This Week (August 19-23): Heavy rain Central to East U.S. Discussion: Severe thunderstorms and 1-2 in. (at least) of rain occur today from Nebraska/Iowa to the Delta region shifting to the Corn Belt tomorrow (Fig. 1). On Tuesday the cold front causing the intense weather sweeps into the eastern Ohio Valley/Mid-Atlantic region. Severe storms will affect rain-soaked Pennsylvania later Tuesday. On WED/THU the Southwest U.S. is wet and some of that rain surges into the North-Central States. A much cooler/drier forecast for Chicago on Wednesday reaching Boston Thursday. Air quality alerts for smoke caused by fires spread from the Northwest U.S./Montana to Minnesota. Fig. 1: The NOAA/WPC 72-hour rainfall forecast is indicated. Climate Impact Medium-range Forecast: Northwest/Northeast warmth. Discussion: GFS/ECM ensembles across on anomalous warmth from the Corn Belt to southeast Canada in the 6-10 day period. Cool temperatures settle into the Northwest. Most of the rain in the 6-10 day period stretches across southern Canada. In the 11-15 day period East warmth early period expands westward (and into the West-Central U.S. late period) while Northwest chill eases mid-to-late period. The GFS is warmer West in the 11-15 day forecast. Fig. 2-3: The Climate Impact day 6-10/11-15 U.S. temperature anomaly forecast is indicated. Models: Medium-range favors widening Central/East warmth. Madden Julian oscillation (MJO) is forecast to rampage on in phase 4 offering more excessive rains to India, Southeast Asia and increase in West Pacific tropical cyclone activity. The influence on the U.S. pattern is a mean ridge in the Gulf of Alaska, weak trough in the western U.S. and a ridge pattern that can affect the Central or East U.S. (or both). ECM and GFS ensembles are in general agreement of widening warmth for the eastern half of the U.S. while the West is temperate. The SSTA pattern favors this regime with a cooler character off the U.S. West Coast/Baja California while east of the Northeast/Mid-Atlantic States is bold warm. Tropics: ALL CLEAR continues. The North Atlantic tropics remain quiet although operational models indicate an attempt at some organizing tropical waves in the 6-10 day period. Gas Population Weight CDD 4-Week Forecast: Warmer-than-normal. The bulk of the influence on the 4-week forecast is warming across the eastern half of the U.S. Fig. 4: The Climate Impact 4-week observation/forecast gas population weight CDD forecast for the U.S.