© 2019 Terry Swails

HOPPING RIGHT ALONG...

April 14, 2017

 

In yesterday's post I stated how I was expecting the SOI (Southern Oscillation Index) to take a deep dive as high pressure established itself over Australia. Thursday the new index came in at negative 16.15 against the base state. That's a hefty drop from yesterday's reading of a positive 10.96. I was right!

 The -16.15 value is the lowest the SOI has been measured over the past 30 days.

You can see the above normal pressure anomalies in and around Australia and the western portion of the central Pacific thanks to a 1028 high.

The reason I care (and I stated this yesterday) is that crashing SOI levels signify an ejection of energy into the tropical Pacific. As it travels east it imparts its will on the weather of North America. In essence it stirs the soup generating mischief and plenty of action in the long wave weather pattern. It usually takes 6-10 days until the energy impacts the Midwest.

 

The new EURO weeklies teleconnect well with the recent drop and indicate an unsettled stretch ahead. Here is what the model shows for total precipitation in the day 2-12 period.

 

Here's a larger perspective showing the energy and wet weather focused on the central United States.

 

As you would expect the mean 7 day 500mb jet is cutting through the Midwest creating multiple storms.

Initially 5,000 ft. temperatures (850mb) are warm in the day 0-7 time frame.

However, as the energy and trough gradually shifts east, these temperatures cool in the day 7-14 day period. I do look for a significant cooling trend April 20-27th.

Moving on to the short term aspect of the forecast I foresee some trouble spots in the first half of Easter weekend. A system coming out of the southwest in 2 pieces will bring a couple rounds of rain. Here's the first Friday/Friday evening.

After a nice break leaving much of Saturday dry, the second system arrives with a cold front late Saturday or Saturday evening. 

While thunderstorms are possible both days, Saturday has the best potential for any severe storms. We'll have a better handle in later forecasts on timing and potential instability. I do expect at least scattered strong storms but whether they can reach as far north as my local area remains to be seen. Areas south of I-80 have the greatest risk. The Storm Prediction Center currently has this for a threat outlook.

The GFS has this for total rainfall through Saturday night.

The EURO has this for total rain for the same period.

Temperatures throughout the holiday weekend look mild and above normal throughout the Midwest. Here's the projected highs Friday, Saturday, and Sunday.

Ending on a positive note, the rain clouds move out of the Midwest by Easter Sunday. The day looks bright and mild and fit for Easter services, egg hunts, and family gatherings. Whatever your faith, I hope it's a special day filled with love and peace. Roll weather...TS 

 

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