Ceaseless Wind

Middle Level Jet Flow Forecast for Wednesday

The jet stream pattern which has provided us with slightly cooler summer and has chilled the northeastern U.S. looks as if it will be shifting more to the central U.S. next week.  This means we will continue to see below normal temperatures and perhaps wetter conditions.

There is some evidence in the computer weather models that the shift will cause a front to stall somewhere in the central Great Plains during this period.  This usually brings enhanced rainfall to areas along and north of the front.  Since summer is a time of deeper moisture (high dew points) to the south of cool fronts, this can mean excessive rain is possible in this zone.

The 6-10 day outlooks issued by the Climate Prediction Center show the cooler temperature departure area in blue and the above average precipitation area in green.  The current thinking is to set this front up more to our south be we in the Ozarks should be watching this for possible adjustment.

The whole stalled front episode will likely be followed by another cool shot which will send our lows into the fifties once again with highs only in the seventies.

CPC 6-10 Day Temperature Outlook

CPC 6-19 Day Precipitation Outlook

The start of El Nino, a pattern of ocean temperatures in the central Pacific Ocean which affects global weather patterns, has been observed and is officially forecast to be with us through winter 2009-2010.

During an El Nino cycle, large areas of the central and eastern equatorial Pacific Ocean experience warmer than normal sea surface temperatures.  This produces a flip-flop of normally observed weather on both ends of this region with coastal areas of western South America, normally stable and dry, subjected to more rain and storms while places like Indonesia and Australia, normally wet, seeing a much drier pattern of weather.

In the United States, the mostly obvious pattern adjustments include a wetter and cooler south with an active storm track and a warmer and drier north with much of the polar air shunted to the northeastern part of the country.  The exact effects depend on the strength of the El Nino and how it interacts with other patterns of weather which develop in the northern oceans and polar regions.

3D view of El Nino in the Pacific

The Ozarks lie in-between these two bullseyes of weather extremes with no strong signal toward any particular weather pattern and therefore have experienced a variety of weather during El Nino years.  Ironically, it is the opposite of this pattern, La Nina, which the Ozarks experienced in full force last year with record rains and severe weather during especially the first half of 2008.

Researchers know that El Nino has a somewhat irregular cycle of about 3-7 years with periods of La Nina occasionally observed in-between.  The  factors which determine the length and intensity of these El Nino/La Nina cycles is still somewhat of a mystery.

You can read more about this phenomenon at these sites:

• NOAA Press Release
• Climate Prediction Center
• El Niño/Southern Oscillation (ENSO) Index
• El Nino Page

An finally by reading this blog and some of links, you already know more than this guy:

I Am the El Nino!