Quantitative Precipitation Forecast Discussion NWS Weather Prediction Center College Park MD 317 AM EDT Thu May 10 2018 Prelim Day 1 QPF Discussion Valid May 10/1200 UTC thru May 11/1200 UTC Reference AWIPS Graphics under...Precip Accum - 24hr Day 1... ...Central Plains to the Upper Mississippi Valley... As deepening moisture interacts with a shortwave trough emerging from the northern Rockies, there remains a good model signal for moderate to locally heavy, and potentially excessive rains, from the high plains of eastern Wyoming and western Nebraska to southern Minnesota and northern Iowa Thu night into Fri morning. As a mid-upper level shortwave trough moves across the northern Rockies Thu afternoon, Overall models are in good agreement indicating surface low development over eastern Colorado This will result in deepening moisture across eastern Wyoming and western Nebraska as increasing southeasterly flow north of the low draws moisture into an east-west oriented boundary stretched across the region. This moisture, along with afternoon heating and the larger scale lift supported by the approaching shortwave, is expected to spur convection developing from southeastern Wyoming across western and central Nebraska Thu evening. As the low level jet continues to amplify, focus for convection and the heavy rain potential is expected to shift further north during the overnight hours to along the 850mb boundary extending from the eastern Nebraska-South Dakota border to the Minnesota-Iowa border. Sustained southerly low level inflow into the western flank of the boundary may support redeveloping convection as it interacts with the approaching shortwave and right-entrance region upper jet dynamics -- raising the threat for heavy amounts across the region through the end of the period. Given the overall good agreement with respect to the larger scale features, WPC QPF was weighted largely toward the HREF Mean. ...Northeast/Mid-Atlantic... A shortwave trough currently centered over the Great Lakes will de-amplify and move progressively east ahead of an amplifying trough over Ontario on Thu. Increasing instability afforded by daytime heating along with moisture pooling ahead of the associated cold front is expected to support renewed convection as the boundary moves across the Northeast and Mid-Atlantic later today. This may produce some brief periods of heavy rainfall, however give the progressive nature of the system, widespread heavy amounts are not expected. Here too, WPC QPF gave significant weight to the HREF Mean. ...Pacific Northwest to the Northern Rockies and High Plains... A well-defined shortwave will continue to dig southeast from the northeast Pacific, with an upper low closing off over the Pacific Northwest-northern Rockies late Thu-early Fri. Modest moisture is expected to support only light amounts west of the continental divide, however pooling moisture along a lingering low level boundary draped east of the Rockies may support some locally heavier totals across central and eastern Montana as interacts with the favorable forcing aloft. WPC QPF reflects a blend of the HREF Mean, along with the NAM, GFS and ECMWF. Pereira