Nowcast...The Big Storm Before the BIG Storm

The current storm system looks to provide plenty of messy issues for many in our Commonwealth. A great deal of uncertainty continues to be factored into even the short term models.

This is where nowcasting becomes important, not just from a short term model aspect.

The most current observations possible will become critical as far as forecasting what may happen to the next tier of counties.

If you have a thermometer, check it.
If it's still raining outside and the thermometer reads near freezing, put on your rain suit, go outside and feel metal objects, observe any ice building up on branches, bushes.
If you hear or see ice pellets bouncing around or pinging, report that as sleet.
If it's snowing, report that especially as soon as changeover begins.
Report if it's sticking to the grass or to the pavement or not at all.
If it's sticking, measure it, preferably in an open area, away from rooftops. Decks do not count, unless you use the one by the pool, which should be away from the house.
If you're traveling, report road conditions as wet, slushy, icy, snow-covered.
Most important, if you're traveling, BE CAREFUL.

This page will be updated frequently, especially as future short term model runs occur. I will be making many references to terms like 850mb, 925mb readings. These are referencing temperatures between 2,500 and 5,000 feet above the surface. This information will prove to be important because if your thermometer reads 32 degrees, yet the 850mb reading is above 32, then it will be likely raining at your location and freezing on contact at the surface.

MS
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4:15am
06z RAP
850mb freezing line just south of Louisville by 7pm
925mb freezing line into central KY
Mix of snow/rain by 5pm with complete changeover by 7pm or so for Louisville.
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5:00am
Widespread Winter Storm Warning products out for our region, including Louisville, Lexington, E'town, and points east into eastern KY.
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5:10am
At Louisville, temperature has dropped from 50 to 39 degrees within the past two hours. It is now 39 at my house as well.
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7:50am
10z run RAP
batch of light precipitation may become freezing drizzle, freezing rain along Ohio River before 3:00pm, maybe even change to s-2now across southern IN.
A brief lull then mostly snow for Louisville by 5pm onward. After dark or a little later, accumulations should begin. By 11pm, at least 2" may be on the ground in Louisville.
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12:40pm
RAP model continues to highlight moderate to heavy snow for the Louisville area, perhaps even shifting the heaviest axis into the area while parts of southern IN could be looking at warning criteria. At this time, 4"+ is looking likely for Louisville. However, this is still a developing storm. Many variables still need to be analyzed and come together. There are indications that a thin stripe of very heavy snowfall could occur with rates -approaching 2"/hr. Therefore, 5-6" are possible between Louisville and Lexington. Still monitoring latest runs. Looking out west for observation data. Temperature remains at 34 degrees at my house.
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1:30pm
Heavy snow falling across southern MO like West Plains and Branson. This could be the snow that will impact our area later this evening and overnight. Still looks like Louisville to Lexington could be in for a major accumulation (4-8")
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2:10pm
1-2" common across parts of southern MO, falling within the past couple of hours. Numerous slide-offs.
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2:15pm
3" south of West Plains MO. This kind of snow is heading toward the area for later this evening/overnight.
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3:15pm
2-4" from Branson to West Plains. Numerous accidents. Sleet falling across Western KY. Sleet reported in Louisville.
Latest RAP continues to paint at least 5" in Metro Louisville. That would put them in a 4-6" range. Nevertheless, Lexington and nearby locations stand to receive perhaps 6-9 inches.
Look for parts of southern IN to go under a warning if this trend continues.