Thursday – Rain Begins – Morning Low 63 / Afternoon High 63 (yeah, the same!)
6am 63 . 9am 63 . Noon 63 . 3pm 62 . 6pm 53 . 9pm 48
Showers should begin around 6 a.m.. Here’s the RAP model turning on the morning rain:
We don’t think it’ll be a continuous rain, but the whole day should be a washout.
A few thunderstorms are possible inside the green area below, but strong or severe weather is not expected:
Rainfall totals through Thursday at 6 p.m. should be around a half inch:
Before I dive into the winter weather stuff, check out the rainfall totals through Monday night. 5″ of rain total!
There may be a few flooding concerns.
Also, expect gusty winds Thursday and Friday. Lawn Santas may not fare too well.
Friday – Rain Continues – Morning Low 39 / Afternoon High 42
Temps will drop into the mid-30s by 3 p.m., and near freezing by 6 p.m. Meanwhile, the rain will continue.
NWS Winter Weather Forecast for Friday Night
At 6 p.m., the rain will start to change to freezing rain.
By 9 p.m., it’ll be freezing rain and/or sleet. After that, the rain shuts off.
NWS-Nashville’s current forecast for ice accumulation:
Note, it’s very little, and limited to the western halves of both counties. It’s also fair to say those at elevation (atop hills, etc.) may also expect a little more ice than is reflected by the above map.
All things considered, the above forecast is a step in the right direction. It pushes the rain through while keeping the freezing line away long enough to prevent a huge problem. However, travel may still be impacted.
All that said, It’s impossible to know right now what we will see. This forecast may change.
A Winter Storm Watch is in effect for our adjacent counties. We are excluded:
Behold, below, the possibilities. Reading through the models should give you an appreciation of what may still happen. We remain 48 hours removed from the event. A lot can change.
One other thing: the models are run in 12 hr, 6 hr, 3 hr, and/or 1 hr intervals. They don’t always even agree with themselves between runs. As @RuthSevereWx said today, these models are only a few pieces in a puzzle. What you’re seeing below are only parts of those puzzle pieces.
Prepare the runway. Here come a lot of models.
SREF (Short Range Ensemble Forecast) – Overnight Freezing Rain
This model likes our freezing rain (in red) chances. Midnight Friday:
3 a.m. Saturday Morning:
6 a.m. Saturday Morning:
The below four-panel model shows Ice (upper left), Freezing Rain (upper right), Rain (bottom left), and Snow (bottom right) which will have accumulated as of 6 a.m. Saturday morning.
Notice that we (1) Miss any snow, (2) Avoid significant — or really any — ice accumulation, and (3) Get only a bit of freezing rain.
The below image shows midnight Friday.
As the precip ends, it falls as sleet and freezing rain. We’re right on the edge of the freezing line. The low resolution of this model makes it impossible to say, but it could very well distribute a wintry mix in, for example, Joelton, while everyone else gets a cold rain.
By 6 a.m., the GFS thinks the precip is long gone.
EURO (not pictured)
This model’s “snow” output still shows 3″+ of snow, beginning Friday afternoon. However, while it has surface temps below freezing in the middle of the afternoon, it still has temps at 5,000 ft above freezing. This suggests not snow, but freezing rain, or maybe sleet.
This is the model that has us concerned. If it’s right (and right now, we don’t think it is), travel will be a mess Friday night.
To avoid further model fatigue, let’s end by hitting on a new one…
SPIA (Scaled Predictive Ice Storm Aftermath) Index
This is a good model to review for ice accumulation. Ice coats trees and power lines, and can mess with the power grid. It’s why of all the types of wintry precip, this one has no friends and is never invited to parties.
This morning, we were in the yellow (1), which means “Some local utility interruptions possible…typically lasting a few hours.”
Now, it has removed us, and given us a welcome “0.” That’s a move in the right direction.
Stay tuned. We’re 48 hours away. A lot can change.
But I like the way it’s trending.
Saturday – Climbing Above Freezing, Readying for Round 2 At Night – Morning Low 29 / Afternoon High 36
Any wintry stuff that falls Friday night will have a chance to melt Saturday during the late morning and afternoon, when we nudge above freezing (hopefully for several hours).
Late Saturday night, more rain arrives. Temps will hover around freezing, but — right now — we think the bad stuff will stay to our NW:
The SPIA Index, however, includes north and northwest Davidson County (poor Joelton!), plus (arguably) Fairview.
Still too close for comfort.
The 18z run of the GFS (Weather Nerds: I don’t have time to wait for the 0z run to come out) has the wintry stuff well to our NW. Here it is at 6 a.m. Sunday:
Again, this certainly may change.
Questions? We’re on Twitter @NashSevereWx. We’ll update this site again tomorrow.
Categories: Forecast Blogs