Winter Storm Warnings are up region wide...
The Pink areas have been upgraded while the other regions are either advisories, or watches. We did hit single digits last night here in Lynchburg with a 7 spot on the board as of 5 am. Roanoke has been as low as 10 and I imagine one of those in between hour observations met our goal of single digit lows.
The storm is moving faster. Start times in the west regions COULD be as early as 5pm, I think the 8 or 9 PM, the first flakes are into Lynchburg. The earlier start time won't translate to more snow because it just means we mix sooner. Mixing COULD be in Southside pre Dawn and Lynchburg as early as 9 am. First sleet mixes in and then by mid afternoon we should have completed the transition to freezing rain in Lynchburg. Sleet may linger a littler longer out in Roanoke and other places along 81.
Here are my broad ideas about the storm. My map may not match XYZ vendor, it happens.
Some ideas and pit falls:
1. I think that the Mt. Empire and NRV into the Roanoke Vally, up 81 to Lexington are the Jackpot areas for snow. Would not be shocked if a person reports a 10 inch total that way.
2. Some model data has had one maximum east of the Blue Ridge VERY south near the NC border and another NORTH of Lynchburg near Charlottesville. We could verify on the low end of the 3-6 inches.
3. I think the worst ice falls in a triangle from near Lynchburg to Charlottesville to Winchester.
4. The window for snow is about 12-15 hours. After the transition to sleet and then freezing rain precipitation stops. This lasts for about 8 hours. During this time, light freezing drizzle will be falling.
5. Between 4 am and 7 am, places most places make it above freezing JUST as some very heavy rain comes in. Rainfall, falling as just rain could reach up to an inch.
Cold air damming.
Cold air damming (No, not what you want to say to the cold when it's 5 degrees outside) is cold air being trapped against the MTS, preventing it from leaving. Cold air is heavier than warmer air and is hard to dislodge. Sometimes once you're just 500 feet up, it's above freezing but down near the ground it's cold.
Here is a 4pm map Monday, you can see the cold air holding WAY down to near Charlotte.
At 1 Am Tuesday, It's getting smaller.
and at 4 am most places are above Freezing.
What saves us from a REALLY bad ice storm is that the cold are finally breaks down as some heavy rain approaches from the west. Most of the time from 4pm or so until 1 am will be light freezing drizzle. Here is SIM radar at 1 PM monday, most of the precipitation as moved out.
And at 7 PM
Finally, 1 AM
We are fortunate that for 12 hours we have temps in the mid and upper 20's and it's just light freezing drizzle. Once that heavy band moves in, we are above freezing in about 2-3 hours. This is preventing a significant ice event. Places east of the Blue Ridge may see 1 to 1.5 inches of rain from that band. With temps in the mid 40's Tuesday afternoon, we could see about a total melt off.
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