**8:28 a.m. Update**
HRRR still thinks we will see some wintry weather around 2-3 p.m. Shown below: 3 p.m.
It might fall as a wintry mix, but HRRR still thinks temps will be 34-35 at 3 pm:
**8:05 a.m. Update**
RAP model thinks the frozen temps will move north of us — missing us — tonight, 5 pm to 10 pm:
This is just one model run. We’ll update these mid-morning.
**7:45 a.m. Update**
The HRRR is suggesting precip may end earlier than expected tonight. HRRR from 4pm – 7 pm:
This would severely limit our ice potential if it happens. Waiting for more model data to arrive.
**Back to the 5:45 a.m. Update**
Three rounds of winter weather were discussed.
1. Tonight – very minor ice accumulation.
2. Saturday Night – additional ice accumulation possible.
3. Sunday Night, Monday, & Monday Night – freezing drizzle, then possibly-accumulating snow.
Round One: Later Today/Tonight – Winter Weather Advisory from 4 pm to Midnight
This forecast would be easier if we were in
- NW Middle Tennessee (Dover, Clarksville, Camden), where ice is expected, or
- On the plateau (Crossville, Cookeville), where it’s expected to only be a cold rain.
For us, however, the NWS said: “You guys are right on the line. That’s what makes this forecast so difficult.”
Freezing temperatures are expected to arrive in Williamson and Davidson Counties juuust before the precip ends tonight. Any alteration in the timing of either the temps or the precip will make all the difference. You should closely monitor reliable weather sources for changing weather conditions through the day — it could be worse, it could be nothing, or it could be what we think now: somewhere in the middle.
Overnight, temps dropped from 36 to 35, where they held steady. Temps are expected to remain above freezing today, then reach freezing by dark tonight:
6am 34 . 9am 37 . Noon 37 . 3pm 35 . 6pm 33 . 9pm 32 . Midnight 31
The cold air is shallow, meaning it’s just sitting on the ground. The air just overhead is above freezing, explaining why the precip will first fall as rain or sleet.
Rain – at times heavy – will continue all day. Here’s the HRRR today from 9 a.m to 6 p.m. The deep reds and blues indicate frozen precip.
Notice how the HRRR starts to change us over to wintry precip by late afternoon.
Less than 0.10″ of ice:
ETA is after dark:
We think light accumulations of ice (0.1″ to 0.15″) will begin after dark. We may see a dusting of sleet or snow atop it before the precip moves east. This is by no means certain.
The probability of us getting any ice accumulation is a bit better than 50%:
Probabilities of ice greater than 0.10″ are a little less:
Notice your chance of ice improves the further NW you are.
Impacts to the power grid are currently expected to minimum to nothing.
However, travel will be hazardous, especially on bridges, overpass, and at elevation.
Rain/Freezing Rain/Sleet/Snow should end around midnight.
Morning and afternoon hours are forecast to be rain-free. We should be above freezing by mid-morning, then reach 38 by mid-afternoon. This should melt any minor ice accumulation.
This is great news for those of you needing to get out Saturday.
Round Two: Saturday Night
Rain returns around 6 p.m. Saturday. Temps will, similar to Friday night, dip near/to freezing, creating another chance of freezing rain and sleet overnight.
NWS is uncomfortable putting accumulation totals on this. There’s too much we don’t know right now. The NWS is considering whether to issue a Winter Storm Watch for us for Saturday night. Again, those to the NW of us have a better chance for wintry precip.
The Weather Prediction Center is unimpressed by our freezing rain potential. It drew us outside the risk area:
Other models indicate a low probability of icing; however, it’s still a bit too soon to draw any conclusions. Also, not all guidance agrees. The SPIA index expects minor power interruptions late Saturday night into Sunday morning:
It’s just too soon to say.
Sunday — 1″ to 2″ of Additional Rain
After the sun comes up, temps are forecast to rise well above freezing, melting any ice that has formed.
The additional rainfall may create some minor flooding concerns.
Round Three: Sunday Night – Monday – Monday Night
Sunday night, the rain is forecast to transition to freezing drizzle, which should last overnight through Monday morning. Precip will continue into the day, and, by Monday night, we may see a changeover to all snow, 1″ to 2″ for areas along and east of I-65.
Of course, that’s a while away. It’s definitely too soon to start talking “snow day.” However, it’s never too late to dream.
This website will be updated from time to time as a supplement to our full coverage on Twitter @NashSevereWx.
Categories: Forecast Blogs