Tuesday, April 15, 2014

Spring and Summer Outlook for Western Kansas

April 15, 2014

*** For official government outlooks please go to The Climate Prediction Center outlook page. ***


For the High Plains of Kansas the climate is characterized by highly variable conditions, both in short and long time periods. The proximity to the Rocky Mountains and Gulf of Mexico moisture source are just two of the reasons for such variability.  But it is more complicated than that.  There are numerous intra-seasonal, multi-seasonal, multi-year, multi-decade and even multi-century ocean/atmosphere cycles and influences on our weather.

The image below is a simplified view of the basic water cycle that exits on earth.

Beyond the water cycle, interactions with with land masses, oceans and the sun are what drives our weather. Understanding these interactions can help (or hurt) long range forecasts.  Because of millions and millions of interactions across the globe and the fluctuation of the suns energy, forecasts beyond just a few days can suffer in accuracy.  The following are just a few of the tele-connections cycles and oscillations that impact our weather (and feel free to Google these for an explanation of each):

The Madden Julian Oscillation (MJO)
Global Wind Oscillation (GWO)
El Niño/La Niña - Southern Oscillation (ENSO)
North Atlantic Oscillation (NAO)
Arctic Oscillation (AO)
Pacific Decadal Oscillation (PDO)
Atlantic Multdecadal Oscillation (AMO)
Solar cycles (this could be a HUGE player in the next couple of decades)

To show the variability in precipitation and temperature, one only has to look at yearly statistics for Dodge City where observations have been kept since 1875.

In looking at the linear temperature trend one could assume steady warming since 1875.  But there have been definite cooling periods as shown below:

It is interesting when looking at the temperature trend since 1998.  There is a downward trend. These trends could all be tied to the sun and to perhaps the phase of the Pacific Decdal Oscillation and Atlantic Multidecdal Oscillation.

Recap of recent weather:

Obviously it has been dry across many areas, especially the western fourth of Kansas.  The drought monitor shows much of far western Kansas in an extreme drought with severe drought conditions extending in central and southeast Kansas.

Although many areas had beneficial precipitation during the late summer and fall, conditions have seen a significant change to drier conditions.  For the 2014 water year cycle  (October 1, 2013 through September 30, 2014), precipitation accumulations were near normal but have tailed off during the typical winter months.

So with the dryness of the winter and early spring the deficit of precipitation has been growing.  Similar conditions exist across the remainder of southwest Kansas.

Looking at the longer term the deficit has been growing at an uneasy rate.  The following graph shows the deficit of moisture at Dodge City since October 1, 2010 and ending April 1, 2014.

Elsewhere across Kansas similar conditions exist since April 2012.

In addition to the growing precipitation deficit the average temperature during the winter was below to much below normal, as expected.  This certainly did not help the winter wheat condition.

The Outlook:

So what is in store?  In a nutshell the prospects for beneficial moisture does appear to be improving!  There are many complicating factors that being considered.  The bad news...during the next 5 to 10 years the overall outlook is for drier than normal conditions.  However, and this is important, there is at least hope for several "wet" periods lasting 12 to 18 months that may occur during this longer term dry period.  One reason for the possible overall dryness is the phase of the Pacific Decadal Oscillation and the phase of the Atlantic Multi-decadal Oscillation.  Those phases take several decades to change.

But the good news?  History has shown that for every "major" drought across the plains, the droughts have been broken by the warm phase of ENSO, i.e., a developing El Niño.  Currently it appears that at least a weak El Niño may be developing.  The water temperatures across the equatorial waters are warming but slowly.

 Many computer models are indicating the warming of the equatorial Pacific waters will be warming,.i.e. showing a developing El Niño.

 For the shorter term (through May) some of the influences will be the AMO, PDO, AO and NAO.

The PDO and AMO are not going to change anytime soon.  More importantly will be the possible warming of ENSO and then the contributions to the Arctic Oscillation and North Atlantic Oscillation.

A phase of the AO is especially important during the winter months.  A negative AO allows brutal Arctic air to spill into the U.S. and this was a case for much of the winter.  During this early spring the AO has gone positive but there has been a trend for a negative phase again.  If the AO does go negative the opportunity for frequent fronts during the spring and into early summer will increase.

The NAO has been nearly neutral for much of the winter.  A negative phase would allow systems to block up (systems would slow down and be farther south).

 The Wrap Up...

The best "educated guess" is for an improving chance for beneficial precipitation.  As the spring progresses the availability of Gulf moisture will be increasing which will enhance the amounts of precipitation that each weather system could produce.  April will likely end up below normal across far western Kansas (where there is currently the driest conditions) but the remainder of the area may be normal to even above normal. Temperatures will average near to slightly below normal for April, but there will still be wild swings.  The chance of minimum temperatures of below 32 is extremely high into late April.  In fact, it would not be surprising to see near freezing temperatures during the first week of May.

At this time it does appear that the month of May could get "wet"!  The chance for above normal rainfall for May is relatively high and optimism is increasing.  Average monthly temperatures though could end up below normal (including the chance for near freezing temperatures the first week of the month).  It does not appear very likely that extremely hot temperatures are in the offing, although there could be one or two days that get really warm, much like what occurred April 12th of this year.

Will try for an update towards the end of April.