It's Complicated

If you want to skip the set-up and get straight to the 7-day forecast, scroll down.  But don't tell me you did that.

Yup, complicated.

So complicated, in fact, that some forecasts for south-central Wisconsin are warning of the possibility of "several inches" of snow on Christmas Eve day (Channel 3), some are calling for mostly rain and just a bit of snow (Channel 27 among them), and some are being completely non-committal or taking the very unhelpful "maybe" approach to forecasting (like the National Weather Service and The Weather Channel).

NWS goes so far as to whip out the dreaded "significant uncertainty" crap...

Notice how the NWS completely skips over Wednesday in the graphic above, opting to show the easier-to-predict Tuesday and Thursday instead.  Cowards.

The one thing we all agree on is the exact thing that makes it so complicated: low pressure will approach southern Wisconsin from the west on Tuesday, and sometime Tuesday night or early Wednesday, it will combine with another low to the east, strengthen significantly, and then essentially stop in its tracks to our northeast.

Two factors create the "significant uncertainty":

1. The exact track of the first low.  If it moves directly over southern Wisconsin, as the image above and some other forecasts seem to suggest, we'd experience southerly winds on Tuesday and all precipitation would fall as rain.  If it tracks to our south, over northern Illinois, the low would wrap cold air into southern Wisconsin and Tuesday precipitation would fall as snow.

2. Where the intense "combined" low decides to slow down.  If it slows just east of upper Michigan, it drives bands of strong winds and moderate snow behind it, counter-clockwise, from the north, during the day on Wednesday.  If it moves farther to the east, we still get strong winds but less snow.

So there's one thing we can be confident about: wind.  Lots of wind from the north and northwest on Wednesday.  Add some snow into the mix, and travel will be a bitch.

Rippeology sees it thusly:

A strong southerly flow (which will actually start setting up late today) will prevent the first low from dipping too far south, which puts the low over southern Wisconsin on Tuesday.  That means rain Monday night and Tuesday.  Then I see the lows combining near Lake Huron on Tuesday night, slowing, and kicking back the wind and moderate snow on Wednesday.  Winds remain strong on Thursday, until another low approaches from the southwest on Friday to accelerate the storm to the northeast.

We'll get to that Friday low in the 7-day forecast below.

Of the 6 weather models I studied this morning, this one best represents what I expect on Wednesday:

Where I depart from this surface forecast, however, is that I think the combined low is strong enough to kick snow back further to west than what is indicated here.

This NOAA model shows heavier bands of precipitation on the back side of the low:

I tend to favor that line of thinking.  If you'd like to see the full animated loop of the above, taking us from now until Wednesday morning, click here.

I'm putting a lot of focus on Christmas Eve because of travel implications, but it's not the only area of concern in the next 7-10 days.  As we come out of the mild spell that I predicted back on December 2nd and head into a significantly more active weather pattern, there are multiple weather events that could impact southern Wisconsin between now and the new year.  One is that low pressure system I mentioned above for Friday the 26th; another storm could impact us on Monday the 29th.

Here's the 7-day Rippeology forecast for the New Glarus/Madison area:

Today: Mostly cloudy, light winds, high of 33.

Tonight: Cloudy with areas of fog developing.  South winds will squeeze a little moisture out of the upper atmosphere, resulting in some light freezing drizzle later tonight.  Low 26.

Sunday and Sunday night: Still cloudy, with drizzle (daytime) and freezing drizzle (nighttime) continuing.  A few flurries may mix in.  Winds start to increase from the south and southeast.  High Sunday of 37; low Sunday night of 30.

Monday and Monday night: Yup, more clouds. Rain (mostly light) develops late in the day as that first low approaches from the west, and continues through the night.  Breezy.  High Monday of 37; low Monday night of 32.

Tuesday and Tuesday night: Rain decreases for a time during the day as the low passes over southern Wisconsin.  Winds continue to increase from the south, then switch to the northeast at night.  Rain changes to snow late Tuesday night, with up to an inch by morning.  High Tuesday of 38; low Tuesday night of 30.

Christmas Eve: Very windy with snow.  Accumulations of 2-4 inches.  High temperature of 32 early in the day; temperatures fall to the mid 20s by late afternoon.  Snow tapers Wednesday night but strong winds continue, creating some blowing and drifting, especially on east/west roads.  Low Wednesday night of 22.

Christmas Day: Still breezy, with some peaks of sun as the combined low starts to push well into eastern Canada.  High of 29; low Christmas night of 20.

Friday: Winds switch to the south as another system approaches from the southwest.  Becoming cloudy with snow developing late.  I'll update accumulation predictions as we get closer.  High of 31.

Looking farther ahead: another snowstorm is possible early the week after Christmas, followed by colder temperatures.  New Year's Eve could be pretty chilly!

Questions?  Feel free to leave a comment.  As always, when something changes, I'll update it here on the blog.  After all, it's complicated.  And there is significant uncertainty.  :)

Dreaming of a White Christmas?

We might fall just a couple of degrees short of today's 50-degree prediction that I made earlier in the week, since the dense fog isn't really conducive to temperature fluctuation.  Still, I think we'll hit 47 or 48 today, and again tomorrow.  The fog isn't going anywhere anytime soon.

So the mild weather may have you wondering about the chances for a White Christmas in southern Wisconsin.  With 11 days to go, here are the three snow chances I see between now and Christmas Day:

1.  Tuesday afternoon (12/16):  low pressure moving out of the southern plains will bring light rain Monday and Monday night.  As the low moves into southeast Wisconsin Tuesday morning, there is a chance for some snow showers to wrap in behind the system.  Chances are much better in northwest Wisconsin, as it'll take awhile for temperatures to fall after 4 straight days of mild weather.  Rippeology's chance of 1" or more on Tuesday: 30%.

2.  Saturday (12/20):  A couple of days ago, weather models were indicating a potentially strong storm for southern Wisconsin, but as of this morning, those same models are taking that storm on a more southerly track, as pictured here:

Surface forecast for Saturday afternoon (12/20)

This forecast could change again in the next 6 days, but I don't think it will.  Multiple high pressure systems to our north will likely block the southern storm from tracking much farther north than this model predicts now.  Rippeology's chance of 1" or more on Saturday: 30%.

3.  Christmas Eve (12/24):  A system coming out of western Canada (an "Alberta Clipper," for fellow weather geeks) could bring some snow late Tuesday (12/23) into Christmas Eve day.  Generally, these systems bring light, dry snow.  Since many of you (and me) will be traveling on Christmas Eve day, I'll keep a close eye on this.  Again, much can change in 10 days.  Rippeology's chance of 1" or more on Christmas Eve day: 40%.

As for the temperature outlook, there are no indications of major cold outbreaks in the next couple of weeks.  We'll stay at or slightly above normal (which is upper 20s) throughout the next 10 days at least, with only slight variations in either direction.  Nighttime lows will mostly seasonal as well.

I'll update the chances of a White Christmas as forecasts change in the next few days.  In the meantime, feel free to read about the historical chances of a White Christmas over at climate.gov.

A Little Ice, Then A Warm-Up

How does 50-degree weather sound for the middle of December?

We could get there -- potentially for 3 straight days next Friday, Saturday and Sunday -- but we'll have to get through a slow Monday morning commute first.

A weak cold front from the west will go through Wisconsin tonight, bringing a mixed bag of precipitation as temperatures fall just below freezing.  Sleet, snow and light freezing rain are all possible, starting around midnight tonight and going through the morning hours.  A few more flurries behind the system will make Monday feel wintry.

If you get up and see snow on the ground tomorrow morning, test your driveway to see if there's a layer of ice underneath.  Just use a broom to sweep away an area of snow (away from the house) to see if ice lurks beneath.  If you're on Twitter, follow @MadisonTraffic to see what's going on on the roads.

After Monday, the warm-up begins.  Temps will slowly increase throughout the week.  Currently, it looks like sun and a southerly breeze will allow highs to reach into the 50s all weekend, before a new front brings rain late Sunday.  Last December, highs were 24, 23 and 20 for the second weekend of the month.

Boring, Boring, Boring!

I'm guessing 9 out of 10 of you (if there ARE 10 of you reading Rippeology) will be elated with the paragraphs that follow.  The other 10% are probably serious weather geeks like myself.

When I started this blog, I had visions of frequent snowstorms, complex weather patterns to challenge me, polar vortices, canceled school days, watches and warnings.  Stuff I could really sink my meteorological teeth into.

Sure, November was the 12th coldest on record in Madison.  And yes, there were a few threats of snow that turned out to be false alarms.  But if you were reading, you would have known they were false alarms.

December is setting up to be the boringest weather month ever -- little temperature fluctuation, mostly mild, and little precipitation.  ZERO. FUN. AT. ALL.

Here's why...

Wisconsin is currently nestled between two winter jet streams.  The jet to the north is keeping all of the cold air well up into Canada.  The jet to the south is keeping all the moisture from reaching the Midwest.  And both are far enough away from us to take winter storms in a different direction.

Here's a great example of what that pattern looks like in the upper atmosphere.  This forecast jet stream is for this Saturday.  Because we're stuck between these two jets, our winds will come predominantly from the west for the foreseeable future -- sometimes switching to the northwest (but without major cold outbreaks), and sometimes switching to the southwest (but without any moisture to speak of).

How long will it last?  Right now, I'd say 2-3 weeks.  Our average high temperature ranges 29-35 during that period, and westerly winds will allow temperatures to surpass those averages for the most part. 

So for the next 14 days (at a minimum), expect above average temps and below average precipitation.  Like I said, boring.

But if anything should change, you'll hear it here first.

Oh, and for those of you who were kind enough to try adding my name to this Weatherist poll, I am humbled by your confidence.  In case you're curious, Doogs got my vote.

The Week Ahead

So, yeah...about that 3-5 inches of snow...

In case you missed it, I went on record on Facebook just after 6am this morning and said I disagreed with the prevailing forecast that every local meteorologist was espousing. 

I was fully prepared to come home tonight and eat crow.  But I'm glad I don't have to.

I felt that snow totals would be lower for two reasons:

1.  While this low was very intense (my barometer said 29.12 inches this morning, which is the equivalent of many Category 3 hurricanes), it lacked a moisture feeder.  There was no southerly flow to pull moisture from the Gulf; there was no easterly flow to pull moisture from the Great Lakes.  So that told me it would be a "fine" snow that would not accumulate quickly on wet surfaces.  After a brief period of big, fluffy flakes during the rain-to-snow transition this morning, the snow did turn to that thin, slowly accumulating snow.

2.  The low was moving northeast too quickly.  To get 4 inches of snow, the low would have to "sit and spin" -- i.e., not move much, if at all.  But it was moving at a good clip even early this morning, and once it does, it's unlikely to stall.

So, here in New Glarus, we got one inch.  Madison looks more like two.  It's not fun to drive in, but it's not 3-5".

Here are the next precipitation events I'm watching...

Wednesday: a disturbance with a trailing cold front will stay mostly to the south of Wisconsin.  Any snow we get shouldn't amount to more than a dusting.

Friday (late): another disturbance will move through northern Wisconsin, but again here, anything we see in southern Wisconsin will be very light.

Next Tuesday/Wednesday: it looks like we may warm up considerably (but briefly) and see a spring-type storm that will bring rain and possibly a couple of thunderstorms.  As that moves out, colder air will settle in again, so rain may change to snow briefly before exiting.

As for temperatures, we'll stay cold through Friday, warm up slightly on Saturday, then cold again Sunday (low 20's if you're going to be at Lambeau Field like I am), and then the warm-up starts Monday.

Any questions?

Freezing Rain Advisory Tonight

On Wednesday, I warned about the potential for icing in southern Wisconsin tonight and tomorrow morning.  The National Weather Service is obviously reading Rippeology, because they issued a Freezing Rain Advisory early this morning.

It goes into effect at 11pm tonight and continues through 8am Saturday.  The advisory area covers points from Dane County southward into northern Illinois.

Here's the National Weather Service statement.

Freezing rain occurs when snow in the upper atmosphere mixes with warmer air in the lower atmosphere, changing the snow to rain.  When surface temperatures are below freezing, that rain freezes on contact.  Southern Wisconsin has not been above freezing since the early morning of November 11th, so the ground and roadways are well below 32 degrees.

The rest of the weekend is also setting up exactly as predicted on Wednesday -- light rain midday on Saturday and then tapering as temperatures reach the low 40s.  Expect rain Sunday and Sunday night, with precipitation changing to snow in the afternoon on Monday.  We could see an inch or two of Monday by Tuesday morning.

More pretty maps and prognostications coming this weekend to give you a better preview of the Thanksgiving holiday weekend.  In the meantime, stay safe if you're going to be later tonight!

Weekend Update (Sorry, SNL)

As promised, I've been keeping an eye on the storm system that we first discussed here on Sunday.  Here's what you need to know about the next few days:

Jet stream models have pushed to the east.  This means that the classic Texas Panhandle Hook set-up is now unlikely to occur.  Rather than one strong low pressure impacting southern Wisconsin, we'll actually see two weaker systems.

System #1 sets up for late Friday night into midday Saturday, bringing some mixed precipitation that could include icing.  If you plan to be on the roads Saturday morning, you'll want to keep an eye on this.  Temperatures will warm into the low 40s later Saturday, melting anything that froze overnight.

System #2 -- the low pressure system coming from the south -- passes through somewhat slowly on Sunday, bringing south/southeast winds and still-warmer temperatures.  This will create enough instability for intermittent rain showers.  As that low pulls north and east of us on Monday, it'll grab the colder air to the north and push it south.  Some snow will wrap in the backside of the system.  Right now, that looks like maybe a 2" event late Monday.

Here's what the Unisys model shows for Monday:

 

The blob of moisture over Wisconsin and Michigan will start as rain and change to snow later in the day.

Cooler air will settle in starting Tuesday, but not nearly as bad as what we've experienced this week.  Light west winds will keep the really cold stuff to our north.  

Looking Way Ahead: the milder west winds give way to another system late Thanksgiving night into Black Friday.  Here's the long-range jet stream model that shows a northwestern flow setting up on Black Friday:

 

This type of shift can lead to some light to moderate precipitation over Minnesota, Iowa and Wisconsin.  So that'll be the next potential storm to watch after we get through this weekend.

Any questions?  Feel free to leave them in the comments!

 

So, Yeah, It's Cold

The home weather station says it's 5 degrees right now.  That's what a Canadian air mass and some fresh snow cover will get ya'.

Here's how the week is shaping up for southern Wisconsin...

Here's a pretty picture of coldness.

Today and tomorrow: just plain cold.  Look for a few flurries this afternoon, with an afternoon high around 18.  Wind chills will approach zero.  Tonight, winds calm a bit as temperatures drop to around 6.  Tomorrow, it warms up to 19!

Winds will move around to the south Tuesday night, creating some instability in the upper atmosphere and a few snow showers.  Most spots will see 0.5-1.5 inches.  Watch for slippery spots Wednesday morning on your workday commute.

Then, a slow warm-up starts to take shape.  The weather will be pretty quiet the rest of the week as temperatures rebound a little closer to normal.  Saturday's normal high is 40, and right now, it looks like we'll hit that.  Any precipitation Wednesday through Saturday should be light and scattered.

Sunday/Monday is worth keeping an eye on.  See yesterday's post for more on the unsettled weather possible.  This is one of those tricky storms that could include rain, ice, snow or all of the above.  I'll be updating throughout the week on that next storm.

Have a great Monday!

Fast-Forward: Stormy Thanksgiving Week?

No three words excite southern Wisconsin forecasters like these: "Texas Panhandle Hook."

The term describes a low pressure system that forms near the panhandle of Texas -- Amarillo-ish -- draws abundant moisture from the Gulf of Mexico, and then heads northeast.  When the track of the low moves over Illinois into lower Michigan, Wisconsin becomes the prime target for heavy snowfall.

Such a scenario may be setting up for early next week, according to a couple of key computer models.

Here's the projected North American jet stream for next Monday, November 24, 2014:

You can see the noticeable dip in the jet stream just east of the Texas panhandle, and the movement back to the northeast, toward lower Michigan.

This image shows the projected path of the low, exactly as described above.

You can see the precipitation over southern Wisconsin.  After a brief warm-up next weekend (and by warm-up, I mean a few degrees above freezing), this storm would contain more than enough moisture to produce significant snowfall.

Quick meteorology lesson: for storms with this track, the heaviest snow will always fall on the northwest side of the low pressure system.  That's because winds move counter-clockwise around low pressure.  As those moist winds wrap to the northwest, they interact with colder, unstable air.  This provides lift in the clouds and generally heavy precipitation.

Am I predicting a big storm?  Not yet.  Eight days is an eternity in weather modeling.  But I'm watching it so you don't have to.

Welcome to Rippeology

True story: until the time I was 17, the only thing I ever wanted to "be" was a meteorologist.

My father was a TV news reporter/anchor when I was growing up in Milwaukee, so unlike most kids my age, I watched the 6:00 news every night to see his reports.  While it was cool to see my Dad on TV, I was really enthralled with the 3-minute weather segment -- especially when storms were in the forecast.

At that time, WITI-TV6 had Ward Allen and his puppet sidekick Albert the Alleycat doing the weather.  It was campy.  It was creepy.  It was weird. 

And it made it very difficult to take the weather seriously.

Then, Channel 6 hired a meteorological upstart by the name of Tom Skilling.  Skilling was a weather academic who took the science of meteorology very seriously.  So seriously, in fact, that he would have daily run-ins with Newsroom management over that damn puppet.  It wasn't long before Skilling issued an ultimatum -- either the puppet goes or he goes.

Skilling was not as happy as he looked.

An early newspaper ad

The decision was an easy one.  And off Mr. Skilling went, taking his weather academia to WGN-TV in Chicago, where he would rapidly earn a reputation as the best meteorologist in the country.

But in his brief time at WITI, Skilling hooked me.  He didn't just forecast the weather, he explained the weather.  He was a teacher who wanted all of his viewers to understand the science behind pressure systems, fronts, jet streams, troughs, disturbances, dry lines, Omega highs, Alberta Clippers, Texas panhandle hooks and everything else that impacted the weather in southeastern Wisconsin.

While I never formally studied meteorology (Carroll College didn't have a program, but offered me way too much financial assistance to turn them down), my inner weather geek never went away.  I was a closet wannabe meteorologist, reading books, watching The Weather Channel for hours on end, and later, studying on the internet.  To this day, I love testing my own interpretations of weather models and long-range forecasts, especially in the winter.

So Rippeology is a way to stay connected with the Skilling in me, put my forecasts to the test publicly, and live out a dream that went dormant but never died.

Welcome.