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Don Paul: A not-so-quick hit of wintry weather

“A persistent colder-than-average pattern appears unlikely until mid- or late-January. There may be some quick hits of cold, and there is a hint of quick-moving storm systems possibly rolling through the Great Lakes around Jan. 9 to 11. However, a persistent large area of low pressure closer to the northwest American coast will have a tendency to pump and re-pump Pacific air back into the lower 48 after these quick hits.”

Those were my words on January 2 here in the Buffalo News. In the interest of transparency, the first "quick hit" I referred to for later this week will not be quite so quick. Several days of bona fide below average temperatures will be with us in WNY, rather than just one or two days. More above-average temperatures will follow on the heels of this cold, ahead of what still appears to be a more persistent period of below-average temperatures in a fundamental pattern shift later in the month. There is also some chance that later pattern shift may produce much below-average temperatures.

Let’s get back to the near term. After a brush with slick roads and some modest midweek snow, we will experience four to five days in which the high temperature stays below freezing. (The average high at this time is 32 and the average low is 19.) Here are projected high temps from National Weather Service HQ. Give or take a degree or two, I’m in agreement.

Thursday, Jan. 10 | Friday, Jan. 11 | Saturday, Jan. 12 | Sunday, Jan. 13 | Monday, Jan. 14

You’ll notice toward the end of this period a buildup of mild, Pacific air over the nation’s midsection, and that’s what will be replacing this Continental Polar Air Mass heading into next week.

This weekend, the American GFS model shows a potent East Coast storm which would at least brush us with some widespread lighter snow. The Canadian GEM model has a somewhat different-looking depiction, but also has WNY on the northwest periphery of this deeper storm. The European ECMWF has a track too far to the south to bring WNY any of the storm’s snow.

Blending these models and their ensembles, as of this early in the week writing, it appears this coastal system is unlikely to have a major impact on WNY, but it will be close enough to bear watching.

After the weekend, the return of a warmer flow from the Pacific becomes evident in the ensembles of the models. Again, ensembles are multiple runs of the models, each member having different initial conditions. The ECMWF ensemble has 51 individual members, and the mean of the ensemble at upper levels shows milder high-pressure ridging moving in from the west.

The GFS ensemble is adamant about the same trend. Ditto for the GEM, so the agreement between the ensembles is good.

Not to belabor the obvious, but I bring you these graphics to demonstrate my projections are evidence-based, and so that many of you who prowl the internet and weather posts can come to recognize some of these signals.

How the upper-air steering pattern will align later in the month is partially tied to an oscillation called the Madden Julian Oscillation/MJO. I have tried to conjure up a way to explain the complexities of the MJO and to supply readily understandable graphics. I have even chatted online with some very scholarly colleagues looking for simplicity where, sadly, there is none. Here is a well-written but esoteric Wikipedia discussion on the MJO. Simple, it ain’t. Read it if you dare.

I bring the MJO into this because it is known to have eight different phases, each of which have different impacts on the eastern United States at different times of the year. If it enters into a phase which is associated with warmer temps for midwinter, its influence might well mitigate the tendency showing up in the ensembles for a colder-than-average late-January and February. Right now, most MJO guidance favors a colder phase by the end of the month. BUT forecasts for the MJO phase and strength beyond 14 days are known to be unreliable.

All that aside, other oscillations and blocking patterns at upper levels remain favorable for colder troughing in the eastern United States and warmer ridging in the West by later this month and next. The patterns shown below will look a little flatter because the many members in ensembles spread out the further out in time you go, which lessens the amplitude of the features in the ensemble mean. The data becomes very smoothed. Here is the GFS mean upper air later in the month, keeping in mind this is lower-amplitude and smooth.

The GEM ensemble mean is a little more pronounced with warm western ridging and cold eastern troughing.

And another long-range American model, the CFS v2, also shows such a pronounced trend by late-January and the first week of February.

Here is a final graphic from the National Weather Service Climate Prediction Center on probabilities for above-average, average, and below-average temps three to four weeks out in time. Note a large part of the Midwest and the east are firmly within higher probabilities for colder than average temperatures.

I’ll let CPC finish my article with their words concerning the experimental three- to four-week outlook: “The highest confidence for above-normal temperatures across the CONUS is confined to parts of the Pacific Northwest nearest to the anomalous ridge axis. The MJO would also support anomalous cold focused from the Northern Plains through Northeast, although the typical El Niño response would dampen this signal across the Northern Plains and Great Lakes.”

I will only add that statistical research done here at NWS Buffalo shows that a weak (as opposed to strong) El Niño has often been associated with colder-than-average temperatures in WNY, so I may differ with CPC’s “dampened signal” in the Great Lakes.

See? No plagiarism, no foul!

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