Strong and severe storms are only possible south of the low pressure (the red “L” in the above image) on days like this. Although we cannot rule out a strong or severe storm or two, I’m feeling no anxiety about the storms tonight.
The Storm Prediction Center has kept the tornado threat south of us:
What’s Happening?
A warm front is heading our way today. Temperatures and dew points will continue to rise. As this happens, lapse rates will grow, and so will rain-and-storm-supportive instability/energy.
Today’s mist and light drizzle only registered a “trace” amount of rain in the official rain can at BNA. The fog and drizzle will continue tonight.
Temps and winds will increase through the day as we wait for the rain and thunderstorms.
ETA
The HRRR model says the morning looks pretty quiet:
We think rain will start mid afternoon.
Any storms would arrive after dark.
More storms would then be possible closer to midnight:
How Bad Will They Be?
The rain will not be continuous during the day. Expect a heavier, more continuous rain in the evening and overnight. Flooding is not a concern right now.
So, what are we talking about? A low threat of damaging winds and a tornado.
The above graphic applies generally to all of Middle Tennessee, not specifically to Davidson and Williamson Counties. Of course, it’s not a “low” threat if it happens to you.
The severe weather threat is higher the further south you go.
I’ve been through the guts of the data — the forecast soundings for you weather nerds — and I’m not impressed by the potential of this system.
This is a very-low-end concern right now. Expect this forecast to change, so keep an eye on the forecast today and especially tomorrow.
Tuesday’s high is 63°. Wednesday’s high: 35°. That’s some arctic air.
A reminder of what I wrote this morning:
Over the past several days, the GFS and Euro models have Drunk Uncled their way around this forecast, from 8" of snow on the ground to no precip at all, and everything in between. The models often do this 7, 6, and 5 days before an "event," and they'll continue to behave like this for the next few days. Putting snow on your roof requires dozens and dozens of very complicated things to come together at the exact same time, and the forecast models just aren't that good. They are getting better, but there is certainly room for improvement.
6 PM – 40º, temperatures falling into the 30s
Overnight tonight, winds will turn out of the south helping to bring in abundant moisture and an increase in cloud cover. Rain will quickly develop through Saturday morning and early afternoon, starting around 10 AM, and spreading over our area by late afternoon. If you have New Year’s Eve plans and are going to be outside at all for any period of time, bring the rain gear.
We don’t rebound quite as nicely temperature-wise on Friday, staying in the mid to upper 40s for highs. Watch below as colder air filters in over the next 24 hours:
Wind direction begins to switch on Friday night to a southerly direction, foreshadowing changes for Saturday.
That would be a pretty interesting story. Right now, our weather does look to get fairly interesting, especially heading into the new year.
Starting Saturday, southerly flow in cooperation with a shortwave (small wave/disturbance in the upper levels of the atmosphere) will kick off some shower activity.
Saturday looks to be a pretty soggy day, as does Sunday, with a couple small breaks of dry weather in between. If you have any outdoor plans this weekend, you’re going to want to move them inside or take the rain gear along.
What About Temperatures?
A gradual warming trend will ensue, particularly Sunday and Monday, where temperatures soar into the 50s and 60s respectively.
The Cold Front
Late Monday night is currently the expected timing for a main batch of showers and some thunderstorms to rumble through the area. A few of these could be strong with one or two isolated severe storms. This is something the Storm Prediction Center is currently keeping an eye on:
For late Day-4/Sunday into Day-5/Monday, a more prominent wave could interact with more appreciable moisture/buoyancy from parts of east Texas toward the lower MS and TN Valley region (and perhaps areas farther north). This could support some severe potential. However, the relatively small wavelength and amplitude of this disturbance, and limited predictability inherent to such a mesoscale-sized system, limit confidence in the timing/location/magnitude of the severe risk.
Sunny skies have quickly become cloudy skies as clouds continue to move into the area.
Satellite imagery shows clouds spreading our direction from the west.
Showers and thunderstorms have also already developed to our west and can be seen on the current radar above. These showers/thunderstorms will continue to move towards us through the remainder of the afternoon.
Back in 1982 on this day, Nashville warmed up to a record 75°. Will we see that today? Not quite, as we’re more on the order of 20° cooler than that record.
The NAM (North American Model) above handles tomorrow’s rain event fairly well. Late Wednesday evening, a piece of atmospheric energy will approach us from the west, setting off a few showers and storms. Activity continues through the overnight hours into Thursday’s AM rush hour, but by then is already pushing east.
If you’ve been outside today, then you have felt the warm, muggy air that is present and setting up just ahead of tonight’s cold front that is expected to pass through overnight.
Winds have stayed around the 15 mph and we’ve seen a few strong gusts here and there. We expect this to continue until the cold front moves through.
