Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 358 AM EDT Sun Oct 21 2018 Valid 12Z Sun Oct 21 2018 - 12Z Tue Oct 23 2018 ...Heavy rainfall threat continues for South Texas... ...Below normal temperatures for the eastern U.S. as most of the western U.S. stays warm and dry... As the cold front that pushed across the East Coast continues to move farther into the Atlantic, surface high pressure will build across the eastern U.S. Dry conditions will settle for the second half of the weekend and into the early workweek. However, a mix of light snow and rain showers can be expected for the lower Great Lakes today. Most of the rainfall activity will occur in South Texas as a stationary front stays put off the middle and south Texas Coast. Copious amounts of moisture will be pulled across the Rio Grande Valley, and will give way to showers and thunderstorms. The heaviest rainfall will occur off the coast in Mexico; however, some localized flooding is possible near the Texas/Mexican border adjacent to the coast. Consequently, a flash flood watch is in effect for the Brownsville region. By Monday, low pressure will begin to lift northward--thus, the heavy rainfall will also lift north across south-central Texas and into southeast Texas. This axis of heavy rainfall will begin to shift eastward toward the central Gulf Coast by Tuesday. Some of this activity could produce localized flash flooding. High temperatures will continue to stay below normal across the eastern and southern U.S. today and overnight. The foothills of North Carolina will receive the first freeze of the year overnight Sunday and into Monday--with much of the Tennessee Valley and portions of the Southeast. By Monday, high temperatures will rebound to near normal. The exception will be Texas as the rainfall activity expected to occur in south and south-central Texas will keep high temperatures in the upper 50s to low 60s--which is nearly 25 degrees below normal. An upper level trough will move toward the Four Corners today, ushering in moisture that will lead to scattered showers and thunderstorms across the Southwest and Central Great Basin. As the trough pushes inland, the rainfall will shift east in the Four Corners region. Otherwise, dry conditions and above normal temperatures are expected for the rest of the western U.S. Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php