The 2021-22 HDD Season Forecast is Adjusted
|2nd Warmest||9th Coldest||4th|
|10th Coldest||9th Warmest||8th Warmest|
Table 1: Climate Impact Company gas population weight HDD forecast for the 2021-22 cold season, previous forecast, 20-year rank and various climatology.
Discussion: The Climate Impact Company gas population weight HDD forecast for the 2021-22 cold season is updated (Table 1). The last forecast shown is from one month ago. Note that December was much warmer than forecast and is projected the 4th warmest of the past 20 years. January is adjusted a little colder and should average a middle-of-the-road 10th coldest of the past 20 years. The month of February is adjusted warmer and now averages 9th warmest of the past 20 years. Additional warmer adjustments are possible for February. The March forecast is adjusted slightly colder and averages 8th warmest of the past 20 years.
Compared to the last 3 winter seasons, the 2021-22 cold season is the warmest Q4 (of 2021), tied for coldest January and tied for warmest February (Fig. 1). Compared to the 30-year and 10-year climatology, the 2021-22 cold season is very warm with each month except January warmer than the already warm 10-year normal (Fig. 2).
Fig. 1: U.S. gas population weight 2021-22 cold season monthly HDD anomalies compared to the last 3 seasons.
Fig. 2: U.S. gas population weight HDD on a monthly basis for the 2021-22 cold season versus the 30-year and 10-year normal.
Despite the warm forecast for the 2021-22 cold season, the coldest month of winter (January) does offer some colder weather. The Climate Impact Company 4-week gas population weight observed weekly HDD anomalies identifiers the warm December but is trending toward a colder scenario in January (Fig. 3).
Fig. 3: U.S. gas population weight HDD anomalies observed for each week of December compared to the January forecast.
The 2021-22 cold season monthly HDD rankings reveal the very warm October and December and middle-of-the-road 20-year rankings for the other cold months (Fig. 4).
Fig. 4: U.S. gas population weight HDD forecasts and their 20-year rankings for the 2021-22 cold season.