Twin Cities air quality reaches unhealthy levels

Posted at 9:14 AM on November 24, 2009 by Paul Huttner (0 Comments)

Twin Cities Air Quality Index (AQI) spikes this week. (Source MPCA)

Air quality has reached unhealthy levels in the Twin Cities and Rochester. As of Tuesday morning, the AQI in the Twin Cities is 131. In Rochester the AQI is 121. Readings over 101 are considered unhealthy for sensitive groups, such as those with respiratory problems like asthma. People in these groups are encouraged to minimize outdoor activity today. An air pollution health advisory remains in effect today.

A stagnant air mass has led to the higher levels of pollutants. November usually brings plenty of wind and fresh cold Canadian air masses to sweep away pollutants. A persistent patter of lighter winds this month has allowed fine particulate matter such as wood smoke particles and automobile exhaust to accumulate.

November is usually our 4th windiest month of the year in Minnesota. The average monthly wind speed for the Twin Cities in November is 10.9 mph. So far this month, the average wind speed in the metro is just 6.9 mph.

Northwest winds will increase Wednesday into Thanksgiving Day. That should sweep away the gunk and allow air quality to improve as we head into the Thanksgiving weekend.

PH

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Thanksgiving Travel: Wednesday snow

Posted at 8:31 AM on November 24, 2009 by Paul Huttner (0 Comments)

Twin Cities NWS weather depiction calls for snow Wednesday.

A clearer weather picture is beginning to emerge for Thanksgiving travel, and it includes snow on the road to Grandmother's house Wednesday.

The second in our 1-2 punch of wet weather this week will bring snow to much of southern Minnesota and Wisconsin. Right now it appears accumulations will be on the lighter side from the Twin Cities west. There could be more significant snow in Wisconsin as the system winds up Wednesday and Wednesday night.

The bottom line is travelers should expect rain changing to snow Wednesday morning. Snow could peak in intensity Wednesday afternoon and evening. With warm ground I expect 1" to 2" possible in the metro, with the best chance of 3" or 4" from the east metro into Wisconsin. If everything comes together, there could be a pocket of heavier snow (3" to 5") in western Wisconsin from Eau Claire to Tomah to Madison by Thanksgiving morning.

Sunshine should return to Minnesota for Thanksgiving Day as the weather improves dramatically this weekend. Black Friday looks excellent, with sunny skies and milder air flowing in from the southwest.

Here's a rundown of the travel forecast for Thanksgiving weekend.

Wednesday: Rain to snow in Minnesota and western Wisconsin. Temperatures steady in the 30s. Northwest winds of 10 to 20 mph with higher gusts. Slushy snow accumulation of 1" to 3" by Thanksgiving morning. Best chance for 3" snow in the east metro and western Wisconsin. Roads mostly wet, but there could be some slick travel after dark and overnight as roads being to ice up a bit.

Thanksgiving Day: A few icy roads in the morning. Clouds give way to bright sun. Breezy and cool. Highs in the 30s.

Black Friday: Sunny and milder. Highs return to the 40s.

Saturday: Sunny and mild again High 45.

Sunday: Partly cloudy. Chance of snow northwest and north-central Minnesota High 40.

PH

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Jet Streaming Returns: We want your weather questions!

Posted at 4:41 PM on November 23, 2009 by Paul Huttner (0 Comments)

I've had many questions from you wondering where our weekly weather show
"Jet Streaming" has gone. We have some good news to announce!

MPR will air a special edition of Jet Streaming will air on MPR News (KNOW 91.1FM metro) on
Sunday, December 13th at 6pm. The one hour show will feature an outstanding line-up of guests and topics.

We will talk with experts about the developing El Nino and Minnesota's winter forecast. We will talk about the future of weather broadcasting and where advances in weather technology will take us in the next few years. We will also talk about the science of snowflakes, the latest climate change news, and the observable effects of climate change in Minnesota. There will also be special surprise guests who you know and love.

But you are the most important guest! And we need your help.

We'll be answering a series of listener questions about weather and climate. Anything is fair game. We would love to hear you ask your question on the show and answer it personally in the classic MPR style. We may also read your question on the show if you're the shy type.

To help us out, please submit your question here on Updraft, or send me an email at phuttner@mpr.org. I will contact you and arrange to get your question on the show if it seems like the kind of question Jet Streaming listeners would like to hear. We need your questions by December 2nd.

Thanks again for all the support for Jet Streaming. You'll love to hear what we have planned for December 13th!

PH

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Thanksgiving Travel: Roll the weather dice

Posted at 8:32 AM on November 23, 2009 by Paul Huttner (2 Comments)

Twin Cities NWS graphical forecast indicates snow Wednesday.

Welcome to my weather nightmare.

First of all, it's Thanksgiving. One of the busiest travel weeks of the year. The magnifying glass is on weather this week.

Secondly, we have a very non-traditional storm system to decipher. Twin low pressure systems are spinning through the Upper Midwest this week. The forecast models, and the forecasters, don't like "non-traditional" weather systems. Give us a nice clean Alberta Clipper or panhandle hook any day.

Here are some of the interesting (and challenging) aspects to this week's evolving weather systems.

-Twin lows developing and deepening right over the Upper Midwest.
-Warm air in place through Tuesday, making for a later changeover to snow.
-Models performance can be questionable in these situations. To quote a recently famous military leader; "We don't know what we don't know."
-There are still significant model differences in timing, precip type and location of precipitation.

NAM forecast model shows "twin lows" rotating into Upper Midwest Wednesday.

So here's the early crack at deciphering the weather code this week for holiday travel. Buyer beware, this forecast may change tomorrow.

Monday & Tuesday: Scattered rain, warm enough for all rain except in far northwest Minnesota, where some icing may occur.

Tuesday Night & Wednesday: Rain changes to snow. The GFS model has been leaning toward a period of 24 hours from late Tuesday night to late Wednesday with periods of snow. The NAM pushes everything east into Wisconsin. The European model would seem to favor a quick 12 hour burst moving off to the east.

The trump card in all of this may be unusually warm ground for late November and temperatures just above freezing for most of the day Wednesday. That could mean mostly wet roads, instead of mostly icy roads.

Thanksgiving Day: Colder with snow east of the Twin Cities. Travel could be slippery between the Twin Cities and Chicago. Highs in the mid-30s with a biting wind. This should be a pretty typical Thanksgiving Day weatherwise. We have a white Thanksgiving about one in every three years in the Twin Cities.

Friday & Saturday: More sun, milder with highs into the 40s. The best days for travel!

Sunday: A chance of snow.

Keep an eye on the forecasts this week. Things may change quickly.

PH

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Gales of November? Not so much

Posted at 4:49 PM on November 20, 2009 by Paul Huttner (0 Comments)

Twin Cities NWS wind forecast shows another tranquil November afternoon.

One of the interesting and perhaps overlooked features of our unseasonably mild November is the wind. Or should I say the lack thereof.

November is typically the 4th windiest month of the year in Minnesota, and most of the Midwest. In the Twin Cities, our average monthly wind speed in November is 10.9 mph. Only the springtime months of March, April and May have higher average wind speeds.

This November our average monthly wind speed is a mere 6.7 mph. That's barely a breath and a full 4.2 mph below the month average so far. It's also one reason our days have felt so balmy, wind chill has just not been a factor this month.

We've also seen 54% of possible sunshine this month. The November average is just 39%. That's a huge difference and one reason why we're feeling so sunny these days.

Temperatures continue to run about 9 degrees above average for November in the Twin Cities. Enjoy the blissfully mild weekend weather. As I posted before, there are big changes on the way next week. I will try and nail down the timing and amounts of any possible snow on Monday. It's going to be a complicated forecast, and a potential meteorologist's nightmare.

PH

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Alaska -46: Winter heading for Minnesota

Posted at 4:37 PM on November 19, 2009 by Paul Huttner (0 Comments)

Forecast lows are colder than -40 in northern Alaska tonight.

You knew it wouldn't last forever.

Bitterly cold arctic air is pooling in Alaska. It was a bone chilling -46 in Bettles, Alaska early this morning. The balmy "daytime" high in Bettles was -38. Ouch.

That mind-numbing arctic air mass is gaining strength under 24 hour darkness in northern Alaska, and there are signs it may make a move on Minnesota the first week of December.

Of course it will modify some, and I don't think we'll see anything approaching -40 in Minnesota yet. But it's going to feel like winter around here very soon. Real winter. We could see our first sub-zero readings of the season in Minnesota in the next two weeks.

There's an atmospheric connection between Alaska and Minnesota. Huge dips in the jet stream called "long waves" tend to space out so that Minnesota and Alaska have the inversely related temperatures. When it's cold in Alaska it's usually warm in Minnesota, and visa-versa. We can look to Alaska before a big pattern change in winter to get and idea of what's headed our way.

Round one of our colder temperature pattern appears to be moving in next week. As I posted this morning, that could mean enough cold and moisture to make for a white Thanksgiving. It looks like the real mother lode of cold air may come calling the first week of December.

In the short run, our weather will improve dramatically as we head toward the weekend. Look for plenty of sunshine Friday and Saturday, and temperatures will make a run well into the 50s by Saturday afternoon. Clouds and rain will increase ahead of the overall pattern change on Sunday.

Get out and enjoy one last shot of mild sunny Indian Summer weather the next few days. Winter is on the way. And this time, I really mean it!

PH

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Forecast: White Thanksgiving?

Posted at 8:31 AM on November 19, 2009 by Paul Huttner (1 Comments)

Twin Cities NWS graphical forecast hinting at snow Monday evening.

The weather maps are brewing up changes for Thanksgiving week.

A developing low pressure system is looking more likely Monday in eastern Minnesota and Wisconsin. Forecast models are hinting at the developing the upper low pretty much right overhead Monday. This system could have enough cold air and moisture in place for snow late Monday into Tuesday.

NOAA GFS 500 millibar(18,000 feet) chart develops upper low Monday.

It's way too early to say for sure how much snow or exactly where it might fall. Systems this far out are just too loosely organized to pin down. In fact, forecasting snow timing, locations and amounts is difficult under the best of circumstances even 24 hours before a storm. Suffice to say the chances for (a few inches of?) snow Monday are increasing.

GFS model paints precip over the area at 6pm Monday.

The first system may be followed by another Alberta Clipper type system Wednesday. A reinforcing shot of sub-freezing cold air could arrive just in time for Thanksgiving, making it likely that any snow that does fall could stick around for a white coating on Turkey Day.

The obvious consideration here is that this could affect holiday travel in the region. Right now travel looks like it could be affected anywhere between the eastern half of Minnesota and Madison Monday into early Tuesday. The second system could affect road conditions anywhere between Fargo and Chicago Wednesday.

Stay tuned.

PH

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NWS: 1" severe hail criteria goes nationwide

Posted at 4:34 PM on November 18, 2009 by Paul Huttner (0 Comments)

Last night's Twin Cities AMS Chapter meeting featured Dr. Joe Schaefer, Director of the Storm Prediction Center (SPC). While I was unable to attend last night, my weather spies tell me he broke some news at the meeting.

You may remember last summer the NWS Central Region which includes Minnesota changed the criteria for severe hail to 1" from the previous 3/4" threshold for issuing severe thunderstorm warnings based on hail size. This move was supported by me and many other local meteorologists. It appears the change was a success. Next year, the NWS will adopt the 1" standard nationwide.

It turns out you need hail closer to 2" in diameter (golf ball size) before you really start to do serious structural damage to windows and cars. Since hailstones that size fall at nearly 100 mph, it's probably wise to stick with the 1" criteria when it comes to people outdoors. I wouldn't want to be caught out on the lake in 1" hail. This is a good move by NWS.

I'm told Joe also said SPC is very concerned and will be watchful this winter for tornado outbreaks along the Gulf Coast and in Florida. El Nino winters have a history of producing deadly winter time tornado outbreaks in the Deep South.

SPC is also talking about how to increase the alert level for killer tornadoes that occur during the overnight hours.

Delta moves NWA meteorologists to Atlanta:

Another little bird told me that Delta Airlines is completing the move of the former NWA meteorology staff to Atlanta. When complete, this marks the first time the "hometown airline" has not had a staff of trained meteorologists based in the Twin Cities in decades.

In theory this should not have an effect on the quality of weather forecasts for airline operations at MSP. However, I for one have always been a big believer in the extra "eyes on the ground" data you get from having a locally based staff of weather professionals based at MSP Airport. After all, this is one of the most challenging locations for flight operations in the world, especially in winter.

I am digging deeper into this topic.

Stay tuned.

PH

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Storm pounds Pacific Northwest

Posted at 8:56 AM on November 18, 2009 by Paul Huttner (0 Comments)

GOES IR satellite image shows potent storm heading for the Pacific Northwest coastline.

We get some pretty good storms in Minnesota, but imagine the pounding they are getting in the coastal areas of the Pacific Northwest today.

A powerful storm racing southeast from the Gulf of Alaska is crashing into the Washington and Oregon coastline. Winds gusts of 50 to as high as 80mph will slam ashore, downing trees in the process. Heavy surf is churning up along the coast, making for some excellent viewing but coming with coastal flooding. Winds along the coast will shift from easterly this morning to west and increase dramatically later today.

Numerous storm warnings are in effect including high wind warnings, winter storm warnings and even an avalanche watch in the Cascades.

Imagine trying to forecast these systems in the days before modern weather satellites allowed us to see storms from space before they reach the coast.

There is a connection between powerful Pacific Northwest storms and our weather in the Upper Midwest. Pacific storms act as huge atmospheric vacuums, sucking up milder air in the central states. This usually produces a southerly wind flow and milder than average temperatures here in Minnesota. This pattern will hold true again this time with temperatures running about 5 to 10 degrees above average through this weekend.

A piece of the Pacific storm will break off and gather in the southern states by the weekend. It may then come north, and has the potential to produce snowfall somewhere between the Twin Cities and Chicago by early next week. This could affect travel plans between the Cities and Chicago if it develops.

Stay tuned.

PH

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Mild November: Open water in December?

Posted at 4:07 PM on November 17, 2009 by Paul Huttner (6 Comments)

Ice free shoreline soaking up November sun on St. Louis Bay in Lake Minnetonka. (Photos by Paul Huttner)

Things are beginning to look a little odd in Minnesota these days.

This is the week when we would expect to see snow cover blanketing the ground in the Twin Cities. Our average date for the first inch of snow cover is November 21st. That's Saturday folks. No sign that will happen this year. In fact we could be pushing 50 again this weekend.

While springtime "ice-out" data is abundant in Minnesota, ice "freeze-up" data is sparse and hard to come by for Minnesota lakes. Maybe we're all a bit in denial when our favorite lake freezes over.

Still I can remember many years when I was skating (foolishly perhaps) on smaller bays in Lake Minnetonka by Thanksgiving weekend. I would say it is quite common to start seeing the first ice forming on ponds and small lakes and bays by this week. And I've seen many years with Lake Minnetonka covered with ice by the first week of December.

Late season boater out for a mid-November ride on Lake Minnetonka.

So far this year there is not a hint of ice on any area lakes or ponds. In fact, I believe all lakes in Minnesota are ice free as of today. And if you look at the GOES 1km visible satellite image below you can see it appears that lakes are ice free well north into Ontario.

College of DuPage visible satellite image form today shows lakes in northern Minnesota and southern Ontario largely ice-free on November 17th.

The medium-range forecast maps do show a cooling trend in the next two weeks. This should bring down enough cold air to freeze up some ponds and small bays by around the first of December. Still, there are indications of periodic warm spells. That might keep the big water open for several weeks to come. That would mean open water is possible on large Minnesota lakes well into December. There is evidence that supports a climate shift induced trend toward later ice-in and earlier ice-out sates in Minnesota.

It's said there really is no bad weather, just different kinds of good weather. Most of us are enjoying our balmy November. The ice fishing crowd? Not so much.

PH

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