© 2019 Terry Swails

WARMER WEATHER BRINGS A MAJOR STORM...

January 17, 2018

We're back in the deep freeze with sub-zero temperatures and wind chills that have fluctuated in the range of 15-30 below for much of the past 48 hours. With another below zero temperature Wednesday morning that makes it 15 of the past 24 days with sub-zero lows in Cedar Rapids. Pretty impressive!

 

I'm happy to say that there's light at the end of the tunnel and our temperatures are set to take a major turn towards the warmer side of the ledger (a really good things since January is averaging about 9 degrees below normal per day).

So what do we owe our good fortune to? Yes indeed, it's the MJO. The Madden Julian Oscillation is coming out of the cold phases and should now make an extended run through the warm phases of 4, 5, 6, and 7 over the next month. That means the next 30 days should see far more near to above normal readings than below.  Here's what the EURO seasonal MJO shows for the period January 16-February 16th. Follow the dotted green lines through the 4 warm phases.

Here are the temperature and precipitation phase correlations for 4, 5, 6, and 7. You can see on the left column phases 4, 5, and 6 are especially mild.

The CFSv2 is buying what the MJO is selling showing these 10 day temperature departures going out to February 15th.

 

Days 0-10:

Days 10-20:

Days 20-30:

Since the next 2-3 weeks are typically some of the coldest of the year this could not come at a better time. For the milder brand of weather to happen much of this period should be dominated by a western trough and an eastern ridge, at the very least a zonal flow.

 

Such a pattern would also imply an active storm track over the middle of the nation as a fight sets up between the cold and warmth over the central U.S. This is a big deal as it should mean above normal precipitation for much of the Midwest...something we've not seen for about 3 months. The 6-10 day outlook already reflects the trend.

Also, if you look at those MJO phase correlations again, notice how 4,5, 6, and 7 (on the right) are relatively wet around the central Midwest. 

The next system to impact the Midwest gets the precip. ball rolling as it brings widespread above normal rain and snow. Look at this bowling ball the EURO shows crossing the region Sunday and Monday. A very energetic system that's loaded with moisture.

As it digs into the Midwest it will generate several days of southerly winds that draw the first wave of the coming warmth into the region by weeks end. In doing so, it means the track of the storm will be into Iowa and my area gets the warm sector and rain as opposed to snow which will fall heavily to the northwest.

 

We're still over 5 days from the arrival of the storm so there will be tweaks regarding the track and precipitation amounts. However, as it stands now this has the potential to be the wettest storm in well over a year in Cedar Rapids and much of my area. The GFS showed this for total precipitation.

Here's a larger perspective. Some totals in SC Wisconsin are as high as 2.4"

One aspect of the storm that will impact precipitation totals is the dry slot. Wherever the surface low tracks there is going to be a 100-150 mile band surrounding it where amounts are lower than those to the east or west. A shift in the track would displace where the lower amounts end up occurring.

 

A shift in track could also impact temperatures and who gets the big snows. I could see a 20 degree range in temperatures from NW to SE in my area alone by Sunday night.

 

On the topic of snow, data over the past 24 hours has pushed the track northwest and again that implies the heavy snow sets up from NW Iowa into Minnesota and NW Wisconsin. For now the EURO, which I feel has a better handle on the thermal profiles, keeps the worst of the snow out of my area. The snow graphic below is not a forecast, just a trend and needs to be treated as nothing more than an early projection of where snow chances are the greatest. We'll know more definitively in a couple days when data is better sampled.

While we wait for the details of the weekend storm you can take heart in the fact that little in the way of Arctic air is expected the next 2-3 weeks. Seasonal chill to above normal temperatures are back on the table. Roll weather...TS

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