Extreme Temperature Diary- December 2nd , 2018/ Topic: Winter 2018/19 United States Forecast

Sunday December 2nd… Dear Diary. The main purpose of this ongoing post will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials)😊. 

Winter 2018/19 United States Forecast

It’s time to make a seasonal forecast as I do at the start of every boreal season. What other clues can tell us about temperatures for the winter across the United States to come? Well, here are my two cents for a broad, rough forecast for the U.S.

 First, I like to look at water temperature anomalies surrounding North America just before the start of a season to get a sense of how much potential heat can be added to the atmosphere across the continent. Here is what we see:

Leading off  water temperature anomalies surrounding most of North America are much warmer than average, so I believe that SSTs will come into play, tending to make winter across the U.S. warmer than long term averages. Anomalies are extraordinarily warm off the Northeast coast. The Gulf of Alaska is particularly warm. Also, in the Pacific we see a distinct warm El Nino signature, although officially as of this post we don’t have one yet. 

Second I like to look at the strength of the Hudson Bay low or polar vortex at the start of winter:

At the start of the winter season there is no Hudson Bay vortex, or if there is a vortex, it’s displaced far to the north and east over Greenland. As mentioned in my post a few days ago the El Ninoish split flow pattern is already prevalent, which should lead to cooler than average temperatures across most of the southern tier of states. Surrounding warm sea surface temperatures and the lack of a strong Canadian vortex will probably lead to warmer than average temperatures across most of the rest of the CONUS. 

Last we can get another clue looking at prior ranking and temperature record count data. For this I like to drag out that “Record Scoreboard” (updated through 11/25/18):

There was a definite cooling trend as fall 2018 rolled along. September started out on the toasty side being ranked 4th warmest since 1895. October was slightly cooler than the average ranking of 62 (44 out of 124). November will be ranked pretty cold once NCEI processes data by about December 7th.  I suspect that fall 2018 overall will be ranked slightly warmer than average…we will see. Will winter continue to see this cooling trend? Probably not. In fact, due to the burgeoning El Nino I thing that there will be a warming trend.

Looking at the Record Scoreboard at the start of another El Nino, the strong one from 2015-2016, we saw another cold November in 2014. Thereafter, December and January were relatively warm with a near average February. I suspect we will see the same effect this winter going out some on a limb with a near average December and a warmer than average January and February. Throw in global warming and I have a bit more confidence in seeing a “mild” winter. Given El Nino it should be quite stormy, so people caught in cold rain, ice,or snow will think that the winter will be anything but mild. Lack of strong arctic intrusions across the Midwest will be key to producing warmer than average temperatures overall for the CONUS. If the northern branch of the polar jet gets strong the forecast of a mild winter will be a bust.

Seasonal forecasters are beginning to “chuck it” giving up on forecasting cool seasons simply because of what carbon pollution is doing to the planet. Here is what we see from the National Weather Service for this winter:

The NWS forecast makes sense to me given El Nino and the lack of a Hudson Bay Vortex. 

Here was my forecast for the fall: https://guyonclimate.com/2018/09/01/extreme-temperature-diary-september-1-2018-topic-fall-forecast-for-united-states/

El Nino has been developing later than predicted, so this is one partial reason why November turned out to be cold. 

Can we get a tad more specific? I think so. Here are NCEI rankings for seasons through summer 2018:

I’ll fill in the ranking for this fall when NCEI processes that number by December 7th here: 70

Notice that the past four winters had a ranking at or above 100, but that of 2014 had a cold ranking of 33.  I think that this winter will be ranked slightly below that of the last four. We remain way overdue to see an average or below average season across the U.S. Carbon pollution is definitely making below average seasons more rare. I’m going to guess that the winter of 2018/19 ranking will be around 90 + or – 10,  with fairly good confidence given all of the warm factors in this post. I think that December will see the lowest monthly average ranking with January or February having the warmest relative averages, which is going out on a limb a little more. Let’s see if this forecast will be a bust or like the last few fairly decent.😅


Here is some other weather and climate news from Sunday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity.)

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The Climate Guy

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