January 2011 Temperature Forecast Update

[Ellinwood]

A look ahead into what the current status of the atmosphere and mid-range forecast has done to the long term outlook.

The updated January 2011 temperature anomaly forecast:

And for reference the old January forecast (issued 7 October):

The changes:

The lingering blocking pattern is what caused the great change in the temperature forecast. As we move into January, the -NAO/-WPO pattern still exists, but is forecast to weaken as the indices trend towards neutral values (the NAO more so than the WPO). Should this blocking pattern break down completely and transfer into a neutral PNA, neutral WPO and weak +NAO, we will see a much more progressive pattern that will allow the above normal temperatures to work back into the eastern U.S.

My original map included a fully progressive pattern throughout the month of January, with the primary storm track going from the Pac. Northwest into Canada as the subtropical ridge lingered over the Desert Southwest. The more persistent blocking along with the strong -WPO allows the cold air to seep further into the mid-continent, which with plenty of available cold air would lead to drastic changes in the forecast like those seen above.

I would expect to start seeing the effects of the more progressive pattern around mid-January, which is somewhat-aligned with the pattern that the latest Euro weeklies show.

There is a risk for a more persistent blocking pattern or reinvigorated blocking pattern heading further into January, which would result in a cooler eastern half of the nation.

[Terpeast]

Sounds reasonable. I'd throw out a similar forecast, except I would go cooler in the Pacific NW. Good luck!

[Ellinwood]

Sounds reasonable. I'd throw out a similar forecast, except I would go cooler in the Pacific NW. Good luck!

Thanks! I was considering going colder in the Pac. Northwest as well, but I figured the more northerly storm track would win out and keep the warmer anomalies in place (at least for the first half of January)... not too dissimilar to what has happened so far this month.

[nzucker]

I would go a little colder in the East as models are hinting at an arctic spell to start the month. Like you, I expect moderation of the pattern later in January but not until some substantial negative departures have been recorded in the I-95 cities.

[Lee]

I would go a little colder in the East as models are hinting at an arctic spell to start the month. Like you, I expect moderation of the pattern later in January but not until some substantial negative departures have been recorded in the I-95 cities.

Agree. Yeah, as seen over the last month, blocking has been stronger and longer lasting than modeled to be. Also, we are running much below average on temps in much of the east thus far. it would stand to reason that if your logic on the pattern evolution played out, temps for Jan would still average near normal for the east,i.m.o..

[Ellinwood]

I am certainly afraid of the big cold anoms that will likely be present over the east in the beginning of the month, but we could be in for a very interesting mid/late January if we can cut off the cold to the north with a succession of systems tracking further N and W.

[RIC_WX]

History suggests that when these cold December patterns reverse, they do so abruptly and dramatically. I can't imagine it will be modeled well in advance either, it almost never is when so many different signals start to shift from favorable to unfavorable at once. 1989 and 2005 are recent examples of this that should loom large in any short term forecast for January.

[nzucker]

Thanks! I was considering going colder in the Pac. Northwest as well, but I figured the more northerly storm track would win out and keep the warmer anomalies in place (at least for the first half of January)... not too dissimilar to what has happened so far this month.

This forecast doesn't make sense to me...if the Northern Plains is that far below average, how can none of the cold seep into the Great Lakes and Northern New England? You have New England as one of the warmest places on the map, and that seems illogical if you're expecting a -AO/-EPO that brings arctic highs into the Plains and creates the cold departures you show.

[Carvers Gap]

I am not looking for graphics as I'm sure those babies are copyrighted. Briefly, could someone w/ access to the Euro weeklies give a brief synopsis?

[Ellinwood]

This forecast doesn't make sense to me...if the Northern Plains is that far below average, how can none of the cold seep into the Great Lakes and Northern New England? You have New England as one of the warmest places on the map, and that seems illogical if you're expecting a -AO/-EPO that brings arctic highs into the Plains and creates the cold departures you show.

I'm expecting AO/EPO to swing neutral. Get systems that track through the Great Lakes much like the Dec. 11 storm along with an occasionally-amplified ridge working north from the southern states and that cuts off the cold. The more progressive pattern allows storms to quickly move off the coast before the trough can dig into too far into the east.

To look at it visually, take a look at a setup similar to this Wed/Thu:

Now imagine it with a more progressive pattern where the trough doesn't dig into the East to bring the massive cold departures back into the region. That's one of the ways I see this working. Of course, the forecasted anomalies aren't really relegated to just one pattern.

[Ellinwood]

Here's a rough analog comparison:

Here's the MTD from Dec 1-18 (using 1968-1996 normals):

And the analog forecast for January:

I should also note that my forecasts are against the 30-year mean (1971-2000)... that might help slightly.

Please also consider that there is still a third of the month to go.

EDIT:

I also took a look at the AO/NAO/PNA values from the analogs... the average seems to be consistent with my overall outlook.

http://www.cpc.noaa...._ao_index.shtml

http://www.cpc.noaa....nao_index.shtml

http://www.cpc.noaa....pna_index.shtml

If anyone really wants me to crunch the numbers for Dec and Jan I can do that tomorrow.