Arctic sea ice at record low levels

Interesting article in today's paper about how ice cover over the Arctic is at its lowest level on record this year. Ice cover has shrunk to about 3 million square km, a million square kilometres less than the previous record lowest year in 2005. Data from the US's National Snow and Ice data Center give slightly different numbers.. showing ice coverage at 4.2 million sq km as of Sept 10th, still the lowest on record (previous record low was 5.3 million sq km in Sept 2005) Whatever the case, it's an amazing stat.. and certainly lends strong support to the global warming theory that has always warned of this consequence. Note however that these reliable ice cover records only go back to 1978 which is not a very long record to make any definite conclusions. One has to wonder what Arctic ice cover levels were like in the years before 1978, especially in the 1930s and 40s when we had some very extreme weather, and some very mild winters.

Nonetheless, you have to figure something is definitely changing up in the Arctic, and a continual reduction of the Arctic ice cover will have major impacts on our climate, sea levels, and economy (with the possible annual use of the Northwest passage) One of the impacts of a reduced Arctic ice cap is that winters would generally be starting later, and we have certainly seen this in southern MB with 8 of our past 10 Decembers warmer than average. So it does appear that we're already seeing some impacts of this exceptional loss of Arctic ice with delayed, shorter, and less severe winters.

It's interesting to note that Winnipeg had its warmest January on record in 2006, following the last record low Arctic ice cover in the fall of 2005. Will this mean we will have another record mild winter this year? Well, it's tough to say since there are other factors which can influence our winters such as a developing La Nina, and other global climatic oscillations. However, one has to certainly consider that there is a good possibility of another warm winter coming up for Southern MB given this year's amazing loss of Arctic sea ice.

Lake effect rainbands affecting Winnipeg and area

A band of lake effect rain has developed off Lake Manitoba this morning and is currently affecting parts of west Winnipeg. Cool air (0c at 850 mb) flowing over the warm open waters of the MB lakes (16-18c) has created these bands of lake effect precipitation which should persist this afternoon into tonight. Currently low level winds are from a 300 degree orientation which is advecting the band into west Winnipeg and areas northwest. Rosser has picked up 4 mm of rain this morning underneath the band. Outside the band, the sun is shining in parts of Winnipeg!

For this afternoon and evening, models indicate low level steering winds should become more northerly, with a 330-350 orientation which should push the Lake Manitoba bands westward through Elie and Sanford and areas west. A 330-340 band off Lake Winnipeg would affect the Patricia Beach and Beausejour areas. (see example of 330 degree squalls from last October) I expect the bands to intensify this evening and tonight off both Lake Manitoba and Lake Winnipeg as a cold pool of -5C air at 850 mb moves over southern MB. This will give a 20C temperature differential between the lake water and 850 mb temperatures, which is getting extreme for lake effect precipitation (you need a minimum differential of 13c for lake effect initiation). There's even a chance that the precipitation could mix with or change to wet snow tonight into Friday morning, although I suspect the warm lake waters should maintain the precipitation mainly as rain.

The good news is that we should see a moderating trend this weekend with dry conditions and warmer temperatures as this cold pocket of air moves east.

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Lake effect update.. Interesting to see squalls starting to re-orient themsleves this afternoon as low level winds become more northerly. The 300 degree rainbands off Lake Manitoba which had been affecting Winnipeg are now weakening, while a new 330-340 band sets up further west between Elie and Portage. See attached Doppler radar image from 12:20 pm showing this lake effect transition in progress. Note also lake effect bands starting to develop off Lake Winnipeg.

Another cold blast coming in..

After a brief reprieve today with temperatures close to or over the 20 degree mark over Southern MB, a cold front will push through this evening bringing in much cooler air for Thursday. Brisk northwest winds on Thursday along with cloudy skies will keep temperatures only in the single digits most of the day, with afternoon highs struggling to hit the 10c mark. There will be occasional showers as well, although amounts should be on the light side here with the bulk of the rain falling through the interlake.

Thursday night will be downright cold as 850 mb temperatures plunge to -5C. This will be cold enough to possibly generate.. wait for it.. SNOW, especially over higher elevations of Southern MB! In addition, the cold air moving over the warm lake waters (currently running around 16 to 18C over the south basins) will generate bands of lake effect precipitation to the south and southeast of Lakes Manitoba and Winnipeg Thursday night into Friday morning. The warm lake waters should keep the lake effect precipitation as rain, however there is a chance that if the instability is deep enough and the bands are intense, the lake effect precipitation could change to wet snow.

Yikes.. a little too early to be talking about the S word!

Unseasonably cool day

Brisk northwest winds have ushered in an unseasonably cool airmass over Southern MB today with temperatures only in the single digits early this afternoon. Normal highs for this time of year are around 18-19C, so we're a good 10 degrees below "normal". With an expected high of only 11c this afternoon, this will be only a couple degrees above the coldest high ever for Sept 11th which was 8.9C back in 1890. (NOTE: this is corrected from an earlier post, which incorrectly stated the coldest Sept 11 was 15.6C back in 1949.. I was looking at the wrong column!) The cool northerly winds have even produced some bands of lake effect rainshowers off Lakes Manitoba and Winnipeg with Beausejour picking up 1.5 mm of rain off Lake Winnipeg this morning.

With such a cool airmass in place, it would seem likely that frost would be a concern for tonight.. However, a storm system from the west is expected to bring increasing clouds overnight with increasing southeasterly winds that should minimize the threat of frost over southern MB tonight. However, look for a chilly evening with patchy frost possible mainly east of Winnipeg. This storm system by the way may bring the season's first snowfall over central AB and SK tonight through Wednesday night!

No doubt about it.. fall is here!

PJ weather station back online..

Well, school's back.. and so is the PJ weather station.. another Charleswood area weather site. The station is located on the roof of Pacific Junction School on Cathcart Ave next to the Assiniboine Forest south of Grant. The station is a good alternate site to Rob's Obs for real time weather data in Charleswood. Note the PJ site has better exposure on top of the roof, so wind readings from their station are more accurate than mine, which tends to register on the low side due to the sheltering effects of houses and trees.