Looking ahead to next week

Dec. 17, 2014:  Now that we are almost a week out, I’m sure many are anxiously looking at the days ahead in the weather department to see how the weather may affect their holiday drive. We have a few things that may need monitoring.  The situation is still pretty fluid (I’ll explain why in a little bit), but here’s what we may be dealing with in the upcoming week to Christmas (we’ll be revisiting this topic as we get closer, and compare how the forecast can change getting closer to an event).  This is just a general outlook; we’ll provide specifics when we get closer to each storm.

There are two storms that could affect holiday travelers heading to or leaving the Stateline.  The first is a clipper-like system moving out of Canada for early next week.

A clipper system brings a chance for rain and snow early next week.

futuretrack2 A clipper system brings a chance for rain and snow early next week.

The models are differing on how fast and how far north or south to take this system, but in general, we are going to see chances for rain and snow Monday into Tuesday.  Clipper systems usually do not bring much precipitation in the first place, so this storm shouldn’t slow you down much if you are hitting the road ahead of the holiday. Be ready for wet weather, regardless.

futuretrack3futuretrack4

The second storm looks to be much stronger on the models.  They also disagree for now on the speed, strength, and placement of the low, but there does look to be wet weather for Christmas in some spots of the nation, especially as you head east into Michigan or toward New York. This storm looks to leave the Stateline alone, but there could be some travel issues ahead if you are leaving the area and heading toward the storm.

stay vigilant

The reason for the uncertainty on the storm tracks? The impulse in the jet stream that will create these storms are still taking shape and are out over the ocean. There are less sensors out over the water versus on the land, which means less data points for the models to mull over before reaching a solution.  As these storms make landfall, the picture can become a lot clearer.

Stay tuned to the forecast, especially over the weekend, for updates, and we’ll make sure we keep you up to speed on how these storms and the forecast is developing.  We want everyone who is traveling to be able to do so safely in order to have a great holiday! – Alex

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This post was written by Alex Kirchner on December 17, 2014

Pesky clouds

Dec. 10- This happens a lot in the winter: not only is it cold, the days are short so there is not much sunlight to soak up, but to add insult to injury, we have plenty of cloudy days, sometime for many days on end.  Why does this happen?

Cold air is dense, so it naturally sinks and hugs the ground. It is hard to dig that air out, so relatively warmer air can sit on top of that layer of air.  This results in a stable atmosphere; warmer air rises, colder air sinks, so you little air movement that would help remove this setup.  We can this an inversion.

Inversions can cause a layer of clouds to stay persistent for days.

Inversions can cause a layer of clouds to stay persistent for days.

During the summer, the sun is able to heat up the ground (which heats the air above it), and remove that inversion by warming the cool, surface air to the point where it can start rising and “break” the inversion (or rise into the warmer air above it).  This promotes mixing in the atmosphere, helping “burn” off any fog, cloud cover, etc. that forms when the atmosphere is very stable.

Lack of adequate daytime heating does not help burn off the cloud cover.

Lack of adequate daytime heating does not help burn off the cloud cover.

The downside in the winter, is that the sun’s angle is low on the horizon (we aren’t getting as direct of sunlight to the earth as we would in the summer), and the days are short, cutting down on the amount of time the sun can heat the earth.  Without adequate heating, this inversion can stay in place for a while.  There is also plenty of cold air to go around in the winter.  As a result, cloud cover stays stubborn for days on end.

For us this week, high pressures is moving in from Michigan (high pressure can help dry the air out by promoting downward movement in the atmosphere, which is why we generally have sunny days with a high moving in), and warmer weather is flowing in from the west.  Between those two, we should see the pesky clouds get cleared out before the end of the week.

Next time we see a long stretch of cloudy days this winter, remember this article and how this all works!

-Alex

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This post was written by Alex Kirchner on December 10, 2014

Late week warm-up

Dec. 9, 2014-

Now that the wintry mess from Monday is out of the way, we can look forward to plenty of quiet weather this week, with a late week warm-up that will put us close to 50 degrees.  We can thank something called the ‘Pineapple Express’ for the warmer weekend weather.

The Pineapple Express is a strong, deep, and persistent river of moisture that develops from the tropics of the Pacific Ocean to the West Coast of the U.S.  The pineapple part is a tribute to the Hawaiian Islands that the river of atmospheric moisture usually develops near.  This wet pattern can produce flooding rains for the western states.

Storms storms and heavy rain will pummel the West Coast (note the bright white clouds- there is a lot of moisture coming in with those storms).

Storms storms and heavy rain will pummel the West Coast (note the bright white clouds there is a lot of moisture coming in with those storms).

Strong and persistent jet stream winds pick up the moisture and deposit it on our western shores, resulting in torrential rain.  In this week’s case, a strong wind storm will slam Washington along with the rain.  Up to 9″ of rain and several feet of mountain snow will fall over the next 3 days in some spots of northern California.  Californians won’t mind the rain too much, as they are in the midst of a historic drought.

The Pineapple Express drives soggy weather onto the West Coast, and indirectly warms up the Midwest

The Pineapple Express drives soggy weather onto the West Coast, and indirectly warms up the Midwest

So what does this all mean for us? To tie this all together, the strong jet stream winds digging into the West Coast are going to push the jet over the Midwest north (like taking a jump rope, having someone else hold the other end, and whipping a wave through it). This will allow unseasonably warm air to rush into the middle of the country, giving us a dose of near-50 degree weather for the weekend.

Now, eventually the storms moving in on the Express will reach the Midwest and drag cold air back in from Canada, but at least for now we get to benefit from the soggy weather out west of a mild warm-up ourselves.  Enjoy it this weekend!

-Alex

 

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This post was written by Alex Kirchner on December 9, 2014

Wet Wintry Weather

Dec. 8, 2014- A cold front pushed in wet, wintry weather that caused some school delays and slippery travel for us in the Stateline. A combination of sleet, freezing rain, snow, fog, and rain showers were seen at different parts of the morning.

The radar image from    this morning.  A combination of rain (green), frozen precipitation (pink), and snow (blue) can be seen.

The radar image from 7 AM this morning. A combination of rain (green), frozen precipitation (pink), and snow (blue) can be seen.

With the variety of winter weather seen today, I thought I’d put together a refresher on terms and how they form, because I’m sure this won’t be the last time this winter that we’ll be talking about these types of precipitation!

The amount of cold air in the atmosphere helps determine the precipitation type.  The deeper the cold air, the more likely the precipitation falls frozen.

The amount of cold air in the atmosphere helps determine the precipitation type.

This graphic shows a cross-section of the atmosphere.  The red color is warm (above freezing) air, and the cold is below freezing (cold) air. The deeper the column of below freezing air in the atmosphere, the more likely precipitation will fall frozen.

RAIN- since this precipitation type falls non-frozen, the air is usually above freezing from the surface to the cloud.

FREEZING RAIN- in this case, there is a layer of below freezing air right at the surface. Rain is able to fall unfrozen until it reaches the surface; there, it can freeze onto anything untreated and below freezing.  This is where we get the glaze of ice that covers all surfaces.

SLEET- with sleet, the column of below freezing air is deeper, rain is able to freeze below it gets to the ground. We get our pellets of ice in this instance.  Despite falling as frozen pieces of ice, sleet can still lead to a slippery layer on the roads and sidewalks.

SNOW- snow, of course, needs a deep layer of below freezing air to get the snow flakes to form.

Thankfully, we do not have to deal with any kind of wintry precipitation for the rest of the week, but keep these terms and how they form in mind.  We will probably be talking about them again sometime!

-Alex

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This post was written by Alex Kirchner on December 8, 2014

Cold Fall

Dec. 4, 2014- Earlier this week, I wrote a recap on the cold November we just went through.  Fall 2014 overall wasn’t much different.

We were stuck with plenty of northwest winds in the jet stream, helping steer in cool to downright frigid air in from the north (see the previous entry http://addins.wrex.com/blogs/weather/2014/12/from-one-end-to-the-other for details).  It’s no surprise that we have plenty of chilly weather to talk about pertaining to the Fall season, and even less surprising that the only thing above average was the snowfall!

Courtesy National Weather Service Chicago

Courtesy National Weather Service Chicago

(This data is for the meteorological fall season, which is all of September, October, and November.  There are 12 months divided into 4 seasons, which comes to 3 months a season.  If we go off of the meteorological definition, then the seasons seem to line up better with the weather; for example, technically most of December is still considered “Fall” going off of the astronomical date (start of Winter, December 21st), yet December can feature plenty of winter-like days early on!)

While a handful of degrees below average does not seem like much, remember this is an average over 90 days worth of weather, so it takes a lot of cold days to add up to 3 degrees worth of cold!  This ranks Fall 2014 as in the top ten for coldest Falls on record.

Thankfully, we are getting a little break from the cold weather with a mild stretch heading into the first two weeks of December.  We could use a little break after plenty of chilly weather this past season!

-Alex

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This post was written by Alex Kirchner on December 4, 2014

From one end to the other

December 2, 2014- Just when you think, “here we go again”, the weather changes on you.  We are coming off a pretty cold November in the Stateline.  Last month ranked as the 6th coldest November on record for Rockford, with the State Climatologist Office for Illinois stating that November 2014 was the fourth coldest for the entire state.

A look back at November 2014

A look back at November 2014

We had plenty of days spent below the freezing point, and almost setting a record for the amount of days to boot.  We were stuck in a predominantly cold weather pattern with Arctic air spilling in from the north.

Our weather pattern for a lot of November featured northwest airflow bringing in Arctic air

Our weather pattern for a lot of November featured northwest airflow bringing in Arctic air

The icy influence of that weather pattern also reared its ugly head for the start of December.

December 1st was very chilly, but the chill will not last

December 1st was very chilly, but the chill will not last

Thankfully, the new month is still very young, and the weather this week and next will be trending in the opposite direction.  What’s occurring is a pattern change that will allow more airflow off of the Pacific.  This will help bring in milder air, especially as the polar jet stream retreats north for a while.

The weather pattern is changing and allowing milder air in from the Pacific

The weather pattern is changing and allowing milder air in from the Pacific

So what does that mean for our temperatures? We felt it already today (Tuesday) with a high of 33 compared to 21 from the day before.  We’ll be seeing a lot more of those 30’s to 40’s for the rest of this week and into next week.

December 8-12 has high chances for warm weather in the Stateline

December 8-12 has high chances for warm weather in the Stateline

This is the Climate Prediction Center’s outlook for next week.  The red colors, in this case, is good for us.  We have a very high probability of having above average weather through next week.  The milder weather may last into the middle of December, too, if you look at the next map.

December 10-16 showing high chances for above average weather

December 10-16 showing high chances for above average weather

80% chance of above average weather? I like those odds!  Keep in mind, above average does not mean very warm (50’s to 60’s).  We’d more likely have plenty of 40 degree days, with a few pushing 50.  We are losing out on day light as we get closer to the shortest day of the year (December 21).  That does play a large role. Countering that is the lack of snow cover; no snow means the sunlight we do get can heat the ground and the air.  Snow cover reflects a lot of sunlight, keeping us cold.

Overall, a mild few weeks will help ease the pain of getting through the cold, dark winter!

-Alex

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This post was written by Alex Kirchner on December 2, 2014

Cold Turkey

Thu., Nov. 27, 2014- Happy Thanksgiving!  I hope your holiday is going well so far.  Here’s a little light reading for you as you digest all that turkey and the fixin’s:

You probably noticed it was very cold today.  In fact, it was one of the top 5 coldest Thanksgivings on record for Rockford (not that we wanted to set a record like this)!

Top three coldest Thanksgivings in Rockford history

Top three coldest Thanksgivings in Rockford history

We tied for 4th place with a high of 25°.  That is 16° below average for this time of year. This is only the 10th time since 1905 that we’ve had temperatures in the 20’s for Thanksgiving!

We also had a few flurries.  We are usually dry for Thanksgiving, so this is uncommon too. Snow has fallen on Thanksgiving only around 30 times over the last 109 years.

I hope you managed to stay warm today.  Good news- we’ll be back in the 40’s by this weekend! Have a great rest of your holiday!

-Alex

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This post was written by Alex Kirchner on November 27, 2014

Thanksgiving travel weather

Monday, November 24, 2014: Naturally, most of the focus has been on today’s snowy and windy weather and its impacts on driving conditions. Many of you may be anxiously waiting for the time when you have to catch that flight or hit the road to your Thanksgiving meal. Here’s a holiday-focused forecast for anyone hitting the road early or looking ahead to Thursday.

Tuesday will be dry and cold, so for those of you early birds zooming out of the Stateline already, good news!  Keep an eye on the roads for any lingering icy spots from Monday, and safe travels!

Wednesday will be interesting.  A clipper system will be moving into the Stateline, right on one of the busiest travel days across the country.

Futuretrack's outlook for Wed., Nov. 26

Futuretrack’s outlook for Wed., Nov. 26, 7 AM

A clipper system is a quick hitting storm, so its impacts vary.  Its full name is an Alberta clipper- Alberta from the province in Canada where these storms usually get their start, and clipper in tribute to the fast-moving sailing ships that used to zip along the oceans and seas. As you may have guessed, this is a fast-moving storm, so it doesn’t stick around long enough to drop a ton of snow.  In this case, there is the possibility of light snow for Wednesday, but accumulations will be very light and shouldn’t slow you down much.  There is the possibility that this storm stays to our south, so most of the Stateline and into Chicagoland will be dry.

Futuretrack's outlook for Wed., Nov 26, 7 PM

Futuretrack’s outlook for Wed., Nov 26, 7 PM

The bigger impact in this case is that these storms usually bring in some very chilly air in their wake, and that’s the case this time around too. Thanksgiving Day will be a cold one for a lot of the Midwest.

Holiday forecast for Rockford and the Stateline

Holiday forecast for Rockford and the Stateline

Friday will also feature a slight chance for snow, but like Wednesday, the impacts will be light if we do get anything.  The rest of the weekend looks dry with temperatures varying between the 30’s and low 40’s.

Overall, there should not be much that slows you down, but keep in mind, we had snow today and there may be some on Wednesday, so practice good winter driving habits if the roads aren’t dry.

If you need a quick update right before you head out the door, jump over to www.wrex.com/weather and click on the Interactive Radar tab.  Once there, look for the Layers tab at the bottom.

The 13 Weather Authority's Interactive Radar allows you to add layers to the radar, like temperature, snow cover, winds, and road conditions.

The 13 Weather Authority’s Interactive Radar allows you to add layers to the radar, like temperature, snow cover, winds, and road conditions.

You can add the Road Weather layer to the map, giving you a snapshot of the road conditions at that time, as well as over the last hour or so.

Interactive Radar's road conditions layer

Interactive Radar’s road conditions layer

This will hopefully give you a good outlook on how the roads look at your location and at the spot you are heading!  Be sure to stay with the 13 Weather Authority on-air and online leading up to Thanksgiving (and the day’s after for the return trip), and have a safe journey to your destination this week!

-Alex

akirchner@wrex.com

 

 

 

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This post was written by Alex Kirchner on November 24, 2014

Record Stretch

Tuesday, Nov. 28- If it’s going to be this cold, we may as well get something out of the deal and set some records, right?  That’s what happened today, and almost happened yesterday, too.

If you look back at the previous entry (Arctic Chill: http://addins.wrex.com/blogs/weather/2014/11/artic-chill), you’ll see a couple things.  1) We’ve been under the freezing point (32° F) for nearly a week, and that likely won’t chance until the weekend, making this a pretty substantial cold stretch.  2) 1951 and 1959 stand out amongst the past cold stretches like this.

Why is that?  Those years were the last time we had weather this cold, or cold enough to set the records that were threatened or fell today.

Here’s how Monday played out (day 1 of the very cold stretch):

Monday's weather threatened to break the record for coldest high temperature

Monday’s weather threatened to break the record for coldest high temperature

Take note that the record was set in 1959.  Now look at the records set for today:

2 records fell on Tuesday- coldest low and coldest high temperature for Nov. 18

2 records fell on Tuesday- coldest low and coldest high temperature for Nov. 18

The coldest high temperature record, standing for 63 years, fell today!  It just goes to show that while unusual, we can have very cold weather in November like this.  Thankfully, it doesn’t happen all that often- we had to wait around 60 years before it popped up as this cold again.

If you are curious about what set up our very chilly weather this time around, head to our website for a web exclusive on the Omega Block pattern that contributed to this long cold pattern.

-Alex

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This post was written by Alex Kirchner on November 18, 2014

Arctic chill

November 13 marked the 2nd day in a row with a high of 30°- that’s also the 2nd day at nearly 20° below average!  The Stateline also saw plenty of flurry and light snow activity, enough that the Rockford airport measured o.3″ of snow by 4 pm, but thankfully the ground and the roads were just a little too warm for accumulation.

The average low for Nov. 12 and 13 is 32°.  We didn't warm up to that value either day.

The average low for Nov. 12 and 13 is 32°. We didn’t warm up to that value either day.

There have been cold stretches like this in the past for the middle of November, but we haven’t had cold like this that stuck around in a while.

Rockford has not been this cold this early in the season since 1995.

Rockford has not been this cold this early in the season since 1995. (Courtesy National Weather Service Chicago)

With flurries in the air, and the threat for snow Saturday night, you may want to start doing your winter prepping a little early, especially as sub-freezing temperatures are expected to last well into next week.

Tasks you might want to start thinking about and doing before winter really sets in

Tasks you might want to start thinking about and doing before winter really sets in

Another item you may want to add to the list is putting up the Christmas lights.  You don’t have to turn them on, but why not put them up before everything gets icy or snowy for a while?  Installing them now means not having to deal with the more treacherous conditions.

Stay warm!

-Alex

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This post was written by Alex Kirchner on November 13, 2014