Thursday Afternoon Update

We still have several hours to go before the snow ends from west to east across the Midwest. I still feel pretty confident in the forecast that was posted last night.

• Cape Girardeau: 0.75” – 1.5”
• Columbus (IN): 1” – 2”
• Chicago: 7” – 9” (I think there can be localized 10”+ amounts.)
• Indianapolis: 2” – 4” (2” to 3” through the city. 3” to 4” on the north side near Carmel and Westfield.)
• St. Louis: 2” – 3”

In order for the snow to come to an end we need the upper-level low to move out of the Midwest.


You can see the upper-level low depicted in the image above. (Click on the image to see a larger version.) It is currently centered over northeast Missouri. The low and associated ripples of energy riding around it will help spark snow showers and snow bands through the evening and overnight hours (east of the Mississippi River).

As expected, temperatures are much colder than advertised by the computer models. The models were keeping temperatures in the lower to middle 20’s for today. Reality shows that temperatures are in the middle and upper teens over Missouri and central/northern Illinois as of 3:00pm CT.

Temperatures this cold will allow snow to come down as the result of high snow-to-liquid ratios. I think places in Missouri will now see ratios of 17:1 to 19:1. What does that mean? That means that the snow will be drier, fluffier and it won’t take much liquid to produce accumulations.

Again, snowfall amounts remain on track with what I’ve been forecasting for the last day or two.

- Posted from my iPhone

Wednesday Night Update

Just getting a chance to look over the data from the evening computer model runs. A couple of the models are trying to back off (a little) on the moisture available to crank out snow. Could this impact snow amounts? Good question.

I continue to think that snow to liquid ratios should be above "normal" due to the strength of the cold air. I think we could see anywhere from a 15 to 1 ratio to as much as a 19 to 1 ratio.

Lets look at some of the numbers from the models. First, here is the North American forecast model, the NAM.

CITY: H20 | SNOW RANGE

• Cape Girardeau: 0.07" | 0.9" - 1.2"
  
• Columbus (IN): 0.09" | 1.3" - 1.6"
  
• Chicago: 0.50" | 7.5" - 9"
  
• Indianapolis: 0.12" | 1.8" - 2.2"
  
• St. Louis: 0.17" | 2.4" - 3.1"
  

Next, we take a look at NOAA's global forecast model, the GFS.

CITY: H20 | SNOW RANGE

• Cape Girardeau: 0.10" | 1.4" - 1.8"
  
• Columbus (IN): 0.20" | 3" - 3.6"
  
• Chicago: 0.46" | 7.3" - 8.3"
  
• Indianapolis: 0.22" | 3.3" - 4.0"
  
• St. Louis: 0.15" | 2.25" - 2.6"
  

Now lets take a look at the European forecast agency's model.

CITY: H20 | SNOW RANGE

• Cape Girardeau: 0.08" | 1.1" - 1.3"
  
• Columbus (IN): 0.11" | 1.6" - 2"
  
• Chicago: 0.58" | 9.2" - 11"
  
• Indianapolis: 0.13" | 1.8" - 2.3"
  
• St. Louis: 0.13" | 1.8" - 2.2"
  

In almost all cases, the numbers dropped slightly from earlier runs. However, that doesn't necessarily mean we are going to get less.

I am going to stay with what I was saying earlier today. The breakdown goes something like this...

• Cape Girardeau: 0.75" - 1.5"
• Columbus (IN): 1" - 2"
• Chicago: 7" - 9"
• Indianapolis: 2" - 4" (2" to 3" through the city. 3" to 4" on the northside near Carmel and Westfield.)
• St. Louis: 2" - 3"

As for timing... Check out my post from earlier today for the details on when the snow arrives.

My "Freak-Out-Meter" holds pretty much the same as earlier. For places like Cape Girardeau, St. Louis, Columbus (IN) it is a 3 out of 10. For Indianapolis it is a 4 out of 10 and in Chicago it is a 6 out of 10.

None the less temperatures will be much colder Thursday and Friday and winds will be gusty out of the west and northwest.

Be sure to leave your snowfall amounts in the comments section of this blog post.

Live Radar Video Feed

I'm going to try something new for Thursday's snow. I am going to embed a live video stream of the radar for the St. Louis metro area. Please let me know what you think of this feature by leaving a comment in the "comment section" below.



I apologize in advance for the ads that run every 15 minutes.

Wednesday Afternoon Update

Still looking like an accumulating snow for much of the Midwest. As is usually the case, some will get much more than others. Totals could range from a dusting to as much as 10”.

In my last post I mentioned that I was waiting for the European forecast agency’s computer model to come in. The data is in and it is keeping in line with the GFS model.

Here is a breakdown of the amount of liquid is available to produce snow according to the European model. I am still looking at ratios generally being around 14:1 to 16:1. Some places could be as high as 18:1.

CITY: EURO LIQUID | SNOW RANGE USING ABOVE RATIOS

• Cape Girardeau, MO: 0.08” | 1.1” - 1.3”
• Carbondale, IL: 0.08” | 1.1” – 1.3”
• Champaign, IL: 0.25” | 3.5” - 4.25”
• Chicago, IL: 0.52” | 8.3” – 9.4”
• Columbus, IN: 0.11” | 1.5” – 1.9”
• Harrisburg, IL: 0.08” | 1.1” – 1.3”
• Indianapolis, IN: 0.18” | 2.7” – 3”
• Mt. Vernon, IL: 0.11” | 1.5” – 1.8”
• Paducah, KY: 0.09” | 1.2” – 1.4”
• Poplar Bluff, MO: 0.03” | 0.4” – 0.5”

Those are a lot of numbers to dissect, but you can see that the range could be from a dusting to 10”+.

Here’s a couple of graphical maps indicating snowfall amounts from two computer models, the North American Model (NAM) and the global forecast model (GFS).

NAM:



GFS:


I want to stress that this isn’t my final forecast as to how much snow will fall. The numbers listed/represented above come straight from a computer model. I am still going with the numbers I had mentioned earlier (Cape Girardeau: 0.75" - 1.5" | Indianapolis: 2"-4" | St. Louis: 2"-3") but I will likely be putting out a more detailed snow forecast later this evening.

Winter Weather Advisories are now posted for much of central Indiana and central/northern Illinois. Remember you can get the latest winter advisories, warnings and watches on my blog by clicking on the “Warnings & Watches” tab at the top of the page.

You can also get the latest by following me on Twitter as I'll be posting updates through the evening and tomorrow. Follow @johndissauer.


- Posted from my iPhone

Wednesday Morning Update

The next round of computer model data is coming in this morning and the models are keeping the upward trend. Last night I mentioned it would be interesting to see how this morning’s runs handle the moisture. Do they take it up, keep it the same or drop it?
I look at several computer forecast models when putting together the forecast. During snow storms I’ll look at upwards of eight different models from various worldwide forecast agencies. So far this morning, NOAA’s global forecast model (GFS) is in along with the RPM.

Let’s take a look at the breakdown of how much water the models are suggesting will be available for snow production.

CITY: GFS H2O | CHANGE FROM 0z RUN

• Cape Girardeau: 0.10” | +0.03”
• Indianapolis: 0.22” | +0.06”
• St. Louis: 0.16” | +0.03”

Looking at the change from last night it may not look like a big change. However, when forecasting snow, it doesn’t take much to make more snow. For Cape Girardeau and St. Louis the 0.03” difference could add an additional half inch and for Indianapolis the additional 0.06” could add an additional inch of snow.

With the amount of cold air coming in with the cold front, I am looking for snow to rain ratios of 14 to 1 or as high as 17 to 1. Going strictly from the GFS model that would put down:

• Cape Girardeau: ¾” to 1.5” of snow
• Indianapolis: 3”-4” of snow
• St. Louis: 2”-3” of snow

I am still waiting to see what the European forecast agency’s computer model comes up with. All I have to look at right now are the numbers from last night’s run. They are fairly comparable to this morning’s GFS. Cape Girardeau – 0.09” | Indianapolis – 0.19” | St. Louis – 0.19”. Numbers from this morning’s European model will be in later this afternoon and I’ll try to give an update when they come out.

Timing: The snow should begin to fall in St. Louis during the pre-dawn hours (2am-4am CT), in Cape Girardeau during pre-dawn hours (5am-7am CT) and in Indianapolis by early afternoon (12pm-3pm ET).

As for my “Freak-Out-Meter”… I am going to keep it at a 3 out of 10 for St. Louis and Cape Girardeau and move it to a 4 out of 10 for Indianapolis. The “Freak-Out-Meter” is hard to score because there are two ways to do it. I could score it on how people’s reaction will be or how the reaction should be. I try to score it to how people’s reaction should be.

Remember you can follow me for more timely updates via Twitter @johndissauer and via my Facebook page.

-Posted from my iPhone

Numbers Going Up?

New data is streaming in as I type tonight. Interesting to note that on first look, it appears NOAA's global forecast model is coming in slightly wetter.

The time frame I am talking about is still Thursday in to Friday morning for parts of the Midwest.

A strong surge of cold air will blow in behind a cold front passing the Midwest Wednesday evening and Thursday morning. Th cold air will work very efficiently at changing the moisture to snow.

Earlier today I showed you what the GFS computer model was suggesting for moisture in Cape Girardeau (0.02"), Indianapolis (0.15") and St. Louis (0.07"). As of the time I am writing this, data is only available through Friday evening.

Here's a look at what the new run of the GFS is showing. Again, this is how much moisture is available, not snow.

• Cape Girardeau - 0.07"
• Indianapolis - 0.16"
• St. Louis - 0.13"

Comparing that to this morning's numbers you can see the model is starting to increase the amounts.

The strength of the cold air is impressive. I think this could generate a 14:1 to 16:1 snow with a few locations seeing higher ratios. This would equate to around 1" in Cape Girardeau, 1.5" to 2.5" in Indianapolis and 1" to 2.5" in St. Louis. There could be a few locations upwards of 3" around central Indiana (likely north of Indianapolis).

It will be interesting to see what Wednesday morning's computer models are showing to see if they continue the trend of increasing the moisture, keeping it the same as tonight's runs or decreasing the moisture.

I am going to slightly increase the "Freak-Out-Meter" to a 3 out of 10. It won't be bad, but for some, this will be the first measurable snow of the season.

Stay tuned...

Light Snow Possible by Week's End

It is starting to look like we could see a little snow across parts of Missouri and Illinois within the next 72 hours. At this point, I want to stress the word “little”. I’m not talking about a major snowstorm. In fact, I’m not sure if the word “snow” or “storm” should even be included in this discussion.

A strong cold front is just beginning to move across the Canadian/United States border. Behind the front, cold air is on the march. At 1pm CT, temperatures were in the single digits in Alberta and British Columbia.


Forecast models are indicating the cold front will pass through Missouri and Illinois late Wednesday night into early Thursday morning. Behind the cold front, the previously mentioned cold air in Canada will spread over the Midwest.

It appears that the strength of the cold air will work on the little amount of moisture in the air and squeeze out a few snow showers Thursday. Both the European Agency’s forecast model and NOAA’s forecast model are suggesting light amounts of precipitation for the cold air to work with. What is “light amounts”? Let’s take a look.

Here is a breakdown of how much liquid water is forecast to fall by the models.

CITY: EURO | GFS

• Cape Girardeau: 0.05” | 0.02”
• Indianapolis: 0.15” | 0.12”
• St. Louis: 0.06” | 0.07”

You can see what I mean by small amounts of liquid to work with. Typically, you can say there is a 10:1 ratio of snow to water. In this case, with the surge of cold air, I think we could see at most a 14:1 ratio. This would mean approximately a dusting to a half inch in Cape Girardeau, a half inch to 1” in St. Louis and 1” to 2” in Indianapolis.

Here is another view of what some of the models are indicating for Cape Girardeau and Chesterfield, Missouri.

Cape Girardeau:

Chesterfield:

The above are called meteograms. The ones I have posted indicate how much snow will fall according to various runs of forecast models and the forecast from the National Weather Service. Remember, a forecast model is just that… A model. It isn’t reality.

Bottom line… Could there be some snow? Yes. Will it be a lot? No. Where do I have my “Freak-Out-Meter”? I’ve currently got it at 2 out of 10.

- Posted from my iPhone

Website Update

Made a small update to the design of the website today. I have added a recent satellite image from the University of Wisconsin and the latest forecast map for today from NOAA's Hydrometeorological Prediction Center (HPC).



You can view the images by scrolling down the site and looking in the right hand column.