Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jun 26 2023 08:30:59 FOUS30 KWBC 260830 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 430 AM EDT Mon Jun 26 2023 Day 1 Valid 12Z Mon Jun 26 2023 - 12Z Tue Jun 27 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS MID-ATLANTIC... ....Eastern U.S.... An anomalously deep upper low will continue to develop and move across the upper Great Lakes today, with an associated surface front pushing across the Ohio Valley into the central Appalachians today. A moist airmass ahead of the front (PWs at or above 1.5 inches), interacting with strong upper level divergence and increasing destabilization during the day is expected to set the stage for widespread convection developing across portions of the Northeast southward through the Mid-Atlantic into the Southeast.=20 While the transient nature of the system and developing cold pools are likely to support progressive storms, the environment is expected to generate intense rainfall rates, which may produce isolated to scattered flash flooding concerns. Wet antecedent conditions supported by above-average rainfall over the past seven days, may leave portions of Virginia into the Southeast more prone to flash flooding. The 00Z HREF guidance shows two areas where heavy amounts are more likely -- one over eastern Pennsylvania into northwestern New Jersey and the Catskill Mountain region of Update New York; and the other centered over south-central North Carolina. HREF Neighborhood probabilities indicate amounts of 2-3 inches are likely across the southern area, with 3 inches or more probable in the northern area. ....Southern Montana into Northern Wyoming and Western South Dakota... Increasing ascent ahead of an upper trough moving through the Intermountain West and increasing moisture supported in part by southeasterly low level inflow are expected to support showers and storms developing across the region later today. Storms are forecast to develop initially across the high terrain in southwestern Montana and northwestern Wyoming this afternoon/evening before propagating east along an axis of deeper moisture centered across southeastern Montana and northeastern Wyoming into the Black Hills region. Although widespread heavy amounts are not expected, locally heavy amounts may produce isolated flash flooding especially given the anomalously wet antecedent conditions. ....Northern Cascades... Easterly low level winds, weak flow aloft, and PWs approaching an inch are expected to support slow-moving showers and storms.=20 These may create isolated flash flooding concerns, especially over areas recently impacted by wildfire. Pereira Day 2 The Day 2 outlook will be updated by 0830Z. Day 3 The Day 3 outlook will be updated by 0830Z. Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9MOuuPeJPAhWewQBTYNfoF4eydDk0CDA2v784Shwkg0w= ktKKCITvD3h5O3Poej8gYXm7K_cLI7MdG8w8CeP1uGBINqI$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9MOuuPeJPAhWewQBTYNfoF4eydDk0CDA2v784Shwkg0w= ktKKCITvD3h5O3Poej8gYXm7K_cLI7MdG8w8CeP1LrI-zxA$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9MOuuPeJPAhWewQBTYNfoF4eydDk0CDA2v784Shwkg0w= ktKKCITvD3h5O3Poej8gYXm7K_cLI7MdG8w8CeP1zip2k4Q$=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) .