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07/21/2019, 10:20 am EDT

U.S. Sunday Weather/Climate Report

Highlight: Heat wave ends, medium-range warm Northeast/Calif. The heatwave ends MON/TUE: The 2019 excessive heat episode affecting the Midwest and Northeast Corridor winds down. Warnings for excessive heat linger one more day Midwest/Mid-South U.S. and 2 more days in the Mid-Atlantic States (Fig. 1). Severe thunderstorms stretch across the Missouri and Ohio Valley(s) today and the Northeast Corridor on Monday. Yesterday 346 wind damage reports were issued due to severe storms from Iowa/Minnesota to New York. Frequent vivid cloud-to-ground lightning accompanies thunderstorm activity ending the heat wave. Excessive rainfall affects eastern Kansas today and Tennessee to New England tomorrow plus the Carolinas/Virginia on Tuesday making impressive 3-day totals (Fig. 2). Fig. 1: NOAA/NWS advisories/warnings for heat issued today. Fig. 2: NOAA/WPC 3-day rainfall forecast the U.S. California becomes the new hot target: After the Midwest/Mid-South/East heat wave collapses early this week a widespread cooler-than-normal pattern affects the Central, South and into the East U.S. During that process California becomes the target for hot weather although not unusually hot conditions are not expected (Table 1). Coastal Los Angeles Basin turns hot this week but the coastal San Francisco Bay area stays cool at the coast. Location MON TUE WED THU FRI Redding (99/64 NML) 106/70 102/69 107/71 103/70 105/69 Sacramento (93/60 NML) 96/63 96/63 99/63 98/63 96/61 San Fran (72/54 NML) 70/56 70/56 70/56 70/56 70/56 Palmdale (98/67 NML) 104/74 104/74 104/74 103/73 102/73 Burbank (90/62 NML) 90/70 95/71 98/72 96/69 93/68  Table 1: Developing heat for California this week/next weekend. Northeast heat returns next weekend: The ECMWF (model) indicates hot weather returns to New York/New England (90-95) next weekend into early the following week (July 27-30). The GFS is not as bold. Tropics: A tropical wave is located east of the Bahamas (Fig. 3) but unlikely to develop as the upper shear pattern increases ahead of the upper trough in the U.S. ending the heat wave. However, the associated rainfall could interact with the stalled cold front on the East Coast Tuesday/Wednesday enhancing rainfall amount (and slowing frontal passage). Fig. 3: Latest North Atlantic satellite view. Medium-range forecast: The Northeast turns hot again in the 6-10 day period while heat lingers in California (Fig. 4). In the 11-15 day period the warm bias remains over the Northeast and California (Fig. 5). Gas population weight CDD forecasts are generally moderately warmer than normal (Fig. 6). Fig. 4-5: The CIC 6-10/11-15 day temperature anomaly forecast. Fig. 6: The Climate Impact Company 4-week U.S. gas population weight CDD anomaly forecast (and past 4 weeks of verification) are indicated.