NA January 2012 Weather Discussion
Posted 02 January 2012 - 00:31
Weather-wise in northern Minnesota, 2012 rolled in not all that different than 2011 with howling winds and snow and rapidly falling temperatures. We've currently got about 4" of snow on the ground after some light snow the day before yesterday and heavier snow yesterday afternoon. Since that snow fell at just under the freezing point, it has a high moisture content... which builds a good base.
Today has been very raw and windy with temperatures falling through the 20s and 10s with a NW wind blowing around 30mph gusting to 45mph. Some areas have seen gusts well over 50mph. The winds are beginning to die down now, however, and temperatures should continue to fall to the lower single digits tonight. Tomorrow we'll see a high around 13˚F with a low around -5˚F for Tuesday morning before the Pacific air moves back in with highs around freezing Wednesday and Thursday.
A big pattern change is in the works to something much more typical of La Niña and closer to last January as heights rise over the Gulf of Alaska and Alaska and Yukon Territory while falling over most of Canada and the western and central U.S. The southeast ridge looks like it will remain in place, though with a cross-polar flow developing and Arctic air finally getting into the country, it could squash the southeast ridge, or at least send off some fireworks.
What this looks like is a strongly positive phase of the "Tropical-Northern Hemisphere" mode of variability that is a common pattern during the three winter months. The positive phase of the TNH sees 500mb height levels rise in the Gulf of Mexico and Florida into the Atlantic as well as strong ridging occurring over the Gulf of Alaska, Alaska, and Yukon Territory. Heights fall across the rest of Canada and across the western, central, and northeastern U.S. and also east of Hawaii underneath the huge GoA ridge.
This pattern is the very definition of extreme winter weather for much of the U.S. as storms can get super charged by subtropical moisture on an unusually far south subtropical jet, but are met by unending bouts of Arctic air that comes straight across the ice cap and floods into the western U.S. It is then pulled eastward. At the same time, the southeast is kept mild by a more southwesterly flow, setting up a clash of air masses that can bring severe weather, tornados, and blizzards to the eastern U.S. Such a pattern is particularly good for blizzards in the lower midwest, Ohio valley, and mid-Atlantic states.
Of course that is still 10 days out, so it's too early to tell. But the GFS has been hinting at such a pattern for a few days now. In the meantime, it appears that the AO and NAO will move towards neutral as heights build over parts of the Arctic (though not necessarily in the classic NAO areas of Greenland/NE Canada). The PNA will also move into negative territory. A neutral AO/NAO with a negative PNA can be a good pattern for northern MN since the bubble of Arctic air can extend south into the state while the storm track still remains relatively far north, bringing frequent storms to the area (spelling snow). A strong positive TNH, however, can shut off the snow guns and leave us with bitter cold, but sunny conditions.
Posted 04 January 2012 - 19:54
Tomorrow will be the mildest day with a high of 40˚F expected, some 25˚F above normal. That is nothing compared to the warmth in parts of southwestern Minnesota where gusty west winds and no snow cover are allowing the temperatures to warm dramatically. Already in Canby, it is 50˚F (10˚C) and tomorrow they can expect a high near 60˚F! That is highly unusual even for southwestern Minnesota in early January. By contrast, areas in the Arrowhead of Minnesota will struggle to get above freezing tomorrow. In fact, while December was over 8˚F above normal here in Bemidji, Grand Marais on Lake Superior saw temperatures 2˚F below normal for December thanks to copious snow cover. It just goes to show how important snow is in the winter temperature equation.
After this mild period, it appears a major pattern change is in the works. It will be one of the great mid-winter flips of recent times. The last great "flip" winter was 2006/07, though this flip appears stronger and more global, more akin to 1981/82. That winter in the upper midwest began on a very mild note with a December as mild as this winter... but January 1982 turned out to be one of the snowiest and brutally cold ones in history. 1949/50 also saw a flip like that here, but that mostly stayed confined to the western/central U.S., so it's not directly comparable.
The culprit behind this pattern shift is a stratospheric warming event that has been predicted since mid-December that is finally coming to pass. Temperatures north of 65˚N at the 10mb level in the atmosphere have warmed from near record lows for early winter to well above normal. That warming is working its way downward through the stratosphere and will put the squeeze on the troposphere.
The GFS super ensemble for 500mb heights over the 6-10 day period shows a major change for the U.S. with the 8-14 day period showing an absolute classic strongly negative AO/NAO similar to that seen in Dec-Feb 2009/10 and Dec into Jan 2010/11. Heights would rise dramatically over Alaska, the ice cap, and also over Greenland with strong height falls over much of western/central Canada, the U.S., and stretching across the Atlantic into western Europe.
The analogs are very telling. January 1969 is the most strongly correlated. January 1994, February 1965, and January 1982 also show up prominently. Other years showing up that only add to the wintry feel are 1970/71, 1978/79, and 2008/09.
If this comes to fruition, I think a lot of people will quickly forget how mild the first half of winter was as they will get plenty of use out of their snow shovels and winter recreational equipment. I hope it brings some heavy snows here. At this point with the near record dry autumn and very dry early winter, even winter snowfall totals well above normal would cause only minor to moderate river flooding, something people here are well prepared for.
Posted 06 January 2012 - 07:05
That all will be changing in a huge way. But first we have to get through another several days of unusual warmth. We'll stay below freezing now until Sunday or so, but temperatures will still run well above normal with lows in the teens and highs in the upper 20s (compared to an average of -5˚F and 15˚F respectively). Early next week, a clipper system will move through and usher the first real Arctic air mass in for the season.. about 2 months late. I think if we can get some fresh snow with it, the cold is quite under-done with the models only predicting lows in the single digits below zero with highs in the single digits and teens.
Beyond that, the stratospheric warming event continues and the Euro model is hinting at it continuing to strengthen and become a major event. The GFS isn't as bullish, but still finds the same solution for the 500mb height anomalies. Either way, both predict a strong displacement and weakening (and a dissipation in the Euro's case) of the polar vortex. I think there was a large pulse of energy from the Indian ocean caused by the MJO favoring that region that caused all of this as suddenly SSTs in the Indian ocean are falling rapidly as global temperature anomalies have risen. That heat has moved up to the stratosphere over the Arctic and will slowly radiate out into space... causing the globe to cool again. It is typical for the Indian ocean to see such cooling during La Niña events. In the mean time, it will mean lots of fun and games for winter lovers in the mid-latitudes.
Currently the models are hinting at massive blocking over Alaska setting up a cross-polar flow and keeping Canada and the northern U.S. in the fridge. The strength of blocking near Greenland seems to be less than we've seen the past two winters, but could still be strong enough to bring wintry weather to western Europe. I'd say the Far East and North America have the better chance for intense cold and snowy weather, however.
Posted 09 January 2012 - 22:06
THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH
DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA.
.DAY ONE...THIS AFTERNOON AND TONIGHT
NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.
.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
A STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH THE REGION TUESDAY
NIGHT AND WEDNESDAY. THIS WILL USHER IN THE COLDEST AIR OF THIS
WINTER SEASON...ALONG WITH THE POTENTIAL FOR ACCUMULATING SNOW. IN
ADDITION...NORTHWEST WINDS WILL INCREASE LATE TUESDAY NIGHT AND
WEDNESDAY...AND SOME BLOWING SNOW IS POSSIBLE IN OPEN AREAS. THIS
MAY REDUCE VISIBILITIES WHEN SNOW COMBINES WITH STRONG WINDS ON
WEDNESDAY. WIND CHILL TEMPERATURES WILL ALSO FALL TO AROUND 20
BELOW BY WEDNESDAY NIGHT...AND DAYTIME HIGHS ON THURSDAY WILL BE
IN THE SINGLE DIGITS.
The first truly Arctic air mass of the season will finally arrive on Wednesday with highs only in the single digits above zero. The pattern after that will definitely be more wintry... though the models still disagree. The Euro has more troughing in the western U.S. which would mean frigid and potentially stormy here while points east aren't quite as cold (but are quite stormy). The GFS has ridging in the southwest with a deep trough in the eastern U.S. This would mean frigid air for the central/eastern U.S. but a less stormy, drier pattern.
In any case, it's finally here.. 2 months late... but better late than never, right?
Posted 11 January 2012 - 19:05
More worrying is if we don't get a good blanket of insulating snow over the ice on lakes, it could cause serious shoreline damage. Despite the very dry fall, water levels remain very high... much as they did in the summer of 2002. Winter 2002/03 started off mild but turned nasty in January and the lack of snow cover allowed water to seep up through cracks in the ice which then froze, expanding the ice sheet outwards, pushing massive heaves up against the shorelines. This caused damage to our lakeshore property that still hasn't fully recovered. Many trees that 40 years ago stood straight up along the berm of land along the shore and leaned at a 30-40˚ angle back in the 90s over the water have since sagged further so that many trees are nearly parallel with the water just above the water level. Many trees died in the past 2 years due to high water exposing and then drowning their roots.
One ash tree that goes out directly over the lake has mostly died... but one branch that used to stick out in the inland direction, but now sticks straight up, is thriving... almost like it's a new tree growing out of a fallen one. I'll have to get a picture of it when the snow melts. In any case, it is the natural progression of things... and there are lots of new trees growing on top of the berm that will probably go through the same process over the next 40-50 years. It's just unique because the place where I grew up was also on a lake and we had nothing of the sort... but we were also on the NE side of that lake, so the prevailing winds were almost always onshore or parallel. Our cabin is on the WSW side of the lake, which only rarely gets an onshore breeze. But it doesn't matter because we're 100 feet from another, smaller lake... so we get the wind no matter the direction it comes from. (Our land sits on an isthmus between two lakes that varies from 200 feet in width to 10 feet in width. There is a small channel that I'm not completely sure wasn't man made between the two lakes).
Anyway.. back to the weather.
Today is a nasty, frigid day. Temperatures have fallen from 30˚F at midnight to 10˚F right now with a NW wind blowing from 25-40mph, creating windchills of around -10 to -20˚F. There is a slight chance for some more snow showers as the wrap around moisture moves through... though no accumulations are expected. Temperatures will reach the goose egg tonight with a high of 7˚F tomorrow afternoon and a low of -3˚F for Friday morning. Because of the lack of snow cover, the air will not be able to get all that cold. Still, temperatures will remain at or below normal over the next 7-10 days.
With the stratospheric warming having backed off a bit before another re-charge next week, the south and eastern U.S. will warm up. The massive block will stay over western Alaska/eastern Siberia with low heights extending across much of the Pacific from the U.S. west coast back to Hawaii and points west. This will result in a strong-split flow that will deliver cold air into the northern 1/4 of the U.S. from the western Great Lakes back to Portland and Seattle with warmth across much of the rest of the U.S. Canada will remain frigid as the vortex in north-central Canada remains strong and the Alaska block prevents Pacific air from getting into the country.
In the longer term, it appears we could be up for a very cold February. Of course the length of that cold will depend on various factors, not the least of which is the evolving state of the La Niña. A major slow down of the trade winds should weaken the La Niña a bit. At this point it is up in the air as to whether the SOI will move back into positive territory, or if there is, in fact, a regime change on the way (perhaps to El Niño for spring/summer).
At this point there are no good analogs for this. 1954/55 is a halfway decent analog for Minnesota. That winter was very mild until mid January and then was frigid and stormy until late March. At this point, I'd say it's a strong contender for the upcoming pattern except that the La Niña actually strengthened during spring 1955 to one of the strongest on record by summer/fall. 1974/75 has been another analog, but that also strengthened to a very strong La Niña for 1975/76.
So at this point, everybody is on a learning curve. We're actually charting new territory!
Posted 14 January 2012 - 04:08
The reason for all of this precipitation is a large low that approached from the central US and more or less passed directly over us but is now progressing towards the north shore of the Gulf of Saint Lawrence.
Today has been very much a "Snow Day" and I haven't been outside all day. We are now in for a cold weekend as arctic air comes down to us on the west side of the low.
Posted 15 January 2012 - 04:28
Posted 18 January 2012 - 19:32
An extreme cold warning has been issued for tonight and the forecast has constantly been revised colder as the models have missed the low level cold air involved with the air mass. Temperatures will drop to around -25˚F (-31.7˚C) tonight *with* a 15-20mph NW wind making it feel as cold as -50˚F, hence the extreme cold warning. In wind chills that cold, exposed skin will freeze in a matter of minutes.
Right now it is 0˚F (-18˚C) with light snow falling and little in the way of wind. It's not often that the warm side of a strong cold front is 0˚F! It shows the power of the cold that has been bottled up in Alaska and Canada.
I've combed through the winters of the past 60 odd years looking for winters with similarities to this one. I found 5:
Now looking at the various atmospheric and oceanic indexes, I'd rank the winters as follows:
1. Tie for 1988/89 and 1952/53
There is also the wildcard of 2006/07. That was a weak/moderate El Niño winter, but the Pacific Decadal Oscillation was neutral/negative, which did temper the effects of El Niño, especially in late winter when the El Niño collapsed.
If you blend those winters together, you get the following for the February-April period:
1988/89 saw a swing to extreme cold in February and remain chilly in March and April across the northern U.S. despite a very positive Arctic Oscillation. 1952/53 saw relatively average temperatures for Feb-Apr. 1974/75 saw cold in March and April. 1953/54 saw a very mild February, then a very cold March... and 1979/80 saw cold for late winter into spring.
The stratosphere at the 10mb level continues to show very warm conditions north of 65˚N, indicating favorable conditions for blocking. The models are hinting at a major warm up in the eastern U.S. as a large ridge builds there... but over the 8-11 day period, the ridge migrates north into NE Canada/Greenland and heights begin to lower underneath in the central and eastern U.S. This will drive the Arctic and North Atlantic Oscillations into a negative phase and could result in a much stormier, colder pattern for the eastern U.S.
This post has been edited by brshort716: 18 January 2012 - 19:34
Posted 21 January 2012 - 00:30
Temperatures will rise throughout the day tomorrow and overnight into Sunday as a storm approaches from the west. At the moment, the models are converging on what could be the largest snowfall so far this winter season. The GFS and Canadian are predicting around 0.5" to 0.6" of liquid precipitation, while the WRF and European models are somewhat less. With that spread and with unpredictable temperatures, we could end up getting anywhere from 2-12" of snow. A few models are also picking up on another snow event about 5 days out.
Temperatures will be above average for a few days and Sunday's high of 25˚F will feel tropical compared to the past couple days. The pattern setting up seems to indicate normal to below normal temperatures with above normal snowfall over the coming two weeks.
Posted 22 January 2012 - 00:21
Going forward, temperatures will be near to above normal... though like with this last cold front, the models underestimated the low level cold associated with it... so it is possible that temperatures won't be as mild as predicted. Precipitation wise, we have several chances over the next 7-10 days for light snows as an active storm track sends many systems through the region.
Posted 24 January 2012 - 19:16
Aside from a few cold days, we have had a mild winter so far. Tomorrow we could break record highs and get into the upper 70s. Thursday could be a bit rough as we have a slight risk for severe weather. While we've had some rain, we have had an over-abundance thus far.
Posted 27 January 2012 - 04:53
Well, the snow was slow to arrive in the last storm, but we did end up with 3-4" of snow with a roughly 10:1 ratio, meaning the snow wasn't powdery.. but not wet either. I believe they call it plaster in the Cascades of Washington as much of the very heavy snow there falls at temperatures in the mid 20s to low 30s, making for "dry" snow with a high moisture content. It's bad for avalanches... but it is good to establish a covering of snow here because it will stand up to warmer temperatures and provide moisture for the ground in the spring melt.
The pattern right now looks to bring mild temperatures and dry weather with a classic Pacific pattern moving back in. The NAO will remain neutral and the AO slightly negative with the PNA slightly positive. The models see a lot of troughing in Alaska and the NE Pacific with a bit of troughing in the far SE U.S. and a large ridge over the western and central U.S. This will drive mild Pacific air across the U.S. Despite the overall flow being out of the northwest here, the cold behind the largely moisture starved systems will quickly moderate with warm Chinook type winds from the west.
Temperatures will be seasonably mild tomorrow and Saturday and seasonable on Sunday before moderating again to well above average with lows in the 10s and highs in the low 30s. It could easily be warmer than that... the models don't usually call out extreme cold or mildness until a couple days beforehand.
In the mean time, we could see some light snow tomorrow. There is a band of snow moving across North Dakota, but it likely will fizzle out for the most part before it reaches here and will stay south. There are chances for light snow here and there, but nothing major at the moment.