Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 457 AM EDT Sun May 26 2013 Valid 12Z Sun May 26 2013 - 12Z Tue May 28 2013 ...More showers and thunderstorms for the plains and Midwest with heavy rains and severe weather possible... ...Cold wet weekend continues across the Northeast... ...Unsettled weather continuing across the Northwest... In addition to the showers and thunderstorms already firing this morning across portions of the northern plains, southeastward through the mid Mississippi valley into the Ohio valley, additional storms are expected to develop later today across these same areas. Moisture from the Gulf of Mexico pooling along a slow moving frontal boundary is forecast to interact with a series of upper level disturbances ejecting out ahead of a broad cyclone over the western U.S. to produce additional showers and thunderstorms, capable of generating heavy rainfall amounts, from the northern high plains southeastward into the mid Missouri and Mississippi valleys. Ongoing convection this morning coupled with the potential for more storms later today may lead to local runoff and flooding concerns, particularly across parts of southeastern South Dakota, northeastern Nebraska to northwestern Illinois - where the heavy rainfall threat is most likely. Further to the south, showers and thunderstorms may develop along and advance eastward from a dryline extending from the Nebraska panhandle south into west Texas. These storms also will have the potential to produce locally heavy rainfall amounts. In addition to the heavy rainfall threat, the Storm Prediction Center has highlighted the potential for severe weather across a large portion of the southern, central and northern high plains later today into tonight. Refer to the Storm Prediction Center convective outlooks for further information on this severe weather threat. Across the Northeast, the wet and unseasonably cold holiday weekend continues as a deep upper low continues to impact the region. This slow moving system that has delivered widespread heavy rains and even some late season mountain snows to northern New York and New England is forecast to continue its slow track to the north today, generating another day of below average temperatures with additional precipitation for parts of upstate New York and New England. Temperatures will begin to moderate and skies begin to clear by Monday however as the low begins to depart, lifting into the Canadian maritime provinces. Across the western U.S., a series of upper level disturbances are forecast to drop into the backside and move through the base of a broad upper trough that is expected to remain centered along the West Coast through the early part of next week. A pair of well-defined systems are expected to drop through the northeastern Pacific to the Northwest coast, delivering light to moderate rains to western Washington/Oregon and northern California, before lifting north into the Intermountain West/Rockies. The leading system is forecast to reach the coast this morning with second system forecast to make landfall on Monday. Pereira Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php