Weekend Storm: Snow Numbers

A significant winter storm is still in the cards for Missouri, Illinois, Kentucky, and Indiana.  If you have plans to travel, you should read this and then reconsider your plans.

Dry air is currently infiltrating the central United States following a passing cold front.  Dew points have dropped below zero, hinting at the arctic origins of the air.

It will take a small amount of time to saturate the atmospheric column, but it should not take long for precipitation to reach the ground as snow.

TIMING:

• Missouri: Snow will start to enter southeast Missouri from the southwest Saturday morning.
• Illinois: Snow will enter Illinois late Saturday morning/early afternoon.
• Kentucky: Snow will enter the extreme southwest corner of Kentucky Saturday mid-morning.
• Indiana: Snow will enter the southwest corner of the state Saturday afternoon.  It should enter central Indiana late Saturday afternoon.

HOW MUCH:

Computer models have been extremely consistent on how much water will be available in the atmosphere.  There is one computer model that has been consistent with lower water amounts - the GFS.

All that being said, there is copious amounts of water available and there will also be cold air in place.  Snow to Liquid ratios will be higher than normal due to the cold.  Normally, we look at 10 to 1.  For this storm, the ratio could range from 12 to 1 to as much as 18 to 1.

After looking over the Friday morning computer model runs (and the last several days worth of data) these are the numbers I think could fall as snow through Sunday night.

INDIANA 

• Bloomington: 8"-12"
• Columbus: 10"-14"
• Indianapolis: 7"-10"
• Shelbyville: 8"-11"

MISSOURI

• Cape Girardeau: 8"-11"
• St. Louis: 7"-11"

ILLINOIS

• Carbondale: 10"-15"

KENTUCKY

• Paducah: 7"-12"

These numbers could still fluctuate as more data comes in over the next 24 hours.  If there is any sleet mixed in, especially in western Kentucky and the Missouri bootheel, it could have significant impact to snowfall amounts.

The attached map may not exactly match what I have forecast above.  It is a display of a blend of computer model snowfall through 7am ET Monday.

Winter Storm Update

I have been monitoring data coming in from Wednesday night's and Thursday morning's computer model runs and it still looks like a winter storm will have a significant impact on the Ohio River Valley.

The upper-level energy for the storm is still located off the southwest coast of California.  It will be better once it is overland and models can get a better sampling of what is happening in atmosphere.  That being said, the NOAA Hurricane Hunters - the pilots and scientists that fly in to hurricanes to collect data - started to fly missions in to the storm over the Pacific earlier this week.  Another mission is scheduled for Thursday evening.  I can't emphasize enough how important is that they collect.  The data goes straight in to the computer models we use to forecast weather.

In Wednesday's update I talked about how much water there will be to work with over the region.  Wednesday night's computer model runs, and Thursday morning's, increased the projected water available.

A 34-computer model average suggests the following liquid equivalent 7am ET Saturday - 7am ET Monday along with the range in data.

INDIANA 

• Bloomington: 0.82" (0.58" - 1.02")
• Columbus: 0.86" (0.61" - 1.05")
• Indianapolis: 0.67" (0.47" - 0.86")
• Shelbyville: 0.76" (0.58" - 0.91"

MISSOURI

• Cape Girardeau: 1.01" (0.82" - 1.22")
• St. Louis: 0.63" (0.43" - 0.83")

ILLINOIS

• Carbondale: 0.91" (0.70 - 1.10"

KENTUCKY

• Paducah: 1.16 (0.88" - 1.55")

Needless to say, that is a LOT of water for a winter storm.  Especially when most locations - north of the Ohio River - will be mainly all snow.

Having enough cold air to create snow will not be a problem with this storm.  (There will be some, mainly along and south of the Ohio River, that may have a little bit of warm air in the atmospheric column which would create sleet, at times.)

Air will be cold enough for higher than normal snow to liquid ratios.  A good rule of thumb is for a 10 to 1 (10:1) ratio.  With the cold air expected to be in place, ratios could go from 12:1 to as much as 18:1.  

This is when the fun begins.  You - or your kids that know how to multiply - can start doing the math on how much snow that could potentially produce.  Multiply the water amount to the snow to liquid ratio.  Example:  0.86 x 14 = 12.0"

Areas that have sleet mixed in will drastically reduce the numbers.  Sometimes by as much as 40%+.

There is a little more massaging of the data that goes in to producing the snow forecast, but this can give you a rough idea.

If the models don't come in overnight/tomorrow suggesting much lower water amounts, this will likely be a "doozy" of a winter storm for many in Missouri, Illinois, Indiana, and Kentucky.  And that isn't talking about the BIG ice storm that will happen further south.

Let's see what Friday's information brings and that could warrant me issuing Freak-Out-Meters for several locations in Missouri, Illinois, Kentucky, and Indiana.  Stay tuned...

Weekend Winter Storm to have big impacts on Central United States

Chatter about a winter storm for the upcoming weekend is in full throat on the inter-webs.  I am just starting to dig in to the data and see what might be coming.

The good news... For most of the people that follow me on here - Missouri, Illinois, Indiana - the thermal profile of the atmosphere suggests this looks to be mainly a snow event, at the moment.  (This does not mean there could not be sleet involved for some.)  It looks to start in eastern Missouri pre-dawn Saturday and exit Indiana Sunday night.

Everyone wants to know how much.  Yes, people are throwing out numbers, but that is all it is at this moment.  Numbers.  To be honest, it is too early to talk specific snow amounts, snow no you will not see me giving snowfall amounts yet.  However, I will show you how much liquid precipitation computer models are suggesting for a few locales.

A 32-computer model average for 7am ET Saturday through 7 am ET Monday:

INDIANA

• Bloomington: 0.47"
• Columbus: 0.48"
• Indianapolis: 0.36"
• Shelbyville: 0.42"

MISSOURI

• Cape Girardeau: 0.79"
• St. Louis: 0.41"

ILLINOIS:

• Carbondale: 0.66"

Yes, at this distance it appears this storm has a hefty supply of water.

We can also look at ensemble computer models.  Instead of a single forecast run, an ensemble uses multiple model runs (often 20–50+).  Each run starts with slightly different initial conditions (temperature, pressure, wind, moisture).  The ensembles can give us a range of how things could happen.

Today, I want to show you how many members of five global ensemble models suggest there will be measurable snow on the ground Sunday evening.

Columbus, IN: 94% - 170 out of 180 members
Indianapolis, IN: 94% - 170 out of 180 members
St. Louis, MO: 94% - 170 out of 180 members

It does make me chuckle that out of 180 members, all three locations have identical numbers.

We know it will be cold, which will allow for some of the snow to be fluffed up, resulting in a higher snow to water ratio.

Winter Storm Watches have been hoisted from New Mexico to North Carolina.  As more data comes in, the forecast will be refined and the picture will become more clear.  As it becomes more clear, we will have a better idea for snow totals and impacts.  I suspect a Freak-Out-Meter will be issued before the weekend gets here.

BOTTOM LINE:  This will be a good weekend to stay indoors and watch the storm through the window.

What are you hoping for from the storm?

How to build your own observatory to watch the solar eclipse

Solar eclipse sunglasses are becoming a hot commodity as we get closer to August 21. If you are not able to find a pair of the special glasses, you can still watch the eclipse with your own eyes. How? Build your own solar observatory with a few household items. Plus, it is perfectly safe for your eyes!

Kids, ask your parents for help building this observatory!

WHAT YOU NEED:

• Shoe box
• 1 piece of white paper (can be a half sheet)
• Utility knife or X-Acto blade
• Tape
• Pin or paperclip
• Small piece of aluminum foil

HOW TO ASSEMBLE

1. Cut a square hole approximately 1″ by 1″ in the lower right small end of the shoe box using the utility knife.

Hint: If the shoe box has a cut-out in the lid, cut the 1″x1″ hole at the other end of the box.

2. Cut a piece of aluminum foil that is slightly larger than the 1″x1″ hole from step 1. Place the piece of aluminum foil over the hole and tape it to the box. Be sure to only place tape on the outside edges of the foil.

3. Use the pin or paper clip and gently make a pin hole in the center of the aluminum foil. The hole is where the sun will shine through.

Hint: If you are using a piece of thin aluminum foil, before taping the foil to the box place the it on a table top. Gently press the pin or paperclip against the foil until a small hole is made. Then tape it to the box. If the foil tears while poking a hole in it (similar to what you see in the picture), you can fix it by taking another piece of foil, put a small hole in it, then tape the second piece over the first piece making sure to line up the holes so light can shine through.

4. Tape the white paper to the inside of the box directly across from the square of aluminum foil with the pinhole. The piece of paper will act as a movie screen for your observer. This is where the sun’s image will appear.

5. Using the utility knife, cut another 1″x1″ hole in the lower right corner of the long side of the box. This will be the hole you look through. You will be able to see the white paper you taped to the inside of the box through this hole.

6. Stand with your back to the sun, close the lid and look through the open square on to the white paper. Adjust the box so you can see the sunlight through the pinhole and on the white paper.

You will see a small image of the sun projected on the white paper.

Mid-week Snow Coming to Central Indiana

We're just about 12 hours from snow arriving in central Indiana. The updated forecast from NOAA NWS Weather Prediction Center suggests there is anywhere from a 50% to 95% probability for a 4" or greater snow in central Indiana.

When looking at an 8" or greater snow they include a large portion of central Indiana in a 40% to 60% probability just north of I-70 and I-69.

The latest 131-computer model average suggests the following for locales in Indiana.

Indianapolis: 7.1" | Range: 4.3" to 9.8"
Columbus: 5.4" | Range: 1.6" to 8"
Lafayette: 5.1" | Range: 3.9" to 6.5"

A note about the type of snow that will fall Wednesday. It will be a heavier wet snow than what has fallen previously this winter. Snow to water ratio's of 8:1 to 10:1. That means it will be a good packing snow (snowballs/snowmen) but also means this is more of a "heart attack" snow. Be careful when out shoveling!

How much snow would you like to see Wednesday?

Prospects of a White Christmas in central Indiana this year

A lot of people starting to ask about the prospects of a White Christmas in central Indiana.

Meteorologists define "White Christmas" as having 1" of snow on the ground at 7am December 25.  Historically, Indianapolis has had a White Christmas 28% of the years since 1899.  The last White Christmas was 2017 and the city has only had it two out of the last 17 years.  So you could say we are overdue for snow Christmas morning.

Let me just say that it too early to say with any certainty if there will, or won't be, snow on the ground for Christmas.  Considering it takes just a few hundredths of an inch of liquid to produce 1" of snow (when it is very cold), it is impossible to forecast this far in advance.

That being said, I have taken a closer look at the long range global computer model ensembles.  Specifically, the ECMWF, GFS, and the CMC.

If you don't know, computer model ensembles are a combination of computer model runs.  Instead of running just a single forecast, the computer model is run a number of times from slightly different starting conditions. The complete set of forecasts is referred to as the ensemble, and individual forecasts within it as ensemble members.

The three ensembles - ECMWF, GFS, and CMC - result in a total of 100 different forecasts, or ensemble members.  Out of the 100, 75 members suggest there will be at least 1" of snow on the ground 7am December 25.  It should be noted that is a 6.3% decrease from Tuesday night's runs.

The images show the various members of the ensembles.

Keep in mind this is just one instance of runs.  This is going to, and likely will, change every six hours as more data becomes available.

One thing that is looking more and more likely is a blast of cold air coming to the Midwest late next week.  For more on that, visit my FB page and scroll down to the previous post.

Let me know what you are hoping for Christmas.  A White Christmas or not.

Turning the Page

DID YOU KNOW: You know I like to come up with interesting stats, so here are a couple for you.

4,799 and 1,404

These are the number of forecasts (4,799) and newscasts (1,404) I will have appeared on Channel 8 News (KLKN-TV) through August 30. I mention the numbers because August 30 will be my last day at KLKN-TV.

This decision did not come hastily. I have been contemplating it for over a year and made the decision at the beginning of the year.

I have thoroughly enjoyed working evenings with Rod Fowler and Megan Conway and most recently in the mornings with Andrew Ward and Katrina Sperl. I have also enjoyed working with the talented team of meteorologists amassed during my time at the station.

I had several goals I wanted to accomplish when arriving at the station in August 2020.

• First and foremost, keep viewers safe and informed when it comes to the weather. And maybe the viewer will learn a few things about weather along the way.
• Secondly, bring professionalism to the weather department.
• Third, build trust with our viewers. (And hopefully gain viewers along the way.) I wanted viewers to know they could tune in during severe weather coverage or on “normal” days and know they could get a straightforward forecast without hype.

I like to think those were met and accomplished.

Finally, I want to thank everyone in Nebraska for welcoming me into their homes and always saying hello when meeting me out and about. Also, thank you for not getting too angry with me when I had to cut-in to programming, wiping out your television shows. Just know, I did it to try to keep every person – regardless of what city they reside – safe.

Additionally, after nearly 23 years, now is the right time for me to get out of the tv weather business.

This does not mean you could not see me filling in a time or two at a station in the future because I still have a love of weather. And I will continue to post weather information on Twitter (@JohnDissauer), Facebook (/DissauerWx) and here on my blog.

What’s next… I am now looking for new career opportunities outside of the television and weather business. (If you know of any opportunities you think would be a good fit, send me a message!)

Saharan dust getting closer to the United States

By now you have probably heard talk about a cloud of dust moving across the Atlantic Ocean that originated from the Saharan Desert in Africa.  The large area of dust is just about to reach the Gulf of Mexico.

(Click image to see larger version)

This is a visible satellite loop over the last 6-hours this morning, ending at 10:50am EDT.  If you look towards the Caribbean you can see the brown colored cloud.  That's the dust!  Look at how far it stretches from nearly the Gulf of Mexico all the way off the screen.  Thousands and thousands of miles.


The dust will help inhibit tropical storm development over the Gulf of Mexico.

NASA computer models project some of the dust could make it to the Midwest as we get towards the end of the week and in to the weekend.  That could make for some very pretty sunrises and sunsets.

For more on the dust layer and tracking it by satellite, check out this page from the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin.