Nowcast Mode Winter Storm 'Leo'

***Scroll down to see latest updates***

Leo? Well, think about it. The beginning of March typically has either calm, benign weather (comes in like a lamb, we'll name her Dolly) or stormy (comes in like a lion thus the name 'Leo').

This storm has the potential for being the strongest storm of the season (yes, the entire winter season). Meteorogically, this is the spring season. Therefore, this will be an unusually strong winter storm for our region.

This page will be updated throughout the day. Although, depending on how much precipitation is falling and the p-type, I may choose to update every few hours today.

Reason: Precipitation, even if it's freezing rain, will be fairly light through mid afternoon, according to the RAP model (latest run I looked at was the 08z run which takes through 9pm tonight).

After 4pm, things should start picking up in intensity for some in our region from the I-65 corridor (Louisville to Bowling Green) to the I-75 corridor (Cincinnati to London).

Brief Synopsis for today: 

Rain will be falling at several stations through 3pm. It appears most of this will be fairly light. But, in Louisville, by 12pm, freezing rain will become the dominant p-type as temperatures should be close enough to the freezing mark.

Lexington will follow shortly with freezing rain. Again, amounts appear light ( 0.1" or less) through 3pm.

Bowling Green may stay above freezing through 3pm. It will be close.

By or after 4pm, things will start going downhill. My biggest concern for this time period through 9pm is the Bowling Green area. They will be facing a long-lasting period of freezing rain. For a time, any moderate to heavy freezing rain will preclude any serious ice accretion on power lines and tree branches. However, amounts will be on the rise as we head into the overnight.

For Louisville, light freezing rain (which is an efficient ice accumulator) should be transitioning to a mix of sleet by 4-6pm time frame and continuing for a few hours through 9pm. Snow may begin mixing in by then.

Lexington could have similar amounts today. However, there is a possibility of an enhanced amount of sleet/freezing rain by the 6-8pm time frame. Let's hope it's sleet. Yet, it will not be a prolonged event through 9pm.

I want to see how this synopsis compares to future runs of the RAP. As a side note, I looked at the NAM (0z) run for comparative purposes. For Bowling Green, a prolonged period of freezing rain from 4pm to 1am is possible.

Louisville could see its heaviest snow by 1-3am overnight and Lexington from 3-7am.

As I conclude this part, some may be disappointed by snowfall totals. I'm seeing a lot of enhanced forecast amounts. I will say there is the potential for those amounts to be realized. However, any sleet accumulation will cut down many snow totals. And I do see a good chance for quite a bit of sleet. Nevertheless, amounts of at least 6" in some areas are likely.
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07:30am
Did you know that just as we have a snow to liquid ratio, there is also a sleet to liquid ratio?
Typically, a 3:1 sleet to liquid ratio is common. For every 1" of liquid precipitation, you would have 3" sleet. I do think a few locations could see up to an inch of sleet, or roughly a third of an inch of liquid accumulation.
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07:45am
Radar - A complex of precipitation is streaking eastward across the Ohio and Wabash rivers. Precipitation should reach Louisville by the 10am hour. Presently, it's 33 degrees at my house in Valley Station, southwest of Louisville Int'l airport. By 10am, we should be at the freezing mark. Therefore, freezing rain will be commencing.
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07:55am
Storm Report - Cape Girardeau MO: Heavy thunder sleet is occurring...0.2" sleet
        Carbondale IL: 0.5" sleet accumulation
        Hamilton IL: Thunder with freezing rain and some sleet...0.2" ice accumulation
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08:00am
At this rate, sleet could become the early p-type leader here in Louisville before 4pm? It looks like any moderate freezing rain is already mixing with sleet across MO and IL. Hope the trend continues. Go away ice.
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3:00pm
According to recent run of RAP through 5am, 2.5" snow for Louisville, perhaps more, depending on ratio. Therefore, I'm still sticking to 2-4" for Louisville. However, am concerned about a southward shift of heaviest snow axis. If this trend continues, amounts may need to be lowered.
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6:30pm
Between 4:00 and 5:00 this afternoon, freezing rain and sleet moved into my area. Small glaze on mother-in-law's deck. My wife slipped and bruised her hip. Sleet has accumulated about 0.1".
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8:10pm
22z run of the RAP showing a heavy band of snow developing just south of Louisville stretching to Lexington between 3 and 5am. Going by the model, snowfall amounts of 3-4" for Louisville and at least 5" for Lexington. This is the most aggressive I've seen the RAP since Louisville was forecast to receive 4-6" earlier in the winter season and the RAP nailed it then. Bardstown to Lexington could see 6+" as long as the sleet is done.
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8:45pm
Sleet accumulation of 0.25" here at my house in Valley Station; read report of 0.30" sleet in Okolona. I still think transition to snow between 9 and midnight here in Louisville.
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9:05pm
NWS Louisville thinking about upping snowfall totals for some. Air is cooling quicker than expected. A transition to snow may occur sooner....Of course, this morning the RAP showed a transition to snow by 9-10pm for Louisville. We'll just have to wait and see.
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9:25pm
Some places in Missouri have received up to 2.5" Sleet accumulation. That would almost be 8" snow if it was all snow instead of sleet.
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10:45pm
Snow/sleet in Valley Station - sleet/snow accumulation of 0.4"
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11:40pm
LAST UPDATE tonight...all snow here in Valley Station...total snow/sleet at 0.7"...Still on target to get at least 3-4" but heavier south. Good night and stay safe.


MS