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Don Paul: It sure doesn't feel like March, but have a sliver of hope

The cruel deep freeze this week has an extra psychological bite because we’re in the first full week of March. March, crikeys!

The average high by this Friday is 39, and we’ll just be pushing the freezing mark this Friday after several days in the teens, with some single-digit lows. The average low this time of the year is in the low 20s. These temperatures would be much below average in mid-January, the statistically coldest part of the winter, let alone March.

Coming with this deep freeze will be a genuinely nasty wind chill, with a brisk southwesterly to westerly wind adding to the misery. The good news for snow haters is the ice cover on Lake Erie. As you may know or may have guessed, it’s very extensive.

I have to add this Monday GOES image includes cloud cover over the eastern third of the lake, and the ice cover away from the thick ice closer to Buffalo is not quite as solid as it appears. There is also some open water along much of the northern shore. Ice cover such as this doesn’t shut all lake effect off, contrary to mythology, but it does turn it way down. With temperatures between now and later in the week, however, the ice cover has no chance of decreasing significantly.

The harsh cold for this week was well predicted. It was hinted at in a Feb. 20 Buffalo News article, and I got more specific in a Feb. 25 article when I wrote this: “By the next day, we’re back to the deep freeze, by March 3 standards. The problem, drat, will be linked to the closer proximity of a lobe of … wait for it … a weakened polar vortex. (Remember: weakened is bad, strengthened is good)

"When the polar jet stream goes into another weakened phase (which has been causally linked to arctic warming), that allows the jet stream to buckle and drop a piece of the polar vortex southward.”

In fact, that is what has occurred, as seen in this National Weather Service HQ upper air ensemble.

That all changes by this weekend. Note the different alignment of those winds as we head into Sunday. The polar air has been cut off at the pass by a more westerly flow aloft, bringing in Pacific air to replace it. That dip in the winds west of us, though, is a low-pressure trough that may usher in a vigorous Great Lakes storm system by Sunday.

Here is how National Weather Service headquarters depicts the surface map with the deepening storm Sunday. If you look at the circulation around the low, you’ll note we’re in a warming southerly flow ahead of the storm center.

(NOAA)

The southerly flow is reflected in forecast high temperatures for Sunday, which will be above average.

Cooler, not cold, temperatures will return behind the storm Monday, but they will be seasonable rather than deep-freeze cold. Monday’s high should be not far from 40, which will still feel like Key West compared to what we’ve got right now. Next week will feel markedly milder than this week.

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The European/ECMWF ensemble mean shows milder high-pressure ridging building over the eastern United States and colder low pressure troughing digging in out west around March 12, which I touched upon in my Feb. 25 article.

When I wrote that article, the ECMWF ensemble mean was gung-ho on a more consistently milder pattern flip for the east with above-average temperatures becoming dominant. Courtesy of Dr. Michael Ventrice and IBM’s the Weather Company, this was the way things looked.

Other ensembles were in rough agreement with a more persistent pattern flip at that time, which led to higher confidence on the warmup. Yes, the warmup is still coming for next week. There is also a chance the contrast between colder pattern out west and the edge of the eastern warmth next week might provide some of the ingredients for additional severe weather in the southeast United States, though that is quite speculative.

But an ensemble fly in the ointment shows up in the ECMWF mean by the following weekend. It shows renewed colder troughing near the Great Lakes. This kind of feature, if it verifies, could not be seen in last month’s extended range data. If you look at the date stamp, it shows up just in time for — you guessed it — the St. Patrick’s Day Parade. There are no signs of it approaching a true deep freeze, but this has the look of a really chilly parade, again courtesy of the Weather Company.

Before anyone asks, I’m not going to even touch precipitation chances for March 16-17. It is simply too soon for that.

I think I should leave you with some warmer optimism for next month and beyond. The North American Multi-Model Ensemble shows a mean temperature for April that will run above April averages in our part of the country and an even warmer tendency for May. Verification for this ensemble has been a little sketchy, but at least I’m not seeing evidence in other ensembles of a chilly spring. May looks especially perky.

(TropicalTidbits.com)

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