Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jun 27 2023 08:11:26 FOUS30 KWBC 270811 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 410 AM EDT Tue Jun 27 2023 Day 1 Valid 12Z Tue Jun 27 2023 - 12Z Wed Jun 28 2023 ....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE NORTHEAST... ....Northeast/Northern Mid-Atlantic... The upper low associated with widespread convection and moderate to heavy rainfall that developed across the eastern U.S. yesterday and continued into the overnight is forecast to transition to an open wave and begin to drift slowly eastward from the Great Lakes into the Northeast today. Ongoing convection over the Northeast and Mid-Atlantic is expected to wane and continue to move east through the remainder of the overnight. However, deep southerly flow ahead of the trough will continue to channel ample moisture and mid-level energy across the region, setting the stage for redeveloping showers and storms later today. PWs over 1.25 across the interior Mid-Atlantic/Northeast to over 1.5 along the coast, in addition to daytime heating, will help support showers and storms developing and becoming fairly widespread across the region during the afternoon. As the upper trough slows, there will once again be the potential for southwest to northeast training storms, raising the threat for heavy amounts and flash flooding. The 00Z HREF is again highlighting portions of eastern Pennsylvania, northern New Jersey, and the Catskill Mountain region of Upstate New York. Neighborhood probabilities indicate that locally heavy amounts of 2-3 inches are likely in the area. This includes some areas that were inundated with heavy amounts over the past 24-hours. Therefore, a Slight Risk was added to this region. ....Northern Rockies and Plains... A slow-moving trough in the West and sufficient moisture will support another day of showers and storms developing over the mountains of western Wyoming and Montana. Farther to the east, leading energy moving out of the trough, interacting with deepening moisture along a strengthening low level jet is expected to support showers and storms developing and moving east through the High Plains into parts of the Dakotas. Although widespread heavy amounts are not expected, locally heavy amounts may produce an isolated flash flooding threat, especially given the wet antecedent conditions across portions of the area. ....Southwestern Kansas/Northwestern Oklahoma... Storms are expected to begin to develop during the afternoon as mid-level energy emanating from the trough in the West moves over the downstream ridge and interacts with moisture deepening along a low level warm front. As the low level inflow into the front increases, guidance shows PWs increasing to at over above 1.75 inches near the Kansas-Oklahoma border. Merging cells, with some potential for backbuilding, may produce some locally heavy amounts and isolated flash flooding concerns before these developing storms are expected to consolidate and track progressively to the east. Pereira Day 2 Valid 12Z Wed Jun 28 2023 - 12Z Thu Jun 29 2023 ....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE NORTHEAST, UPPER MIDWEST, AND THE NORTHERN ROCKIES... ....Northeast... An upper trough will continue linger over the Northeast, channeling both deep moisture and mid-level energy across portions of the region. Daytime heating is likely to help support additional showers and thunderstorms, with locally heavy amounts possible, especially across portions of eastern Upstate New York into New England. ....Upper Midwest... Mid-level energy emanating from the trough in the West, along with an amplifying trough approaching from the northwest over central Canada is expected to support an increasing chance for rain across portions of the region on Wednesday into early Thursday.=20 Deepening moisture (PWs increasing to around 1.5 inches), along with some potential for west-east training, may produce at least some locally heavy amounts from northern Minnesota to the western U.P. of Michigan. ....Northern Rockies... With an upper trough remaining positioned to the west and a relatively moist airmass still in place, isolated to scattered showers and storms are expected to develop once again across the region. These may produce locally heavy amounts and generate isolated flash flooding concerns, especially given the wet antecedent conditions. Pereira=20 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!6CGmyCsWbOn9xQDKuaJ78hSG1Jl5l_0lwA9A28aHsGtF= MUFuShgtsdrcFcw88poKutHZm4RyXlWHGFi7ZjnoWYXVAS8$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6CGmyCsWbOn9xQDKuaJ78hSG1Jl5l_0lwA9A28aHsGtF= MUFuShgtsdrcFcw88poKutHZm4RyXlWHGFi7ZjnoAtjdl-U$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6CGmyCsWbOn9xQDKuaJ78hSG1Jl5l_0lwA9A28aHsGtF= MUFuShgtsdrcFcw88poKutHZm4RyXlWHGFi7ZjnogoEDdns$=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) .