NOAA OFFICIAL WINTER OUTLOOK....I HAVE MY DOUBTS!
There's been lots of banter recently about the coming winter and its overall severity. The official outlook from NOAA (which I have doubts about) could be considered kind and gentle, especially in regards to temperatures.
Winter 2018-2019 Temperature Outlook:
For the upcoming 2018-2019 winter, NOAA's Climate Prediction Center (CPC) temperature forecasts for the most part reflect typical weak El Niño temperature anomalies in the United States. This includes:
Warmer-than-normal conditions being favored across the western half of the United States, from the Upper Mississippi River Valley east into New England, and in Alaska.
Equal Chances of Warmer-, Near-, and Colder-than-Normal from the Ohio and Tennessee river valleys south to the Gulf Coast.
Locally, the odds are tilted slightly to warmer-than-normal for northeast Iowa, southeast Minnesota, and western Wisconsin.
Since 1980, there has been a shift in weak El Niños toward warmer. All 6 of these winters were either near- or warmer-than-normal. The strongest signal for warmer-than-normal has been in December. Meanwhile, February has had a tendency of being colder-than-normal.
In addition, most of the climate models favor warmer-than-normal conditions for the area.
However, over the past 15 years, there has not been a trend for either warmer-than-normal or colder-than-normal winter temperatures in our area. In addition, other climate signals can overwhelm weak El Niños, so this decreases the confidence some.
While temperature impacts associated with El Niño are favored, El Niño is not the only player this winter, so the temperatures could be highly variable throughout the winter. This is often the case with weak El Niños. During these 12 weak El Niño winters since 1949-50...
Warmer-than-normal conditions are anticipated across much of the northern and western U.S., with the greatest likelihood in Alaska and from the Pacific Northwest to the Northern Plains.
The Southeast, Tennessee Valley, Ohio Valley and Mid-Atlantic all have equal chances for below-, near- or above-average temperatures.
No part of the U.S. is favored to have below-average temperatures.
Wetter-than-average conditions are favored across the southern tier of the U.S., and up into the Mid-Atlantic. Northern Florida and southern Georgia have the greatest odds for above-average precipitation this winter.
Drier-than-average conditions are most likely in parts of the northern Rockies and Northern Plains, as well as in the Great Lakes and northern Ohio Valley.
So why is the outlook from NOAA so mild and relatively uneventful. Well, as far as I can tell it's tied to the CFSv2, the U.S. climate model. Its interpretation of sea surface temperatures, the type and strength of the late developing El Nino, and a bias towards warmer temperatures long term, lead it down a trail most other models aren't traveling. I can't say it's wrong but I will say it will be a big coup if it ends up right.
Just look at what the CFSv2 is showing today for winter temperatures and precipitation (December-February).
Winter temperatures CFSv2
Winter Precipitation CFSv2
From what I have seen there are two big big drivers in the strength and severity of winter. One is the El Nino which is shown to be weak and centrally located in ENSO 3.4 The warmest waters in the tropical Pacific are centered near the Dateline as opposed the South America. This important distinction makes this a Modoki El Nino
This is a very different form of the traditional El Nino, especially when the Modoki is categorized as weak (as it's forecast to be). See below the dramatic difference in temperatures between a strong and weak El Nino. The solution with a colder winter is where I see the modeling going. I have a hard time visualizing what the CFSv2 is doing.
One final factor that I feel is significant is what the weather world is calling the "blob". Its an expansive area of above normal temperatures in the north Pacific centered over the Gulf of Alaska.
Such anomalous warmth in that area would promote a winter ridge over western Canada. That in turn would argue for a downstream trough over the eastern U.S.opening the door for Arctic air masses to penetrate the eastern half of the nation. It could also assist with the development of sratospheric warming events and perhaps a visit or two from the Polar Vortex. You can see below the position of the jet around the ridge and the influx of cold air it would generate.
Personally, I'm sticking with my idea of a colder than average winter with slightly above normal snowfall. It's NOAA against me in this fight. I highly respect their work but I respectfully disagree with their willingness to buy into the CFSv2 lock stock and barrel. Roll weather...TS