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 24 August 2017

Comparison of NOAA and JAMSTEC Nine-Month Forecasts - Plus Harvey Update

Written by Sig Silber

Harvey 10PM CDT Monday Aug 28, 2017: 36 Hours Before Storm Heads North and Dies: Update Viewable Just After you Click "Read More"

Our monthly report on seasonal outlook updates normally consists of two parts. First we report on the new NOAA outlook and compare it to the prior NOAA Outlook and then in Part II we compare the new NOAA outlook to the new JAMSTEC outlook which not only covers Alaska and CONUS but the World. In our report published on August 19, we were unable to compare the NOAA and JAMSTEC outlooks because JAMSTEC was late. The next day they posted but it was not possible to do more than report on their Nino 3.4 forecast which differed dramatically from the NOAA Nino 3.4 forecast. In this report, we present what normally would be Part II of our monthly report, namely the comparison of the NOAA and JAMSTEC forecasts. 

weather.caption for Updates


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


Tropical Storm Harvey Discussion Number  35 NWS National Hurricane Center Miami FL 1000 PM CDT Mon Aug 28 2017

The center of Harvey has been moving east-southeastward over the extreme western Gulf of Mexico this evening.  Although there is no deep convection near the center of Harvey, thunderstorm activity has continued to increase well north of the center, along the immediate northwest Gulf Coast and has spread inland over the Greater Houston area, worsening the catastrophic flooding situation.  Another band of heavy rainfall is moving inland over portions of southern and southwestern Louisiana.  Widespread rainfall totals of 30 to 36 inches have been observed in southeastern Texas and the Houston Metropolitan Area.  Storm totals could reach 50 inches in some locations, which would be historic for the area.

A NOAA National Ocean Service observing site near Matagorda Bay has continued to report sustained tropical-storm-force winds this evening, and data from this and other nearby stations still support an initial intensity of 40 kt.  Given the current structure of the cyclone and the lack of convection near the center, little change in strength is expected while Harvey moves over the northwestern Gulf of Mexico.  After landfall in about 36 hours, gradual weakening should occur as the circulation moves farther inland.

Harvey has been moving east-southeastward or 120/3 kt.  The storm is forecast to turn northeastward, then north-northeastward over the next couple of days as a ridge to the northwest of the system weakens and Harvey is steered around the western side of a ridge over the eastern Gulf of Mexico.  The track guidance has shifted slightly eastward and the new NHC track has been adjusted in that direction.

Key Messages:

1. Ongoing catastrophic and life-threatening flooding will continue across southeastern Texas.  Additional rainfall accumulations of 10 to 20 inches are expected across the upper Texas coast, with isolated storm totals as high as 50 inches.  Please heed the advice of local officials.  Do not attempt to travel if you are in a safe place, and do not drive into flooded roadways.  Refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard.  A summary of rainfall totals compiled by the Weather Prediction Center can be found at: www.wpc.ncep.noaa.gov/discussions/nfdscc1.html [Editor's Note: Click Here to Read]

2. The flood threat has spreading farther east into Louisiana. Additional rainfall amounts of 10 to 20 inches are expected in southwestern Louisiana, with rainfall amounts of 5 to 15 inches expected in south-central Louisiana. Rainfall amounts of 5 to 10 inches are expected in southeast Louisiana and coastal Mississippi and Alabama.  Please heed the advice of local officials and refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard in these areas.

3. While Tropical Storm Warnings have been extended eastward along the coast of Louisiana and a Storm Surge Watch has been issued, the impacts of winds and storm surge are expected to be secondary compared to that of the rains.

FORECAST POSITIONS AND MAX WINDS [Editor’s Note: Looks like two days of have precipitation and the this storm finally moves inland]

INIT  29/0300Z 28.2N  95.3W   40 KT  45 MPH

 12H  29/1200Z 28.1N  95.0W   40 KT  45 MPH

 24H  30/0000Z 28.5N  94.5W   40 KT  45 MPH

 36H  30/1200Z 29.5N  94.0W   40 KT  45 MPH

 48H  31/0000Z 30.7N  93.4W   35 KT  40 MPH...INLAND

 72H  01/0000Z 33.4N  91.9W   30 KT  35 MPH...INLAND

 96H  02/0000Z 35.5N  90.0W   25 KT  30 MPH...INLAND

120H  03/0000Z 38.0N  86.5W   20 KT  25 MPH...POST-TROP/INLAND

 Harvey Track

 Harvey Precipitation Estimate

The most current information on Harvey can be found here.

Now we begin our comparison of the NOAA and JAMSTEC Forecasts (Focus on next nine months i.e. three seasons)

Part I of our Monthly Seasonal Outlook Update (published on August 20, 2017) which focused on the NOAA forecast and compared it to the previous NOAA forecast can be accessed by clicking here.

Below is the July 1 and August 1 JAMSTEC Nino 3.4 forecasts side by side with the older forecast on the left and newly issued forecast on the right. The Nino 3.4 index is the most widely used measurement to predict the expected phase of ENSO. +0.5C and above suggests El Nino and -0.5C and below suggests La Nina.

July 1, 2017 JAMSTEC Nino 3.4 Forecast. August 1, 2017 JAMSTEC Nino 3.4 Forecast

 

As you can see there has been some change but not a lot in the JAMSTEC Nino 3.4 forecast and there remains a period of time where the JAMSTEC forecast is in the warm range of ENSO Neutral (November through January).

 Here is the NOAA forecast for the Nino 3.4 Index.

CFSv2 Forecast as of August 20, 2017

As you can see there is a big difference with NOAA predicting ENSO Neutral with a cool bias from now though perhaps October or November and then actual La Nina values of the Nino 3.4 Index perhaps from November through February of 2018.
So we would expect to have very different Temperature and Precipitation forecasts from these two agencies. And we do. The analysis is made additionally complex because the Nino 3.4 Index is very highly correlated with worldwide weather but the correlation includes a lag as conditions along the Eastern Equatorial Pacific take some time to impact weather at locations some distance from the Eastern Equatorial Pacific. Also some believe that it is the change in the value of the Index not just the value of the Index that impacts weather. And there are other factors that go into a nine-month forecast (NOAA looks out 15 months but JAMSTEC only nine months so we can only compare them for nine months). We are not attempting to explain or critique these forecasts. All we are doing is comparing them.

Below is a quick summary of the temperature and precipitation forecasts for three time periods and from left to right the NOAA forecast for Alaska and CONUS (the contiguous mid-latitude U.S), then JAMSTEC for North America (which includes Canada and Northern Mexico), and then JAMSTEC for Europe and surrounding areas. Larger graphics are provided later in the report but I have not that for Europe as the map shown is quite understandable in the size shown

This presentation of the key graphics is kind of a tease to keep you reading but you can see the evolution of the weather pattern through Fall, Winter and into Spring. For some readers, these two sets of summary graphics may be all the information they wish to look at and that is fine. Others have an interest in other parts of the World and may find some value in the commentary that I provide.

Temperature

Season NOAA Alaska Plus CONUS JAMSTEC North America JAMSTEC Europe

Fall

SON 2017

Temp

SON US Temperature Issued on August 17, 2017, NOAA Forecast SON Temperature Based on Aug 1, 2017 JAMSTEC Forecast SON Europe Temperature JAMSTEC Aug 1, 2017 Forecast

Winter

DJF

2017/2018

Temp

DJF 2017 0 2018 US Temperature Issued by NOAA on August 17, 2017 DJF NA Temperature based on JAMSTEC Aug 1, 2017 Forecast DJF 2017 - 2018 Europe Temperature based on JAMSTEC Aug 1, 2017 Forecast

Spring

MAM 2018

Temp

MAM 2018 Temperature Issued by NOAA on August 17, 2017 MAM NA Temperature based on Aug 1 JAMSTEC Forecast MAM 2018 Europe Temperature Based on Aug 1, 2017 Jamstec Forecast

 

There is not much change period to period (Fall to Winter to Spring) in the NOAA Temperature Outlook but there is a lot of change period to period in the JAMSTEC Temperature Outlook for North America (look for the blue) and also for Europe.

Precipitation

Season NOAA Alaska Plus CONUS JAMSTEC North America JAMSTEC Europe

Fall

SON 2017

Precip

SON US Precipitation Issued by NOAA on August 17, 2017 SON 2017 NA Precipitation Based on Aug 1, 2017 JAMSTEC Forecast SON Europe JAMSTEC Precipitation Aug 1, 2017 Forecast

Winter

DJF

2017/2018

Precip

NOAA DJF Precipitation Issue on August 17, 2017 DJF NA Precipitation based on JAMSTEC Aug 1, 2017 Forecast DJF 2017 - 2018 Europe Precipitation based on JAMSTEC Aug 1, 2017 Forecast

Spring

MAM 2018

Precip

MAM 2018 Precipitation issued by NOAA on August 17, 2017 MAM US Precipitation based on Aug 1, JAMSTEC Forecast MAM 2018 Europe Precipitation Based on Aug 1, 2017 Jamstec Forecast

 

For NOAA the big change with respect to Precipitation is the progression from Fall to Winter to Spring. For JAMSTEC, in the above, the change from Period 1 (Fall) to Period 2 (Winter) is very dramatic for North America and also Europe. And the change from Period 2 (Winter) to Period 3 (Spring) is also dramatic.

A note about terminology; the deviations from climatology/normal are color coded but also labeled "A" for more than normal and "B" for less than normal. The area designated EC means Equal Chances of being more or less than normal. JAMSTEC relies on their color coding. In my comments I have used EC to cover all the situations where a clear anomaly is not shown.

Now the Comparison of the NOAA and JAMSTEC Forecasts.

JAMSTEC works in three-month intervals which correspond to seasons and does not change the selection of months each time they update but does so every three months. So we have SON 2017, DJF 2017-2018, and MAM 2018 to work with from JAMSTEC and the same three-month periods are available from NOAA. So everything lines up very nicely this month. I show the NOAA Maps first followed by the JAMSTEC maps. I extract North America from the Worldwide JAMSTEC map and use that to compare with the NOAA Maps. I also extract and enlarge Europe including parts of North Africa and Western Asia form the Worldwide JAMSTEC maps.

SON 2017

Temperature

NOAA SON 2017

SON 2017 Temperature Issued by NOAA on August 17, 2017

And here is the SON temperature forecast for North America that I extracted from the JAMSTEC World Forecast

SON JAMSTEC Temperature extracted from Aug 1, 2017 World Forecast

NOAA shows it warm everywhere.  For JAMSTEC, the Northwest is cool.

And now the JAMSTEC WORLD FORECAST (for this graphic my comments are mostly related to areas other than Alaska and CONUS as those comments appear with the graphics above)

SON Temperature Forecast from JAMSTEC Aug 1, 2017 forecast.

For the World, JAMSTEC sees a cool Siberia. There are a few small cool areas shown for Africa.

Precipitation

NOAA SON 2017

NOAA SON 2017 Precipitation Issued August 17, 2017

And here is the SON 2017 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast.

North America SON 2017 Precipitation Extracted from Aug 1, JAMSTEC Forecast

For CONUS, NOAA shows a small part of Southern Alaska to be wet and the Southern Tier from Texas east is wet. JAMSTEC is showing most of Alaska wet. For CONUS, JAMSTEC shows the area that NOAA has as wet as being dry - which is a dramatic difference. JAMSTEC also shows the Northern Tier west of Minnesota wet and California dry. New England is wet.

 JAMSTEC WORLD FORECAST

SON 2017 Jamstec Precipitation Forecast From Aug 1, 2017

Of interest is the dry Eastern South America, Australia, and wet parts of Africa, Southwest Asia and Central America. Korea and to the north is dry.

DJF 2017/2018

Temperature

NOAA DJF 2017 - 2018

DJF 2017 - 2018 Temperature NOAA Issued on August 17, 2017

And here is the DJF 2017 - 2018 Temperature Forecast for North America that I extracted from the JAMSTEC World Forecast

DJF 2017 - 2018 North American Temperature extracted from JAMSTEC Aug 1 Forecast

NOAA shows a warm Alaska and a warm CONUS except for an EC North Central. JAMSTEC shows a cool Eastern Alaska and a mostly cool CONUS West except for California and parts of states bordering California.

JAMSTEC WORLD FORECAST

DJF 2017 - 2018 JAMSTEC Temp from Aug 1, 2017

For JAMSTEC it is cool in many place including Eastern Brazil, Central Australia, Far-Eastern Siberia and just north of the Equator in Africa to the east extending into Saudi Arabia and Iran. Greenland is cool.

Precipitation

NOAA DJF 2017 - 2018

NOAA DJF 2017 - 2018 Precipitation Issued on August 17, 2017

And here is the DJF 2017 - 2018 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast

DJF 2017 - 2018 JAMSTEC Precipitation for CONUS based on Aug 1 forecast

NOAA shows part of the Southeast dry and a wet anomaly in the Central Rocky Mountain States. JAMSTEC shows the Eastern Half of CONUS mostly wet with a very dry Southwest but not including New Mexico and Colorado.

JAMSTEC WORLD FORECAST

DJF2017-2018 JAMSTEC Precipitation Forecast from Aug 1, 2017

Northern Europe is wet, Southern Europe is dry. Australia is wet. South America is mostly wet, India is slightly dry. The Maritime Continent is dry, Southern Africa is mixed but mostly dry.

MAM 2018

Temperature

NOAA MAM 2018

NOAA MAM 2018 Temperature Issued August 17, 2017

And here is the MAM 2018 Temperature Forecast for North America that I extracted from the JAMSTEC World Forecast

MAM 2018 North America Temperature Forcast Extracted from the Aug 1 JAMSTEC Forecast

NOAA shows Alaska and most of CONUS warm except for the North Central extending a bit into the Northeast which is EC.  For JAMSTEC, a very small part of the Northwest and extreme Western Alaska is cool.

JAMSTEC WORLD FORECAST

MAM  2018 JAMSTEC Temperature from Aug 1, 2017

The Eastern Mediterranean is cool as is western Australia. South America is mixed but more warm than cool but a lot of EC. Greenland is cool.

Precipitation

NOAA MAM 2018

MAM 2018 Precipitation Issued August 17, 2017

And here is the MAM  2018 Precipitation Forecast for North America that I extracted from the JAMSTEC World Forecast

JAMSTEC MAM 2018 precipitation extracted from their Aug 1 2017 Forecast

NOAA shows a small North Central wet area and a small Southwest dry area. JAMSTEC shows an overall dry pattern with the Great Lakes area being wet. Southern Alaska is also wet.

JAMSTEC WORLD FORECAST

JAMSTEC MAM 2018. Precipitation from 1 Aug 2017

Parts of the Equator and further south are wet. Europe is dry.

Conclusion

Both forecasts are based on ENSO being primarily Neutral. But the winter bias of JAMSTEC is near El Nino and the winter bias of NOAA is a near La Nina or possibly even La Nina Conditions. That adds up re the Nino 3.4 Index to a difference of close to 1C which if it was starting from pure Neutral would be either an El Nino or La Nina. As it is the two deviations from Nino 3.4 = 0 are of opposite signs so both forecasts are for ENSO Neutral Conditions for January 2018 but they are biased in different directions so this produces different forecasts. In Spring the bias is similar in both forecasts but the magnitudes are different. So we are dealing with a complex situation of differences between the two Nino 3.4 Index forecasts.

One value of doing this sort of analysis is that as the projected value of Nino 3.4 changes we have the basis for extrapolating between these two sets of forecast maps if the Nino 3.4 forecasts come closer together. If they become farther apart, it may still be possible to make some reasonable guesses as to how this will impact weather. Of course on September 21, NOAA will release a new set of maps and two days later we should be posting our analysis of their new maps and hopefully also JAMSTEC will be on time with their maps.

Some Housekeeping Issues.

The next Regular Weekly Weather and Climate Report will be published on August 28. If you are reading this Update Report and wish to transfer to the Current Weather and Climate Report, Click Here for the list of Weather Posts. That link takes you to the archive of all weather articles written by Sig Silber so you can if the new Weekly Weather Report has been published go there or back to an earlier report but please keep in mind that the graphics in earlier reports in some cases auto-update and the text may no longer apply to the graphics shown. Remember, if you leave this page to visit links provided in this article, you can return by hitting your "Back Arrow", usually top left corner of your screen just to the left of the URL box.

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