My official Winter Outlook for 2024–25
Can’t ignore La Nina and long-term trends entirely.
Lovers of winter weather for a cozy fireplace, hot cocoa or hot toddies, skiing, or a White Christmas know recent decade trends have not been our friend, especially for November and December nationally, and all months in Georgia.
This 7 Global Model blend concurs for this winter:
My system for making outlooks relies more on the Analog Method and largely ignores computer models.
The Pacific Ocean is the 1000 pound gorilla in long-term weather and climate variability because of its size impacting energy into the atmosphere.
REMEMBER, ENSO El Nino/La Nina is a coupled atmosphere-ocean pattern.
3 KEYS:
- La Nina
- Warm Pool (Marine Heat Wave) North Pacific NW of Hawaii (-PDO)
- Cool SSTA South of Alaska favors -PNA
As of November 18th not meeting official La Nina levels as of now:
I see this winter as being a very weak La Nina or cool Neutral ENSO based more in the West or Central Pacific and not an East-based La Nina. (I’ve seen a number of experts say East based but I don’t see it, although I am not an expert on ENSO).
The significance is that when the La Nina is focused closer to ENSO region 1.2 and/or region 3 winters tend to be colder, when the La Nina is focused more on ENSO region 3.4 they tend to be the warmer version of a La Nina. Or in other words more East of or West of 120º:
But the North Pacific and Atlantic also play a role, along with other factors previously discussed like Solar Cycle, the Polar Vortex AO, the stratosphere wind QBO all of which can be wild cards that could overwhelm the La Nina since I think it will be weak or neutral.
The relative Niño-3.4 for October — the average across the Niño-3.4 box for the second map here — was -0.87 °C, much stronger than the -0.28 °C from the traditional method. So yes, the relative measurement might be reflecting La Niña, while the traditional measurement is still neutral! This relative index is not NOAA’s official metric, though, because it is a newer index and is still being studied and evaluated. The CPC and others around the world are working on confirming if the relative index better matches global ENSO impacts on our weather and climate.
Notice Key #2 is the PDO (Pacific Decadal Oscillation), and the latest observed data indicates it’s the strongest since the 1850s and the signal for that as reported by BAMwx research is hard to ignore on temps, precip., and snowfall:
CURRENT OCEAN SEA-SURFACE TEMPERATURE ANALYSIS:
IMPACT ON UPPER-LEVEL JET STREAM PATTERN:
One of the early pioneers of long-range weather forecasting BEFORE modern computer models was Jerome Namias of the U.S. Weather Bureau and Scripps Oceanography Center. He published this paper way back:
INFLUENCE OF CURRENT PACIFIC OCEAN SSTAs ON THE JET STREAM:
So even in a mild winter there can be cold pulses.
NOW HERE IS A SYSTEM USING NORTHERN HEMISPHERE OCEAN ANALOGS AND SOUTHERN HEMISPHERE OCEAN ANALOGS COMBINED:
NOW USING AN “AUTOMATED” SYSTEM USING ONLY NORTHERN HEMISPHERE OCEAN ANALOGS:
FINALLY HERE I CHOSE ANALOG YEARS BASED ON WEAK OR MODERATE LA NINA OR NEUTRAL IN THE MODERN ERA POST 1982 ONLY:
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MY BOTTOM LINE WINTER OUTLOOK FOR 2024–2025:
I have chosen what I think are the best analog years out of all the options I’ve covered in the last 3 blog posts about winter. I am putting more emphasis on the -PDO and overall Northern Hemisphere Ocean SSTA patterns INSTEAD of a La Nina emphasis…
So in the aggregate or the mean/average of all 3-months summed together December-February the temperatures here in North Georgia look warmer than average with precipitation near-normal to a bit below-normal. Again, this is the winter on average NOT every month, or every day or every week.
As usual the precipitation forecast for winter has lower confidence than the temp outlook.
SNOW looks below-normal. Are there any signals for normal or above-normal snow? YES. Some combos yield analogs with normal to above-normal snowfall in North Georgia. But I can’t give them enough weight on their own to make that my outlook.
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