Friday Thru Sunday Looks Nice, But Cooler

The severe threat has ended in both Davidson & Williamson Counties. No tornado warnings!

Friday – Clearing Out, Great Alternate Trick-or-Treating Night – High 70

We’ll wake up to wet grass and 56. Expect 66 by lunch, then 70 by mid-afternoon. Low 60s by sundown, 54 by 10 p.m.

The Weekend Looks Nice & Dry, But Cooler

Saturday: wake up to 46, then 59 by lunch, high 63, 54 by 7 p.m.

Sunday: wake up at 38, afternoon high of 59.

Next chance of rain: Wed/Thu.

Details on the Tornado Watch, Effective Until 1 a.m.

There are two storm lines to our west.

Last Line (above) will speed into western and Middle Tennessee. The two lines may even merge.

The result: “Severe storms look likely this evening in Middle Tennessee with possible tornadoes.”

Tornado Watch has been issued, effective until 1 a.m. Friday morning.

Remember: a Watch means conditions are favorable for a tornado. It requires preparedness and your attention. A Warning means a tornado is occurring or imminent, and requires immediate action.

Charge your phones. Review where you will go in case of a Tornado Warning. Don’t have a plan? Consult this Severe Weather Checklist.

This blog will not be updated for the very latest/in-storm info. No Warnings will be posted here. Consult all reliable weather sources. We’ll be posting frequent updates @NashSevereWx.

Trick or Treaters, Go Now! ETA of “Possible” Severe Weather 9 pm - 10 pm

The main blob of rain has moved east of us. It left a “tail” which should squirt us with rain around 7-ish. If you must Trick or Treat, Go Now!

However, our attention is focused on 9 p.m to 10 p.m. (or maybe later), when a new line of storms is predicted by the HRRR to arrive after forming in Arkansas/Missouri, crossing the MS River and trucking through West Tennessee.

We still think the main concern will be damaging straight line winds, but we cannot rule out a tornado.

Here’s the HRRR delivering the storm line to us around 9:30 – 10 p.m.:

More on this on Twitter @NashSevereWx.

 

The Website Is Back! (“So What? When’s It Going To Storm?”)

We’re Back!

I’ve weathered two crises* this week: the Cardinals losing to the Sox, and, even worse, the website crashing to earth like an innocent pop-up between Adam Wainwright and Yadier Molina (love you guys, but you have to own it). (*not actual crises, not even close).

This afternoon, I posted this synopsis of the severe weather set-up for today:

The storms in the purple box above haven’t been frightening. As of 3:45, there were no warnings on them.

The initial rain blob will depart after rush hour, followed by a break in the rain. Then, we’ll see if the storms in the purple box make it here. 

Our atmosphere is made up of several layers. The layer about 1,500 feet overhead is blowing at 60 mph. The downdraft part of any storm can transport those winds to the surface, so SPC included us in their Damaging Wind outlook. SPC says there is a 15% chance of a damaging wind event (58+ mph) happening within 25 miles of you:

Outside the storms, sustained winds are around 20 mph, with gusts maxing out at 40 mph (at the airport). With saturated grounds and high winds, weak/shallow rooted trees are coming down. A Wind Advisory is effective until 10 p.m.

This was our first report of the day, from Williamson County.

We’ve had several other reports of downed trees and telephone poles.

Substantial helicity (atmospheric “twist” or rotation) poses a very small tornado threat. Other important tornado-making ingredients are missing. In fact, we are just outside SPC’s 2% probability of a tornado (but no one is ruling it out):

I’ll be shocked to see any lightning or hail.

Look for this “next round” tonight after the initial rain blob passes. At 4:46 p.m., our NWS said “strong to severe storms still possible as we go through the evening, but probably not before 8 p.m.” In other words, any severe threat should arrive after 8 p.m.

We’ll update this forecast tonight exclusively on Twitter @NashSevereWx.

Friday – Clearing Out, Great Alternate Trick-or-Treating Night – High 70

We’ll wake up to wet grass and 56. Expect 66 by lunch, then 70 by mid-afternoon. Low 60s by sundown, 54 by 10 p.m.

The Weekend Looks Nice & Dry, But Cooler

Saturday: wake up to 46, then 59 by lunch, high 63, 54 by 7 p.m.

Sunday: wake up at 38, afternoon high of 59.

Update on Trick-or-Treat Rain/Storm Chances

Today – Breezy & Warmer – High 61

10a 44 . 1p 57 . 4p 60 . 7p 55 . 10p 50

Here’s how cold we were at 4 a.m. this morning:

Our official low was 29 (at 5 a.m. and 7 a.m.).

We are rapidly warming up. A few clouds will stream in, but no rain.

Sunday – Pleasant – 44/62

7a 45 . 10a 53 . 1p 60 . 4p 61 . 7p 55 . 10p 49

No overnight freeze! Scattered clouds. No rain.

Next Week – Mid-Week Rain/Storms?

Warm Air: Monday’s high is 63. Tuesday, we warm to 73; by Wednesday, 77! All this is driven by south winds driving in warmer air. This process is called “warm air advection.”

Cold Front: A cold front trailing from a strong low pressure center will drag across the central U.S., and collide into our warm air.

Our NWS wrote this morning: “Models continue to show differences [about when this will get here], with the GFS about 18 hours faster with the main band of moisture [rain/storms] than the ECMWF. . . . We continue to see some potential for strong storms sometime from late Wednesday through late Thursday.”

The GFS thinks this rain will arrive Oct 31 in the afternoon, ending mid-evening (see below). The ECMWF starts the rain near the end of trick-or-treating.

NWS & other weather sources (and probably your apps) are dealing with the ETA uncertainty by spreading rain chances of 20% to 50% from Wednesday through Friday. When trying to express rain/storm chances in percentages, this is the way to do it. Just keep in mind this was done to “hedge their bet,” because we don’t know when the rain/storms will be here.

The Storm Prediction Center is also watching this system. Model differences prohibit any substantive forecast, but the ingredients for strong or a few severe storms may be present.

So, What Should We Do About Trick-or-Treating? With the models unable to settle on a consensus, there’s no reason to move the designated night, at least not yet. But, you should be thinking about Plan B. Here’s how the GFS predicts the precip October 31 at 7 p.m.:

We’ll update this forecast tomorrow. Questions about Davidson or Williamson Co.? We’re on Twitter @NashSevereWx.

One More Cold Night, Then Warming! Possible Storms Next Week

Rest of Tonight – Overnight Low 29

7pm 45 . 10pm 38 . 1 am 35

[Editor’s Note: The Intern does not live in squalor].

Anyone else look like this getting out the shower this morning?

images

I’m cheap and have not turned the heat on. I’m a poor college student. It’s how we survive…

We are 20 degrees below average. The official low this morning was 30 degrees. It has been 212 days (March 27, 2013) since we were this cold.

blame canada

Saturday – **Freeze Warning** – Overnight Low 29, Afternoon High 60

7a 31. 10a 45 . 1p 56 . 4p 59 . 7p 54 . 10p 49

There is another Freeze Warning in effect from 12 a.m. to 9 a.m. Saturday for all of Middle Tennessee. RIP uncovered vegetation.

Winds out of the south will thaw us out. No rain in the forecast.

Sunday – Warming – Morning Low 43, Afternoon High 63

7a 44 . 10a 51 . 1p 60 . 4p 62 . 7p 54 . 10p 47

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The sun will shine above southerly winds, which will warm us up. No 30s in this forecast!

Monday – Warmer

Temps climb even higher, and we may even reach 70!

Storms Next Week? [Editor’s Supplement]

We’re pretty sure it’s going to rain next week. Uncertainties include (1) timing and (2) whether it’ll storm.

The two main medium-range weather models disagree.

GFS

As we tweeted this morning, this model — if it verifies — suggests storms Trick-or-Treat morning:

Dew points would approach 60, providing plenty of storm fuel for the colliding cold and warm airmasses:

This model run doesn’t necessarily suggest Stormageddon. Note the parent low pressure center (L) is displaced way far north (Chicagoland). The system is also slightly positively tilted (the axis of the storm line is oriented more NE to SW; negative tilt is NW to SE), which suggests a less-robust system. This system should depart in time for Trick or Treating.

ECMWF

We are not allowed show you the graphics themselves, but here’s how it differs from the Thursday morning GFS:

These storms are expected to arrive just as Trick-or-Treating ends, and present a less-stormy solution than the GFS.

Important: when these models disagree like this, and when you’re looking at them 150 hours from the target time, take them with a grain of salt. Also consider these models run 4x and 2x a day. Previous runs have disagreed with current runs. I think the Wed-Thu-Fri ETA for rain is a good bet, the rest of it is in Voodoo/Guess-land

We’ll keep you posted. It bears watching because severe weather certainly is possible, but not currently expected, by mid-week.

Questions? We’re on Twitter @NashSevereWx.

Overnight: Freeze Warning (& Lawn Mowing Emancipation Day!)

Rest of Tonight – High 55, Overnight Low 29

Just to help put in perspective of how cold it is…Louisville, KY is experiencing some very wet snowflakes falling around 3 this afternoon!

For the independently wealthy, it’s still not too late to drop everything and take that vacation in the Bahamas. You may really consider it when I tell you the forecast low is 29 degrees with a wind chill of 27.

Last time we were this cold it was March 21, which, ironically, was the first full day of Spring.

Friday – **Freeze Warning** – Morning Low 29, Afternoon High 51

7a 31. 10a 40 . 1p 48 . 4p 50 . 7p 44 . 10p 38

There is a Freeze Warning in effect from 1 a.m. to 9 a.m. Friday for all of Middle Tennessee.

Vegetation left outside and unprotected will be damaged or killed. The end of the growing season is here. That means: no more lawn mowing!

It won’t be quite this cold tomorrow, but you get the picture.

It’ll be sunny, with highs into the 50s.

Friday night football games are going to be cold, of course. Be prepared.

Saturday – Warming – Morning Low 32, Afternoon High 60

7a 32 . 10a 45 . 1p 56 . 4p 59 . 7p 54 . 10p 49

Morning frost will be possible in some areas.

If you have an early soccer game, or you’re hosting a slumber party and will have a flag football game at 8:30 a.m. (but you have to be there at 8 a.m.), be ready for damp fields as the frost wears off. An extra pair of shoes and socks for the ride home is a good idea.

All in all, a much warmer day. Winds will shift out of the south and blow in warmer air.

Sunday – Warmer

Temps climb even higher, and we may even reach 70!

Rain chances arrive Wednesday.

Questions? We’re on Twitter @NashSevereWx.

The Freeze is Coming

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Rest of Tonight – High 55, Low 37

It would be a good time to go on that last minute tropical get away.

Tonight, expect much-cooler temps. Overnight lows will be in the 30s.

Winds will calm down a bit as the evening progresses.

Thursday – Cooler & Windy – Morning Low 37, Afternoon High 58

7a 38. 10a 47 . 1p 55 . 4p 57 . 7p 49 . 10p 41

Another very cold morning. Temps will try to warm, but will be stopped when some of the coldest Canadian air of this whole ordeal arrives.

Patchy frost may be a problem. Set your alarms a few minutes early so you can scrape the ice off your car.

 
Friday – Freeze Watch – Morning Low 32, Afternoon High 50 

7a 34 . 10a 41 . 1p 48 . 4p 49 . 7p 43. 10p 36

Unknown

A Freeze Watch is in effect from 1 a.m. until 9 a.m. This may be upgraded into a Freeze Warning. All outdoor vegetation could be killed.  

The sun will be shining, but it will not feel warm out at all. Some of us will be lucky to get into the 50s.

Pull out the winter gear for Friday Night football.

Saturday – Very Cold Morning

28 is the forecast morning low! So if Friday’s potential freeze did not kill your plants, Saturday morning’s will.

Good news! Winds shift out of the south early in the day, raising temps to the low 60s.

Lows that night will only cool the the 40s.

Sunday – Warmer

The warming trend continues.  We could actually see 70s early next week ahead of another front.

Questions? We’re on Twitter @NashSevereWx.

“Unseasonably Cold Canadian Air Mass” & “Hard Killing Freeze”

By the end of this week, you won’t need this breathspray to feel Canadian.

Rest of Tonight – High 60, Low 42 

This morning we picked up 0.11″ of rain officially at the airport.

Tonight, another cold front will be sweeping through. We may get a brief shower as the front arrives. Here’s the HRRR at 1 a.m.:

We’ll also get a reinforcing blast of cold air.

Check out these scary-cold phrases for the end of the week for middle Tennessee. This is from the NWS’s latest Hazardous Weather Outlook:

Wednesday – Cooler & Windy – Morning Low 39, Afternoon High 55

7a 43 . 10a 48 . 1p 53 . 4p 54 . 7p 50 . 10p 45

We’ll wake up in the 40s, but unlike the past few days, we won’t warm up much. Winds will be coming out of the NW at 10 – 15 mph (gusting even higher at times). Make sure to grab the jackets!

Hi-Res NAM model forecast temps (looping from Wednesday at 2 am to 8 pm) shows cold Canadian air diving in:

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Thursday – Still Cold + Small Rain Chance – Morning Low 32, Afternoon High 57 

7a 40 . 10a 48 . 1p 55 . 4p 56 . 7p 49 . 10p 41

Yet another cold front will push through, further reinforcing the cold air.

There is a very slight chance of a passing shower as the front passes. Pull out the winter clothes if you haven’t already. Even colder air is coming is weekend as we deal with another cold front.

Friday & Saturday – Very Cold

29 degree wind chills are forecast Friday morning. The temp is expected right at freezing, warming into the low 50s.

Saturday morning’s wake-up temp will be 30 (!) degrees. Light winds will shove wind chills into the upper 20s. Fortunately, temps will start to slowly warm back into reasonable levels. We should reach 56 by noon, on our way to a high of 61.

This early season cold is very unusual this time of year.  These temps are more indicative of December. To illustrate this, here’s the GFS 2-Meter Temperature Anomaly for Saturday morning (translation: this is how much colder-than-average the GFS model thinks it will be Saturday morning). We’ll be 20 degrees below normal:

It seems our weather this year has been unusual. No real snow, not much (if any) Spring severe weather season, a cold snap in May, and a cooler/wetter-than-average Summer. We never even reached 100 this year.

Questions? We’re on Twitter @NashSevereWx.

Getting Even Colder This Week - Hard Freeze Saturday?

Tonight/Overnight – Rain Approaching

Rain looks like it will hold off until we’re asleep.  By 4 a.m. Tuesday, it’ll start slowly dragging through middle Tennessee, and may linger into the morning commute:

Tuesday – Light, Cold Morning Rain, then Partly Cloudy

Wake Up 46   Mid-Morning 54   Lunch 60   High 62   Late 50

(I’m about to take a hard right turn, but don’t worry, I’ll quickly get you back to Tuesday’s weather . . . )

Because we’re moving into the Fall Severe Weather Season, today our NWS resumed weekly weather briefings. Their first graphic was about severe weather:

However, there is no severe weather in the forecast for the next few weeks. Instead, the news at the briefing was the cold temps.  Tuesday will be our last “mild” day for a while.

Wednesday – Saturday: Getting Colder!

Wednesday morning temps may be in the mid-30s:

On top of that, a north wind will be driving the wind chill into legitimate cold temps Wednesday morning.

Wednesday’s high: 52.

Wake Up/High Temps

Thursday 36/60

Friday 34/52

Saturday 32/61 – NWS thinks cold temps may end the growing season Saturday morning, when a hard freeze is possible.

Next Week – October 28 to Nov 3 – Still Cold!

No cold weather relief is in sight. There is a high probability temps will be below the norm for this time of year:

Along with the colder-than-normal temps, we will likely see more rain than normal (1″):

Questions? Need to air a weather-related grievance? Find us on Twitter @NashSevereWx.