The band of snow that moved through overnight added a heft amount of snow to our overall storm total. I picked up 3.5" at my place in Cape Girardeau from 10pm Friday through 4am Saturday.
Here is a list of snowfall totals from StormTeam weather watchers, the NWS, Twitter, and Facebook.
Illinois:
Kentucky:
Missouri:
Tennessee:
*Amounts submitted through Facebook and Twitter.
In the upper left panel is the probability forecast of at least 4" of snow. In the upper right panel is the probability forecast of at least 8" or greater snow. In the bottom left panel is the probability forecast of at least 12" or greater snow. In the bottom right panel is the probability forecast for at least 0.25" ice accumulation.
As you can see, the models are suggesting amounts anywhere from 2" to up to 12" of snow across the region. Notice there is a little variance from the 6z run of the same model as the 6z run (US map earlier in post) has the heavy 10"-12" band of snow a little further east.
Other points of snowfall amounts:I have had several people asking about other points in the Missouri bootheel and southern Illinois. Unfortunately, NOAA only provides data points for this type of data for specific locations in the area. There aren't any locations in either the bootheel or in southern Illinois. Of course on air we will be giving forecasts for the entire area.
With this storm the track means everything. There will be a very sharp cut-off of snow on the north side of the storm. A deviation of the storm track of 25-30 miles could mean the difference in getting 0" instead of 6" of snow.
The above numbers are not our forecast. These are just numbers from a computer model.
Just as the title of this post says, a major winter storm is looking more likely Thursday and Friday for parts of Missouri, Illinois, Kentucky, Tennessee, and Arkansas.
I am looking over new data just in from the night runs of NOAA's global forecast model (GFS). If I were to have to make a snow forecast with the data in hand right now, I would have to say that the heaviest band of snow could be setting up along a line from Poplar Bluff, Missouri and Paducah, Kentucky. Snow will also be north and south of that line. Snow could even be falling from eastern Arkansas in to western Tennessee.
For Cape Girardeau, the precipitation type looks to be all snow. The amount of precipitation is pretty impressive. The GFS pumps out 0.82" of liquid. Even on a 10:1 ratio would bring the snowfall amount to 8.2" of snow. Using a couple of different methods shows that the snow ratio could be between 10:1 to 17:1. The ratio could be going up through the event as the cold air moves in. Overall, tonight's GFS run puts down 11.4" of snow. That's a decent amount. ;)
As I mentioned, it looks like it will be snow south of the area as well. In Jonesboro, Arkansas it looks like it will start out as rain. Then mixing with perhaps an hour or two of freezing rain (1/4"?). Then it changes over to all snow. Quite a bit of snow in Jonesboro too. Perhaps around 8.7".
Here are some of the other model's snowfall amounts.
It appears that there will be a pretty sharp cut-off of the snow on the northern edge of the band.
Keep in mind the amounts mentioned above are not forecast amounts. These are numbers coming straight from the computer model. We will continue to be going over the weather data over the next 60-72 hours.
Bottom line... How much snow is still in question. As of right now, it appears that the biggest threat for southeast Missouri, southern Illinois, and western Kentucky will be snow.
You can see how the model brings in snow by Thursday morning. The moisture amounts aren't that impressive. When it changes over to all snow, there is 0.275" of liquid to work with which would come out to around 3.3" of snow. Conversely, last night's run of the same model was indicating a little over 14" of snow for Cape Girardeau. This morning's run also puts down 9" of snow for Paducah, Kentucky. As you can see, there are huge swings in the models from run to run. I would like to see them settle down a little bit before I start to get excited.
In their discussion, SPC points at damaging wind being the main threat from any storms that develop later this evening in southeast Missouri, western Kentucky, northwest Tennessee.
A couple of things to note.
We could be up on the edge of the amounts shown in the map so we'll have to keep a close eye on it.
A tornado watch means that conditions are favorable for the development of thunderstorms capable of producing large hail, damaging wind, and tornadoes.
The main threat will be hail.
The nose of the jet streak is rounding the trough and is shooting right in to southern Missouri. The above image depicts .
Dew points are often times a huge player in cool-season severe storms. A recent NWS study from the Paducah, Kentucky office has shown that the possibility of cool-season severe storms substantially increases when dew points rise above 48°. This model is indicating dew points over 50° Saturday night.
When looking at the instability it doesn't look that impressive. You can see a bulls eye of heightened CAPE over the region at 6am CT with values around 500 j/kg. Normally that wouldn't be too impressive. However, will cool-season storms, it has been found that instability isn't a huge player for severe storms to develop. To give some perspective, CAPEs will often times be over 3,000 - 4,000 j/kg (if not higher) in the summer.
The GFS is indicating over 1.5" of rain Saturday evening through Sunday morning.
Reminder: Time reads from right to left. Red line is air temperature at surface. Green bars indicate rain. Grey blocks indicate clouds.
The model is hinting at a nice jet streak shooting up through Arkansas and Missouri. To the southeast of the jet streak, temperatures would most likely warm in to the 50's (and 60's south). Moisture from the Gulf of Mexico would be streamed up ahead of the storm. Put all of those ingredients together and we could be talking about a severe weather outbreak for someone from the middle Mississippi River Valley to the Gulf Coast. 
a cold note. The question is, "How cold has it been?"
Here is our forecast from Tuesday afternoon. At the bottom of the image is our forecast. Overlayed in the smaller yellow text is reports of snow from co-op oberservers, the National Weather Service, and the public. (click the image to see a larger version)
midnight, 0.75" and it is still coming down.
