econintersect.com
       
  

FREE NEWSLETTER: Econintersect sends a nightly newsletter highlighting news events of the day, and providing a summary of new articles posted on the website. Econintersect will not sell or pass your email address to others per our privacy policy. You can cancel this subscription at any time by selecting the unsubscribing link in the footer of each email.



posted on 02 December 2017

NOAA Updates December, 2017 Outlook - What a Difference Two Weeks Makes!

Written by Sig Silber

A negative Arctic Oscillation (AO) early in December and an Active Madden Julian Oscillation (MJO) in the second half of December combined are likely to be good news for those who live in the Eastern Third of CONUS who like cold weather. The far West and part of the Southwest and the Southern Central Plains are likely to be drier than normal for December. The dry area shown in the new December map may turn out to be larger than shown as per my comments in tonight's report. The prior wet Northern Tier anomaly is gone. Ski equipment and related items may be able to be purchased at sale prices in December.

Seasonal Outlook Update


Please share this article - Go to very top of page, right hand side for social media buttons.


NOAA Update of their Outlook for December 

NOAA has, as usual, issued an update for the month following the last day of the prior month. This update was issued on Thursday November 30. In this Update Report, we present the Updated Outlook and compare it to the Early Outlook for December issued on December 16, 2017 two weeks ago. Please note: all small graphics can be enlarged by clicking on them. 

  Temperature Precipitation
Prior Issued on November 16, 2017 Temperature December 2017 Issued on November 16, 2017 December  2017 Early Outlook Precipitation Issued on November 16, 2017
Updated on November 30, 2017 December 2017 Temperature Issued on November 30, 2017 December Precipitation Outlook  Issue on November 30, 2017
  This is a pretty big change. Reminds me a bit of JAMSTEC which tends to show East/West divides rather than North/South divides for ENSO events. Looks like NOAA is coming around to the JAMSTEC way at looking at things. Where did the Northern Tier wet anomaly go? And the dry anomaly is shifted west more than slightly. There is reason to believe that the dry anomaly may cover a larger geographic area than shown.

 

Here is the NOAA Discussion released with the December Update.

30-DAY OUTLOOK DISCUSSION FOR DECEMBER 2017

THE UPDATED TEMPERATURE AND PRECIPITATION OUTLOOKS FOR DECEMBER 2017 ARE BASED ON THE WPC TEMPERATURE AND PRECIPITATION FORECASTS DURING THE FIRST WEEK OF DECEMBER, THE CPC 8-14 DAY TEMPERATURE AND PRECIPITATION OUTLOOKS, THE LATEST DYNAMICAL MODEL GUIDANCE, AND THE TYPICAL INFLUENCES ASSOCIATED WITH LA NINA. THE MADDEN-JULIAN OSCILLATION (MJO) CONTINUES TO STRENGTHEN WITH ITS ENHANCED (SUPPRESSED) PHASE OVER THE EASTERN INDIAN OCEAN AND MARITIME CONTINENT (WESTERN HEMISPHERE). THE ENHANCED PHASE OF THE MJO IS FORECAST TO PROPAGATE EAST TO THE WEST PACIFIC AND IT MAY INFLUENCE THE CIRCULATION PATTERN AND TEMPERATURES ACROSS THE MID-LATITUDES LATER IN DECEMBER.

A MAJOR LONGWAVE PATTERN CHANGE IS LIKELY TO OCCUR DURING THE FIRST WEEK OF DECEMBER AS A HIGHLY ANOMALOUS UPPER-LEVEL RIDGE BECOMES ANCHORED ALONG THE WEST COAST WITH AN AMPLIFYING UPPER-LEVEL TROUGH DOWNSTREAM OVER EASTERN NORTH AMERICA. FOLLOWING A MILD START TO DECEMBER, THIS MAJOR PATTERN CHANGE IS LIKELY TO USHER IN OUTBREAKS OF BELOW TO MUCH BELOW-NORMAL TEMPERATURES TO THE EASTERN THIRD OF THE CONUS THROUGH AT LEAST MID-DECEMBER. THE D+11 GFS AND ECMWF ENSEMBLE MEANS ON NOV 30 ARE IN EXCELLENT AGREEMENT, MAINTAINING THIS ANOMALOUS LONGWAVE PATTERN. THE 6Z GFS ENSEMBLE MEAN FEATURES A POSITIVE  500-HPA HEIGHT ANOMALY CENTER OF 300 METERS OVER THE ALASKA PANHANDLE WHICH STRONGLY FAVORS A STABLE PATTERN OVER NORTH AMERICA AND BELOW-NORMAL TEMPERATURES ACROSS THE EASTERN U.S. THE GFS ENSEMBLE MEMBERS INDICATE A NEGATIVE ARCTIC OSCILLATION (AO) INDEX THROUGH THE END OF WEEK-2. THE PREDICTED EVOLUTION OF THE MJO IS EXPECTED TO INCREASES THE CHANCES THAT THE BELOW NORMAL TEMPERATURES PERSIST INTO THE LATTER HALF OF THE MONTH. THE CFS MODEL AT WEEKS 3-4 (ENDING ON DEC 28) INDICATES BELOW NORMAL TEMPERATURES FROM THE MISSISSIPPI VALLEY TO THE EAST COAST. BASED ON EXCELLENT MODEL AGREEMENT AND CONTINUITY REGARDING THIS HIGHLY ANOMALOUS PATTERN, BELOW-NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN THIRD OF THE CONUS. THE HIGHEST ODDS FOR BELOW NORMAL TEMPERATURES ARE FORECAST ACROSS THE UPPER OHIO VALLEY WHERE THE MOST ANOMALOUSLY COLD AIR IS EXPECTED DURING EARLY TO MID-DECEMBER.  

THE PERSISTENCE OF A HIGHLY ANOMALOUS RIDGE ALOFT AND EXCELLENT AGREEMENT AMONG TEMPERATURE TOOLS SUPPORT INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE WESTERN U.S. PROBABILITIES AND COVERAGE FOR ABOVE NORMAL TEMPERATURES ARE REDUCED ACROSS THE NORTHERN ROCKIES AND NORTHERN GREAT PLAINS COMPARED TO THE DYNAMICAL MODEL GUIDANCE. THIS MODIFICATION IS RELATED TO AN INCREASING CHANCE OF BELOW NORMAL TEMPERATURES AFFECTING THESE AREAS LATER IN THE MONTH, IF THE ENHANCED PHASE OF THE MJO PROPAGATES INTO THE WEST PACIFIC AND INFLUENCES THE MID-LATITUDE CIRCULATION PATTERN.  ALTHOUGH PERIODS OF ANOMALOUS COLD ARE EXPECTED TO AFFECT THE GREAT PLAINS DURING DECEMBER, LARGE POSITIVE ANOMALIES AT THE BEGINNING OF THE MONTH AND AN EXPECTED VARIABLE TEMPERATURE PATTERN RESULT IN EQUAL CHANCES (EC) OF BELOW, NEAR, OR ABOVE NORMAL TEMPERATURES FOR THIS REGION.

BELOW-NORMAL PRECIPITATION IS FAVORED ACROSS THE WESTERN U.S. DUE TO THE LIKELIHOOD OF A PERSISTENT UPPER-LEVEL RIDGE THROUGH AT LEAST MID-DECEMBER. LITTLE TO NO PRECIPITATION IS LIKELY FOR CALIFORNIA DURING THE FIRST TWO WEEKS OF THE MONTH. HIGHER PROBABILITIES OF BELOW NORMAL PRECIPITATION WOULD BE FORECAST ACROSS CALIFORNIA, BUT THE CFS MODEL INDICATES AN UPPER-LEVEL TROUGH APPROACHING THE WEST COAST DURING THE WEEKS 3-4 PERIOD. A COLD FRONT, ASSOCIATED WITH THE ONSET OF THE MAJOR PATTERN CHANGE, IS EXPECTED TO RESULT IN PRECIPITATION AMOUNTS OF 0.5 TO 2 INCHES ACROSS THE EASTERN U.S. DURING THE FIRST WEEK OF DECEMBER. FOLLOWING THIS FRONTAL PASSAGE, A PROLONGED PERIOD OF ANOMALOUS NORTHERLY FLOW ENHANCES ODDS FOR BELOW NORMAL PRECIPITATION FROM THE CENTRAL AND SOUTHERN GREAT PLAINS NORTHEAST TO THE MIDDLE MISSISSIPPI VALLEY. THE FAVORED AREA OF BELOW NORMAL PRECIPITATION ACROSS THE SOUTHERN GREAT PLAINS IS CONSISTENT WITH THE ONGOING LA NINA. A LARGER COVERAGE OF INCREASED CHANCES OF BELOW NORMAL PRECIPITATION WOULD BE FORECAST FOR THE EASTERN U.S., BUT PRECIPITATION AT THE BEGINNING OF DECEMBER AND POTENTIAL FOR WAVES OF SURFACE LOW PRESSURE TO DEVELOP WITH THE AMPLIFIED TROUGH LIMIT FORECAST CONFIDENCE ON BELOW NORMAL PRECIPITATION VERIFYING.

A STABLE PATTERN WITH AN ANOMALOUS TROUGH (RIDGE) OVER THE ALEUTIANS (EASTERN ALASKA) AND PERSISTENT SOUTHERLY FLOW AT THE SURFACE ENHANCES ODDS FOR ABOVE NORMAL TEMPERATURES THROUGHOUT ALASKA. PRECIPITATION TOOLS AT ALL TIME LEADS DURING DECEMBER AND THE LONGWAVE PATTERN FAVOR ELEVATED ODDS FOR ABOVE NORMAL PRECIPITATION ACROSS THE ALEUTIANS, SOUTHWEST ALASKA, AND ALONG THE SOUTHERN COAST OF MAINLAND ALASKA.  DOWNSLOPING SLOW, ASSOCIATED WITH PERSISTENT SOUTHERLY FLOW OFF THE ALASKA RANGE, TILTS THE ODDS TO BELOW NORMAL PRECIPITATION FOR PARTS OF EASTERN MAINLAND ALASKA.

Where it might be helpful I have extracted some of the commentary from the NOAA Week  3 and 4 Discussion released today.

Week 3-4 Forecast Discussion Valid Sat Dec 16 2017-Fri Dec 29 2017

The precipitation outlook is likewise based on the objective dynamical guidance, which is broadly consistent with the forecast circulation pattern and, to lesser extent, the low-frequency La Nina footprint. Below-normal precipitation is most likely for the central U.S. where anomalous northerly mid-level flow is forecast. This area extends through the Southwest and up the West Coast downstream of the forecast upper-level ridge. There is a slight tilt toward above-normal precipitation centered over the Northern Rockies, where upslope precipitation may become more frequent as surface high pressure noses southward over the High Plains. There remains a great deal of uncertainty over the eastern U.S. where the ultimate position of the mean frontal zone will likely determine precipitation anomalies over the forecast period. Anomalous mid-level flow over southern and southwestern Alaska favors above-normal precipitation south of the Alaska Range, while precipitation deficits are more likely over parts of interior Alaska.

Sometimes it is useful to see how the Monthly forecast fits with the 6 - 10 Day , 6 - 14 Day and Week 3 and 4 forecasts. I do not have a good Map of a 1 - 5 Day forecast.

First Temperature

6 - 10 Day Forecast Temperature 8 - 14 Day Temperature 3 - 4 Week Temperature
The new monthly forecast is to the right. Does it appear to be reflective of the three parts of the month for which we have forecasts?                            →                                                     

December 23017 Temperature Issued on November 30, 2017

                        ↑

←  It seems to fit  together. Meaning that if you believe the forecasts above you should have no problem with the composite.

 

December 2017, Temperature Outlook Issued on November 30, 2017

And then Precipitation

6 - 10 Day Forecast Precipitation 8 - 14 Day Precipitation 3 - 4 Week Precipitation
The new monthly forecast is to the right. Does it appear to be reflective of the three parts of the month for which we have forecasts?                               →                                                                           December Precipitation Outlook  Issue on November 30, 2017

                    ↑

←  I have a problem with this one. Alaska looks ok but if you believe that the three short-tem outlooks above are correct, then the full month outlook to the left is not correct unless the first five days of the month produce enough precipitation to average down the sum of the three graphics above. Of course neither forecast may be correct or the short-term forecasts may be too dry but they do not agree with each other very well.

 

December 2017 Precipitation Outlook Issued on November 30, 2017

Sometimes it is useful to compare the present month outlook to the three-month outlook to see what we might learn about the next two months which in this case are January and February 2018.

December 2017 Plus December  -  February 2017/2018 Outlook

December and DJF 2017 2017-2018 Updated on November 30, 2017

One can mentally subtract the First-Month Outlook from the Three-month Outlook and create the Outlook for the last two months in the three-month period.

For both temperature and precipitation if you assume the colors in the maps are assigned correctly, it is a simple algebra equation to solve the month two/three forecast probability for a given location = (3XThree-Month Probability - Month One Probability)/2*. So you can derive the month two/three forecast this way. You can do that calculation easily for where you live or for the entire map.

*The concept is that the probabilities of a deviation from climatology in the First Month and the combined Month Two and Three forecast that one derives must average out to the probabilities shown in the three-month maps.

An issue with the above procedure when we do it at the end of a month is that we are comparing a three-month map produced for release on the third Thursday of the month with an updated Single-Month map issued on the last day of the month. So the question one has to deal with is whether the changes for the next month change what NOAA would have issued for the three-month period if they were updating that as well on the last day of the month.
Our conclusion is that it could be that the updated December maps are telling us something about the previously issued three-month maps. The MJO is a cyclic event difficult to forecast so it probably does not tell us much about the second and third months in the three-month period other than perhaps the early part of January 2018. But the Arctic Oscillation being forecast to be very negative might well impact subsequent months. So I am inclined to conclude that January and February might be colder in the Northeast than suggested by the three-month map. This could have an impact on winter related economic activity in the Northeast. 

For those who missed the Weekly Report which provides additional detail on how this will unfold with respect to the Days 6 - 10, 8 - 14 and weeks 3 and 4, you can access that report here. There will be a new Weekly Report on Monday December 4.

A Look Back at November

For many parts of the U.S. November has been warm and dry record breaking. This is especially true for the Southwest.

The Weather Underground (more specifically Bob Henson in this article) published in their Category 6 Blog the below graphic which was credited to NOAA but I was unable to update it to cover the full month. But here it is.

November through Nov 26 Mean Temp Ranking from Weather Underground

The numbers are rankings of the average mean temperature in the recent historical records. As you can see there were a number of near records and records through that period and the situation has not changed during the last week of November.

And here is what I was able to generate.

November Average Temperature for the Southwest

It is certainly a less interesting chart but still it shows that it has been very warm in the Southwest.

Click here for a list of Sig Silber's Weather Posts

>>>>> Scroll down to view and make comments <<<<<<










Make a Comment

Econintersect wants your comments, data and opinion on the articles posted. You can also comment using Facebook directly using he comment block below.




Econintersect Weather








search_box
Print this page or create a PDF file of this page
Print Friendly and PDF


The growing use of ad blocking software is creating a shortfall in covering our fixed expenses. Please consider a donation to Econintersect to allow continuing output of quality and balanced financial and economic news and analysis.







Keep up with economic news using our dynamic economic newspapers with the largest international coverage on the internet
Asia / Pacific
Europe
Middle East / Africa
Americas
USA Government





























 navigate econintersect.com

Blogs

Analysis Blog
News Blog
Investing Blog
Opinion Blog
Precious Metals Blog
Markets Blog
Video of the Day
Weather

Newspapers

Asia / Pacific
Europe
Middle East / Africa
Americas
USA Government
     

RSS Feeds / Social Media

Combined Econintersect Feed
Google+
Facebook
Twitter
Digg

Free Newsletter

Marketplace - Books & More

Economic Forecast

Content Contribution

Contact

About

  Top Economics Site

Investing.com Contributor TalkMarkets Contributor Finance Blogs Free PageRank Checker Active Search Results Google+

This Web Page by Steven Hansen ---- Copyright 2010 - 2017 Econintersect LLC - all rights reserved