding possible Valid 271530Z - 272100Z SUMMARY...Highly focused/efficient heavy rain bursts with localized 2-2.5" in less than 90 minutes may pose similarly focused incidents of flash flooding, particularly near urban areas. DISCUSSION...A very humid/unstable airmass exists across Middle TN extending into south-central KY and northern AL. GOES-E WV suite shows a very broad, well defined TUTT (Tropical upper-tropospheric trough) cell retrograding across the southeast with the core over central GA attm; resulting in an area of enhanced low to mid-level moisture (per CIRA LPW) and clearing across the area of concern.=20 Thermal profiles denote solid saturation, weak capping and just small adjustments of the surface profiles result in large MLCAPE values over 3000-4000 J/kg. With solid morning insolation in the clearing east of the outer cirrus deck of the TUTT cells, temperatures are already reaching required values for convective initiation reaching mid-80s and Tds in the mid to upper 70s.=20 Visible imagery and RADAR mosaic show the incipient boiling Tcu expanding across southern Middle TN into N AL. Combined with the best heating, there is some modest upper-level divergence at the western exit of the 40-50kt 3H jet on the northeast side of the TUTT before it arcs northward across central KY. As such, stronger updrafts will become scattered to numerous but given weak inflow in the low levels should remain narrow initially. Overall vertical loading of the available moisture given strength of the updraft should support wet-microburst/pulse downdrafts capable of 2-2.25" totals in sub-hourly to hourly duration.=20 Outflows will trigger next updraft development and any colliding outflows will result in a larger slab ascent for the subsequent up/downdraft cycles; though similar results are likely to occur of up to 2" totals. Overall the pattern support a broad outward propagation from the initial centroid over southern TN/N AL more in line with the 12z ARW solutions.=20 Any flash flooding is likely to be limited in areal coverage (though broadening slightly with each cycle/broader downdrafts, but still sub-county focused); with greatest potential across impermeable surfaces near urban centers. However, 1hr FFG values are in the 1.5-2" range across S TN/northern AL where 0-40cm relative making potential a bit greater in these areas.=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!63GCCt2wWdVbrzxIQgMnreX_Gls426haxKUJ5YmUot8d5SR6BCXB7_oIlOoCQyrz95hR= 4L-_vWHRmxS38hSR6jrG_cU$ for graphic product... ATTN...WFO...BMX...FFC...HUN...JKL...LMK...MEG...MRX...OHX... PAH... ATTN...RFC...ALR...ORN...TIR...NWC... LAT...LON 37668597 37468452 36938414 36328424 35578470=20 34578524 33828582 33498674 33878818 34658876=20 35698870 36788797 37398707=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) .