Tonight: Rain, Maybe a Thunderstorm

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

TodayRain Tonight – High 66

Although we expected a cloudier morning, the ETA for rain remains 7 PM tonight.

Located to our south is a storm system spinning around a low pressure center. This will travel north and deliver rain and thunderstorms tonight.

Severe weather is possible with this system in Texas, Louisiana, Mississippi, and Alabama today.

(Follow @spann in Alabama).

Although a few thunderstorms are possible in Middle Tennessee, the closest “severe” hazard to Davidson or Williamson County is a 5% wind threat, which, while close to us, does not include us:

A lot of rain is on the way:

Rain will continue through Monday morning, ending sometime mid-day. Rain could linger into Monday night. By then, we should have collected over 1″.

“Mom/Dad, am I going to have my baseball game Monday night?”

“No way. Sorry.”

Extended NWS Forecast

This site supplements @NashSevereWx on Twitter.

More Rain On The Way

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

(By the way, on the above radar: see the blue stuff that’s not moving near the radar site? That’s radar clutter, not rain).

TonightClouds Approach – 10 PM 47

Here comes the next weather system. This is the water vapor imagery (the white colors indicate a large amount of water in the air, the dark colors indicate drier air):

That water vapor image looks like rain is streaming in here tonight, but it’s not. The rain arrives tomorrow.

SundayChilly Morning; Evening Rain – Wake Up 38, PM High 66

As clouds continue to pile in, we’ll look toward the southwest as the next rainmaker arrives.

By 7 PM, the Hi-Res NAM turns the rain switch to “ON,” see below:

This model matches the official NWS “rain start” time. Individual results may vary.

A few thunderstorms are possible, but severe weather is forecast to stay well south of us:

Monday Morning Rain; Afternoon Clearing – Wake Up 55, PM High 65

Rain and a few thunderstorms will continue through the wee hours, ending around noon.

By the time it’s all over, we’ll collect about 1.15″ of rain. Your [ball must roll on ground] game is very likely to rain out.

There’s a small chance of a few additional light showers Monday night and Tuesday.

The rest of the week looks pretty good!

This site supplements @NashSevereWx on Twitter.

Review of Last Night’s Storms, Next Rain/Storm Event (Sun/Mon)

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

Last Night In Review

Actually, instead of “last night,” I should say “early this morning . . . ”

  • We had three concurrent Severe Thunderstorm Warnings:

  • Just after the storms pushed east and out of Davidson and Williamson Counties, straight-line winds at 80 mph destroyed two commercial roofs and uprooted trees in Rutherford County.
  • Several Bradford Pear trees — apparently made of #ButterWood — fell. It’s unclear whether the flapping wings of a butterfly toppled them before the strong winds arrived. You all cheered their demise.
  • Stephen Hook (@NERR568) sent this timelapse of the storm as it passed through the greatest town in the South according to literate gardeners and gun owners:

  • At 4:01 AM, I nerded out over a Mesoscale Convective Vortex, whereupon I spiraled out of control, prompting this:A fair assessment. I own it. And I don’t apologize. If your Weathernerd doesn’t occasionally spiral out of control wxnerding out, you need another Weathernerd.

TonightClearing; Chillier – 10 PM 52

Saturday – Cooler, Mostly Sunny – Wake Up 41, Noon 56, High 60, 10 PM 49

SundayClouds Increase; Raining After Dark – Wake Up 41, PM High 68

A low pressure system will approach from the SW, arrive in Middle Tennessee Sunday night, and drench us. Anywhere between 0.75″ and 1.01″ of rain is expected.

Rain will continue overnight and into Monday morning:

Rain isn’t forecast to end until noon/early afternoon Monday. Your [ball must roll on the ground] game Monday night will very likely get rained out.

Thunderstorms are expected to accompany the rain. Currently, severe weather is not expected; however, if the surface low passes more to our NW (instead of passing straight over us), a few severe storms may be possible.

Highs: Wed (62°), Thu (71°), and Fri (72°).

This website supplements content found on Twitter @NashSevereWx.

Storms Out, Cooler Temps In

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

TodayClearing Out; Windy – High 68 / 52 by 10 PM

We escaped with no Tornado Warnings, and 3 Severe Thunderstorm Warnings.

The winds were pretty strong. Just as the line crossed east out of N Williamson and S Davidson Counties, the leading edge of it showed clear signs of rotation, and prompted a Tornado Warning in Rutherford County.

Anyway, for the rest of today, a cold front will clear away the rain. The afternoon will be windy, with sustained winds around 12 MPH, gusting to 27 MPH.

SaturdayMostly Sunny, Cooler – Wake Up 41, PM High 60

I’m optimistic about [ball must roll on ground] games tomorrow morning. Depending on how your field drains, you should be good tomorrow. It’ll be a wee bit chilly, but we’ll warm up.

Rain Chances Return Late Sunday, Monday, and Tuesday

 

Tornado Watch for Davidson & Williamson Counties until 10 AM

TORNADO WATCH for Davidson & Williamson Counties, effective until 10 AM.

Several tornadoes in the entire Watch box are possible, but the risk of EF2+ tornadoes is low.

The risk of severe winds (60+ mph) is moderate, but the risk of 70+ mph winds is low.

The risk of severe hail (1″) is moderate, but the risk of 2″+ hail is very low.

A “Watch” means conditions are favorable for the development of tornadoes and severe thunderstorms. Be on the lookout for threatening weather conditions and listen for any warnings.

A “Warning” means a tornado is occurring or imminent. A Warning urges immediate action. Ideally, you should move to a lowest level, interior room. Cars and trailers are NOT safe places to be in a tornado.

Not that warnings will NOT be posted to this website.

The Storm Prediction Center felt like the segment of the approaching storm line north of I-40 (ETA 4 AM to 5 AM) was unlikely to meet Tornado Watch criteria. That “northern” segment of the line is undergoing a general weakening trend. The segment of the line south of I-40 showed signs of intensification, and it’s moving into a storm-friendly environment. Both trends may change, so stay tuned.

The tornado threat will end upon passage of the squall line, which will be well before the expiration of the Watch at 10 AM.

This site is a supplement to @NashSevereWx on Twitter. Monitor multiple reliable sources for weather information, and heed all warnings.

Current Radar Loops

 

 

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Evening Update on Overnight Severe Weather (ETA 4 AM)

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

Temp & Rain Probabilities Next 36 Hours (auto-updating)

Severe Weather Possible Tonight

The latest (8 PM) outlook from the Storm Prediction Center trimmed back — but did not eliminate — our severe chances tonight.

Despite dewpoints in the low 60s (plenty high enough to fuel storms) today, a “cap” aloft (temperature inversion) has prevented significant storm development today.

The cap is now gone (arguably there’s a tiny one at 850mb) according to the 7 PM weather balloon:

These are impressive, but not “hide the women and children,” severe parameters. The good news is that we should see those parameters decrease a little more later tonight.

Storms to our west are expected to form a giant squall line, whose main feature will be damaging straight-line winds. When the squall line arrives, the probability of it packing 60+ mph wind gusts within 25 miles of you has, as of the 8 PM update from the SPC, decreased from 30% to 15%:

In addition, upper atmospheric dynamics will support intense updrafts conducive to large hail formation. The probability of large hail falling within 25 miles of you decreased, at the SPC 8 PM update, from 15% to 5%:

Although damaging straight-line winds and large hail are the main threats, one or two tornadoes are possible along the squall line. We cannot rule them out. The probability of a tornado occurring within 25 miles of you remains at 5%:

The hazards remain:

The squall line will arrive so late, it’s probably more accurate to call it “early.”

The ETA remains between 3 AM and 7 AM:

The HRRR thinks we’ll see the line at 4 AM.

This “wee hour” ETA will aid in the overall weakening of the squall line compared to the punch it will pack in Arkansas and West Tennessee. The above-described hazards and probabilities take the weakening into account. Stated another way: despite the fact it will have weakened, the possibility of severe weather remains.

Consider getting a wake-me-up app (see the above banner) and/or a NOAA weather radio. It’s possible a Tornado Warning may be issued while you sleep. Charge your phones. Have helmets for kids. Have shoes nearby. Get to the lowest level of your home, and shelter in an interior, windowless room. Yes, this is a hassle and the odds of a tornado hitting you are small, but — and feel free to disagree — I think your safety is worth a half hour to 45 minute inconvenience. #EndOfSermon

The storms should clear before noon Friday. Expected rainfall estimates continue to decline; currently, rainfall totals are forecast to be a little under 0.5″, which is excellent news for those hoping to get in your [ball must roll on the ground] game Saturday. Davidson County should see an additional 0.45″, Williamson County an additional 0.47″. Totals in your backyard will obviously vary.

Winds behind the squall line will be strong, sustained at 19 mph, with gusts in the 20s. We’ll hit 70 tomorrow afternoon, then winds will slacken off after sunset.

The weekend will actually be nicer than this graphic suggests:

Do NOT rely on this website for severe weather watches and warnings. This site supplements content found on Twitter @NashSevereWx. Monitor multiple reliable weather sources, and heed all warnings.

Morning Update: Details on Today/Tonight’s Severe Weather Potential

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

Temp & Rain Probabilities Next 36 Hours (auto-updating)

Posted After 7 AM Thursday

ThursdaySevere Weather Possible Late Tonight – PM High 77

We could see a few showers/thunderstorms pop up. These will be scattered around Middle Tennessee, and a few could be strong or severe. The HRRR thinks a few storms will arrive early this afternoon (see below); however, another model (NSSL WRF – which performed well yesterday) does not think we’ll see afternoon storms.

Meanwhile, additional warm, humid, storm-fueling air will arrive from the south, setting the stage for severe weather late Thursday night/early Friday morning.

A squall line is expected to form in Arkansas, cross the Mississippi River near midnight (see below), and move into Middle Tennessee while we’re sleeping.

We remain, thankfully, outside the ominous “Moderate Risk” category.

However, we are included in the “Slight Risk” category. Don’t think “slight.” Think “elevated.”

The tornado threat remains mainly confined comfortably off to our west. Our probability of a tornado within 25 miles of you is 5%:

The probability of damaging winds (58+ mph) occurring within 25 miles of you is 30%:

The probability of 1″ hail within 25 miles of you is 15%:

Thus, the main threats are damaging winds and large hail, but an isolated tornado or two cannot be ruled out.

The rain/storms should be gone by 10 AM Friday morning. Total 36 hour rainfall looks to be just about 1″. The weekend looks nice.

I’ll be along early this afternoon to update tonight’s severe weather situation.

The website supplements @NashSevereWx on Twitter.

Storms Tonight (meh), Storms Tomorrow Night (yikes)

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

Temp & Rain Probabilities Next 36 Hours (auto-updating)

TonightRain/Storms Possible and Severe Weather Chances Diminishing – 10 PM 70

Caution: some of the models are a bit drunk with storms for us. They all over the place with storms tonight, and are way overdoing it.

Now that the sun has set, the storms approaching Nashville have lost a key storm-making ingredient, and are moving into a less storm friendly environment.

My prediction is that we will see some rain, but not the “Goofy” amounts the models showed earlier today. But, please be cautious of the lightning. #Respect

Earlier this afternoon, the SPC (Storm Prediction Center) issued an outlook for severe weather much closer to us, such that the yellow “Slight Risk” area sits tangent (touching, but does not include) to both counties:

Screen Shot 2014-04-02 at 8.36.53 PM

Tonight’s probability of damaging winds (58+ mph) and/or large hail (1″+) happening within 25 miles of you is 5%; if you go one county to the west, that probability increases to 15%. Wind, then Hail, outlooks are shown below:

Note: This 5% chance was issued earlier today using the overzealous models…Thus, if this were a horse at the races, I would not bet on it! Still can’t rule out severe storms tonight, but we think it’s unlikely.

Screen Shot 2014-04-02 at 8.35.28 PM

Screen Shot 2014-04-02 at 8.35.38 PM

We remain excluded from tonight’s tornado probability outlook:

Screen Shot 2014-04-02 at 8.35.47 PM

ThursdayOff/On Rain & Thunderstorms Early; Severe Weather Potential Very Late – Wake Up 63°, PM High 77°

Rain occurring tonight/overnight/early Thursday will end, replaced by a humid airmass carried into Middle Tennessee by south winds. A few storms may fire off during the day, but the main concern is late Thursday night/early Friday morning.

Since the risk for severe weather exits in the overnight hours, please have a way to be woken up by a NOAA weather radio or download the STORM WATCH app (IOS only, sorry!) to wake you up.

From the NWS (in blue):

Attention then turns to the west as [a] severe weather outbreak [is] expected to get underway Thursday afternoon across Louisiana, Arkansas, and Missouri, then spread into Mississippi, West Tennessee, and Western Kentucky by Thursday evening.

Here’s the outlook from the Storm Prediction Center for Thursday:

Storm Prediction Center Apr 2, 2014 1730 UTC Day 2 Convective Outlook 2014-04-02 20-43-36 2014-04-02 20-46-25

If you’re traveling west Thursday, you need to be very aware of the weather around you. This is a dangerous severe weather setup, especially for the area outlooked in red, above.

We’re under a “Slight Risk.” The same weather system forecast to occur in the above-outlooked red region will move east into Middle Tennessee.

Here’s the good news: any widespread/substantial severe weather is expected to weaken by the time it reaches the Tennessee River very late Thursday night/early Friday morning:

BTW, it occurs to me everyone may not know exactly what we’re talking about when we refer to the Tennessee River. See the yellow line inside the black rectangle, below:

Anyway, once the system reaches the Tennessee River very late tomorrow night, it’s expected to weaken. Back to the NWS:

Weather models (GFS, Euro, SREF, NAM) all indicate storms will undergo significant weakening after reaching the Tennessee River and spreading eastward across [Middle Tennessee] after 1 AM Friday morning.

Reasons for weakening:

1.  The storms will be running away from the main axis of instability, which will be located in Arkansas.

2.  Strong storm-supporting winds near the “top” of the atmosphere will be moving north, and out of Middle Tennessee.

3.  The nighttime ETA means the sun won’t be out to further destabilize our atmosphere as the storms arrive.

The result: diminished severe weather ingredients. For the wxnerd, CAPE values will be around 1,000, and there will be a mature-storm-killing veer-back-veer wind profile.

All that said, severe weather remains possible for us while we sleep. The severe ingredients will be decreasing, but they’ll still be there. The main threats are damaging winds and large hail, and an outside chance of a tornado or two.

Notice this from the SPC’s Probabilistic Outlook for late Thursday night. We’re in the shaded (“hatched”) area:

Storm Prediction Center Apr 2, 2014 1730 UTC Day 2 Convective Outlook 2014-04-02 19-38-00 2014-04-02 19-52-38

This means that despite the anticipated weakening, the probability of a significant severe weather event happening within 25 miles of you while you sleep tomorrow night is at least 10%.

Hi-Res NAM model Thursday 8 pm – Friday 1 pm:

Friday – Thunderstorms Early; May Still Be Severe – Wake Up 62°, PM High 72°

SPC still includes us in the “slight risk” area for Friday:

Storm Prediction Center Apr 2, 2014 0730 UTC Day 3 Severe Thunderstorm Outlook 2014-04-02 20-12-40 2014-04-02 20-16-18

We think most of the severe threat will quickly depart off to our east Friday morning.

Additional info coming tomorrow.

This website supplements content found @NashSevereWx on Twitter.

New Severe Chances for Tonight, Plus Severe Wx Tomorrow Night

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loops

Temp & Rain Probabilities Next 36 Hours (auto-updating)

You’re going to hear a lot about severe weather today and tomorrow. But, first things first.

Afternoon NWS Severe Weather Briefing (good summary of what’s below):

TodayIncreasing Clouds – High 81°

TonightRain/Storms, with a Small Chance of Severe Weather – 10 PM 70°

The new run of the HRRR (below) still thinks a shower/thunderstorm blob will arrive around 8 PM tonight:

The Storm Prediction Center has moved today’s outlook for severe weather much closer to us, such that the yellow “Slight Risk” area now sits tangent (touching, but does not include) to both counties:

Tonight’s probability of damaging winds (58+ mph) and/or large hail (1″+) happening within 25 miles of you is 5%; if you go one county to the west, that probability increases to 15%. Wind, then Hail, outlooks are shown below:

We are excluded, barely, from tonight’s tornado probability outlook:

ThursdayOff/On Rain & Thunderstorms Early; Some Severe Weather Potential Late – Wake Up 63°, PM High 77°

Rain occurring tonight/overnight/early Thursday will end, replaced by a humid airmass riding transported by south winds.

From the NWS (in blue):

Attention then turns to the west as [a] severe weather outbreak [is] expected to get underway Thursday afternoon across Louisiana, Arkansas, and Missouri, then spread into Mississippi, West Tennessee, and Western Kentucky by Thursday evening.

Here’s the outlook from the Storm Prediction Center for Thursday:

If you’re traveling west Thursday, you need to be very aware of the weather around you. This is a dangerous severe weather setup, especially for the area outlooked in red, above.

We’re under a “Slight Risk.” The same weather system forecast to occur in the above-outlooked red region will move east into Middle Tennessee.

Here’s the good news: any widespread/substantial severe weather is expected to weaken by the time it reaches the Tennessee River very late Thursday night/early Friday morning:

BTW, it occurs to me everyone may not know exactly what we’re talking about when we refer to the Tennessee River. See the yellow line inside the black rectangle, below:

Anyway, once the system reaches the Tennessee River very late tomorrow night, it’s expected to weaken. Back to the NWS:

Weather models (GFS, Euro, SREF, NAM) all indicate storms will undergo significant weakening after reaching the Tennessee River and spreading eastward across [Middle Tennessee] after 1 AM Friday morning.

Reasons for weakening:

1.  The storms will be running away from the main axis of instability, which will be located in Arkansas.

2.  Strong storm-supporting winds near the “top” of the atmosphere will be moving north, and out of Middle Tennessee.

3.  The nighttime ETA means the sun won’t be out to further destabilize our atmosphere as the storms arrive.

The result: diminished severe weather ingredients. For the wxnerd, CAPE values will be around 1,000, and there will be a mature-storm-killing veer-back-veer wind profile.

All that said, severe weather remains possible for us while we sleep. The severe ingredients will be decreasing, but they’ll still be there. The main threats are damaging winds and large hail, and an outside chance of a tornado or two.

Notice this from the SPC’s Probabilistic Outlook for late Thursday night. We’re in the shaded (“hatched”) area:

This means that despite the anticipated weakening, the probability of a significant severe weather event (significant: near-hurricane force winds) happening within 25 miles of you while you sleep tomorrow night is at least 10%.

Storms may rejuvenate during the daylight hours Friday, but if that happens it will most likely occur east of us.

Additional info coming later today.

This website supplements content found @NashSevereWx on Twitter.

Severe Weather Sleepover Thursday Night?

Current Official Hourly Observation (taken at :53 on the hour)

Current Radar Loop

Temp & Rain Probabilities Next 36 Hours (auto-updating)

Tuesday Night – Partly Cloudy, Pleasant – Upper 60s!

The record high for today was 86° (1963). We came close: 82°!

Wednesday – Partly Sunny; Increasing Clouds/Winds; Chance of Showers Late – Wake Up 56 / Afternoon High 79

Clouds and winds will increase through the day. Expect sustained south/southwest winds at 5 to 15 mph, gusting up to 20 mph.

The SPC (Storm Prediction Center) does not include us in an severe weather outlook Wednesday.

Storm Prediction Center Apr 1, 2014 1730 UTC Day 2 Convective Outlook 2014-04-01 14-53-51 2014-04-01 14-56-28

We may see no-worry showers/storms very late Wednesday night, into Thursday morning.

Thursday – Off & On Thunderstorms; Severe Storms Possible Very Late – Wake Up 62 / Afternoon High 77

I think we will remain mostly rain free for much of Thursday; however, “intermittent impulse activity” will be present during the day, so we can’t rule out rain/thunderstorms all day. In fact, you should expect rain/storms at some point during the day Thursday.

The concern is late Thursday night through dawn Friday. During this period, the SPC has us under a Slight Risk of severe weather:

Storm Prediction Center Apr 1, 2014 0730 UTC Day 3 Severe Thunderstorm Outlook 2014-04-01 14-58-37 2014-04-01 15-06-07

Why? Well, storm-friendly atmospheric instability will increase Thursday night, into the wee hours of the early morning on Friday.

Meanwhile, a cold front will move west-to-east into Middle Tennessee, with an ETA around sunrise Friday.

This means the window of opportunity for severe weather exists while we’re sleeping Thursday night and early Friday morning. This is good, and bad, news.

The bad news is that most of us will be sleeping.

The good news is that the nocturnal arrival of the severe weather system is diminishing projected severe weather indices (Showalters, CAPE, low level jet, and omega fields) — it could be worse, and it probably will be worse for those to our west, where the system will be arriving during daylight hours.

Nevertheless, severe weather ingredients are in place, and we all need to carefully watch this system as we hone the ETAs and expected impacts.

As for rain, there is some hope [game that requires a ball roll on the ground] will happen Saturday. If the cold front arrives around sunrise Friday, we’ll have time to dry out. We think we’ll get under 1″ of rain Thursday & early Friday:

Stay tuned, y’all. You’ll be hearing a LOT more about this tomorrow and Thursday.

The weekend looks nice. Mostly sunny, highs in the low 60s.

Official Extended NWS Forecast

Screen Shot 2014-04-01 at 1.20.11 PM

This website supplements info @NashSevereWx on Twitter.