Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Tue Sep 16 2025 Valid 12Z Tue Sep 16 2025 - 12Z Thu Sep 18 2025 ...Slow-moving coastal low to bring heavy rain potential along the Mid-Atlantic coast... ...Heavy rains possible across the Central to Northern Plains Tuesday and Wednesday... ...Tropical moisture from Mario to begin to push into Southern California... ...Below average temperatures likely where wet weather occurs next two days, otherwise above average temperatures expected across much of the CONUS... The large scale mid- to upper-level flow across the Lower 48 is becoming increasingly amplified, resulting in slow-moving systems affecting the CONUS. Along the Mid-Atlantic coast, complex interaction between a low pressure system developing over the warm Gulf Stream and a cold upper-level low centered over the interior Mid-Atlantic is forecast to steer the low pressure system northwestward into the eastern shores of North Carolina and Virginia today. A swath of moderate to heavy rain has developed near the Mid-Atlantic coast early this morning and has begun to expand farther inland. Meanwhile, deeper thunderstorms and heavy rain forming just offshore near the circulation center of the system is forecast to push onshore across the eastern shores of North Carolina to Virginia during the day today. The system is forecast to stall tonight into much of Wednesday over eastern Virginia to eastern North Carolina. The slow and meandering movement of the system will support potential for additional heavy rainfall amounts across northeast North Carolina into southeast Virginia and the southern Delmarva Peninsula with two day totals of 2-5" possible. Note that these areas have been dry over the past month or two with much of the area in DO (abnormally dry) drought conditions. Across the mid-section of the country, rounds of heavy rain associated with clusters of thunderstorms can be expected today into Wednesday across large sections of the central to northern Plains in response to a mid- to upper-level system pushing out of the northern Rockies. From Wednesday into Thursday, a low pressure system is forecast to become more consolidated over the north-central U.S. Showers and thunderstorms will increase in coverage today and especially on Wednesday across the central to northern Plains, with these showers/thunderstorms continuing into Thursday as the system will be moving rather slowly. These rains will bring relief to areas of western Nebraska and southern South Dakota that are experiencing abnormally dry (D0) to moderate drought (D1) conditions. The remainder of the central to northern Plains that may receive heavy rains are not in drought conditions due to greater rains over the past few months. Tropical Storm Mario, currently moving northwestward well off the west coast of the Baja, will begin to bring upper-level moisture into southern California, southern Arizona and southern New Mexico later today. While Mario is forecast to weaken as it moves northwestward, the tropical moisture ahead of the system may bring showers into far southern coastal California and the offshore islands Wednesday, with these showers pushing farther north into much of southern California on Thursday. Temperature wise across the lower 48, much of the CONUS will see above average temperatures over the next few days in the last full week of summer. Exceptions to this will be in the above-mentioned regions where heavy precipitation is possible, across the Mid-Atlantic Tuesday and Wednesday, and across the central to northern Plains Wednesday into Thursday where below average temperatures are likely due to this heavy rain potential. Kong/Oravec Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php