Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 435 AM EDT Sun Apr 23 2017 Valid 12Z Sun Apr 23 2017 - 12Z Tue Apr 25 2017 ...Heavy rain possible over parts of the Southern Mid-Atlantic and the Southeast... ...Heavy rain possible over parts of the Pacific Northwest... ...Snow for the Northern Rockies and Cascades... Low pressure over the Tennessee Valley and parts of the Southeast will deepen as the storm moves eastward to the Southeast Coast by Monday evening. The system will produce showers and thunderstorms from parts of the Southern Mid-Atlantic to the Tennessee Valley and southward to the Central Gulf Coast that will move to the Southeast Coast by Monday evening. Rain will also develop over parts of the Ohio Valley to the Northern Mid-Atlantic Coast on Sunday evening that will, likewise, move to the Northern Mid-Atlantic Coast by Monday evening. In addition, a weak upper-level low over Southern Florida will move northeastward out over the Western Atlantic by Monday. The storm will produce showers and thunderstorms over Southern Florida through Sunday night. Upper-level dynamics will then surge eastward across the northern Rockies and interact with a cold front across the northern Plains, where a new low pressure system is expected to develop on Monday. Temperatures will be cold enough to support wintry precipitation near the U.S.-Canadian border from the northern Plains eastward into the upper Great Lakes on Monday. Meanwhile, much below normal temperatures from the central and southern Plains into the Midwest this weekend will be replaced by much warmer temperatures by Monday afternoon ahead of the developing low pressure system in the northern Plains. Farther to the east, a low pressure wave developing along a frontal boundary is bringing rain across the mid-Atlantic and showers and thunderstorms into the Deep South. This system is forecast to gradually deepen as moisture associated with a weak tropical low moving up from Florida begins to interact with the associated upper-level trough. This will keep wet weather in place across the southeastern U.S. as well as Florida for the rest of the weekend. The rain should begin to head northward up the East Coast on Monday as the low pressure system centered near the southeast U.S. coast deepens. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php