Beau Dodson's WeatherTalk Blog

 

** For planning purposes, if you have travel plans this weekend into early next week, then you will want to monitor updated forecasts **

This event will be harsh on livestock and outdoor pets, as well.  Especially if we have wind and snow (moisture).

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Remember, all models are wrong. Some are just more wrong than others.

We do not use any single model to make a forecast. There is a lot more to it than just the models. Especially true for winter forecasting in our region.

The GFS model had been keeping precipitation out of our region. Over the past 24-hours it has trended north.

This was the last holdout in the model guidance. The other guidance packages (over 200 of them) have been showing snow in our region.

Confidence in snow Friday night through Sunday is now 40% to 50%. Monitor these numbers over the coming days.

Those numbers have increased from the previous update.

Keep in mind that my northern counties (Ste. Genevieve County, MO, over towards Mt. Vernon, IL) might end up with little or no snow. This is highly dependent on the exact storm track.

We aren’t confident in this, yet.

A shift of 25 miles will make a big difference in snow totals.

This system is still out over the Pacific Ocean. We are threading a needle with our snow forecasts.

The data has slowed by six to twelve hours. That pushes the primary concern into Saturday and Sunday.

What falls will stick. It will be cold.

Snow ratios will be high with this event. The bitterly cold air will mean snow ratios of 15:1 to 30:1

What are snow ratios?

Typically, 0.10″ of precipitation (melted) equals one inch of snow.

With this system, 0.10″ of melted liquid precipitation could be 1.5 to 3.0″ of snow. It does not take much precipitation to create a decent snow event.

There will also likely be a sharp cutoff in snow totals from north to south.

Radar may show snow falling, but it could be virga. Virga is precipitation that falls from the clouds but does not reach the ground. It is evaporating.

This is normal with bitterly cold temperatures. It is rarely too cold for snow, but it can impact how the storm acts.

High Confidence (5/5) that very cold air will be in place across the region Friday night into next Tuesday.

That means Friday night, Saturday night, and Sunday night will likely be in the single digits to lower teens. Even colder if we have snow on the ground.

Low Confidence (2/5) in precise storm track and precipitation amounts.

Yesterday, that number was (1/5). It has gone up a bit.

It appears that the risk of sleet and freezing rain will remain to our south. I will be monitoring this.

Some data brings sleet into the Bootheel and northwest Tennessee.

Attached are the official WPC/NOAA/NWS winter weather outlooks for Friday night through Sunday.

The first graphic is for late Friday night into Saturday morning. The second graphic is for Saturday mid-morning through Sunday morning.

This shows you the probability of 0.25″ or greater of MELTED precipitation.

As I said, snow ratios will be high. Thus, 0.25″ of liquid precipitation would be 3 to 6 inches of snow.

The light green indicates a slight risk of three or more inches of snow. That means a 10% to 30% chance.

The dark green (which has now been introduced) represents a 30% to 50% chance of three or more inches of snow.

The light blue represents a 50% to 70% chance of three or more inches of snow. Yesterday, there wasn’t any dark green or blue in our region.

As you can see, the numbers have increased compared to yesterday’s post.

I will be monitoring this product for trends.

We are now within five days of the event.

I am making a general forecast. That way, you can plan ahead.

It is not possible to give you specific amounts for one location. Not yet.

There is high confidence that a winter storm will impact portions of the Ohio or Tennessee Valley. The question is where and how much?

The majority of guidance indicates that snow will affect our region from late Friday night through Sunday. It has slowed by several hours.

It is possible that the bulk of this event will hold off until Saturday and Sunday.

Again, let’s not forget that this is a bitterly cold air-mass.

Single digits are possible this coming weekend. Brrr.

If we end up with snow on the ground, then Saturday night and Sunday night will be even colder.

That means temperatures below zero into the single digits. Wind chill values of -15 to 5 above. Double brrr.

It is still just a little too early for specifics.

It is too early for winter storm watches or winter weather advisories. Those are usually issues 24 to 48 hours in advance.

Typically, an accurate snow forecast is made 24 to 48 hours in advance.

A general idea of what will happen will be known from 48 to 84 hours in advance.

Beyond 84 hours, we are giving you a broader view of the system. That is what this update is.

That gives you enough time to make plans.

Let’s look at some raw model data.

Here is the EC AI model.  It usually scores the highest in accuracy.

What is the chance of six or more inches of snow?

The GFS model.  It typically scores the lowest in accuracy.

What is the chance of six or more inches of snow?  It has been trending northward.  It was WAY south yesterday.

Radars and Lightning Data

Interactive-city-view radars. Clickable watches and warnings.
https://wtalk.co/B3XHASFZ

Old legacy radar site (some of you like it better)
https://weatherobservatory.com/weather-radar.htm

If the radar is not updating then try another one. If a radar does not appear to be refreshing then hit Ctrl F5. You may also try restarting your browser.

Backup radar site in case the above one is not working.
https://weathertalk.com/morani

Regional Radar
https://imagery.weathertalk.com/prx/RadarLoop.mp4

** NEW ** Zoom radar with chaser tracking abilities!
ZoomRadar

If the radar is not working, then email me: Email me at beaudodson@usawx.com

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