Wednesday, January 23, 2013

Welcome Thaw by Monday (time for a little midwinter "magic")

17 F. high yesterday in the Twin Cities.
24 F. average high for January 23.
26 F. high on January 23, 2012.

2/10ths of an inch of snow fell on the metro early Wednesday morning.

1.6" snow so far in January, 7.6" less than normal, to date.
17.4" snow so far this winter. Average snowfall as of January 23: 31"

Thaw possible Sunday, likely by Monday.

Winter Magic

We live in Minnesota for many reasons. The lakes, great schools, strong work ethic, a sense of tolerance and progressive pride. As much as we grumble about cold fronts most of us like the change of seasons; the traditions that help to define us. Fishing Opener. Aquatennial. State Fair. Deer Hunting Opener. Winter Carnival.

In 1885 a clueless newspaper writer in New York City referred to St. Paul, then the fastest growing city in America, as "a little Siberia, unfit for human habitation in winter." So city officials decided to throw a big party, a snowy, icy in-your-face... highlighting ice palaces, parades & massive toboggan slides. It's grown ever since, a source of civic pride. You really should check it out. The St. Paul Winter Carnival runs thru Feb. 3.

A subzero relapse this morning, again early Saturday, gives way to a thaw Sunday and Monday. A slushy coating is by late Sunday, even a rain-snow mix Tuesday, and we can't rule out a couple inches of slushy snow - but the brunt of any moisture tracks east of Minnesota.

What a shock.

One more subzero surge the first few days of February, then long-range models suggest moderation. I suspect the worst of the chill may be over by February 6.

Then again, I'm a naive optimist.

* file photo above courtesy of photographer Tom Maloney at The St. Paul Winter Carnival.

Coolest Celebration on Earth. The St. Paul Winter Carnival kicks off tomorrow, and runs thru the first few days of February. No significant snow is in sight, but major, ice-statue-threatening thaws are probably not going to be a problem in St. Paul this year. We may approach or even top 32 F. for a couple hours next Monday and Tuesday, but right now I do not see a meltdown. Here's more on the history of the St. Paul Winter Carnival: "In 1886, Saint Paul was America’s fastest growing city. Growing from 39,000 residents in 1880 to 120,000 residents in 1886, Saint Paul had also become America’s third largest rail center. To celebrate their city’s success, Saint Paul business leaders produced the inaugural Saint Paul Winter Carnival, which was held during the first two weeks of February in 1886. In addition to showcasing Saint Paul, the business leaders wanted to disprove a New York newspaper reporter who had described their beloved city as “another Siberia, unfit for human habitation in the winter.” Patterned after Montreal’s Winter Carnival, the first Saint Paul Winter Carnival included parades, skiing, snow shoeing, a blanket tossing contest, and push ball, a game played with giant balls. The most successful attractions were its ice castle and six large toboggan slides. Throughout its 125-year history, the Saint Paul Winter Carnival has been an integral part of the social fabric of Saint Paul. Carnival reaches out to the people of the Greater Saint Paul area to weave a tapestry of cultures with educational and cultural programming."

Something For Everyone. After a subzero start this morning, temperatures struggle into the low teens tomorrow, before tumbling (just) below zero Saturday morning. Then a more substantial warming trend begins, a good chance of highs near freezing by Sunday and Monday, before another cold front has us reaching for parkas by the middle of next week. Graph: Iowa State.

Slush Alert. It's been a long time since we've seen a "plowable snowfall", in fact the last 2"+ snow in the metro was December 9 (10.5"). It's all or nothing, right? After a welcome early-week thaw the ECMWF model prints out .35" liquid Tuesday, but it may be just warm enough aloft for some of that moisture to fall as rain or sleet. That said, there is a potential for a couple inches of slushy snow Tuesday before another surge of Canadian air arrives by midweek.

Predicted Snowfall By Saturday Night. The latest NAM model (NOAA) prints out significant lake effect snows downwind of the Great Lakes. An unusually mild start to winter means that there's very little ice on the Great Lakes, so the current (subzero) air passing over (open) water is able to maximize snow squalls downwind. An inch of snow is possible over central Minnesota, a couple inches of slush from Richmond to Norfolk, Virginia, maybe 8" for the hills of West Virginia and Lower Michigan.

Cold Start To February. The models are fairly consistent from run to run, showing another delightful dollop of frigid air sailing south between Feb. 2-5, a few more nights below zero. But I don't think it will be quite as cold as earlier this week.

NAEFS Extended Trends. The forecast from January 31 to February 6 shows another chunk of numbing air, with temperatures well below average, from the Dakotas into the Great Lakes during the first week of February. I still expect moderating temperatures, maybe 30s, by the second week of next month. I hope that's not just wishful thinking.

Sudden Stratospheric Warming = Cold Intrusions Over Lower 48 States. Meteorologists look for cues. One big cue for subzero air is (paradoxically) sudden warming in the stratosphere, the upper atmosphere, where temperatures warm with altitude. This happened a couple weeks ago, as described by climate scientist Gavin Schmidt: "Stratospheric sudden warnings happen when there is a large planetary wave - usually originating in the tropics - that propagates northward and upward and disrupts the normal polar vortex. Think of it as an ocean wave breaking on a tide pool. The temperatures in the stratosphere near the pole go up a lot because of anomalous downward movement. The connection between the SSW and the surface winds are a well known phenomena - see papers by Baldwin and dunkerton a decade or do ago. After an SSW you get (after about 5-10 days) a negative phase AO associated with very non-zonal jet streams, leading to large temperature excursions (both +ve and -ve)."  Image above courtesy of NOAA.

Arctic Oscillation Forecast. The AO reached a minimum earlier this week, coinciding with subzero air draining into the Lower 48 states of the USA. A more positive phase implies warming (nationwide) next week east of the Rockies. After February 1 it's anyone's guess - a wide divergence of solutions. I still suspect a very cold start to February, followed by moderation with 20s and 30s returning by the second week of February. Graphic above: NOAA.

Good Explanation Of Arctic Oscillation. Why should you care whether the phase of the Arctic Oscillation (AO) is negative or positive? Because if you know which way the atmosphere is leaning, you can make a better long range forecast. "Unusually mild winter with a persistent Pacific breeze [positive phase like we had most of last winter] or outbreaks of bitter cold [negative phase, like we've seen since mid-January of this winter]". This may be more than you've ever wanted to know, but here's a good description from The National Snow and Ice Data Center: "The Arctic Oscillation refers to opposing atmospheric pressure patterns in northern middle and high latitudes. The oscillation exhibits a "negative phase" with relatively high pressure over the polar region and low pressure at midlatitudes (about 45 degrees North), and a "positive phase" in which the pattern is reversed. In the positive phase, higher pressure at midlatitudes drives ocean storms farther north, and changes in the circulation pattern bring wetter weather to Alaska, Scotland and Scandinavia, as well as drier conditions to the western United States and the Mediterranean. In the positive phase, frigid winter air does not extend as far into the middle of North America as it would during the negative phase of the oscillation. This keeps much of the United States east of the Rocky Mountains warmer than normal, but leaves Greenland and Newfoundland colder than usual. Weather patterns in the negative phase are in general "opposite" to those of the positive phase, as illustrated below. Over most of the past century, the Arctic Oscillation alternated between its positive and negative phases. Starting in the 1970s, however, the oscillation has tended to stay in the positive phase, causing lower than normal arctic air pressure and higher than normal temperatures in much of the United States and northern Eurasia."

Arctic Oscillation graphic above courtesy of J. Wallace, at the University of Washington.

ENSO Outlook for 2013. Here is a prediction of ENSO probability (El Nino, La Nina) from The International Research Institute for Climate and Society. Odds favor "ENSO-neutral", which might help our ability to pull out of a long-term drought over the Plains and Upper Midwest. The worst-case scenario would be a La Nina cooling phase, which correlates with drought and much drier than average weather during the summer, especially central and southern Plains. We'll see.

Serious Lake Effect. Subzero air passing over the (warmer) Great Lakes whipped up plumes of lake effect snow squalls, pumping heavy snow into downwind communities. This is a little unusual for late January, when ice should be covering most of the Great Lakes - this scenario is more typical of late November or early December. Image courtesy of the Marquette, Michigan National Weather Service office and CIMSS, University of Wisconsin.

Utility-Enhanced Snow Squalls. This post from the Pittsburgh NWS caught my eye - steam from a local nuclear power plant "seeding" the clouds, enhancing snowfall rates: "Check out the band of snow being generated by the Beaver Valley Nuclear Power Plant near Shippingport. Up to an inch of snow has fallen as a result of the steam billowing from the stacks."

"Ask Paul." Weather Related Q&A:

Hi Paul,

"I've wondered for years how meteorologists measure the dewpoint when temperatures drop below 32F degrees. I'm thinking of a wet bulb freezing below 32F and yet see dewpoint readings down to single digits and even below zero."


Very best,

Fred Opie

Fred, this is a great question, one that is (sadly) beyond my pay grade. I turned it over to the local Twin Cities office of the National Weather Service. Michelle Margraf at NOAA was kind enough to provide a very thorough response:

From NOAA's Michelle Margraf:

The dew point is measured by automated sensors at temperatures above or below freezing by determining the temperature at which dew or frost condenses on a chilled mirror hygrometer.  In fact, it's common for water vapor in the air to stay in liquid form (super cooled droplets) down to -20 degrees Celsius, making it easy for it to condensate on the chilled mirror. Another method to determining the dew point, which is used by ASOS sites, is to calculate the dew point from measurements of temperature and relative humidity. Before automated equipment were available, the dew point was calculated by using the "dry bulb" temperature and "wet bulb" temperature, and a psychrometric calculator.  

Here's a link to the National Weather Service directives on calculating the dew point from data gathered with "dry bulb" and "wet bulb" thermometers:

Here's a paragraph from the attached document describing how to take wet bulb temperature readings when temperatures are below freezing (i.e. make sure the wick is frozen before taking a measurement).  

If the dry-bulb temperature is 37°F or less:

1. At least 15 minutes before determining the wet-bulb temperature, immerse the wick into
water that has been kept at room temperature. Remove any excess water from the wet-bulb.
2. At observation time, stand as far from the psychrometer as practical and ventilate it by
means of the fan, whirling apparatus, or sling for approximately 10 seconds.
3. Read the wet-bulb temperature to the nearest 0.1° and make a mental note of the reading.
4. If the wet-bulb temperature is less than 32°F, examine the wick. If the wick is not obviously
frozen, touch it with clean ice or some other cold object to cause ice to form on it.
5. Repeat steps 2 and 3 until the lowest wet-bulb reading (indicated by two successive readings
of the same value) is obtained. At this time read both thermometers then convert to degrees
Celsius to the nearest 0.1°C.
6. Record the dry- and wet-bulb temperatures in columns 19 and 20 on MF1M-10.
7. Obtain the difference between the dry- and wet-bulb temperatures. Use this difference and
the wet-bulb to compute the dew point on the psychrometric calculator.

Thanks Michelle!

Top Ten Sky Sights for 2013 for Minnesota

January 21 – Very close pairing of Moon and Jupiter
February 12-20 – Best view of Mercury this year
March 10-24 – Best view of comet PANSTARRS (Astronomers are still not sure if this comet will be great or a dud. How will it pan out?)
May 21-30 – Conjunction of Mercury, Venus, Jupiter (The wackos may be out again for this one, you know, planets aligning, end of world, etc)
June 23 – Biggest full Moon (Will be hyped but hard to tell the difference between this and other full moons)
August 12 – Peak of Perseid meteor shower
October 18 – Penumbral lunar eclipse
Mid Nov thru Dec – Comet ISON (Not sure of this one yet either but it looks promising.)
December – Venus as a beautiful evening object
Dec 13-14 Geminid meteor shower (I threw this in to make ten but it will be hindered by nearly full moon this year)

* my thanks to Parke Kunkle, Faculty of Minneapolis CTC and a volunteer at the amazing Bell Museum. You can sign up for the Astronomer's Update through the Bell Museum. They run monthly updates that include where to look for these sights and others. If you love astronomy (one of the many benefits of living in Minnesota's Big Sky Country) you should absolutely do this. Aurora image above courtesy of NASA and the International Space Station.

First Sunrise In 65 Days. Is a lack of sunlight making you a little loopy? Just be glad you didn't settle in Barrow, Alaska. Details from the Alaska NWS: "Residents of Barrow, Alaska watched the sun climb above the horizon for the first time in 65 days, after it set on November 18, 2012. The sun skirted along the southern horizon for about 43 minutes today. Tomorrow it will remain above the horizon for 1 hour and 27 minutes. The amount of sunlight will rapidly increase in Barrow until May 10th, at which point the sun will remain above the horizon for 24 hours a day for nearly 3 months. It was clear in Barrow today and a FAA webcam captured the short but welcome return of sunshine. Watch the sun trace across the horizon in the video below."

Hurry Up Spring. Tim Butz snapped this photo from his home in Ellicott City, Maryland yesterday.

Soul-Soothing. Stare at this image of palm trees in Miami for 30 seconds. Your blood pressure may drop a few notches. Then again it may just make you nutty. Image courtesy of the Miami National Weather Service.

Hot Tub Boat Combines Cruising And Soaking. Hey, I've found the perfect boat! I wonder if they'll have one of these at The Boat Show, which kicks off next Thursday at the Minneapolis Convention Center. has the hot, soggy details: "Can’t decide between lounging in the hot tub or going boating? Well, why not do both? People in and around The Netherlands can already do so, in a HotTug. Now, North Americans can also get in on the action, with the Hot Tub Boat. Manufactured in Seattle, the 6-passenger 15-foot (4.6-meter) vessel features an 8-foot (2.4-meter) rectangular hot tub, heated up to 104ºF (40ºC) by a built-in diesel boiler. The boat itself is propelled by a 24-volt electric drive system, maintaining a cruising speed of 4 knots..."

Comfortably Numb. Kind of sad when 17 F. seems....reasonable. Compared to International Falls we experienced a Club Med Vacation. INL woke up to -20, with a "high" of -5. Elsewhere highs ranged from 1 at Hibbing to 12 St. Cloud to 17 in Rochester.

Paul's Conservation Minnesota Outlook for the Twin Cities and all of Minnesota:

TODAY: Subzero start. Clouds slowly increase. Winds: SE 10. High: 10

THURSDAY NIGHT: Light snow or flurries - dusting/coating possible. Low: 8

FRIDAY: Dusting of flakes early, then clearing and windy. High: 17

SATURDAY: Fading sun, slow moderation. Wake-up: -7. High: 15

SUNDAY: Mostly cloudy, flurries at night. Wake-up: 13. High: near 30

MONDAY: Early slush, then milder. Wake-up: 22. High: 33

TUESDAY: Light rain-snow mix. Some slush possible. Wake-up: 26. High: 31

WEDNESDAY: Slow clearing, colder again. Wake-up: 7. High: 14

Climate Stories...

Obama's Climate Challenge. Here's an excerpt of a long, but thorough Rolling Stone article: "...Now Obama gets another shot at it. "The politics of global warming are changing fast," says Kevin Knobloch, the president of the Union of Concerned Scientists. Thanks to a year of extreme weather and Hurricane Sandy, a large majority of Americans – nearly 90 percent – favor action on global warming, even if there are economic costs. The U.S. economy is on the road to recovery and no longer offers an excuse for inaction. Big Coal, traditionally the loudest voice against climate action, has been weakened by a glut of cheap natural gas and the economic viability of solar and wind power. China has new political leadership that appears open to discussing a global agreement to cut carbon. And Obama himself has nothing left to lose..."

Graphic Illustration by Victor Juhasz, Rolling Stone.

New Analysis Shows Simple Math: Keystone XL Pipeline = Tar Sands Expansion = Climate Change. Here's an excerpt from a blog post at The Natural Resources Defense Council: "New research confirms what we have heard time and again from the industry itself: the proposed Keystone XL tar sands pipeline will be a direct cause of an increase in tar sands oil development. More tar sands oil taken out of the ground means more dangerous pollution that hurts our climate and health. And, this new research also shows that tar sands will cause even more climate pollution than we previously thought due to the impacts of the high carbon byproduct petroleum coke. This is especially important in a time where our communities are feeling the damage of climate change in violent storms, wildfires, droughts and floods. Just recently a federal advisory panel—established by Congress in 1990 to analyze climate research—released the draft of its third National Climatic Assessment. The report confirmed there is “unambiguous evidence” that the earth is warming...."

Two Hopeful Signs The Obama Administration Will Not Approve The Keystone XL Tar Sands Pipeline. Joe Romm at Think Progress has the story; here's the intro: "50-50. Those were the odds you could get in DC for a bet on whether or not Obama would ultimately approve the Keystone XL tar sands pipeline.

But this week I think the odds turned against the pipeline, for two reasons:
  1. Obama devoted far more of his second inaugural address to climate change than anybody expected — and framed the issue in stark, moral terms.
  2. The State Department decision won’t come until after March, which means it will almost certainly be made by the new Secretary, climate hawk John Kerry...."

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