Why so cloudy?

Jan. 31, 2017: Sunshine is in the forecast! Not just a few glimpses, either. By the end of the work week, the sky should be mostly sunny for a short stretch.

sunny outlook

 

The trade off: the weather gets colder. The colder air is drier, helping get rid of any extra moisture to help make clouds.

Midwest RPM 4km Hi-Res with fronts

The colder air helps get rid of one of the main mechanisms for creating all of the cloudy weather over the last few weeks: a temperature inversion. WARNING: there’s a lot of science ahead!

A temperature inversion is when a layer of colder air gets trapped under a layer of warmer air.

temperature inversion

 

Remember: warm air rises, cold air sinks. Under this setup, the cold, dense air near the surface doesn’t want to rise too far, since it’s colder than the air around it. We’d have to either warm up the lower layer of air a lot until it’s warm enough to rise past the upper layer, or we get the upper layer cold enough that the lower layer can rise as well.

temperature inversion1

Where do the clouds come in? As the lower layer starts to heat up, it rises like warm air likes to do. However, it can only go so far before it hits the “lid” of warmer air over top of it. Clouds form right where the “lid” is, and can get “trapped” there, since the lower layer isn’t getting much warmer. As long as the inversion is in place, the weather remains mostly cloudy like we saw over the last few weeks.

temperature inversion2

Not helping was all of the melting snow recently. This adds moisture to the air, creating more clouds and fog that don’t want to clear out.

In the case of this week, the air gets back to its “usual” set up (getting colder as you rise through the atmosphere) with a new round of colder air sliding in. That gets rid of the clouds, brings back the sun, yet drops our temperature for a few days.

Ok, that was a lot of science. Comment on our Facebook page or email me at akirchner@wrex.com if you have any questions!

-Alex

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This post was written by Alex Kirchner on January 31, 2017

Not much snow for January

Jan. 25, 2017: For the first time in over 2 weeks, we’ll be seeing measurable snow fall tonight. Our last legit snow in Rockford was on January 9th, with a whopping 0.2″ falling. We average 10.3″ of snow in January, so we better get going on the snow if we hope to have an average month!

least snowy januarys

Pending tonight’s snow, we are currently ranking high in the least snowiest January’s. With 0.2″ total, January 2017 stands at 2nd for least amount of snowfall in a January. If we add 1″ onto our total, we’d still be in the top 10 for least snowiest.

Tonight’s round may be our last real shot of snow in the area, as flurries are in the forecast, which won’t lead to much through the end of the month. We likely won’t be seeing a dry overall month, though. After all of the rainfall this month, we stand just under 1″ above average with a few more days to go. That makes this particular month very interesting; above average for precipitation, but well below average for snow!

-Alex

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This post was written by Alex Kirchner on January 25, 2017

“Back to” January

Jan. 23, 2017: Enjoying the milder weather that we’ve had lately? We even reached the middle 50’s over the weekend, but that all goes away this week.

Here’s the pattern we’ve seen lately, though cooler air has already started to sneak into the region.

Cold Blast 2

The jet stream flips to out of the northwest by midweek, pushing in much colder air from Canada.

Cold Blast 2

Those chillier conditions should arrive by the second half of this week, pushing highs back down into the 20’s to 30’s, which is where we typically are for highs this time of year.

normal jan

During the transition, rain mixed with snow is expected to fall between Tuesday night and Wednesday night.

SOGGY MIDWEEK

We should mainly see rain since we do not cool off that quickly, though minor snow accumulations of around 1/2″ are possible Wednesday night. It will look and feel like winter again by Thursday!

-Alex

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This post was written by Alex Kirchner on January 23, 2017

La Niña check-in

January 20, 2017: We are roughly half way through the current winter, so here’s a check-in on one large influence on how the overall winter conditions play out: La Niña. A weak La Niña has set up this winter in the Pacific. Despite its weak strength, we are getting a pretty good helping of what a typical La Niña brings to our area: precipitation.

el nino to la nina

A quick refresher: La Niña is when ocean temperatures in the Pacific near South America are colder than usual for an extended time during the winter.

la nina

This influences the jet stream pattern over North America, and generally brings a wet and cooler conditions to the northern U.S. We generally get a wetter winter, but not necessarily a colder winter.

How do we rank so far in temperature and precipitation? Temperatures haven’t been far off of average so far this winter. We’ve had some very cold days, but they’ve been balanced out by some pretty warm ones too.

la nina temps

Precipitation is a different story, and this is where we can point to La Niña as a possible influence. December was definitely above average for snowfall, but essentially was near average for precipitation. After a lot of rain (doesn’t have to be snow!) earlier this week, January is well on the way to be above average for precipitation (and way below average for snow).

la nina precip

Looking ahead, February shouldn’t see much of an La Niña influence, since the ocean temperatures in the Pacific look to warm back to average and stay there for a while. While we are under La Niña’s spell, plan on a few more soggy stretches before the winter is over.

-Alex

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This post was written by Alex Kirchner on January 20, 2017

Soggy January, But Not the Wettest

January 19, 2017: This week has felt a lot more like spring than winter, but that’s how it goes sometimes in January.

We have seen a lot of rain as a result instead of snow, with a lot of that water running off and flooding streets, or sitting in your backyard and creating a muddy, soggy mess. In both cases, the frozen ground isn’t letting the water soak in.

If you are curious, while things seem extra soggy, this definitely won’t be the wettest January on record, at least not yet. We are above average for the month by a half inch, and we may add to that total with 12 days left to the month. We can chalk this particular January up to being wetter than normal. Looking at some of the wettest January’s on record, however, we don’t even crack the top 25. In fact, if the month ended today, we’d only be at 33rd (records date from 1906 to 2016)!

WATERLOGGED

The wettest January on record for Rockford was in 1947, when 5.8″ of precipitation fell! That’s the water equivalent, meaning we saw plenty of snow that winter too. Unfortunately, data is missing for that January, so we don’t know just how much snow fell that month at this time.

Overall, it’s been soggy, but as we can see, it isn’t the wettest ever, yet, or even in the top group. We’d have to see over 3″ of precipitation before we can start that discussion.

-Alex

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This post was written by Alex Kirchner on January 19, 2017

Goodbye Ice, Hello Spring?

If you are tired of seeing freezing rain and icy roads in the forecast, you get your wish for a while, with a mild to warm forecast this week!

Temperatures will warm up away from freezing for a while during the day, reaching the 40’s for much of the week. By the weekend, we may even see temperatures flirt with the 50’s!

Cold Blast 2

We have favorable jet stream winds that are keeping the cold air at bay, and allowing much warmer air to spill across the Midwest. This means when our next storm arrives by Friday, we only have to worry about rain and not freezing rain or snow since conditions are so warm.

The only thing we won’t see are record-breaking temperatures. While a few days may get close, late January has some pretty impressive records for each day this weekend that likely won’t get broken:

January 19th’s record high: 51°,1921

January 20th’s record high: 60°, 1906

January 21st’s record high: 55°, 1964

The long-range forecast looks to stay fairly mild into next week before it all comes crashing down, so if you don’t like the cold, enjoy the warm stretch this week!

-Alex

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This post was written by Alex Kirchner on January 17, 2017

Weekend Icy Threats

Jan. 12, 2017: Good news for us- our area stays dry for a little while, giving us a break from an active week so far. More icy rain is on the way this weekend, however.

DMA CUTOUT FLY IN

Round 1: This round misses the Stateline, but it will be important to pay attention to if you are making weekend plans out of town. A wintry mix of sleet, rain, and/or snow starts falling southeast of I-80 after 6 pm Friday, and lasts through noon on Saturday. Minor ice accumulations are possible. Again, this won’t affect us, but it will impact your plans if you are heading to Chicago or Indiana for the weekend.

DMA CUTOUT FLY IN 2

Round 2: This bout of precipitation takes the form of light snow or flurries. We may see a few of those float through the Stateline late Friday night into early Saturday morning. Accumulations will be minor, just like round 1. We won’t see much if any impacts from this round, but don’t be surprised if we get a dusting of snow by Saturday morning.

DMA CUTOUT FLY IN 3

Round 3: Pay attention to this round. Freezing rain is possible starting Sunday night into early Monday before temperatures warm enough to have all rainfall. The duration of the freezing rain is up in the air right now. There is potential, however, for enough freezing rain to cause traffic headaches with very slippery roads, plus a coating of ice on trees and power lines. For now, pay close attention to the forecast through the weekend for updates on this round of icy weather.

-Alex

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This post was written by Alex Kirchner on January 12, 2017

Icy issues

January 10, 2017: Temperatures are much more tolerable now that conditions are hovering above 0° C instead of 0° F (so 32° F vs 0° F), but there are a few issues we’ll be dealing with during the rest of the week.

freezing rain explainer

Even if the atmosphere is above freezing above us, as long as we are at or a little below the freezing mark, freezing rain will make roads and sidewalks slippery, and ice over everything else. The rain itself doesn’t freeze until it reaches the surface, freezing on contact. To avoid all this, either we have to be above freezing near the ground for rain or stay below freezing to give us snow.

Midwest RPM 4km Hi-Res with fronts

The next chance for freezing rain and icy roads is Wednesday evening. Another storm system whips through the region, producing rain Wednesday afternoon since the atmosphere is warm enough. As temperatures cool and colder air moves in with the system, we’ll be below freezing at the surface, creating the potential icy rainfall for much of the evening and night.

DMA 24hr RPM 4K Ice Accumulation

The good news? The situation appears to be mostly drizzly during the time when we are below freezing, so the icing on the roads may not amount to much. Futuretrack, for now, shows minor amounts of ice accumulation, but remember, this may change as we get closer to the event.

winter weather advisory

In summary: beware that roads may be icy again Wednesday night, and plan accordingly. If you do have to be out and about, take it easy on the roads (slow down, and do not break or steer sharply). We’ll be dry for a longer stretch from Thursday morning through Friday night, then snow may pop up by the weekend. We’ll have more on that the closer we are to the weekend.

-Alex

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This post was written by Alex Kirchner on January 10, 2017

Relief on the Way

January 6, 2017: This week’s cold snap wasn’t the worst we’ve had this winter, but it does stack up in a couple areas. All the more reason that “warmer” weather soon will feel like a heat wave.

For starters, we had the coldest day of this winter, so far (still plenty of time to go!), beating Dec. 15th, by 1°.

not the coldest

The last blast of Arctic air, however, was definitely colder and longer than this round of bitter air. We’ve so far only had one night below zero, and we barely made it there. The last go-round featured several night, with a few of those in the teens below zero.

coldest 2016-17

Regardless of which cold snap was worse, we could use a little warmth, right? It arrives in a sense this weekend, and we’ll definitely feel it next week. Here’s the pattern we’ve had this week:

Cold Blast 2

 

Look at how far south the cold air makes it! Temperatures were in the 30’s today as far south as Mississippi, and that’s definitely cold for them! They’ll be dealing with a few inches of snow into the weekend.

Cold Blast2

The pattern reverses course by next week, with the polar jet stream retreating north, and southwest winds aloft driving in much warmer air. In face, we may see mostly rain next Tuesday since the weather will be warm enough for that by then.

Just a few more days, folks!

-Alex

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This post was written by Alex Kirchner on January 6, 2017

Closest to the Sun

January 4, 2017: You would think that being as close to the Sun as we are right now, the weather would be a little warmer?

earths orbit2

That’s right: as of today, the Earth is at the closest point in its orbit with the Sun.

earths orbit

Here’s some neat trivia for you: it seems counter intuitive, yet it happens every January. The Earth’s orbit isn’t quite a regular circle, and more of an ellipse. This leads to the Earth being closer and farther away from the Sun at different times during the year.

earths orbit3

During the summer, we are get to be as far away from the Sun as possible within Earth’s orbit. The key point here- our seasons have a lot more to do with the tilt of the Earth and less to do with Earth’s position in its orbit. Right now, the Northern Hemisphere (the part we live in) is tilted away from the Sun as much as it can, leading to less energy getting to our part of the globe. We passed the farthest tilt point on Dec. 21 (the winter solstice, the start of Winter), and will be tilting slowly toward the Sun more and more until the start of Summer (the summer solstice).

-Alex

 

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This post was written by Alex Kirchner on January 4, 2017