Discussion: The NOV-MAR 2023-24 cold season monthly HDD forecast for selected cities within the PJM-East and PJM-West zones are warmer than both the 30-year and 10-year normal (Fig. 1-2). The projection is preliminary as wide deviations from normal due to events unable to forecast at the current long-lead is inevitable as noted with cold and warm extremes of the past 2 years in December and January. However, due to the tendency of warmer than normal climate across the Northern U.S. during an El Nino winter, deviations from the current forecast favor warmer (not colder) solutions.
NOV-23 is similarly warm to last year for both PJM-E and PJM-W. Last year, DEC was cold especially for PJM-E. In 2023, DEC is forecast warmer than the 10-year normal.
During the past 2 years, JAN has produced both cold (2021) and warm (2022) extremes. In 2024, the JAN forecast is warmer than the 10-year normal. During mid-winter, the key to cold risk is snow cover. The mid-winter storm track is energetic across the Southern and Eastern U.S. However, due to the warmer than normal western North Atlantic, all rain is consistent near the coast. During an El Nino winter, Canada is generally warmer than normal. Consequently, East Coast storms are followed by seasonably cold air (not arctic air) and well inland, snow cover is limited. The mid-winter snow cover across the Northern U.S. is below normal and consequently the milder forecast.
FEB-24 is the “cold month” of winter 2023-24. However, the cold risk is biased toward the West-central U.S. mostly to the west of Chicago and not reaching the East U.S. Therefore, the PJM-West HDD forecast for FEB is near normal while PJM-East stays warmer than normal. FEB-24 is not as warm as the past 2 years. The cold season finishes with a warmer than normal MAR primarily due to lack of any late season snow cover.
Fig. 1: The Climate Impact Company PJM-Cities East monthly HDD forecast for the 2023-24 cold season vs. last 2 years and 30-year/10-year climatology.
Fig. 2: The Climate Impact Company PJM-Cities West monthly HDD forecast for the 2023-24 cold season vs. last 2 years and 30-year/10-year climatology.
Fig. 3: The Climate Impact Company Richmond monthly HDD forecast for the 2023-24 cold season vs. last 2 years and 30-year/10-year climatology.