Subj : HVYRAIN: Excessive Rainfall Discussion To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Wed Jun 28 2023 08:21:19 FOUS30 KWBC 280821 QPFERD Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 420 AM EDT Wed Jun 28 2023 Day 1 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, MID MISSISSIPPI VALLEY, 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. PWs are forecast to generally remain near or above 1.5 inches in the deep southerly flow ahead of the associated front. This along with daytime heating will help to generate additional rounds of moderate to heavy rainfall. Supported by a period of south to north training ahead of the slow-moving front, the overnight HREF guidance continued to show the threat for localized amounts of 2-3 inches, maximized along an axis extending from central Massachusetts into New Hampshire, and northeastern Vermont. There are still concerns regarding the need for a targeted upgrade to a Slight Risk, however with the HREF painting its heavier amounts across areas away from those most recently impacted with heavier accumulations, opted to maintain the Marginal Risk for now.=20=20 ....Upper Midwest... Mid-level energy emanating from the trough in the West, along with an amplifying trough approaching from the northwest over central Canada are expected to support an increasing chance for rain across portions of the region on Wednesday into early Thursday.=20 The general consensus of the HREF guidance shows heavier precipitation spreading initially into the Minnesota Arrowhead region in the warm advection pattern and along a ribbon of deeper moisture (PWs around 1.5 inches) nosing through the region. This will likely be followed by the afternoon development of storms in the more unstable air farther south across northwestern Wisconsin. While individual storms are likely to be progressive, some of the guidance does show some potential for west-east training, which may produce locally heavy amounts and an isolated flash flooding threat. ....Northern Rockies... With an upper trough remaining positioned to the west and a relatively moist airmass still in place, isolated to scattered, slow-moving 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. The 00Z HREF continues to show some appreciable probabilities for rain totals of 1-2" and probabilities of exceeding 2, 5, and 10-year ARI values, maximized near the the track of low-to-mid level center moving across southwestern Montana. ....Central Plains through the Mid Mississippi Valley... Some of the models showed the growing potential for heavy rain and possible flash flooding to occur from Nebraska eastward into the mid Mississippi Valley as mid level energy moving over the top of the ridge interacts with a deepening moisture pool (PWs 1.75-2 inches) coinciding with a low level warm front. Some of the hi-res guidance members are showing upscale growth with one or more of these clusters of developing storms, with redeveloping storms producing heavy amounts. Where these heavy amounts may occur is far from certain, with the models far from agreeing on where and if this development may occur. A Marginal Risk was drawn to highlight the area where HREF probabilities for amounts exceeding 2 inches and 2-year ARI values are relatively higher.=20 However given the uncertainty, this area will likely be adjusted with updates later today.=20=20 Pereira=20 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!9Z_wttmAv9saFHcHeyaWQzpfkZ_gHBRW3_9LQwJPMkRN= 1HQpSaxdEVFl8RdXD7U1sud_ptXkpP69Zzo9FKW7cEyO1vQ$=20 Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9Z_wttmAv9saFHcHeyaWQzpfkZ_gHBRW3_9LQwJPMkRN= 1HQpSaxdEVFl8RdXD7U1sud_ptXkpP69Zzo9FKW7hjv0sio$=20 Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9Z_wttmAv9saFHcHeyaWQzpfkZ_gHBRW3_9LQwJPMkRN= 1HQpSaxdEVFl8RdXD7U1sud_ptXkpP69Zzo9FKW7SxnpSXY$=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) .