Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 839 AM EDT Wed Sep 18 2019 Valid 12Z Wed Sep 18 2019 - 12Z Fri Sep 20 2019 ...Tropical Depression Imelda to bring heavy rain to parts of Texas and Louisiana... ...Above average temperatures over the Plains and Midwest... The overall weather pattern across the continental U.S. will be rather amplified aloft through Thursday with an upper level ridge encompassing much of the central and southern U.S., a closed low developing off the East Coast, and a big upper level trough and cold front across the West Coast and Intermountain West. The ridge is expected to result in temperatures on the order of 10 to 20 degrees above average from the central Plains to the Upper Midwest on Wednesday. The western U.S. trough should keep below average temperatures in place for the Rockies and Great Basin, with perhaps some snow for the highest mountains. For the Mid-Atlantic and Northeast, a high quality airmass will become established over the region as a strong surface high from Canada governs the overall weather, making it feel more like autumn compared to recent days with lower dewpoints and cooler temperatures. Tropical Depression Imelda quickly developed near the Texas coast yesterday and is slowly moving inland across southeast Texas. This storm is expected to bring heavy rainfall to parts of coastal Texas and Louisiana, and then to areas farther north as it continues its very slow northward track. A High Risk for excessive rainfall and flash flooding is in effect from the Houston metro to Galveston. The highest rainfall amounts will likely be realized from Tyler, Texas to the greater Houston area, where 6 to 12 inches will be likely with isolated higher amounts possible. Elsewhere across eastern Texas and southwest Louisiana, rainfall totals should be more in the 3 to 6 inch range. D. Hamrick Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php