ERCOT JUN/JUL 2023 CDD Forecast Trending Much Hotter

U.S. Population Weight CDD Forecast MAY-SEP 2023 Less Warm Than Last 3 Years
06/14/2023, 7:30 pm EDT
Mid-Troposphere Wet RH Favors Tropical Development
06/16/2023, 9:28 am EDT
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Highlight: South-central/Southeast severe storms, Southeast flooding becomes life-threatening, Midwest drought strengthens. Latest ERCOT/SPP CDD forecast.

Fig. 1: Latest NOAA/NWS weather watch, warning, and advisory areas.

Discussion: Today’s focus remains on the very hot and humid weather stretching across Eastern Texas and Southern Louisiana (Fig. 1). Temperatures reach or exceed 100F with a heat index approaching 110F in this evolving long duration heat wave. Heat Advisories are posted for this area and add Southeast Florida today. The other major weather story is the persistent severe weather, heavy rain, and flash flooding just to the north of the heat wave zone. Flooding occurring in Alabama/Georgia now will expand and worsen and become a life-threatening issue into next week. The severe weather risk area includes the southern Great Plains today where a tornado outbreak is likely and extends to the Gulf Coast (Fig. 2). The southern Plains to Gulf Coast severe thunderstorm risk is maintained into the weekend (Fig. 3-4). The NOAA/WPC 7-day rainfall forecast indicates extreme rainfall for the Southeast U.S. most-focused on the Florida Panhandle (Fig. 5). The extreme rain is due to a persistent East Coast upper trough inspired by the cool North Atlantic warm hole (NAWH) off the East Coast. Along the southern periphery of the upper trough, dynamics are consistently dramatic to drive severe weather and heavy rains. However, the Midwest drought concern is strengthening. While the national CDD outlook for summer 2023 is likely cooler than the very hot signatures of the past 3 summer seasons, ERCOT is rapidly making a recovery on CDD projections. Despite the cool start to June, ERCOT should rocket to above to well above normal CDD for June and that bias is also applied to the July forecast (Fig. 6). The U.S. population weight CDD forecast trend is much warmer for the week of June 23-29 (Fig. 7).

Fig. 2-5: NOAA/SPC severe weather outlook for Thursday through Saturday and the 7-day U.S. rainfall forecast by NOAA/WPC.

Fig. 6: Climate Impact Company ERCOT System CDD projection for the 2023 warm season.

Fig. 7: Latest U.S. population weight CDD forecast utilizing all models, their consensus, and comparing with 72 hours ago and climatology.