10/18/2022, 3:13 pm EDT

U.S. Winter 2022-23 Outlook: Mild Pacific influence defeats polar vortex (except in February).

Executive summary: Waters in the northeast Pacific are warmer than expected and are likely to stay that way for a while. Consequently, a milder Pacific influence on North America climate for upcoming winter is likely limiting the cold influence of the polar vortex except for February. The outlook indicated in the latest Climate Impact Company winter 2022-23 outlook is reasonably similar to the forecast issued last month. However, the potential colder scenario caused by stronger presence of the polar vortex is looking less likely. Ominous is the dry forecast for California and the coastal Gulf of Mexico region as drought in those areas worsen. The heating demand in the East is clearly below normal while commerce traffic on the Mississippi River Valley caused by drought and low river levels continues. Fig. 1-2: The Climate Impact Company constructed analog winter 2022-23 temperature and precipitation anomaly outlook.  Forecast methodology: The forecast is based on a constructed analog rooted in regional SSTA and correlation to prevailing climate patterns. Analogs are taken only from the past 25 years due to the unique tendency of warming oceans during that time. Three processes are used including a global SSTA analog, ENSO analog and optimum climate normal (OCN). The global SSTA analog identifies many regions of current unique SSTA influential to North America climate, projects their progress into early next year using the International Multi-model Ensemble (IMME) projection for February and correlates the climate pattern of those years to produce about 25% of the forecast. The ENSO analogs for winter emphasize a La Nina climate with La Nina fading by late winter. The ENSO analogs account for 25% of the forecast. OCN is the 10-year normal minus El Nino years due to the uniqueness of the modern-day climate compared to the conventional 30-year normal. OCN weighs heavily on the winter outlook accounting for 50% of the forecast. In November, a 4th forecast parameter is added…snow cover projections. The snow cover projections are not reliably available in October. November 2022: The late autumn climate forecast is unusually (and scary) dry. Usually, winter storm season gets underway in November therefore the widespread dryness in the forecast is surprising. Propelling the dryness and warmer revision is a persistent Pacific zonal flow across the U.S. Normally, a Pacific zonal flow brings a wetter climate to the West Coast, particularly the Northwest States therefore that part of the forecast is low confidence. Drought conditions in the West and Central U.S. worsen and river travel on low water levels on the Mississippi River have increased difficulty due to the very dry forecast. Fig. 3-4: The Climate Impact Company temperature/precipitation anomaly climate forecast for November 2022.  December 2022: The constructed analog produces a “polar vortex” pattern in North-central Canada. Most of the attendant chill remains in Canada due to the lingering (mild) Pacific zonal flow across the U.S. On occasion, the Canadian chill extends to the Upper Midwest States. The Interior West is adjusted colder where early season snow cover becomes established. However, the lack of snow in the East forces a warmer revision. A normally active storm track (for a La Nina climate) extends from the Tennessee Valley to New England otherwise early winter is very dry especially West. Fig. 5-6: The Climate Impact Company constructed analog December 2022 temperature and precipitation anomaly outlook.  January 2023: The forecast stays warm due to influence of warm SSTA either side of North America in the middle latitudes. Westerly Pacific influence defeats the polar vortex. Consequently, snow-eater mid-winter mild temperatures remain in the forecast across the North-central U.S. A weakness in the upper air pattern supports presence of a Mid-Atlantic low-pressure area that can cause locally chilly air and above normal precipitation (possibly snow well inland). The outlook continues to produce widespread remarkably dry regimes as droughts worsen and river levels continue to lower. Fig. 7-8: The Climate Impact Company constructed analog January 2023 temperature and precipitation anomaly outlook.  February 2023: La Nina is breaking down, possibly quickly. Part of breaking down a cold ENSO regime is presence of an active Madden Julian oscillation (MJO). The MJO may help to spawn mild climate in January lingering in the East in February but followed by a cold outbreak that attacks the Great Plains during late winter. Arctic air is involved and a surge reaching Texas is likely. The Louisiana to Northeast U.S. storm track will feature rain, ice, and snow while the northern tier states regain snow cover lost during a mild mid-winter. California remains very dry as extreme drought continues. Fig. 9-10: The Climate Impact Company constructed analog February 2023 temperature and precipitation anomaly outlook.  March 2023: The cold season ends on a warm note. Much of the Central and East U.S. is warmer than normal while much-needed significant precipitation finally arrives in drought-stricken Mid-south States. The Northeast, Florida and California are very dry to start meteorological autumn. Fig. 11-12: The Climate Impact Company constructed analog March 2023 temperature and precipitation anomaly outlook.  U.S. gas population weight HDD summary: The Climate Impact Company U.S. gas population weight HDD forecast for each month of the 2022-23 cold season reveals a warm start to the season with warmer than the 10-year normal HDD forecast for November and near the (warm) 10-year normal in December. The outlook is in-between the 10-year/3-year normal in January and spikes cold to slightly colder than the 30-year normal in February and finally ending on a mild note in March. The 2022-23 forecast is close to the mild November of 2021, near the average of the past 3 years in December and 2nd coldest of the past 4 years for January. Last February spiked cold and a similar scenario is possible in 2023. Finally, March is likely to finish warm. Fig. 25: The 2022-23 cold season monthly gas population weight HDD forecast compared to the 30-yuear/10-year normal. Fig. 26: The 2022-23 cold season monthly gas population weight HDD forecast compared to the last 3 winter seasons and the 10-year normal. Fig. 27: The 2022-23 cold season monthly gas population weight HDD anomaly (versus 30-year normal) compared to the last 3 years.