© 2019 Terry Swails

IF THE SHOE FITS...

September 26, 2019

With October just around the corner we're getting into that time of year when the MJO (Madden Julien Oscillation) becomes an important player in long term forecast trends. For quite time its been in phase 1 and that's been a factor in the mild and wet September the central Midwest has experienced.

 

All of the region has witnessed above normal temperatures by 2 to 6 degrees.

Precipitation has been off the charts with much of my immediate area 2 to 4 times above the running mean.

Heading into October the MJO is projected by hold nearly stationary in phase 1 while gaining amplitude. Here's what the EURO is forecasting out to October 9th. A strong phase 1 signal.

The phase correlation for phase 1 in October points to more warmth and wet weather over the central Midwest until the MJO gets into a different phase. Take a look.at what phase 1 brings

The upper air pattern associated with MJO phase 1 would resemble what the models are predicting for this coming weekend and much of next week. Ridge east, trough west. The shoe fits!

The temperatures are certainly in sync with the above normal readings of phase 1. Here are the temperature departures in 5 day increments. This is off the EURO ensemble control.

 

Days 0-5

Days 5-10

Days 10-15 out through October 10th.

Last but not least precipitation is also projected to be above normal which is in line with phase 1. The EURO ensemble control shows this for amounts over the next 15 days...ending October 10th.

That's a very wet run with departures more than 6" above normal in parts of my area.

On the topic of heavy precipitation, it certainly seems more than likely that some part of the Midwest will incur excessive precipitation over the next week. I base this on PWAT's (water vapor) that are projected to reach near record levels for early October. There's also a strong baroclinic zone that's nearly stationary for several days. Any rain that falls in that type of set-up is likely to be heavy and repetitive. There's going to be some hydrology issues somewhere, especially with the ground as saturated as it is. These are the PWAT's the EURO shows Tuesday night.

Once again, these values are up to 300% above normal. That's a super strong signal for big-time rainfall. We'll see.

 

The first volley from this set-up is shot Friday and appears to be aimed at SE Iowa and northern Illinois. The NAM shows this for total rainfall through Saturday.

 

 

The 3k NAM only goes out 60 hours but looks pretty similar, just a bit further southeast.

The EURO on the other hand is further north so there are some positioning issues that need to be resolved with the heavy rain axis of this first disturbance.

I guess the bottom line is that soggy times are ahead. We'll know more in coming days on just how wet. Roll weather....TS

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