Colder in Early February

Jan 25 2018 5:00 PM CST| 0 Comments | Wisconsin | Long Range Forecast

CPC 8-14 day forecast indicating good chance of below average temperatures

Last week I talked about storm #2 (1/27) coming after #1 (1/22). In the 7 days since this system has trended weaker, further north, and the trough deamplified.

Cold front will pass through early Saturday morning with little to no precipitation.

We talked about the arrival of first episode of -PNA all winter and what that could bring. We talked about the moisture reservoir developing in the gulf of Mexico noting that moisture would be better for #2 as it came through this weekend. Things were looking optimistic for those seeking bigger snows and warmer temperatures. For the record, it has been warmer than average. The 1/22 storm brought much needed precipitation to southern Wisconsin, thunderstorms, and heavy snow to the north.

PNA Barely Negative

PNA and Arctic Oscillation. PNA is consistently flat or positive, barely negative. I'm still not that interested in the AO trends, definitely trending negative in the next week.
The PNA oscillation went negative last Tuesday, but only barely negative. It's just "meh". It has been meh since November. Since January 16 we saw the first major snowstorm of the winter across the Great Lakes that produced 14" of snow in northwest Wisconsin. The western trough was either not deep enough or too amplified (narow) to push things into the southern great lakes. It's crazy to think how low we were in October and November and how consistently positive we have been since then. I believe the PNA trend is symptomatic of a large scale pattern determined to push cold into the United States. We will be heading into positive territory soon. The AO is trending negative again suggesting cold will "uncork" into the United States.

GROWING COLD

The upper level flow is already changing down stream to end our chances of a classic snow storm, at least in the foreseeable future. We will need to be creative if we want a big snowstorm in Wisconsin. Either that or wait it out.

500mb wind showing ridge building in the west and cold shots decending in the northern plains and eastern North America.

By the time we enter February we will be back in northwest flow. The pattern looks to be very amplified across the northern Pacific ocean, very chaotic at 180hr+ in a way that builds a ridge in the west and pumps warm air pole-ward.

GFS ensembles for Feb 2 with upper level trough over the center of north America. The exact position is likely to change but the general pattern is one that favors cold across Wisconsin.

The question I have is will it get as cold as late December in Wisconsin? I think it can. I wonder if this time the cold will be positioned slightly further west enough to allow a storm track across the Ohio Valley? This would line up with our analogs for JFM, somewhere between the December "best match" and the -QBO/-ONI average. I'm curious to find out which (if any) turn out correct! I'm leaning more towards the -QBO -ONI composite right now. Also how long will it last? Some models keep it cold into March but it's tough to say.

Experimental forecast for JFM. May or may not correct.

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