Winter Weather Again?

No, you aren't misreading this blog title incorrectly, it appears we may have another shot of winter weather for late tonight into early Wednesday morning. Some of us will also likely experience a wild 24-hour temperature swing. A strong cold front is set to move into our state late Tuesday into early Wednesday. With a strong northwest flow, this front will track from the central plains southeast into the southern United States, ultimately tracking through Arkansas! Let's take a look at few points of interest.

• Warm air will nudge northward today, while the northern half of Arkansas will remain in the mid 40's and low 50's, some of southern Arkansas could reach the 60's. Don't get used to it, the warmer air will soon vanish.
• The mentioned cold front will make it's entry late tonight into the early morning hours of Wednesday. Some of northwest Arkansas could experience mid to low 20's early Wednesday. Stronger winds will accompany the front, making it VERY chilly Wednesday morning.
• Once the cold front has swept through Arkansas, it will keep high temperatures very chilly throughout the day on Wednesday.
• Rainfall is very likely ahead of the front, as the cold/warm air collision occurs. As this cold front progresses southeast, some of the colder air could interact with the residual moisture. This could lead to some **LIGHT** winter mix.
• This is a tough forecast, as we are not 100% sure on the magnitude of the cold air, or how far southeast this interaction could occur. Nonetheless, accumulations should be minimal and travel impacts would be isolated if any whatsoever. 
• As always, with any winter weather forecast, this is subject to change. You should be well seasoned to this aspect, as our last winter weather event took us all for a loop!

Let's take a look at a few models. As always, the text below each model graphic pertains to the respective graphic posted above it.

Tuesday Afternoon Tempertatures

Here is a look at temperatures this afternoon (Tuesday). Notice we are fairly mild, with even some low 60's along the warm air in southern Arkansas.

Late Tuesday Night Temperatures 

By late Tuesday, this strong cold front will make it's presence known. We've edited the graphic above, giving you a simple representation of this front. Notice the warm air prior to the front, with the cold conditions forcing it's way southeast. This interaction will induce a strong aspect of lift, giving way to rainfall later today. 

Wednesday mid-day Temperatures 

Fast forward to mid-day Wednesday, the cold front is now approaching the southeastern regions of the United States and we are COLD here in Arkansas. Afternoon temperatures could dip into the 20's across far northern Arkansas. 

Winter mix late Tuesday/early Wednesday

So what about this chat about winter weather? Notice the GFS model perception for late Tuesday/early Wednesday. As we mentioned earlier widespread rain looks likely for Tuesday evening, as suggested here. As the cold air and moisture interact, a light winter mix could occur. This model valid for 06Z is suggesting this mix could be occurring across western Arkansas.

Most high elevations should be below freezing (NWA), which could lead to a better chance for this mentioned winter mix. While areas like the River Valley (Fort Smith for example) could see more rain than anything, as temperatures may struggle to dip below freezing prior to the moisture exiting.

Wednesday Early Morning

By early Wednesday morning, this winter mix could still be on-going across portions of northern, central and perhaps some of southwest Arkansas. Here is the issue, cold air will soon begin to  retreat as the moisture progresses southeast. The GFS may be a little too aggressive with this solution, don't be surprised if you live in the areas just mentioned and you only see a cold rain. Northern Arkansas does have a higher elevation aspect, which could aid in keeping sufficient colder air in place longer. 

 Lastly, we leave you with our own thoughts for this system. These sort of graphics are always tough, as winter weather forecasting can be so fluid with each data run. However, we feel this range is practical. The pink shaded region is the area we suspect has the highest chances to see any sort of winter mix. Portions of southeast Arkansas (non-shaded) have the lowest chances, likely only seeing that dreaded cold rain.

With this being said, if you live in southeast Arkansas don't be surprised if you see a few flakes or some light sleet Wednesday morning during your commute. The cold air combination with what moisture is left will be sporadic with the cold air forcing and elevation changes. As we mentioned earlier, this doesn't appear to be a huge widespread winter weather event. However, be mindful of roadway conditions early Wednesday in case they have become slick. Accumulations and travel issues should be VERY limited if any.

Thanks for reading.

-AW

Severe Storms and Snow!

Today will be the last full day of mild weather before some very chilly cold air intrudes. So, if you're not a fan of cold air, soak it in! Normally a large and powerful shot of strong cold air comes with a price here in Arkansas, usually in the form of severe thunderstorms. This weekend looks to hold that reputation, as a few thunderstorms are possible prior to our next cold front. This system is interesting, as some of us may see some light snowfall as the low pressure system exits to the east.

• Temperatures will top out in the low to mid 50's this afternoon. There could be a few low 60's across southern Arkansas as well. We will remain mostly cloudy and rain chances will become more persistent later in the day.
• As the cold front approaches from the northwest, some strong to possibly severe thunderstorms could initiate. While not every thunderstorm will be severe, there is a marginal potential for a few of them to strengthen to severe status. 
• There will likely be a large temperature difference across Arkansas early Saturday morning as the cold front is making it's way across our state. Don't be surprised if portions of northwest Arkansas dips into the 30's, while southeast Arkansas is holding steady in the low to mid 60's.
• Eventually the arctic air will engulf Arkansas, giving way to very chilly air. Sunday morning looks VERY cold, with temps likely in the 20's and maybe a few teens across northern Arkansas.
• There is a limited snowfall potential on the backside of this system as the low pressure exits. However, moisture will be limited and impacts look minimal (if any).

Let's look at a few models, the text below each graphic is pertaining to the respective graphic above the text itself. 

Friday Afternoon Temperatures 

Here is a look at temperatures for this afternoon. Notice we are fairly mild, as mentioned above. Mostly low to mid 50's with a few of us likely climbing into the 60's.

Early Saturday Morning

Fast forward to early Saturday morning, you can clearly see the cold front across eastern Oklahoma. Temperatures will begin tanking throughout the morning. Check out that temperature gradient, mid 60's across SE Arkansas with 30's in NW Arkansas!

Saturday Night

By Saturday night, the cold air is officially here. The entire state will likely be well into the 30's with below freezing conditions for numerous counties. Make sure you bundle up for church Sunday morning, as temperatures will only decrease into the morning hours.

We've included two simulated radar graphics above. Widespread rainfall will help limit the over instability potential for severe thunderstorm development. However, a few thunderstorms could strengthen to severe limits. The greatest potential will likely be across southern and central Arkansas, where instability is greatest.

By Saturday morning, as the cold air overlaps with what moisture is left, we could experience some flurries or light snowfall. Don't pay attention to the exact locations portrayed by this model, especially across SW Arkansas. We simply posted this to give you an idea of the scenario itself. As the low pressure system exits, the backside could cool enough to support some light winter mix/snow. The best chances for any accumulation would be across northern/northwest Arkansas in the highest elevations. Don't be surprised however if you see a few flurries on Saturday.

Don't give up on winter just yet, we still have plenty of time for a good snow! These sort of setups are not how we get our big snow events here in Arkansas. We need that cold arctic air already in place, with a solid wave of moisture for anything significant.

-AW

Total Lunar Eclipse Jan. 20th-21st

This Sunday night into Monday morning (January 20th-21st), the moon will pass into the shadow cast by Earth causing a total lunar eclipse. During a lunar eclipse, a full moon will turn a rusty color. What's even better is that during this lunar eclipse, the moon will be near its closest approach to Earth, making it a supermoon. Be sure to make plans to view this total lunar eclipse since it will be the last total lunar eclipse visible in the United States until 2022.

Why do we have lunar eclipses?

The simple answer is “because the moon sometimes passes through the shadow of Earth.” But there’s more to it than that. For one, it has to happen during a full moon. When the moon is full, it means the sun, Earth, and moon are in alignment. 

Joss Fong/Vox

Now, you might be thinking: “Why don’t we have lunar eclipses every full moon?” The answer to that questions is that the moon’s orbit isn’t perfectly matched up with Earth’s; it’s tilted 5 degrees. Which means that during most full moons, the shadow misses the moon. 

You don’t need any special equipment or protective glasses to view it (unlike with a total solar eclipse). But a pair of binoculars will give you a better, more detailed view of the moon’s geography as it darkens in shadow.

What’s a supermoon?

The moon’s orbit around Earth is not a perfect circle. It’s an ellipse, a saucer shape that’s longer than it is wide. As the moon follows this orbit, it’s sometimes closer to Earth and sometimes farther away. At perigee (the closest spot in its orbit to Earth) it’s around 31,068 miles closer to Earth than at apogee (when it’s farthest away).

NASA

Meanwhile, we see different phases of the moon — full, crescent, waxing, and waning gibbous — depending on if the sun-facing side of the moon is facing the Earth.

A supermoon is when these two cycles match up and we have a full moon that’s near its perigee. The result is that the full “super” moon appears slightly larger and slightly brighter in the sky. This occurs about one in every 14 full moons. The difference between a normal full moon and a supermoon isn’t all that significant though, and sometimes not even distinguishable to an untrained human eye. 

Why does the moon turn red during a lunar eclipse?

During a total solar eclipse, like the one North America saw in 2017, the entire sun turns black, revealing the sun’s atmosphere. What happens during a total lunar eclipse is a bit less dramatic, but beautiful nonetheless.

When sunlight passes through the atmosphere, the gases trap and scatter the blue light in the spectrum. (This is why the sky appears blue.) The red, orange, and yellow wavelengths pass through into Earth’s shadow and get projected onto the moon. So basically a total lunar eclipse is like projecting the sunset and sunrise onto the moon.

When can I see this?

The Jan. 20-21, 2019 total lunar eclipse will last 1 hour and 2 minutes and the full experience (from the start of the partial eclipse to the end) will last 3 hours and 17 minutes. Below is a chart of the timeline, phases, and events for this total lunar eclipse. The best time to view this in Arkansas is between 10:41-11:43 pm this Sunday night!

Get ready for this special nocturnal hour where the full moon will become fully tinted with the red-orange color of sunset. Be sure to send Arkansas Weather any pictures you capture! You can send them to us on Facebook or Twitter!

Weekend Winter Weather

As we've mentioned all week, chances of winter weather look likely for this weekend. While this won't be a large widespread event over the entire state, some of you will still experience impacts. Several of our northern Arkansas counties could experience a winter mix throughout the weekend. We fully expect a few counties to be placed in a winter weather advisory. In this blog we'll go over timing, likely impacts, and show everyone some data. Let's go over a few key points.

• The "action" will start late tonight into early Friday morning. We mention "action" with some sarcasm, as initially we only expect rainfall to move in from the west. Rain will gradually become more widespread throughout the day. 
• There is some limited winter weather potential during the morning hours Friday across the northern half of the state. This should be most noticeable in the highest elevations.
• Friday evening a switchover from a cold rain to a winter mix will occur once again. Likely a mix of sleet/freezing rain. Snowfall will be limited, we'll explain the reason for this later.
• Rainfall will continue throughout the night Friday, into Saturday morning. There is a potential for a switchover to snowfall on Saturday morning (northern Arkansas). Although we expect this to be very limited.
• There could be some residual moisture left over once the main system exits to the east Saturday evening. While temperatures will struggle to dip below freezing, we won't rule out a few snow flakes Saturday night.
• Winter weather often steals the spotlight with any system. However, don't forget about all the rainfall we'll experience. Some areas could pick up an inch or more of throughout the weekend.

Let's look at some model data, remember all of the following text is pertaining to the model images posted above the text itself.

By tomorrow morning, some of you may be dealing with some pesky rainfall on your way to work. We don't expect many issues for most of the state, as temperatures at the surface will likely support a cold rain. However, some of northern Arkansas (high elevations) could experience some light freezing rain/sleet. Isolated slick spots can't be ruled out, but we aren't expecting significant impacts.

Fast forward to Friday evening, it's still raining out there. Also, notice the pinks colors on this simulated radar image. This represents frozen precipitation likely freezing rain or sleet pellets. Notice the coverage is more evident than the morning timeframe. There could be slick spots and some roadway issues late Friday night. 

By early Saturday morning, you guessed it, still raining. Some of the rains showers could be moderate, adding to already saturated grounds. Notice across extreme northern Arkansas, snowfall is attempting to mix with the rain. Looking over some of our data, the mid-levels aloft will be gradually warmer than the temperatures at the surface. This is NOT good support for snowfall. While some flakes could fly, we don't expect anything significant.

Some of you have asked, why do we expect more of a freezing rain/sleet mixture rather than snowfall? Notice in the graphic above, looking at around 850mb (around 5,000 feet above), the flow is from the SW. This flow will aid in warming aloft, increasing the temperature above us. Remember, the atmosphere has a vertical structure, there is differences in wind flow and temperatures. This warming can drastically alter the precipitation we experience here at the surface! For snowfall, we need to lose the warm nose directly above the surface.

Lastly, let's take a look at the freezing rain potential. The NAM (3km) is pretty aggressive with ice totals, but we are on board with it. The GFS is also similar in placement, but a little less adamant about the totals. A safe bet would be a light glaze of ice on elevated surfaces, trees, and exposed items outside. It doesn't take much for ice to cause issues on the roadways, so be careful this weekend.

Bottom line, ice is a bigger concern for us. Snowfall chances are there, but VERY limited and confined to our northern most border. A solid rain event for the rest of the state is in store. If you live within the northern tier of our state, your chances are higher. If you live in elevations above 1,200 feet, your chances are even higher. 

Thanks for reading!

-AW