The Spring season of 2008 is going to be dominated by the continuing strong La Niņa event which has been raging since last Autumn across the equatorial Pacific. Moderate and strong La Nina events in the Spring season have a strong correlation to particular types of weather pattern for the Plains and the Midwest. This specific Spring time Moderate / Strong La Nina Pattern features Below and Much Below Normal temperatures and Above Normal rainfall especially across the Midwest and into portions of the Deep South.
The real forecast issue that meteorologists will have to deal with this Spring will be the condition of the La Niņa event by the time we reach MAY 2008. If the La Niņa event is still in the Strong criteria as we move into early Summer ... then the odds strongly favor a particular weather pattern. If on the other hand the La Niņa event is weakening we will end up with a significantly different weather pattern for the Summer months across the Plains and the Midwest. This is going to be the key issue in figuring the Summer forecast at 2008 and it is very important that energy and agricultural traders keep this in mind. The Summer 2008 forecast will be based upon a forecast or extrapolation of an event that is still several months down the road and that is always a risky proposition.
REVIEW OF WINTER 2007-08
The link below shows the WxRisk Winter 2007-08 forecast. If you would actually take a look at the forecasts and the Map issued with regard to the overall pattern you would see that the December and January forecast force quite accurate. However my February 2008 forecast was not nearly as good. This is mainly because I anticipated the La Niņa to weaken as ee moved into February. And I really did not happen so as a result the basic or fundamental assumption I had for the month turned out to be wrong. And not surprisingly so did the February forecast .
http://wxrisk.com/Seasonalforcst/WINTER07-8/EXESUMMARY.htm
| DEC 2007 JET STREAM | DEC 2007 PRECIP | DEC 2007 TEMPS |
 |
 |
 |
| JAN 2008 JET STREAM | JAN 2008 PRECIP | JAN 2008 TEMPS |
 |
 |
 |
| FEB 2008 JET STREAM | FEB 2008 PRECIP | FEB 2008 TEMPS |
 |
 |
 |
These next two maps show the overall
pattern and I have highlighted the mean Jet stream position with a
rather thick black line over the CONUS for the winter months
of December January and February. Map#1 number one refers to the
temperature pattern for DJF and as you can see temperatures
were generally above normal over Texas the Delta the deep south into the
Northeast US while over the western third of the US into portions of the
Plains temperatures were below normal. 
This next Map shows the precipitation pattern we experienced
during the winter months of December January and
February. Again the superimposed
thick black line shows the Mean Jet stream
position and as you can clearly see the Great Basin region
has been pretty wet along with a large area from of
the central Plains into much of the Midwest and New England.
However areas to the south of the Jet stream
have for the most part been rather Dry this
winter. That being said FEB
2008 has turned much wetter over the Deep
South.
If we take a look at the Winter by region we can see that the precipitation patterns are clearly distinguishable over the central Plains into the Midwest. As you can see for most of the Winter the dark blues and purples show Nuch Above Normal rainfall extending from eastern Colorado are across the central Plains and into the Midwest which is where the mean storm track was located.
| PLAINS
PRECIP DEC 1- FEB 29 |
MIDWEST
PRECIP DEC 1- FEB 29 |
 |
 |
With the temperatures we can see much of the same sort of thing. Again note how the coldest temperatures were located just to the north of where the Jet stream position was... over the central and upper Plains into the western Great Lakes. To the south and east of that we can see Above Normal temperatures across much of the lower Midwest and especially over the ECB.
| PLAINS TEMPS DEC 1- FEB 29 |
MIDWEST TEMPS DEC 1- FEB 29 |
 |
 |
As we prepare the Spring 2008 forecast we want to start paying attention to some of the trends we are seeing in February. There are numerous cases where the early Winter pattern is significantly different than what we see late in the Winter / early Spring and this can result Missing the pattern changes and thus your seasonal forecast often ends up in trouble. However in this particular Spring season the strong La Niņa event is still the dominating factor. And if we look at the temperatures for the month of February we will see essentially an unchanged pattern.
| FEB TEMPS for CONUS 2008 |
 |
Over the Plains temperatures from the Rockies westward were quite mild but when we look at the eastern portions of the central and upper Plains temperatures during February 2008 were way below normal. This continued into much of the WCB region as well.
| PLAINS TEMPS FEB 1- FEB 29 |
MIDWEST TEMPS FEB 1- FEB 29 |
 |
 |
Precipitation for February 2008 can be seen here with very dry conditions over much of the central and upper Plains... but very wet conditions over almost all of the Midwest. This very distinct rainfall pattern between the Plains the Midwest occurs because the Jet stream has been so strong and powerful that these systems racing in from the West coast are developing their rain shields too far to the east to affect the Plains and as result.... the Midwest is getting slammed with heavy and rain and snow events.
| PLAINS PRECIP FEB 1- FEB 29 |
MIDWEST PRECIP FEB 1- FEB 29 |
 |
 |
The persistent nature of
this weather pattern we seen over the central Plains and then into most
of the Midwest has produced a large area of saturated ground that
appears to be growing as the wet pattern continues into March. These two
images show the trend rather clearly. First let's take a look at the
short-term trends s with regard to droughts and rainfall. As you can see
from the short-term trend Map much of the Midwest and the Northeast is
now experiencing Much Above Normal with regard to soil moisture and
saturation and many areas in Midwest are supersaturated.
Also note the area of adequate or above normal soil moisture over the
central Rockies. It should be pretty clear then that we can see where
the mean storm track has been for much of the Winter running from Utah
Colorado across the Plains into the Midwest and New England. Alston did
he notice of the deep South region where are the extensive drought is
shrinking rapidly as the one continues in the short-term.
The long-term soil moisture and drought Monitor
trends which can be seen here
This Map shows the lingering
drought over the Deep South but it is not nearly as bad as it was Last
Summer and Autumn. In addition the long term
trends for Above and Much Above Normal rainfall over portions of the
Midwest and the Northeast can be seen as well .
All seasonal forecasts regardless of whom or what companies actually make them... are all based upon certain critical assumptions which a meteorologist HAS to make in order to project the forecast for the next 90 or 180 days. Sometimes these are critical factors are overpowering and the forecast becomes relatively easy. This was the case this winter and the Summer of 2006. In the examples that were two or three overpowering the factors which really gone it to the entire weather pattern across the Western Hemisphere.
This particular winter which is now coming to a close the dominating factor was the strong La Niņa which actually exceeded most of forecast expectations made back in the Autumn of 2007. There NO computer forecasts or private forecasts that I know of which called for the La Nina to reach the "strong" intensity criteria for several weeks during the middle of this past Winter.
My particular winter forecast --again by referring to the link above called for a month or La Nina to dominate the weather pattern-- in the months of December and January but I anticipated the La Niņa to weaken during the month of February and early March. As a result my December and January forecasts were very good and quite accurate with the overall pattern temperatures and precipitation. However the February forecast was a disaster since it was premised on the idea of the moderately La Nina weakening which clearly did NOT happen!
There were some other factors of course besides the La Nina... such as the QBO and the Sea surface temperature anomaly patterns in the North Atlantic Ocean which were hostile towards the idea of any sort of sustained blocking patterns developing over Greenland or Eastern Canada.
As we move into the Spring 2008 forecast (and then take an early look at the Summer 2008 forecast) we can see that the La Niņa is going to be the dominating factor once again. The reason for this is that there is a significant difference in the historical climatology between a strong / Moderate La Nina versus a Weak La Nina. Thus ANY forecast that is premised on the idea of a strong / moderate La Nina continuing thru the Spring and into the middle portions of the Summer.... HAS to reflect the conditions we see during Spring and Summer months of a strong or moderate La Nina. On the other hand if you are forecasting a Moderate La Niņa for the Spring with a weakening La Niņa during the Summer months (the DTN forecast) then your forecast is going to be significantly different because the patterns we expect with a weakening La Niņa during the Spring and Summer months is different.
WHAT ARE THE SPRING TIME CONDITIONS MODERATE / STRONG LA NINA EVENTS BRING TO THE CONUS?
These Next two images come from the climate prediction Center ( CPC) ENSO diagnostic discussion web page. The first map shows three different maps which all representative of the the typical precipitation patterns the CONUS experiences in La Nina events. the top map represents the areas of above normal and the little normal rainfall with weak La Niņa events... no matter presents moderate lightning events and the bottom map represents the top of rainfall patterns we see with strong La Nina events. one thing that you'll notice is that regardless of the type of La Nina event the spring season seems to favor an area of much below normal rainfall over the western corn belt / upper Mississippi Valley which extends into the eastern portion of the Plains.
| LA NINA SPRING RAINFALL |
LA NINA SPRING TEMPERATURES |
 |
 |
This next image refers to the temperature patterns we see during the Spring season with weak Moderate and Strong La Nina events. The Top map ...weak La Nina -- shows very little correlation between any sort of temperature anomalies over the Plains or the Midwest but there is a tendency for the Pacific Northwest to run somewhat below normal. In the moderate and strong winning events we can see a large area of below normal temperatures over the Pacific Northwest and northern Rockies and into the far upper portions of the Plains near the Canadian border. On the other hand there is a large area of Above and Much Above Normal temperatures that extend from eastern Texas of the Delta and the entire Deep South.
Now that we know what the typical La Niņa spring time patterns with regard to temperature and precipitation typically look like... the next issue is to determine what sort of La Nina event will the CONUS and southern Canada see this Spring and possibly into the Summer of 2008?
This next map is presented so
that the reader can more easily
comprehend that La
Nina and El Nino events occur within a certain geographical region along
the equatorial Pacific Ocean. The
ENSO region consists of several
sectors .... ENSO 1+2 ENSO 3
ENSO 4 and ENSO 3.4.
Officially an El Nino or La Nina event is declared when the SSTA
(sea surface temperature anomalies) have reached
a certain level for a 5 month time period over the
ENSO region known as 3.4 .
As of March 1 the La Nina event in region 3.4 reached its peak of nearly -1.90c in the first two weeks of FEB. Since them the La Nina has showed very slow warming.
HISTORY OF SHORT
La NINA EVENTS ( weak) vs
STRONG La NINA EVENTS
this next table -- called the ONI index-- comes from the Climate Prediction Center --and it shows a history of all the La Niņa and El Niņo events in the critical ENSO region of 3.4 since 1950. I have highlighted two different types of La Nina events. The YELLOW shading highlights the long lasting La Nina events while the AQUA BLUE shading highlights the short duration La Nina events.
By highlighting the history of all the La Nina events since 1950 it should be readily apparent that in the yellow shaded / LONG lasting La Nina events the sea surface temperature anomalies in ENSO region 3.4 reached or exceeded -1.5c while in the short duration La Niņa events the sea surface temperature anomalies did NOT reach -1.5c
CRITICAL POINT: they' have been 4 long-lasting La Nina events since 1950. In every instance the sea surface temperature anomaly dropped to -1.5c or lower and the total event lasted 27 to 36 months.
In the 4 of the 5 short duration La Nina events Sea Surface temperature anomalies never exceeded -1.5c ...except in the 1988-89 La Nina event. they are for the odds and the climate history of logging events strongly indicate that the current La Niņa event will continue for at least the rest of 2008 possibly into early 2009. The CURRENT La Nina event may not have the same intensity as it has right now but the climate history of La Nina events is very clear -- this La Nina event still has a long way to go
| DESCRIPTION: Warm (red) and cold (blue) episodes based on a threshold of +/- 0.5oC for the Oceanic Niņo Index (ONI) [3 month running mean of ERSST.v3 SST anomalies in the Niņo 3.4 region (5oN-5oS, 120o-170oW)], based on the 1971-2000 base period. For historical purposes cold and warm episodes (blue and red colored numbers) are defined when the threshold is met for a minimum of 5 consecutive over-lapping seasons. |
|
ear |
DJF |
JFM |
FMA |
MAM |
AMJ |
MJJ |
JJA |
JAS |
ASO |
SON |
OND |
NDJ |
|
1950 |
-1.7 |
-1.5 |
-1.4 |
-1.4 |
-1.3 |
-1.2 |
-0.9 |
-0.8 |
-0.8 |
-0.8 |
-0.9 |
-1.0 |
|
1951 |
-1.1 |
-0.9 |
-0.7 |
-0.4 |
-0.2 |
0.1 |
0.3 |
0.5 |
0.6 |
0.7 |
0.7 |
0.6 |
|
1952 |
0.3 |
0.2 |
0.1 |
0.1 |
0.0 |
-0.2 |
-0.3 |
-0.3 |
-0.1 |
-0.2 |
-0.2 |
-0.1 |
|
1953 |
0.1 |
0.3 |
0.4 |
0.4 |
0.5 |
0.4 |
0.4 |
0.4 |
0.4 |
0.3 |
0.3 |
0.2 |
|
1954 |
0.3 |
0.2 |
-0.2 |
-0.6 |
-0.8 |
-0.8 |
-0.8 |
-1.1 |
-1.2 |
-1.1 |
-1.1 |
-1.0 |
|
1955 |
-1.0 |
-0.9 |
-0.9 |
-1.0 |
-1.1 |
-1.0 |
-1.0 |
-1.0 |
-1.4 |
-1.8 |
-2.0 |
-1.7 |
|
1956 |
-1.2 |
-0.7 |
-0.6 |
-0.6 |
-0.5 |
-0.5 |
-0.6 |
-0.8 |
-0.8 |
-0.9 |
-0.8 |
-0.7 |
|
1957 |
-0.5 |
-0.1 |
0.3 |
0.6 |
0.7 |
0.9 |
0.9 |
0.9 |
0.9 |
0.9 |
1.2 |
1.5 |
|
1958 |
1.7 |
1.5 |
1.1 |
0.7 |
0.5 |
0.5 |
0.4 |
0.2 |
0.0 |
0.0 |
0.2 |
0.4 |
|
1959 |
0.4 |
0.5 |
0.4 |
0.2 |
0.1 |
-0.2 |
-0.4 |
-0.5 |
-0.4 |
-0.3 |
-0.2 |
-0.3 |
|
1960 |
-0.3 |
-0.3 |
-0.3 |
-0.1 |
-0.1 |
-0.1 |
0.0 |
0.0 |
0.0 |
-0.2 |
-0.2 |
-0.2 |
|
1961 |
-0.1 |
-0.2 |
-0.2 |
-0.1 |
0.1 |
0.2 |
0.1 |
-0.3 |
-0.6 |
-0.6 |
-0.5 |
-0.4 |
|
1962 |
-0.5 |
-0.5 |
-0.4 |
-0.5 |
-0.4 |
-0.3 |
-0.2 |
-0.3 |
-0.4 |
-0.6 |
-0.7 |
-0.7 |
|
1963 |
-0.6 |
-0.3 |
0.0 |
0.1 |
0.1 |
0.3 |
0.7 |
0.9 |
0.9 |
0.9 |
1.0 |
1.0 |
|
1964 |
0.9 |
0.4 |
0.0 |
-0.5 |
-0.7 |
-0.7 |
-0.7 |
-0.8 |
-1.0 |
-1.1 |
-1.1 |
-1.0 |
|
1965 |
-0.8 |
-0.5 |
-0.2 |
0.0 |
0.3 |
0.7 |
1.0 |
1.3 |
1.5 |
1.6 |
1.6 |
1.5 |
|
1966 |
1.2 |
1.1 |
0.8 |
0.5 |
0.3 |
0.2 |
0.2 |
0.0 |
-0.2 |
-0.2 |
-0.3 |
-0.3 |
|
1967 |
-0.4 |
-0.5 |
-0.6 |
-0.5 |
-0.2 |
0.0 |
0.0 |
-0.2 |
-0.4 |
-0.5 |
-0.4 |
-0.5 |
|
1968 |
-0.7 |
-0.8 |
-0.8 |
-0.7 |
-0.4 |
0.0 |
0.3 |
0.3 |
0.3 |
0.4 |
0.7 |
0.9 |
|
1969 |
1.0 |
1.0 |
0.9 |
0.8 |
0.6 |
0.5 |
0.4 |
0.4 |
0.6 |
0.7 |
0.7 |
0.6 |
|
1970 |
0.5 |
0.3 |
0.2 |
0.1 |
0.0 |
-0.3 |
-0.6 |
-0.7 |
-0.7 |
-0.7 |
-0.8 |
-1.1 |
|
1971 |
-1.3 |
-1.4 |
-1.2 |
-0.9 |
-0.8 |
-0.8 |
-0.8 |
-0.8 |
-0.8 |
-0.9 |
-1.0 |
-0.9 |
|
1972 |
-0.7 |
-0.3 |
0.0 |
0.3 |
0.6 |
0.8 |
1.1 |
1.4 |
1.6 |
1.8 |
2.1 |
2.1 |
|
1973 |
1.8 |
1.2 |
0.5 |
0.0 |
-0.5 |
-0.8 |
-1.0 |
-1.2 |
-1.4 |
-1.7 |
-1.9 |
-2.0 |
|
1974 |
-1.8 |
-1.6 |
-1.2 |
-1.1 |
-0.9 |
-0.7 |
-0.5 |
-0.4 |
-0.5 |
-0.7 |
-0.8 |
-0.7 |
|
1975 |
-0.6 |
-0.6 |
-0.7 |
-0.8 |
-0.9 |
-1.1 |
-1.3 |
-1.3 |
-1.5 |
-1.6 |
-1.7 |
-1.7 |
|
1976 |
-1.6 |
-1.2 |
-0.9 |
-0.6 |
-0.5 |
-0.2 |
0.1 |
0.3 |
0.6 |
0.8 |
0.8 |
0.8 |
|
1977 |
0.6 |
0.5 |
0.3 |
0.2 |
0.2 |
0.4 |
0.4 |
0.4 |
0.5 |
0.7 |
0.8 |
0.8 |
|
1978 |
0.8 |
0.5 |
0.0 |
-0.3 |
-0.4 |
-0.3 |
-0.3 |
-0.4 |
-0.4 |
-0.3 |
-0.2 |
-0.1 |
|
1979 |
-0.1 |
0.0 |
0.1 |
0.2 |
0.1 |
0.0 |
0.1 |
0.2 |
0.3 |
0.5 |
0.5 |
0.6 |
|
1980 |
0.5 |
0.4 |
0.3 |
0.2 |
0.3 |
0.3 |
0.2 |
0.0 |
-0.1 |
0.0 |
0.0 |
0.0 |
|
1981 |
-0.2 |
-0.4 |
-0.4 |
-0.3 |
-0.2 |
-0.3 |
-0.3 |
-0.3 |
-0.2 |
-0.1 |
-0.1 |
0.0 |
|
1982 |
0.0 |
0.1 |
0.2 |
0.4 |
0.7 |
0.7 |
0.8 |
1.0 |
1.5 |
1.9 |
2.2 |
2.3 |
|
1983 |
2.3 |
2.1 |
1.6 |
1.3 |
1.0 |
0.7 |
0.3 |
-0.1 |
-0.5 |
-0.7 |
-0.9 |
-0.7 |
|
1984 |
-0.4 |
-0.2 |
-0.2 |
-0.3 |
-0.4 |
-0.4 |
-0.3 |
-0.2 |
-0.2 |
-0.6 |
-0.9 |
-1.1 |
|
1985 |
-1.0 |
-0.9 |
-0.8 |
-0.8 |
-0.8 |
-0.6 |
-0.6 |
-0.5 |
-0.6 |
-0.4 |
-0.4 |
-0.4 |
|
1986 |
-0.5 |
-0.5 |
-0.3 |
-0.2 |
-0.1 |
0.0 |
0.2 |
0.4 |
0.6 |
0.9 |
1.0 |
1.2 |
|
1987 |
1.2 |
1.3 |
1.2 |
1.1 |
1.0 |
1.2 |
1.5 |
1.7 |
1.6 |
1.5 |
1.2 |
1.1 |
|
1988 |
0.7 |
0.5 |
0.1 |
-0.3 |
-0.9 |
-1.3 |
-1.4 |
-1.2 |
-1.3 |
-1.6 |
-2.0 |
-2.0 |
|
1989 |
-1.8 |
-1.6 |
-1.2 |
-0.9 |
-0.7 |
-0.4 |
-0.4 |
-0.4 |
-0.4 |
-0.3 |
-0.2 |
-0.1 |
|
1990 |
0.1 |
0.1 |
0.3 |
0.3 |
0.2 |
0.2 |
0.3 |
0.3 |
0.3 |
0.3 |
0.3 |
0.4 |
|
1991 |
0.4 |
0.4 |
0.3 |
0.3 |
0.6 |
0.8 |
1.0 |
0.9 |
0.9 |
0.9 |
1.3 |
1.6 |
|
1992 |
1.8 |
1.7 |
1.5 |
1.4 |
1.2 |
0.9 |
0.5 |
0.2 |
-0.1 |
-0.1 |
0.1 |
0.3 |
|
1993 |
0.4 |
0.4 |
0.5 |
0.7 |
0.7 |
0.7 |
0.4 |
0.3 |
0.3 |
0.3 |
0.3 |
0.3 |
|
1994 |
0.2 |
0.2 |
0.2 |
0.3 |
0.4 |
0.4 |
0.5 |
0.5 |
0.7 |
0.9 |
1.3 |
1.3 |
|
1995 |
1.2 |
0.9 |
0.6 |
0.3 |
0.2 |
0.1 |
-0.1 |
-0.2 |
-0.5 |
-0.6 |
-0.8 |
-0.8 |
|
1996 |
-0.8 |
-0.7 |
-0.5 |
-0.3 |
-0.2 |
-0.2 |
-0.1 |
-0.2 |
-0.1 |
-0.2 |
-0.3 |
-0.4 |
|
1997 |
-0.4 |
-0.3 |
-0.1 |
0.3 |
0.8 |
1.3 |
1.7 |
2.0 |
2.2 |
2.4 |
2.5 |
2.5 |
|
1998 |
2.3 |
2.0 |
1.4 |
1.1 |
0.4 |
-0.1 |
-0.7 |
-1.0 |
-1.1 |
-1.2 |
-1.4 |
-1.5 |
|
1999 |
-1.5 |
-1.2 |
-0.9 |
-0.8 |
-0.8 |
-0.8 |
-0.9 |
-1.0 |
-1.0 |
-1.2 |
-1.4 |
-1.7 |
|
2000 |
-1.7 |
-1.4 |
-1.0 |
-0.8 |
-0.6 |
-0.6 |
-0.4 |
-0.4 |
-0.4 |
-0.5 |
-0.7 |
-0.7 |
|
2001 |
-0.7 |
-0.5 |
-0.4 |
-0.3 |
-0.1 |
0.1 |
0.1 |
0.0 |
0.0 |
-0.1 |
-0.1 |
-0.2 |
|
2002 |
-0.1 |
0.1 |
0.2 |
0.4 |
0.6 |
0.8 |
0.9 |
0.9 |
1.1 |
1.3 |
1.5 |
1.4 |
|
2003 |
1.2 |
0.9 |
0.5 |
0.1 |
-0.1 |
0.0 |
0.3 |
0.4 |
0.5 |
0.5 |
0.6 |
0.4 |
|
2004 |
0.4 |
0.2 |
0.2 |
0.2 |
0.3 |