- Feb 28, 2019

METEOROLOGICAL WINTER ENDS...

Back in early February I made a post about how I was seeing the signs of a big drop coming in the SOI (southern oscillation index). I felt this was a signal that convection in the Indian Ocean was advancing east of Australia and this would do two things. First, it would spur the MJO (Madden Julien Oscillation) to enter the cold phases of winter signaling another Arctic outbreak towards March 1st. Secondly, I expected a major storm shortly after the SOI fall bottomed out as the deep negatives would be a prod to excite and energize the southern (sub-tropical jet stream).

Well, as you can see the fall of the SOI since February 8th to the 27th has been dramatic.

The largest negatives occurred during the period February 18th-20th. The lowest daily SOI level of -43.61 was reached on the 19th. A week later the severe blizzard that hit parts of Iowa, Minnesota, and Wisconsin took place. That is no coincidence and a storm that could be anticipated from a crash like that.

The other anticipated result of the SOI drop was the MJO surge into phases 1,2, and 3, the holy grail of cold at this point in the winter. That transition is still in motion as we speak. You can see in the phase diagram below (dotted green lines) how the MJO is getting set to leave phase 1 and enter 2 on its way to 3. Notice on the right the temperature departures associated with those specific phases. Lots of cold across the country.

Longer term, the next question becomes what happens after phase 3. The EURO forecasts the MJO to take a hard left just before entering the much warmer phase of 4. How soon that happens determines whether or not we get out of this cold pattern towards the middle of March.

The GFS thinks the warming is coming, the EURO obviously has reservations. It's a little too early to make the call due to the uncertainties I just presented. However, I favor a colder solution. One thing is quite certain, a very cold period lies ahead. Here's the temperature departures for the next 15 days in 5 day increments.

Day 0-5.

Day 5-10

Day 10-15

The next 45 days the departure looks like this on the CFSv2.

The worst of the coming chill is going to be centered around the period Sunday-Tuesday. Record lows are still on the table Monday. The EURO forecasts these lows.

Highs on Monday are barely above zero. Possibly the coldest March highs ever recorded in spots. 2 above is the coldest high ever measured in Cedar Rapids during the entire month of March.

Wind chills early Monday could reach 25 to 35 below.

You can see the frigid winds at their peak early Sunday. A very tight pressure gradient as the Arctic high builds in.

Most of the snow with the Arctic intrusion stays to the south. However, some light accumulations could work into the southern half of my area Saturday night, mainly near and south of I-80. The EURO has this for snow through Sunday. The snow up in Minnesota and Wisconsin falls Friday.