Over the past 30 days the SOI (southern oscillation index) has been running negative reflecting higher than normal heights (pressures) over the western Pacific near Darwin, Australia. Today's SOI index was -17.83.
Over the next few days a significant change is projected that will reverse the trend and allow heights to fall. With lower pressures the SOI will make a significant rise into positive territory. I'll tell you why this is important after I show you the upcoming change.
Here's today's sea level pressure anomaly over Australia
Now here's Tuesday's forecast anomaly. The colors go from brown to blue down under.
You should care because a rise in the SOI correlates to a building ridge over the eastern United States. Here's what that looks like at 500 mb (jet stream level).
The ensuing SW flow will bring warmth and moisture into the central part of the nation. The end result is a summery feeling air mass and what looks to be the warmest temperatures of the year. Here's the precipitable water levels (PWAT's) the GFS forecasts next Wednesday. They are nearing 2" yielding dew points that are clustering close to 70.
The GFS has this for 10 day highs. First Cedar Rapids and then the Quad Cities. Look at those 80s!
The EURO 10 day highs look like this for both cities. Still seeing 80s.
The CFSv2 day 5-10 temperature departures look this way. Well above normal as you would expect.
For those of you wondering, in my posts a few days ago I was anticipating a cooler pattern into next week. None of the data I was looking at (or me) was showing this change coming so fast. My feeling was the pattern would not undergo this reversal until about a week later. At this time of year wave lengths are shortening and pattern amplification/change can happen quickly. Whatever the reason, I was clearly beat on this development.
So, for the first time all year I see the light of summer and several days of warm humid Midwest weather. Let me be right! Roll weather...TS