Sunday Update: Ready for an ice storm (Issued at 2:00 pm)

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Now is the time to wrap up your preparations for an ice storm. I would recommend everyone be home and safe by dark. Conditions will deteriorate overnight. The NWS Nashville is having a conference call this afternoon that I will be sitting in on. That info will be in my 6:00 update.

Please note that ice accretion has occurred across parts of northern Cumberland County and eastern Putnam County over the past couple of days that will create vastly different conditions for those folks. At my house in Rinnie, we haven’t been above freezing all weekend. Some trees already have significant icing.

My official forecast is rather unchanged, with a few exceptions:

Round 1: The ice storm begins

What: Freezing rain of up to 1/4 of an inch

When: Sunday night (mainly after midnight) and the Monday morning hours

NOTE: I would plan to be home before dark this evening, just to be safe.

Round 2: After a possible break mid-morning to noon (give or take an hour)

What: Freezing rain and sleet of around 1/4 inch accumulation (locally higher amounts)

When: Monday afternoon to early evening

NOTE: This heavier wintry mix will fall when temps are warmer than the morning ice. So, while the morning ice is from lighter precip, the morning temps will be colder and allow for more ice accretion. The precip gets heavier in the afternoon and evening but temps should be warmer and slow down ice accretion. That is why I’m expecting similar ice amounts for both rounds, though the second will be heavier precip. Please note that if temps do not rise as expected, ice accretion will be heavier and we’ll be looking at 1/4 – 1/2 inch of ice with this second round.

Round 3: Wintry mix transitions to snow

What: Snow to a depth of 1-2 inches (locally higher amounts possible)

When: Monday evening/overnight

NOTE: If the transition to snow happens sooner, we can add an inch or two of snow to this forecast. If the transition occurs later, we can take away from the total.

NOTE: Winds will be very light during the duration of this event. That will make a big difference in damage. Remember, it was the wind that caused so much of the icing damage in 2015.

Important Note: I should begin by saying that some of us already have 1/4 – 1/2 inch of ice on trees that are in exposed and open areas. In these areas, the ice storm, obviously, will be significantly worse than what happens in other areas that don’t already have ice. This means the ice storm will be more severe for folks across the northwest end of Cumberland County (ie Mayland to Rinnie). Eastern Putnam is also under the gun (Monterey), as well as much of Overton and Fentress Counties. Again, if you have icing on trees right now, add what I’m forecasting to that total. I have some trees with close to an inch of ice already and they will end up with as much as 1.5 inches of ice when all is said and done. What an example of the various microclimates across the plateau!

NOTE: Those of you south of Interstate 40 in Cumberland County will likely fare better in this ice storm than the north end of the county will. Your temps are expected to rise a few degrees on Monday and that should help you out. If those temps do not rise, you will see worse conditions than expected. Just one degree can make a huge difference with ice accretions.

From this morning’s post, with some edits.

Worst Case Scenario:

We don’t get a break Monday morning and precip is more than anticipated and/or temps don’t rise to near or slightly above freezing. This would take ice totals into the 1/2 – 3/4 inch territory, with some folks picking up an inch of ice. Even in the worst case scenario, I still don’t see widespread 1″ or greater amounts of ice, like we did in 2015. Some locations may get that much, though.

Also, even in the worst case scenario I still don’t see us getting gusty winds. That will significantly reduce the damage from the ice.

*In a worst case scenario, we end up with around an inch of ice and up to 4 inches of snow on top of that. (Chance of this happening at about 20%).

NOTE: IF you have ice already in your trees, you will experience the worst case scenario for ice. In fact, some isolated locations will likely get over one inch of ice on the trees, especially since some of our trees already have more than half an inch of ice on them. Snow amounts are still uncertain.

Best Case Scenario:

1. The storm pulls up warmer air and the afternoon and evening freezing rain potential turns to plain rain. That would nearly avoid an ice storm in the afternoon, although the morning ice would still be troublesome.
2. The wrap-around snowfall is lighter than expected (or mixes heavily with sleet) and we only get one inch-or-less of snow Monday night.
3. Sleet mixing in at all times, keeping both ice and snow totals lower.

*In a best case scenario, we end up with less than 1/4 inch of ice (below ice storm criteria) and only a dusting of snow on top of that. (Chance of this happening at about 20%) (30% for those of you south of I-40 in Cumberland County)

**Please not that worse conditions are expected west of the plateau (Monterey–Cookeville–Nashville), with better conditions east of the plateau (Harriman–Knoxville)

REMARKS

The various microclimates across the plateau make this forecast especially challenging, especially across the north and western portions of Cumberland County. Never the less, a winter storm is expected for all of us over the next 48 hours or so. Always prepare for the worst, and hope for the best. Make sure you have heat, water, and food. And make sure the fur babies are good, too.

I’m tracking it all and I’ll be making another update at 6:00 pm. You all take care and thank you for trusting me with your forecast!