Earlier this morning, warm winds rushing in from the south ahead of an extensive frontal system draped across central and eastern North America pulled 32 + degree Fahrenheit (0 + C) temperatures into the southern coastal area of Hudson Bay. These temperatures were around 30 to 35 degrees (F) above normal. An odd event to say the least. One that would have been far less likely to happen without the added kick provided by global warming in the range of 1.2 C above 1880s averages.
(Temperatures rose to above freezing at around 4 AM EST along the southern shores of Hudson Bay on January 11, 2017 according to this GFS model summary. Middle and long range forecasts indicate that at least two more such warming events will occur over this typically frigid region during January. Image source: Earth Nullschool.)
Such a kick has been pushing climate zones northward — sparking numerous instances of unseasonable weather. Meanwhile, some researchers have indicated that the Jet Stream has also tended to produce higher amplitude ridges and troughs as the Northern Hemisphere polar zone has warmed faster than the rest of the world. In these more extensive ridge zones, this climate change related alteration to atmospheric circulation provides big avenues for warm air to enter typically frozen regions during winter (please see Arctic Melt ‘Already Affecting Weather Patterns Where You Live Right Now’).
Today’s warming event was driven by a northward extending bulge in the Jet Stream running up over Alberta and on into the North Atlantic near Greenland. Similar ridging in the Jet Stream is expected to occur over Central Canada five to six days from now on Monday and Tuesday of January 16-17, again over extreme southern Hudson Bay on Wednesday, January 18, and once more over the southern half of Hudson Bay on Monday, January 23rd.
Warming during the 16th and 17th is expected to range from 30 to 38 Fahrenheit (17 to 21 C) above average. Meanwhile, the longer range forecast may see temperatures hit near 40 F (22 C) above average for some regions if the model guidance ends up being correct.
(Numerous instances of above-freezing temperatures are predicted for Hudson Bay during mid-to-late January. The most intense warming is showing up in the long range forecast for January 23rd. Image source: Tropical Tidbits.)
It’s worth noting that the five day forecast is rather uncertain and the longer range forecast at this time is highly uncertain. That said, the models do indicate a particularly strong tendency for Jet Stream ridging and associated anomalous warming for this region.
Today’s warming occurred in association with strong frontal storm system anchored by a 976 mb low. This coming Monday’s warming is expected to come in conjunction with a much less stormy warm front. The long range model for January 23rd shows an odd event where another strong frontal storm pulls a curtain of rainfall over much of southern Hudson Bay (which typically receives only frozen precipitation at this time of year).
(Light to moderate rain could fall over a large portion of Hudson Bay during late January as a very extensive frontal system is predicted to pull moisture and warmth from the Gulf of Mexico. An odd winter climate/weather event to say the least. Image source: Tropical Tidbits.)
Over the past two years, large ridges have tended to drive warm air into the Arctic over the Bering Sea, through Alaska and Northwest Canada, and up through the North Atlantic and the Barents. But during early 2017, ridging appears to be setting up for Central and Northern North America — which is providing the warmer middle latitude air mass with an invasion route toward Hudson Bay. And such periods of anomalous warmth will tend to have a weakening effect on sea ice cover in this vulnerable near-Arctic region.