The La Nina Myth and the Winter Ahead

Warning: this post is pretty heavy on the "weather geek" meter (at least for an amateur).  If you want something simple and vague, go buy a Farmer's Almanac. Alternatively, lose yourself in the utter irresponsibility of AccuWeather's 90-day forecast.

Last year's Rippeology winter preview went about as well as I could possibly expect.  With one of the strongest El Ninos on record dominating weather globally, I made 5 predictions last November:

• Milder temperatures
• Fewer snow events (but not necessarily less snow than normal)
• More ice events
• A brown Christmas
• An active February

Each of these was correct with the exception of "an active February," which I missed by (literally) about 100 miles.  February was indeed a very active month in Wisconsin, but the heaviest precipitation stayed largely to the north/northwest, more on a La Crosse to Green Bay line.  This may have been due to El Nino staying stronger, longer, than most forecasters expected.

Regardless, I consider last year's outlook to be pretty good for a self-taught weather hobbyist who never took a single meteorology class.  So there.

Quick recap on El Nino and La Nina, because it comes into play in this year's winter outlook as well.  Each recurring phenomenon refers to either a warming (El Nino) or cooling (La Nina) of the equatorial waters in the central and eastern Pacific ocean.  To qualify for the label, sea surface temperatures must depart at least a half degree from average for a prolonged period of time.

Last year's El Nino rivaled the strongest occurrence on record, which occurred in 1997-98, and beat that event in duration by a half a year (19 months in 2014-16, versus 13 months in 1997-98).

Generally after a strong El Nino or La Nina occurs, there is a period of stabilization where sea surface temperatures mostly stay within a half degree of the average.  But earlier this spring, it looked as though we would slide directly from a strong El Nino into La Nina -- a rare oceanic feat only accomplished 3 times since we started measuring surface temps in 1950.  Those slides happened in 1972-73; 1988-89; and 1997-98, when a prolonged 32-month La Nina followed what was then the strongest El Nino on record.

Here's the Climate Prediction Center's recording of all sea surface readings since 1950.  These are done in 3-month rolling averages, so "DJF" refers to December/January/February.

We often associate La Nina with colder, snowier conditions in the Midwest.  But it's interesting to note that in those 3 instances above, when El Nino slid directly into La Nina, Madison recorded below-average snowfall in the winters when La Nina finally settled in for the long haul.  Average Madison snowfall for the last 30 winters is about 51 inches.  But here's what we had in those "slide" winters:

1973-74:  42.9 inches
1988-89:  36.2 inches
1999-00:  34.1 inches

But if you love winter, don't be discouraged.  That's because despite the myth of La Nina equating to extreme Wisconsin winters, in actuality, our heaviest snowfall years are associated with little or no sea surface anomalies at all. 

Here are the 8 snowiest Madison winters in the last 30 years, and the the El Nino/La Nina condition during those winters:

2007-08 (101.4 inches):  Weak La Nina
1978-79 (76.1 inches):    No departure
1993-94 (73.7 inches):    No departure
1985-86 (72.4 inches):    No departure
2008-09 (72.0 inches):    No departure
1992-93 (71.2 inches):    No departure
1987-88 (62.2 inches):    Weak El Nino
1995-96 (60.5 inches):    Weak La Nina

So what about the coming winter?  Right now, all indications point to a weak La Nina -- not the stronger one that looked possible just 4 months ago.  Warmer waters off the northwest coast, thousands of miles away, are actually preventing this year's La Nina from rapid cooling.  So, even though the Climate Prediction Center is predicting a La Nina winter, it looks to be relatively weak.  Current ENSO (El Nino Southern Oscillation) anomaly maps shows lighter blues in the Pacific:

If history is any guide, that could lead to a snowy winter in southern Wisconsin.

And that, deep into this post, is my first prediction for Winter 2016-17 in southern Wisconsin: above average snow, probably in the 60-70" range.

Here, then, are your Rippeology headlines for this winter:

1. Above average snowfall (including a very white Christmas);
2. More frequent light to moderate snowfalls and fewer "whoppers" -- as the stronger northern jet resulting from La Nina can favor Alberta Clippers over Texas Panhandle hooks;
3. Early cold and snow (and very possibly a white Thanksgiving);
4. Slightly below to below average temperatures (thanks in part to snow pack and #5...);
5. Up to 3 polar vortex events leading to extreme cold (I won't bore you with solar activity, but let's just say a less active solar flaring pattern can aid the vortex).

About that early cold: there are some solid indications that the last half of September and most of October will feature below-normal temps in the Midwest.  Technically, that's fall, not winter.  But it could certainly be a precursor to an active November.

There are plenty of other factors that could still shape our winter.  Hurricane activity is one of those, and there are still 8 weeks to go in the Atlantic hurricane season.  If anything changes, I'll let you know.  Otherwise, stay tuned to Rippeology for the next 6-7 months for the best amateur winter weather forecasting in New Glarus (disclaimer: small sample size).

And if you prefer to get your medium to long-range weather from an actual pro, there are none better than Jeremy Nelson at WISN-TV12 in Milwaukee.  Follow him on Twitter here.

~Scott

P.S.  New to Rippeology?  See how it all started in my inaugural post.




 

Here We Go...

Let's get right to this.

The computer models have now nudged the track of the low north again, right over Chicago, where they had it tracking early yesterday.

 

There's good news and bad news if you live in the Madison/New Glarus area.

Good: heavy snow stays to our north.  The Green Bay/Fox Valley area should get the brunt, and the heaviest totals will extend back toward Tomah.  Confidence level here is about 80%.

Bad: as temperatures fall to and below the freezing mark, there's a better chance now that we will see freezing rain and/or sleet in our area.  That mixed pre-slopitation will change to all snow as the low moves away Thursday morning.  Confidence level here is about 60%.

So, the question becomes: when will our temperatures fall to freezing, and will the ice stick?  Let's walk through the day tomorrow....

We'll have periods of rain throughout the day tomorrow (possibly even some rumbles of thunder).  Temperatures will struggle to get out of the 30s.  Wind will pick up throughout the day as the low gets closer.  Persistent northeast wind will lower temperatures slowly, until we finally hit the freezing mark sometime between midnight and 3am tomorrow night/Thursday morning.  Rain will continue fall, but will freeze on some surfaces on contact.  How much ice accumulations will depend on: 1) how quickly surfaces cool after a warm day today; 2) how heavy the rain gets, and 3) whether trucks get out and apply salt. 

Here's how the models see temperatures in our area at midnight:

The low will start to pull away mid-morning on Thursday, and at that time, precipitation should change to all snow.  I'm thinking about a 6-hour period of snow, falling at an average rate of a half inch an hour, giving us about 3 inches of total snow.

That's not much, unless it's falling on top of ice.  Personally, I think the roads will take some time to cool, so I'm not expecting much ice accumulation, if any.  But it's worth watching.

For my friends to the north, I think the highest totals will be in the 10-14" range, with the highest amounts WSW of Green Bay.  Slightly closer to home, areas about 50-70 miles north of Madison could see some brief thunder snow, which could cause locally higher amounts.

The fresh model runs look like this.  The highest totals are overstated, but the locations of the heaviest snow seem to be spot-on.

The main concern in south-central Wisconsin will be road conditions on Thursday morning.  Let's all take the responsibility to share what we're seeing/hearing via social media.

I'll update forecasts tomorrow if anything changes!

Deconstructing Goliath; Bonus January Outlook

One of the benefits of being a hobby/amateur forecaster is that I really have no "skin" in the game.  While I really do want to give you good insight and accurate forecasts, my career doesn't depend on doing so.  So, unlike the pros, I'm happy to admit when I made a miscalculation in the spirit of learning and doing better next time.

While I realize I'm grading my own homework here, I thought it might be fun to deconstruct yesterday's storm against my own forecast.

What I Got Wrong:

1. The biggest thing I got wrong was the high temperature, and that impacted other parts of the forecast.  I predicted a high of 33, thinking that the warm air wrapping around the low would drive up the temperature as the system approached in the late afternoon.  Instead, I recorded a high of 28 in New Glarus -- also the official high at the Madison airport.
2. Because of the colder temperatures, we saw more snow accumulation than I expected.  I predicted 2-4".  Madison's official snowfall was 5.9", and here in New Glarus, I measured 4.5".  Still within the meteorological margin of error, I suppose, but I was low nonetheless.

Here's what the early snow totals look like around the region (click to enlarge).

What I Got Right:

1. First and foremost, I was ahead of this storm by 6 days.  While it's risky to start talking about a December 28th storm on December 22nd (as I did on Facebook), I felt that with the holidays and folks traveling, the reward outweighed the risk.
2. I got the "pre-slopitation" right.  Here in New Glarus (and nearly all other locations I was tracking), we had sleet, freezing rain and snow.  In fact, the sleet was steady for almost a 5-hour period between 2pm and 7pm, when precipitation changed back to snow.
3. The wind forecast was also correct.  The highest speed I recorded was 34 MPH, but other reports were as high as 60 MPH (which I accurately predicted would occur in the far southeast corner of the state).  
4. I mostly got the timing right.  I said the storm would start mid-morning.  Here in New Glarus, it started at 8am.
5. Finally, and this might actually be the most important thing, I said in a Saturday Facebook post that driving would be a really bad idea on Monday.  Safety is important to me in winter forecasts.  As you probably heard, emergency services responded to hundreds of crashes, rollovers and slide-offs in southern Wisconsin alone.

With that, let's look ahead to what January may have in store.

All models are currently showing a southern jet stream through at least the third week of the month.  This allows colder Canadian air to infiltrate the Midwest, setting us up for seasonably cold temperatures.  I don't see any polar vortices on the horizon; in fact, there's a chance we could get through January without even seeing subzero temperatures.  I don't know if that's ever happened before in January, but I'm looking into it with the State Climatology Office.  I'll keep you posted.

At the same time, major storm systems for the first couple weeks of January seem like they'll be relegated to both the east and west coasts (a trademark of El Nino winters), with very little action here in the Midwest.  The GFS model is showing a weaker disturbance next Thursday, January 7th, so I'll keep on eye on that.  Otherwise, there's not much out there.  Of course, that can change.

Finally, I want to say "thanks" to those of you who are genuinely interested in Rippeology.  Obviously, I enjoy it, but it is a bit of work.  Since Saturday, the blog has had over 250 visitors, which is pretty cool.  I appreciate your interest!

As always, let me know if I can answer any questions for you, either here or on Facebook.

~Scott

The Ice Man Cometh

In my November 13th winter preview post, I predicted, among other things, "more ice events" than usual this winter.  That should start to materialize tomorrow in Southern Wisconsin.

In fact, with temperatures hovering between 29 and 35, depending on your location, we could see the full gamut of winter pre-slopitation Monday and Monday night, including freezing rain, rain, sleet and snow.  Oh, and a shit-ton of wind.

Officially, the National Weather Service has posted a Winter Storm Watch for all 72 Wisconsin counties.  But the nature of the storm will be very different from north to south.

Here's the scoop:

The same intense low pressure creating extreme blizzard conditions right now in parts of New Mexico and Texas will push northeastward toward central Illinois overnight tonight.  Normally, this kind of "panhandle hook" track (explained here) would put much of Wisconsin in a heavy snow area.  But with El Nino's influence, this low will be so strong that it will wrap warmer air all the way over to the northwest side of the low.  With that warm air aloft, precipitation then starts as rain, and ends up falling to the surface either as sleet or ice, depending on the surface temperature.

Here's how the National Weather Service sees the map shaping up for 6am Monday (and remember, you can click on any image to enlarge):

That orange color represents freezing rain.  You'll see the low positioned in extreme southwestern Missouri.  What happens after that depends completely on where the low goes from there.  A track toward Rockford or Chicago keeps us in relatively "warm" space, meaning that rain and sleet are more likely.  A track toward Detroit puts us in a colder position, meaning more snow and freezing rain.

The GFS weather model, which forecasters rely on to predict the position of pressure systems, seems to split the difference between those tracks -- maybe just east of Chicago, but just west of Detroit.  These two images show the 12-hour advance of the low...

 

In all winter storms, pinpointing the track of the low is the key to accurate forecasting.  But in this storm, low track is even more important, because temperatures will hover right around the freezing mark.  That means that two areas only 10 or 20 miles apart, with only a 1-2 degree temperature difference, could see completely different types of precipitation at the same time.  

In fact, the only thing really certain about this storm is wind.  As the low gets closer during the day tomorrow, look for east/northeast winds to gust as high as 35-45 MPH.  This wind forecast shows lower Lake Michigan taking the brunt of the strongest winds:

Wind and ice, as all Wisconsinites know, is a terrible combination if you want to drive somewhere.  And an extra word of caution about that driving thing -- you may step out of your house and office, and driving conditions will seem fine.  But 5 miles down the road could be a completely different story.  If you are on Twitter, and you absolutely have to drive Monday or Monday night, keep your Twitter feed on Madison Traffic, 511 Wisconsin and Ready Wisconsin for timely updates on weather, traffic and crashes. 

If ice accumulates to more than a tenth of an inch -- which is likely in parts of South-Central and Southwestern Wisconsin, power outages and downed trees are also a distinct possibility.  So today is the day to get prepared for that eventuality.  Ice of a quarter inch or more is considered an extreme ice storm, and that can't be ruled out in some locations.

Mateo Earth models show New Glarus right in the sleet/ice (yellow) band for a lengthy period of time.  Here's 1:00pm Monday and 1:00am Tuesday:

Okay, I'm sure that's a lot more than you wanted to know about freezing rain.  What about the snow?

We can be pretty sure that snow amounts will be lowest in the far Southeastern part of the state, and highest in the Northwest.  Some locations won't see any snow at all.  In the New Glarus and Madison areas, I think we see 2-4 inches as the low passes to the east on Monday night.  That's not much, unless there's a layer of ice and sleet underneath it.  

So here's my official New Glarus forecast, subject to change as I watch the low progress today:

Monday:  Sleet and freezing rain starting mid-morning, changing to all rain for a brief time in the early afternoon, and changing back to sleet and freezing rain around sunset.  Total sleet and ice accumulation about 0.15 inches.  High 33.  Strong east wind of 15-25 MPH becoming northeast late in the day, with gusts up to 40 MPH.

Monday night:  Sleet turning to snow in the evening, accumulating 2-4 inches before diminishing late.  Winds remaining strong and gusty from the northeast, creating blowing and drifting snow.  Low 29.  

If you're traveling to the north or northwest Monday or Tuesday, look for snow totals as high as 8-14 inches toward the Eau Claire area.  

FYI, there is another chance of light snow on Wednesday, as a weaker system approaches from the west.  Late this week, we'll see our coldest temperatures of the season, with highs only getting into the teens in most places.

I'll take your questions both here and on Facebook!  And remember, you heard about this storm on Rippeology before anyone else was talking about it.  First post was last Tuesday morning on Facebook.  Just sayin'. 

Amaze Your Friends During Tonight's Storm

Wanna really geek out (like me) on tonight's snowstorm?  Here are 3 ways to amaze your friends with your meteorological savvy:

1. Pay attention to wind direction.  For most of the day and evening, the wind will be coming from the west.  When it starts to switch counter-clockwise -- first to the southeast, then to the east, then to the northeast -- you'll know that the heaviest band of snow is imminent.  That's because the heaviest bands of snow always fall to the northwest of the center of the low pressure system.  So, if the low is centered just south of Chicago, for instance, the counter-clockwise wind will put us in a northeastern wind, and to the northwest of the low -- the perfect recipe for a heavy snow band in south-central Wisconsin.
2. Strike up a conversation about "water content."  Fun fact: in a typical Wisconsin snowstorm, ten inches of snow would equate to one inch of rain -- meaning the water content in the snow is only about 10%.  When snowstorms come from the south, bringing gulf moisture with them, water content can be more like 30-40%.  This particular storm, however, will have even less water content than the average storm, because it has very little oceanic moisture to draw from.  The snow develops not because of moisture, but because of strong energy and lift in the upper atmosphere.  
3. Talk climatology.  And deer hunting.  Here are some fun facts: A) the average November snowfall in our area is about 2.5 inches; B) if we get 9 inches of snow, that will amount to 20% of the 45 inches we usually get in an average winter; C) the first regulated Wisconsin deer hunt was in 1851; D) last year on the eve of gun season, a warm front came through on Friday night, resulting in fog advisories on Saturday morning.  Near my house, at least, this didn't stop people from shooting at things they thought might be deer.

Any other fun stuff you want to know?

Storm Track, Intensity Now More Certain

Did your iPhone beep at 4:15 this morning?  That's because southern Wisconsin is now under a Winter Storm Warning.

Now just 12 hours in advance of the season's first major snowfall, the track and intensity of the storm appears even more certain.  Many models show the storm as more intense, and not quite as compact, as what was previously thought.

Snow should start right around dinner time tonight.  I'll be watching it from Kristi's Restaurant in New Glarus.  It'll get heavy at times overnight and start to taper late tomorrow morning -- except for those of you in far southeastern Wisconsin, where some lake enhanced snow will linger until late afternoon Saturday.

I'm going to stand by yesterday's predictions, knowing that I might be a little low when all is said and done.  It's quite possible that New Glarus could be more in the 8-9" range, rather than the 6-7" I predicted yesterday.

Here are some of the vital maps.  Click any image to enlarge.

First, the watch/warning area.  Areas in pink represent a Winter Storm Warning.  This is a wider north-to-south area than what was originally expected.

Here's The Weather Channel's current snowfall forecast, putting extreme southern Wisconsin in an 8-12" area.  They've named this storm "Bella."  I hate this practice of naming winter storms.

Here's the local WISC-TV snowfall map.

Here's the text of the Winter Storm Warning.

And finally, here is my list of the vital preparations you should take today:

• Get gas and oil for your snowblower; test start your snowblower
• Stock up on booze
• Find some sucker to take your Badger football tickets tomorrow
• Watch this video from my favorite amateur weather forecaster

Let me know if you have any questions or additional preparation tips!

Friday Night Snow in Southern Wisconsin

Deer hunters must be absolutely giddy about this.  When gun season opens Saturday morning, they'll be greeted by a fresh blanket of snow with which to track deer and keep their Busch Light cold.  

We're still a good 36 hours away from it, but there's some agreement in some computer models about southern Wisconsin's first snow event of the season.

There is significantly less agreement among forecasters about how much snow we'll get.  Forecasts still range from completely non-committal, to "light accumulations" to AccuWeather's aggressive 6-10" forecast.  Here's that map:

Officially, the National Weather Service has issued a Winter Storm Watch from 6pm Friday to 3pm Saturday.  That watch calls for snow ranging from 4 to 7 inches in extreme southern Wisconsin (Madison and Milwaukee included) and Northern Illinois.

Here's what's pretty certain:

• Low pressure will approach from the west late Friday
• It'll be a pretty fast-moving system
• Temperatures will support mainly snow, as a cold pocket sets up today and tonight
• It'll drop the heaviest snow in a narrow, elongated band
• Temperatures Saturday night will be the coldest of the season (mid-teens with single digit wind chills)

What's less certain:

• Exact track of the low, although most models show the Wisconsin/Illinois border as a primary focal point
• System strength (how low the pressure gets)
• The potential for brief lake-effect snow midday Saturday along Lake Michigan (from Sheboygan to Kenosha)

Storm track is always a key ingredient in predicting how much snow will fall in any one place, but in this case, the track is particularly important.  That's because the storm is very compact.  A nudge to the north or south changes snow totals dramatically.  If it does nudge, I think it nudges south.  Here's how Mateo Earth sees it at 4:00am Saturday morning...

Here are my early projections for snow fall, starting 6pm Friday and ending Noon Saturday:

Wisconsin Dells:  1-2"
Madison:  5"
New Glarus:  6-7"
Milwaukee:  7" (possibly more at the lakeshore)

Updates to come, especially if the track fluctuates!