NOAA Nov-Dec-Jan Outlook: Majority of Ski States to See Unseasonably Warm Start to Winter

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nov-dec-jan outlook, seasonal outlook, NOAA
Nov-Dec-Jan temperature outlook. Credit: NOAA

The November-December-January 2022-2023 temperature outlook depicts elevated odds for above-normal seasonal mean temperatures for western Alaska, much of the western U.S. to include the central Great Basin, central and southern Rockies, and Southwest, eastward to include much of the central and southern Great Plains, areas of the Southeast and along the Atlantic seaboard. The greatest likelihood for warmer than normal temperatures is for the Southwest and southern Great Plains.

For precipitation, above-normal seasonal precipitation amounts are favored for the west coast of Alaska, the Pacific Northwest, and the northern Rockies. Drier-than-normal conditions are most likely along the southern tier of the U.S. from California eastward to the southern Plains and Southeast with the greatest likelihood for southern Texas.

nov-dec-jan outlook, seasonal outlook, NOAA
Nov-Dec-Jan precipitation outlook. Credit: NOAA

Areas depicted in white and labeled “EC” (Equal-Chances) are regions where climate signals are weak and so there are equal odds for either above-, near- or below-normal seasonal mean temperatures and total precipitation amounts.

La Nina conditions remain in place in the Pacific Ocean and its influence continues to contribute to the temperature and precipitation outlooks through the upcoming winter months into early Spring 2023.

The full discussion is below:

The NDJ 2022-2023 temperature outlook favors above-normal temperatures for much 
of the western U.S. eastward to include much of the central and southern Great 
Plains, areas of the Southeast and also along the Atlantic seaboard. The 
expectation of La Nina conditions and enhanced odds for associated 
common impacts - on average over many events - is a primary driver of the 
evolution of the temperature outlooks from NDJ 2022-2023 through the MAM 2023 
lead. Multiple types of guidance was utilized for this assessment and included 
La Nina composites, ENSO regression / correlation information, statistical 
forecast tools and dynamical model forecasts. 
Although some of the participant models within the NMME and C3S suite 
maintained the colder signature starkly shown in last month's data typically 
associated with La Nina in areas of Alaska, Canada and the northern U.S., in 
general, the NMME overall ensemble mean probabilities are considerably warmer 
in this month's set of forecasts. For many of these areas in the U.S. and 
southern Canada, however, calibration based on historical forecast skill 
dramatically decreased probabilities and so confidence is low. Moreover, 
further inspection of 200-hPa height information from the NMME suite indicated 
that anomalous positive heights forecast at higher latitudes last month are 
reduced in this months forecast with a weaker mean Hudson Bay trough in the 
warmer NMME solutions. This strongly hints at a considerable change in the 
forecast AO phase over the winter months. Predictability of the seasonal AO 
phase is low. Given the reasons and associated uncertainty noted above, along 
with large areas of positive SST anomalies in both the north Pacific and 
Atlantic, incorporated in the CA statistical guidance, there was not 
significant changes at this time to the favored below-normal temperature 
forecast evolution from DJF 2022-2023 through MAM 2023 despite the warmer 
overall NMME solution this month. 
The official outlooks over time increase coverage of below-normal temperatures 
for the Pacific Northwest eastward to the northern Plains and western Great 
Lakes in DJF 2022-2023 and JFM 2023 and relax this area northward (less 
coverage and lower probabilities) in FMA and MAM 2023. 
A forecast for elevated odds of overall colder conditions for the Northeast is 
implied in the outlooks from NDJ 2022-2023 through FMA 2023. La Nina events are 
often characterized by high subseasonal variability especially for the 
north-central CONUS, Ohio Valley and Northeast as these areas are strongly 
impacted by variations in the AO/NAO and potential stratospheric influences 
(typically more likely during the second half of winters) - all of which are 
very difficult to reliably predict at these lead times. Consequently, the 
coverage of Equal-Chances (EC) is large in some of these areas from JFM to MAM 
The greatest odds for above-normal temperatures slowly shifts from the 
Southwest to the Southeast over the period from NDJ 2022-2023 to FMA 2023 with 
a minimum in both probabilities and coverage in the southern Plains during the 
JFM 2023 season. 
For Alaska, enhanced chances for below-normal temperatures for southeast Alaska 
and the Alaska Panhandle are introduced in DJF 2022-2023 and maximize in JFM 
2023 before decreasing and timing off after MAM 2023. Anomalously positive 
ocean surface temperatures tilt the odds for above-normal temperatures for 
parts of the west coast of Alaska through JFM 2023. 
Odds for favored above-normal temperatures are increased for the south-central 
southern Plains during MAM, AMJ and MJJ 2023 from the previous set of outlooks 
due to severe drought conditions currently ongoing and with the prospects for 
below-normal winter precipitation. If realized, this increases odds for 
above-normal temperatures during the spring and early summer months. 
The remaining set of temperature outlooks remain generally the same from the 
September release and are based on the ENSO/OCN and other consolidation 
forecast tools for which long term temperature trends  contribute significantly 
at times in various regions. 
For the NDJ 2022-2023 precipitation outlook, above-normal seasonal 
precipitation amounts are most likely for the west coast of Alaska, the Pacific 
Northwest and northern Rockies. Drier-than-normal conditions are most likely 
the southern tier of the U.S. from southern California eastward to the southern 
Plains and Southeast. 
Similar to that described above for temperature, the evolution of the 
precipitation outlooks through MAM 2023 are anchored to first order from 
potential typically observed impacts during La Nina winters - on 
average over many events. The greatest odds for below-normal precipitation 
during NDJ and DJF 2022-2023 are positioned primarily for southern Texas. 
In addition, consolidation of both statistical and dynamical model guidance 
(NMME, C3S) modified the base state La Nina favored impacts and this approach 
was primarily followed in the outlooks through MAM 2023. Long term 
precipitation trends , especially positive (more wet) trends  in numerous areas 
in the Midwest and eastern CONUS, contributed to the outlooks over this 
forecast period as well. The later set of outlooks are primarily based on long 
term precipitation trends .

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