The Tale of Two Cold Fronts

Current Temps and Radar

Today – Getting Colder – Temps Falling Through the 40°s

A cold front slid through Middle Tennessee around 7 AM this morning, and since that time temps have dropped.

7 am

Our high temperature for the day was reached before the cold front arrived to Nashville early this morning. Around 3 AM this morning we were 58 degrees and held onto the 50’s until the front marched into Davidson and Williamson Counties at 7 AM.

This afternoon we will stay mostly cloudy and temps will likely not reach the 50’s. Additionally, winds will be from the north at 10mph – 15mph.

The HRRR is showing that we will reach the upper 40’s for an afternoon high temperature.

staying cold

Overnight the temperature will dip below freezing under mostly cloudy skies, and winds will continue to blow from the north at 10mph – 15mph.

Tuesday – Mostly Sunny & Cooler – Wake Up 30°, High 46°

Morning temperatures will begin below freezing and only reach the mid 40’s for an afternoon high.

Mostly sunny conditions throughout the day will make this chilly Tuesday a bit more bearable.

Overnight, the temperature will dip below freezing once again with the help of a northerly breeze and clear skies.

Wednesday – Warmest Day of The Week – Wake Up 30°, High 57°

Temps will rebound from freezing to the upper 50’s by the afternoon because of a mostly sunny sky and the return of a southerly wind.

Be sure to enjoy Wednesday afternoon because it will be the warmest day of the week.

A cold front will slide through Nashville overnight and knock our temperature below freezing. Temps will struggle to get above freezing on Thursday. We will remain cold for the rest of the week.

extended
This website supplements @NashSevereWx on Twitter, which you can find here.

One More Cold Morning

Current Temps and Radar

Friday – Cold Start, then Warming Up – Wake Up 19°, Lunch 43°, High 50°

The morning low will be in the upper teens, but sunshine and a southerly wind will help us rebound into the upper 40’s.

Overnight temps will get into the 30’s.

Saturday – Warmer – Wake Up 33°, High 61°

A south wind and mostly sunny skies will help get us into the upper 50’s.

The rest of the weekend we will have rain chances, but temps will remain pleasant. In fact, we’re trending toward mild temps over the next few weeks:

Extended:

For your enjoyment:

This website supplements @NashSevereWx on Twitter, which you can find here.

Watching the Snow Approach

Current Temps and Radar

Tonight – Snow or #Snowdome?

Note: this will probably be our last web update tonight. We’ll put updated info on Twitter @NashSevereWx for the rest of the evening.

As I write this, the models are trending #Snowdome.

Weather models expect that what is currently (at 3 PM) a robust, fast moving line of snow, will disintegrate into as weaker mess of rain/snow upon arrival later tonight.

Watch what the HRRR does to it tonight:

Notice the HRRR isn’t eliminating all snow. It’s just weakening.

The NAM4 at midnight dries up all our precip:

But then does something interesting around 4 AM —- delivers another shot of moisture, and inexplicably types it as rain (this would be snow):

If these models are correct, we will be lucky to get a dusting.

All models are showing that the chance for snow will be completely over by 7 AM on Thursday.

Other stuff to consider:

1.  The air temperature will drop a lot faster than the surface temperature. We are going to make it into the 50°s today, so it’ll take a while for the roads to get cold enough to create travel problems.

2.  Brine applied to the roads will lower the freezing temp of the precip.

3.  If travel is going to be a problem, it’ll be early Thursday morning when the temp is expected to drop into the 20°s.

4.  Bridges, Overpasses, At Elevation: they freeze up first.

5.  Thursday’s temps will stay below or very close to freezing, so this won’t be one of those days where anything we gets melts before lunch.

Thursday – Freezing – Wake Up 24°, Lunch 32°, High 34°

It’s going to be really cold. The snow is riding a cold front. Wake-Up wind chills will be in the teens.

Overnight our temperature will dip back into the teens.

Friday – Warming – Wake Up 19°, High 48°

A light southerly wind will return and slowly usher in a warmer air mass.

We will continue to warm into the weekend.

Extended:

This website supplements @NashSevereWx on Twitter, which you can find here.

Rain Sunday, A Slushy Coating to 1/2″ Possible Early Monday

Current Temps and Radar

Expect 20°s tonight.

Saturday – Sun to Start, then Clouding Up – Wake Up 24°, High 48°

Clouds will increase as a low pressure system races towards Nashville.

A few of the regional weather models think we may seen afternoon rain, but that’s not in the forecast until late Saturday night.

Sunday – Soaking Rain, Snow Late – Wake Up 33°, High 46°

Rain will begin to fall in the Music City during early morning hours. The GFS has the rain knocking at our door between midnight and 6 AM.

showers

The low pressure system will move overhead during the afternoon. The heaviest rain will fall during this time.

afternoon showers

According to the GFS model, the rain will begin to transition into snow overnight as we get on the back side of the low pressure system.

snow

Although it looks like we could get a few snow flurries, the Canadian model is showing that accumulation will mainly stay north of the Tennessee/Kentucky border.

accum

Today, NWS-Nashville wrote we “could have anywhere from just a slushy coating to maybe one half inch. It is always hard to forecast snow here..and there are never any guarantees. Regardless of accumulations, temperatures will fall below the freezing mark across the mid-state by Monday morning, and any remaining moisture is likely to freeze.”

Well then.

Extended:

extended

This website supplements @NashSevereWx on Twitter, which you can find here.

The

Current Temps and Radar

Today – Partly Sunny – High 54° 

Showers moved through Middle Tennessee this morning ahead of a cold front. As the front moves through today, winds will become northerly at 10mph – 15mph with 20mph wind gusts. Despite that passage of the cold front, temps will still reach the mid to upper 50’s this afternoon.

Unfortunately, today will be the last time we get into the 50’s for a while… Be sure to enjoy it! The cooling trend begins overnight with temps dropping into the mid to upper 20’s under mostly cloudy skies.

Friday – Mostly Sunny – Wake Up 28°, High 43°

Nashville will be mostly sunny as cool/dry air funnels in on a northerly wind. Even though we will be mostly sunny, temps will struggle to get into the lower 40’s!

Friday night we will get into the 20’s once again.

Saturday – Mostly cloudy – Wake Up 25°, High 46°

Clouds will build into Middle Tennessee throughout the day ahead of a disturbance.

There will be no storm (Editor’s Note: I’ve thrown a flag on this) but we do have a chance for showers beginning after 7 pm.

extended

Rain is likely Sunday, possibly changing to snow late Sunday night/Monday morning. The GFS model for midnight Sunday shows a potential for some rain changing to snow:

snow yo

That’s very little snow, and it may not even happen. The GFS model has been all over the place. I’m not a believer.

This website supplements @NashSevereWx on Twitter, which you can find here.

Thursday Showers, Sunday Rain/Snow?

Current Temps and Radar

A weak disturbance coupled with a cold front will approach Middle Tennessee from the northwest overnight. The National Weather Service is giving Nashville a slight chance for showers beginning after 1 AM tonight.

Thursday – Showers – Wake Up 40°, High 54° 

Weather models suggest a weak line of showers will arrive a little before 7 AM. The High Res NAM is putting said showers on our doorsteps around 4 AM.

10z showers

These showers will slightly intensify from drizzle to showers after sunrise. Here is a look at the High Res NAM at 8 AM.

14z showers

Hit and miss showers will continue until noon. After noon, we will have hit and miss drizzlers as the cold front moves through Middle Tennessee until about 7 PM.

We will lose our chance for rain overnight, but remain mostly cloudy.

Friday – Mostly Sunny – Wake Up 31°, High 45°

Despite the passage of a cold front the day before, our high will reach the mid 40’s under mostly sunny skies.

Clouds will begin to build in ahead of a weekend cold front.

Rain is likely Sunday, possibly changing to snow late Sunday night/Monday morning. GFS model for midnight Sunday shows a potential for some rain changing to snow:

That’s very little snow, and it may not even happen.

This website supplements @NashSevereWx on Twitter, which you can find here.

Meh Flurries Tonight, Clearing Tuesday

Current Temps and Radar


Tonight – Flurries

Go east for a better chance of snow. We’ll just get a trace of snow, whitening on rooftops, that kind of thing.

trace

Looks like flurries will continue off-and-on overnight, but the main snow event is happening around 6 PM well off to our east.

or, depending on your point of view


Tuesday – Party Cloudy – Wake Up 32°, High 43°

We will hold on to a chance for no-worries-flurries until 9 AM. After 9 AM, a cool/dry airmass will slide into Middle Tennessee and help us become partly cloudy after noon.

Overnight we will clear and dip into the upper 20’s.

Wednesday – Sunny – Wake Up 27°, High 48°

We will begin the day below freezing, but sunny skies will help us rebound into the upper 40’s during the afternoon.

Unfortunately we will become mostly cloudy overnight with a slight chance for showers as a disturbance nears. The NWS gives us a “chance” for rain on Thursday.

This website supplements @NashSevereWx on Twitter, which you can find here.

Snow Tonight? Or SnowDome?

Current Temps and Radar

Friday – Rain, Sleet & Snow. Mostly Rain. – High 38°

Note: this forecast can change rapidly. Follow us on Twitter @NashSevereWx, and consult other reliable weather sources. This website is not constantly updated the way @NashSevereWx is.

A low pressure system will continue to move to the northeast and bring us precipitation. A mix of rain and sleet is expected, but mostly just rain.

sleet and snow

This afternoon, we think it’ll just rain. Total Blerg.

Tonight, however, the short range models are still not in agreement.

The 4km NAM believes a line of showers will transition into snow and blow over Nashville at 7 PM.

7z snow

The HRRR and the RAP models are both picking up on the Music City’s #snowdome… The line of snow appears to dry up just before reaching the city.

The HRRR shows a dissipating line of snow flurries arriving at 8 PM.

2z no snow

By 10 PM, HRRR fully activates the #snowdome

4z snowdome

By 4 AM, the threat for snow/rain will end and give way to cooler and drier conditions.

Our chances of picking up 1″+ of snow accumulation are around 10-20%:

WPC

We will most likely stay well below 1″ of snow accumulation. Weather models have been trending towards lower snow chances, the surface temp will remain at or above freezing during the entire event, and the snow ratio looks to be very low. Accumulation looks meager at best, more likely impacting higher elevation, and some bridges/overpasses.

The National Weather Service believes Nashville could pick up 0.25″ of snow accumulation. Locations just north of I-40 and well east of I-65 have a chance for close to 0.5″ of snow to stick to the ground.

snow accum

Our streak of 1,443 days without 1″+ of snow looks safe. From @615Dave:

Even if we do sneak a dusting out of this, temps will warm through the 40°s Saturday, and melt it all away.

Saturday – Sunny – Wake Up 30°, High 47°

Any snow that managed to accumulate (mostly on grills, gnomes, bridges/overpasses, and cars) will quickly melt away after sunrise. Temperatures will manage to rebound into the upper 40’s with the help of sunny skies.

Partly cloudy skies overnight will help keep our low temp from dipping below freezing.

Sunday – Sunny – Wake Up 30°, High 47°

We will have partly sunny skies with a chance for rain beginning in the morning, and continuing into the overnight hours. After midnight the rain could potentially begin to transition into snow.

A low pressure system will slide east of Middle Tennessee and bring us a chance for snow as we become submerged under the back side of the low. Colder air will wrap around the back side of the low are and possibly transition the rain into snow after midnight. The GFS shows snow trickling into Nashville between midnight and 6 AM.

snowy

A few extra snow flakes could fall Monday morning, but little to no accumulation is expected. Meh. This forecast has been back-and-forth the past few days, and will very likely change again.

Extended:

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This website supplements @NashSevereWx on Twitter, which you can find here.

Snow Possible Friday Night

Current Temps and Radar

Today – Mostly Cloudy – High 49°

We will remain mostly cloudy and rain-free despite an approaching low pressure system spreading a few light showers in our general direction. We think the air will be too dry aloft for us to see rain today. Most of the showers will stay south near Tennessee’s border with Alabama and Mississippi.

Overnight, we will remain mostly cloudy as temps near the mid 30’s.

Friday – BLERG! Rain, Possibly Snow Late – Wake Up 34°, High 41°

The Blerg Returns.

The Euro, GFS, Canadian, and NAM models are all in agreement that precipitation will arrive in the form of rain before sunrise (6:54 AM). Here is a look at where the NAM High Res is showing the showers at 5 AM:

NAM 10z

It will continue to rain off and (mostly) on all morning and into the afternoon as the low pressure system continues to move east northeast. Precipitation will continue to fall in the form of rain throughout the rest of the afternoon.

During the early evening (6 PM) the liquid-only precip may begin to transition into a rain and snow mix. The Euro, GFS and Canadian models are all pointing to a transition occurring between 6 PM and Midnight. Here is a look at the GFS during the aforementioned time frame.

GFS snow

The National Weather Service if forecasting the best chance for all-snow to be between Midnight and 3 AM Saturday. Between 3 AM and 6 AM our snow chances will end as the pesky low pressure system streaks northeast along the East Coast, and out of our neck of the woods.

GFS snoww

The Weather Prediction Center believes that Middle Tennessee will have a chance to pick up 1″ or more of snowfall accumulation. Davidson County will have a 40-50% chance, with Williamson County having a 30-40% chance.

WPS Snow

This seems a little high considering that the models have all been trending towards lower snow chances, the surface temp will remain at or above freezing during the entire event, and the snow ratio looks to be very low. Accumulation looks meager at best, more likely impacting areas of higher elevation.

Our streak of 1,443 days without 1″+ of snow looks safe. From @615Dave:

Even if we do sneak a dusting out of this, temps will warm through the 40°s Saturday, and melt it all away.

Saturday – Partly Sunny – Wake Up 32°, High 48°

Temps will reach the upper 40’s.

Editor’s Note: I deleted a GIF of celebrating Patriots. Replaced it with this.

Mostly cloudy conditions overnight will help keep temps from dropping below freezing!

Extended:

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A low pressure system will move across the Midwest Sunday and Monday. When the disturbance is east of Middle Tennessee, we will have a small chance for snow as cold/moist air wraps around the back side.

low snow

Our best chance for snow will be late Sunday night into Monday morning.

This website supplements @NashSevereWx on Twitter, which you can find here.

Friday Snow? “Uncertainty Certainly Still Exists” (Also, Monday?)

Current Temps and Radar

Thursday – Clouds – Wake Up 33°, High 47°

Late Thursday night, the National Weather Service is giving us a slight chance for rain/snow. They believe that this “slight chance” will begin after 1 AM. After consulting the models it appears that Nashville will most likely stay snow free overnight and into Friday morning. The models think the precip won’t arrive until Friday after sunrise.

Friday – SNOW? – Wake Up 35°, High 41°

Don’t want to read all this? Scroll down to the orange text, below!

The center of a low pressure system will pass south of Middle Tennessee Friday. The northern edge of this weather system will deliver us either rain or snow.

The Euro, GFS, and NAM weather models believe the precip will get here after 6 AM. It’s more likely to arrive around noon. (If it arrives during the early Friday morning hours, a lot of what we’re about to say will change, but right now think the precip will arrive before/around noon).

The GFS is showing that rain will arrive to Nashville between 6 AM and 12 PM. The heaviest precip will arrive at noon and fall as rain:

18z GFS precip

If the models are just a little off, and the low pressure center is a bit further south, we may not see much/any precip at all. But, assuming the models are right, when the precip arrives:

  • Temps at 5,000 feet will be at, or just below, freezing, but temps at the surface will be just above freezing. This suggests potential for a wintry mix, but with temps above freezing, it won’t stick.
  • It’s not really that simple, though, because of “evaporative cooling.”

Alert!

When the rain starts falling, it descends through dry air and evaporates. This process takes energy away from the environment, causing the surrounding air to cool.

So, basically, the falling precip can lower our temps, but, it cannot lower the temps below the wet bulb temperature. The wet bulb temp is a measure of the lowest temperature that can be obtained by evaporating water into the air. The wetbulb temp in Middle Tennessee will be near or below freezing Friday afternoon/early evening.

By 3 PM, the GFS thinks it’ll be colder at 5,000 feet, but a bit warmer at the surface, but with all this evaporative cooling potential + margin of error potential in the temp profiles, it’s all a really close call. Still GFS says “still just rain.” The Euro is leaning this way, and so are we.

At 3 PM, the NAM thinks there will barely be enough evaporative cooling to produce a rain/snow/mix.

0z snow nam

The GFS thinks a changeover from rain to snow is more likely after 6 PM. Between 6 PM and Midnight, the precipitation will be mostly snow with a few rain drops mixed in.

0z -6z rain into snow

According to the GFS model, Friday at midnight to Saturday at 6 AM will be our best chance for snow, as colder air funnels into Nashville on the back side of the departing low pressure system:

6z - 12z snow

This will also be the window of time that snow will have a chance to stick to the ground and accumulate. Most of the accumulation will occur east of I-65. The Euro believes that we will have a total of 2-4 inches of snow fall in Nashville, but only a small fraction of that number will stick to the surface. The thinking at this moment is that we could see 0.1 – 0.6 inches of snow accumulation in the city, and places near the Plateau could get near 1 inch of accumulation. These “accumulation numbers” are largely meaningless right now.

In summary: Rain will begin to fall during the morning, evaporative cooling will help transition the rain into snow during the afternoon or early evening, and overnight we maaaaybe will have snow with minor accumulation. Very little of it is expected to stick into Saturday because temps will warm into the low 40°s by noon.

If I had to describe Friday’s forecast in one GIF:

Saturday – Becoming Sunny – Wake Up 31°, High 45°

Snow chances will end by noon as the low pressure system continues to move eastward. Here is a look at the GFS between 6 AM and 12 PM.

12z - 18z mslp type

The afternoon will be sunny with temps reaching the mid 40’s. So, any snow from the day/night before will melt.

We will stay dry overnight and temps will near 32°.

Extended

extended

Looking ahead: We will have another chance for snow on Monday!

Looking at long range models, it appears that the chance for snow will begin during the morning and end overnight. Here is a look the GFS from 6 AM through 12 PM.

12z - 18z snow

We will keep you updated as more information surfaces about Monday’s chance for snow. For now, we’re focused on one crisis at a time.

This website supplements @NashSevereWx on Twitter, which you can find here.