September 2019 Rivals 2018 & 2016 Heat
Fig. 1-4: The September 2018 and 2016 state temperature ranks. SEP-18 was 3rd warmest on record while SEP-16 was 11th warmest on record. The September temperature anomalies so far are very warm and will turn warmer especially in the previously cool northeast sector based on the GFS ENS day 1-15 temperature anomaly forecast.
Discussion: The gas population weight CDD value for last September was 241 (Fig. 1) and 236 in September 2016 (Fig. 2). The projected September 2019 value is that range given the excessive heat across the West and South U.S. (Fig. 3) and warm forecast the next 15 days erasing the previous cool northeast sector regime (Fig. 4). In October 2018 and 2016 a range of 84-88 CDD were observed (compared to the normal 53). The 84-88 range is a reasonable projection for October 2019.