GFS isn't showing it. The Euro isn't showing it. But it looks to me like conditions may be right for some wintry weather in our area starting next weekend.
Let's start with the surface map for Friday morning, November 2nd:
That low to our south looks to be a slow mover on Friday and Saturday. Depending on how it ultimately tracks, it could produce some snow in the upper Midwest on Friday night.
There are plenty of indications that we'll have a sufficient cold pocket in place to support snow over a 7-10 day period, starting with that low on Friday.
There's the Euro ensemble throwing down cold...
GFS showing anomalous cold in the middle part of the country...
The CFS weekly with troughiness in the middle of the country for the 11/3-10 period...
And the day 10 GFS showing a clear path for low pressure systems out of the Gulf of Alaska to make their way to the center of the country...
All of these indicators of cold and energy would suggest the possibility of wintry weather. It's far too early to get more specific than that, but now you know what I'll be watching for over the next several days!
It's been over a year since I blogged on Rippeology. Last year's winter forecasting was done almost entirely on Facebook, and for those of you who followed along, thank you. I was very happy with the way last year's forecasts verified.
So, apparently I post a lot about weather.
Before we take a look into the Winter 2018-19 crystal ball, a few notes for those of you who might be new to Rippeology:
I'm not a meteorologist. I'm a self-taught weather hobbyist who has geeked out over this stuff since I read my first weather book at age 7. I don't suck at it, but I wouldn't plan your March wedding around this forecast either.
Like almost all of my weather forecasts, this one is specific to southern Wisconsin. If you live somewhere else and need some prognosticating, feel free to ask me on Facebook.
In the event you find it stupid that anyone would barf up a winter outlook this early in the season, let me say this: there's a high degree of confidence in the guidance already available. I could wait another month, but with the exception of some clearer definition around long-range patterns (LRC, for example), I don't expect much to change. So a forecast today would be pretty similar to one I might issue closer to Thanksgiving.
Finally, the impatient among you are welcome to scroll all the way down to the end of the post for the summary forecast. That, however, would make you a bit of an asshole, considering I put a lot of work into this. So if you do that, don't tell me you did.
All that being said, let's get to it.
First, let's set the stage with some basic information:
Average snowfall in Madison is about 50" per year.
Last year, Madison got about 44" of snow. About half of that fell from mid January to mid February. Follow the green line (click any image to enlarge):
Last year, we experienced a couple of pretty cold periods: from December 23rd to January 6th; from January 13th to 17th; and from February 2nd to 12th. Also unseasonably cold in early April.
Any winter outlook should start, in my opinion, with a look at ENSO trends, or El Nino Southern Oscillation. You've heard of El Nino (warmer than average sea surface temperatures in the eastern equatorial Pacific Ocean) and La Nina (cooler than average temps in that same region). Those temperatures impact global weather, sometimes mildly, sometimes extremely. Here's a typical Nino winter in North America:
Generally speaking, El Nino results in a somewhat warmer and less snowy winter for us in Wisconsin. La Nina generally produces the opposite. Remember the winter of 2007-08 and our record 102" of snow? That was a moderate Nina year.
But these are not absolute predictors.
Last winter, weak La Nina conditions were present and our snowfall was just a bit under average. This year, the Climate Prediction Center estimates a ~70% chance of El Nino conditions developing in the Nov/Dec/Jan/Feb period.
In fact, most models predict sea surface temperatures between 0.5 and 1.5 degrees (Celsius) above normal. We can categorize that as a weak-to-moderate El Nino.
Knowing that, we can look back at Madison winters with similar moderate Nino conditions. It happened in the winters of 2002-03, 2009-10, and 2014-15. Here's Madison snowfall for those 3 winters:
2002-03: 29" of snow
2009-10: 52" of snow
2014-15: 34" of snow
So what the hell happened in 2009-10? An 18" blizzard on December 9, 2009. Video:
Take that freakish storm out of the equation, and all 3 of these weak-to-moderate Nino winters produced about 40% less snowfall than our 50" average.
So, if ENSO modeling was all we had, we'd be looking at a better than 50/50 chance of below average snowfall for Madison this winter. But there's more to consider.
For instance, we know that snow cover in Canada is already running way above normal right now.
Why is that important? Because snow pack further cools the Canadian air that will continue to spill south throughout the fall. The temperatures we've been experiencing in October have been much below normal, due in part to the snow-cooled air that follows the cold fronts coming through southern Wisconsin. If that continues (and there's no reason to believe it won't), the colder air interacting with surface lows in our area is likely to produce frozen precipitation a little earlier than we might otherwise expect it.
That, and the fact that El Nino won't fully set up until mid-winter, is a hint of early snow in our neck of the woods.
What else we got? Well, we have models up the wazoo. Meteorologist Ben Noll publishes them on his website (click on "snow maps" in the upper right).
The ECMWF (Euro) model thinks we'll have below average snowfall every month except, possibly, December.
The UKMET model thinks we'll have above average snowfall January through March, with February being especially snowy. But the British are prone to hyperbole.
The MeteoFrance model agrees about a snowy February, but thinks every other month will be below normal.
As far as temperatures go, the CFS monthlies have us above average every month except February.
See a trend there? With the exception of the Euro, models are currently pointing to a colder, snowier February.
So which models do we trust? All of them combined, but none of them individually. What I really look for in these long-range models is some level of agreement. And we have that to some degree.
Let's get to it then.
SUMMARY FORECAST:
OMG, did you actually scroll all the way down here without reading the rest?
OK then. Here's where I think we are. We get 3 phases of winter:
November and December: average snowfall (about 18-20"); average temperatures.
January to mid-February: below average snowfall; slightly below average temperatures until we start to see Nino impact.
Mid-February to early April: slightly above average snowfall; slightly above average temperatures.
All totaled, I think we finish the winter 10-25% under our average snowfall, and while there will be occasional cold spells, I don't see a prolonged deep freeze for us.
STUFF YOU'LL ASK ME:
Snow for opening weekend of gun season? Probably not, or at least not much.
A white Thanksgiving? The RRWT guidance indicates a cold snap November 21-26, so a snowy Thanksgiving weekend isn't out of the question.
A white Christmas? Likely.
Best time to take a warm weather vacation? Last two weeks of February.
Now, do me a favor if you would. Go back to Facebook and share my original post linking to this blog. The more people following Rippeology, the more fun I have doing weather for you guys.
The Autumnal Equinox arrives at 3:02pm Wisconsin time on Friday, September 22nd. That's the time that the sun shines directly on the equator as it passes from north to south, giving the entire planet nearly equal day and night.
In the southern hemisphere, that exact same time marks the Spring Equinox.
Here are 3 predictions for the fall season in southern Wisconsin, which lasts until December 21st:
1. Fall colors will be spectacular
Summer weather -- both during and after the growing season -- has a great impact on the color display we see in the fall. This summer's conditions have been perfect:
A lot of rain during the height of growing season (July). At my house, we recorded 11.5 inches of rain in July, although the Madison airport recorded a bit less than 7 inches.
That was followed by an unusually dry, cool and sunny period, particularly in the last half of August and early September.
The timing of those conditions is nearly perfect for an excellent color show. The dry, cool nights of late August allow chlorophyll to be blocked from the leaves of the tree, giving the vibrant oranges, reds and yellows an opportunity to take over.
There is one caveat here: some places that received too much rain mid-summer (the southwestern corner of the state, for instance) could have problems with fungus and early dropping of brown, dead leaves. Location is everything.
The August cool spell may also result in a slightly earlier peak than normal -- perhaps the first week of October (instead of the middle of the month).
2. In the short term, temperatures remain mild, but...
The 3-week period of unusually cool weather has been replaced by very summery conditions. While not technically an "Indian Summer," which by definition can only occur in November, our recent warm spell certainly feels like summer in Wisconsin.
In the short term, that trend will continue. The same strong high pressure in the eastern U.S. that's keeping recent hurricanes Jose (and probably Maria) off the coast creates a ridge that southern Wisconsin benefits from. Winds rotate clockwise around high pressure, bringing us a southerly flow that keeps temperatures warm.
Models now expect a new pattern to take shape in early October, and it won't likely relent very soon. Look for a normal or below-average October, which will likely produce our first hard freeze. Follow me on Facebook for the latest in medium-range weather observations.
3. Developing La Nina may result in an earlier, harsher winter
La Nina -- the cooling of sea surface temperatures in the equatorial Pacific Ocean -- seems to be taking shape somewhat rapidly. Weather models are now suggesting that a moderate La Nina may be in effect by November or December.
Generally, La Nina results in colder, snowier winters in our part of the country (as opposed to milder winters sponsored by El Nino). This is because La Nina promotes certain storm tracks that are conducive to heavier snow events (including the mother of all winter storm tracks, the Texas panhandle hook).
Last year's winter essentially only lasted a month (which blew my Winter Outlook all to pieces). December was very snowy, but the rest of the winter was, by and large, relatively mild. El Nino was in place last winter.
This year, I'd expect our first significant snowfall to occur around or before Thanksgiving. That would be two-thirds of the way into the fall season.
Have questions? Post them here or on Facebook and I'll do my best to answer!
If I was going to get a meteorology degree, and I could
choose my own teacher:Jeremy
Nelson (dude is onto something with the BSR and LRC stuff, and owns a lot
of colored pencils)
Social Media Follows:
Best Twitter account that will get you pumped about chasing
storms:Reed Timmer
Best Instagram account by a meteorologist: Jeremy Nelson
Like every other science, the study of weather is a continual learning experience. When I see professional meteorologists use a term or idea that I don't know, I study it. For the last month, I've been geeking out on Atlantic/Pacific oscillation patterns and how they impact the lower 48. The learning part is a lot of fun for me.
I also try to learn by evaluating my own forecasts. For instance, with this latest storm, I've learned that many Rippeology followers don't have the appetite for a 13-minute video. If I do video again, I'll cut that down by two-thirds. Promise.
But I just watched that video again and took inventory of what I got right and what I got wrong. Here's that:
Got right:
Issuance of Winter Storm Warning to cover
southernmost counties on Thursday;
Dusting of snow Friday morning;
Snow totals of 7-11”;
Highest snow totals (lake enhancement) in the
east and southeast;
Frozen precipitation in northern Illinois;
Extreme cold behind the storm
Here are the preliminary snow totals from the National Weather Service out of Sullivan/Milwaukee, which shows the concentration of 8-12" (in orange) in the eastern part of the state.
Got wrong:
Timing/intensity: didn’t expect the 9-hour lull
between rounds one and two, and thought heaviest snow would be Friday night;
Leaning on Kuchera conversion ratio from liquid
to snow (10:1 method averaged out much better);
Low track – slightly farther south/east than
anticipated
So that's a learning experience for me. Thanks to all of you for being patient (and interested) as I continue to study.
That's the look-back. Now, let's look ahead at what the coming week might bring...especially as we get closer to weekend holiday travel.
First, you'll be happy to know that today's sub-zero high temperatures are the coldest we should see for the rest of December. As I mentioned in Wednesday's video, we're going to get a bit of a warm-up as the week wears on. The upper 20s and low 30s (maybe mid 30s by Friday) will feel downright balmy. Shorts weather!
There are a couple shots at precipitation in the next 7-8 days. The first is Wednesday. A relatively weak Alberta Clipper is forecast to move through -- mostly impacting the northern part of Wisconsin. This could be a 2-3" snow event, if it materializes at all. If you're traveling north Wednesday, I'll help you keep an eye on that.
The second potential system will be Saturday or Sunday. Both GFS and ECMWF set up a boundary in our area between that milder air and some colder air pushing in from the west/northwest.
GFS has this boundary at 6am Sunday...
While the Euro sets it up 12-18 hours later...
Generally, a transitioning of air masses results in some precipitation in between. But it's too soon to tell if this sets up in the Great Lakes region or a little farther south. I'll watch the Saturday through Monday models throughout the week and keep you posted.
If you're getting on an airplane Thursday, Friday or Saturday, I don't see anything major in the lower 48 that would cause widespread delays or cancellations. Of course, it's still very early. Sunday/Monday bears watching.
If you have specific travel plans that you want to discuss, just let me know! Otherwise, I'll update this post throughout the week as models begin to show more clarity. In the meantime, stay warm!
I'm just going to go ahead and assume that most of you look at multiple forecasts when you're interested in the weather -- rather than just relying on Rippeology. If you're doing that, you're seeing some forecasts "back off" yesterday's projected totals a bit, putting southern Wisconsin more in the 5-8 inch range for this weekend's storm.
Here are the National Weather Service snow maps from yesterday and today. Note the retreat in snow totals.
Yesterday, I predicted 8-11 inches. I'm sticking with that forecast today for 5 reasons. First, nothing about this storm has changed in the last 24 hours. Timing, temperature, intensity and duration are all nearly identical. The only thing that has changed slightly is the location of the low pressure development (see the last point below), and that actually works in favor of my slightly higher totals.
Second, there are two pieces of energy in play here, and at some point, they will combine into one. Bernie Rayno from Accuweather did an excellent job of explaining this in his video yesterday. When and where those two pieces of energy combine makes a huge difference. As I draw it out on paper, I have them combining somewhere near Waterloo, Iowa (my birthplace!), which bodes well for higher snow totals in southern Wisconsin. Because...
Third, as the low strengthens and tracks through northern Illinois Sunday, it seems inevitable to me that the low will shoot heavier snow bands to its northeast -- right in the direction of southern Wisconsin. With southeast winds and strengthening energy to the south/southwest, it just makes sense that some bands in our area will briefly produce snow rates at 1-2" per hour. That alone can pad snow totals in a short period of time.
Fourth, this is a 30 to 36-hour storm. Pretend for a moment that the average snow rate is only a quarter of an inch per hour. That's 8-9 inches. Granted, we'll see some periods where the snow rate is .10 to .25 inches an hour...but all it takes is a couple of hours in heavier bands (as discussed above) to rack up the snow totals.
Fifth, this morning's models have the low developing farther south than prior runs, giving it the ability to tap some gulf moisture before heading in our direction. GFS has the low moving out of the Texas panhandle and into Oklahoma by Noon Sunday. This, too, suggests the possibility of some heavier bands.
Everybody interprets model data differently, and the dynamics of this storm are only now really starting to set up. Truth will reveal itself at some point when the snow finally stops while we're all sleeping Sunday night.
