UNDENIABLE, MAJOR CHANGES AHEAD

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Sifting through a day's worth of fresh data, what I came away with was the fact that a pattern change is coming; that's undeniable. What it means is a bit more uncertain. It's essentially a sure bet that we will see a significant warm-up that should open the door to improved chances of precipitation. That said, our proximity to the storm track means it could be rain or snow, or some of both, when it arrives. That's where the uncertainty rears its head in the week 2 to 3 period.

One thing's for certain, we can sure use a break in the cold. In Dubuque, the last time the temperature reached freezing was January 15th. As of Monday morning, that had produced 405 consecutive hours of temperatures below freezing, and counting. While the south could reach 32 on Wednesday, it looks like Thursday is the day everybody goes plus freezing. Hot dang baby!

Before I get into that, my climate guru, Steve Gottschalk brought up something interesting. On Sunday, February 1st, he measured 1.3" of fluff in some light snow. He notes that since 1960, he has had 1/2 inch or more of snow on February 1st 11 times (about a 17% chance). Far more interesting is the fact that 10 of those 11 years, his February snowfall was above normal (91% of the time). Anyway, if you buy into trends like that, the odds are stacked that the month ends up with above-normal snow. Hmmm, my take is that will take some doing.

 1962 - 28.0"

 1965 - 6.1"

 1967 - 17.6"

 1972 - 13.2"

 1978 - 12.2"

 1981 - 12.6"

 1988 - 13.1"

 2010 - 15.0"

 2011 - 23.6"

 2014 - 16.2"

 2015 - 15.5"

1965 was the only year with below-normal snowfall at 6.1"

Another good bet is the fact we won't be seeing any rain or snow of consequence through February 10th and probably longer as we make the transition from an east-based trough to one that is west-based. That is essentially the pattern change referenced above that is driven by the phase change of the PNA (Pacific North America) from positive to negative.

You can see once the PNA conversion occurs around the 10th, the mean of the EURO weeklies holds the negative phase through March 20th.

So, next Tuesday is when the negative flip occurs, and if you watch the EURO mean 500 MB animation below, you can observe the western ridge getting beat back and evolving into a trough on the 17th. That cuts the connection to Arctic air, and we get a big bump in temperatures.

These are the mean temperature departures for the 10-day period ending the 17th, coincident with the transition to the negative PNA. Up we go.

One of the factors that Nick and I have been postulating about is what other teleconnections would come into play to influence the negative PNA. We had been seeing signals that the AO (Arctic Oscillation) and NAO (North Atlantic Oscillation) were going to be largely in negative phases. The implication of that is that cold air would be in place over the northern US to fight with the warmer and more moist air that the -PNA would thrust northward. That attack would set up an active storm track in the week 2 and 3 period, with rain or snow systems brushing the center of the nation.

What I'm seeing in the weeklies today is that the mean of the AO (I use the mean in green, not the control in blue), shifts from strongly negative to near to slightly positive about the time the PNA flips.

The NAO does a similar dance, and suddenly you find yourself in a warmer environment. It still implies far more moisture, but temperatures, as Nick noted yesterday, are not nearly as conducive for snow, with rain likely to be the precipitation of choice.

Not surprisingly, the meteograms of the EURO and GFS ensembles for the next 2 weeks are rather toasty, especially next week. No snow to be had with readings like this.

The EURO

The GFS

There's not much doubt about it; the writing is on the wall—we are going into another extended warm-up. Literally, this has been the story of our winter: down, up, down, and now up again. What's intriguing is that this up phase is not likely to be the end game. There is a pretty good chance that we get another flip to cold in 2-3 weeks that carries into mid-March. In fact, the WPO (Western Pacific Oscillation) is shown going negative on February 20th and staying that way until March 20th. It means a ridge builds back into the western Pacific that would reopen the door to somewhat colder air in the 2-3 week period. The pattern should still have moisture, and if there's a window for a snowier pattern, this is our opportunity locally.

Regarding the stormier pattern, it's at least 10 to 14 days away. First, the transition to the negative PNA has to occur (early next week). Then, once SW flow is established, moisture can enter the upper-level wind flow. That also takes a few days time. However, when we get out to the 17th, as evidenced by available water vapor, the return is in full swing. Look at the jet sweeping south of California into Texas, aimed at the Midwest. The moisture in blue and green is just about to the Iowa border. That's when things should turn more active, and hopefully then we'll get some much-needed precipitation with several disturbances coming out of the western trough.

There are numerous details to refine, but in the big picture I feel there is a good chance this is broadly how the change plays out. At the very least, it will turn warmer, with highs by Thursday afternoon cracking freezing. Amen to that and roll weather... ON A SERIOUS NOTE, IF I DON'T MEET MY FINANCIAL GOALS, THIS WILL BE THE LAST YEAR OF THE SITE. IF YOU LIKE THE CONTENT, THE FUTURE IS UP TO YOU. T.S.

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