11/30/2022, 5:51 am EST

U.S. Month 1-3 Ahead Outlook: Colder short-term forecasts into the East force a December update.

Executive Summary: The Climate Impact Company month 1-3 ahead climate outlooks for the U.S. valid for meteorological winter are updated. The forecast is updated due to colder East U.S. short-term forecasts. Later December is likely warmer in the East. However, short-term cold forces a monthly average closer to normal rather than warmer than normal as previously indicated. The January outlook is revised warmer for the southern half of the U.S. while February remains cold to very cold across the northern half of the nation. Methodology: The December outlook is an adjustment between consensus and operational models. The mid-to-late winter forecast remains based on La Nina climatology, optimum climate normal and consensus of NCEP CFS V2 and ECMWF operational climate forecasts.   Climate discussion: Snow cover becomes a leading catalyst to guide temperature forecasts as meteorological winter arrives. Snow cover is above normal across the northwest quadrant of the U.S. supporting a colder look which was expansive across the entire western half of the nation in November. The northeast quadrant of the U.S. generally lacked snow (except the eastern Great Lakes region) during late autumn biasing the November regime warmer than normal. Snow cover is expected to increase Great Lakes and Interior Northeast in early December supporting a colder regime ahead. Ocean waters have cooled significantly off the West Coast of North America and east-southeast of the Canadian Maritimes. The cooling waters have resulted in persistent strong upper trough patterns across or down wind of those cooling zones which should persist this winter season coupled with a still strong La Nina climate pattern. U.S. drought: Drought remains expansive across the U.S. with drought intensity likely to continue across much of the Great Plains with expansion in the Gulf States biased toward the Southeast U.S. Mississippi River water level: Water level recovery has occurred during late November for the southern basin. However, reliable precipitation to end the low water issue is not forecast for the winter season. U.S. gas population weight HDD forecast: The outlook is updated and indicates colder than 10-year normal monthly solutions through February. Winter 2022-23 is cold North and warm South and on average colder than recent winter seasons. Fig. 1: The Climate Impact Company U.S. population weight HDD forecast compared to the last 3 winter seasons and the 10-year climatology. December 2022: Northwest U.S. chill extends eastward following new snow cover from the Great Lakes eastward. A Greenland high-pressure block forces a cold trough on the East Coast early-to-middle December. No arctic air is involved but moderately cold weather is likely and made colder if snow cover is generated by the upper trough. The trough departs just after mid-month and the East turns warmer. The Northwest to North-central is colder than normal with occasional periods of frigid arctic air with sustained snow cover. The Southern States are generally warmer and drier than normal. The East Coast is adjusted stormy with interior snows likely to help enhance locally cold weather the first half of the month. Fig. 2-3: The Climate Impact Company temperature/precipitation anomaly forecast for December 2022.  January 2023: The updated mid-winter forecast indicates broad warmer changes south of prevailing snow cover. The northern states remain cold. The prevailing storm track is in-between the opposing thermal regimes. The Ohio Valley is snowier and cold be colder than indicated. The Northwest is also snowy. The southern tier of the U.S. is quite dry. Fig. 4-5: The Climate Impact Company temperature/precipitation anomaly forecast for January 2023.  February 2023: The final month of meteorological winter maintains a cold to very cold pattern across Canada extending to the Central U.S. and possibly the Northeast States. Expect a snowy month Interior East/Northeast U.S. The West Coast storm track is also quite potent while the southern states remain dry. Fig. 6-7: The Climate Impact Company temperature/precipitation anomaly forecast for February 2023.