Rain Tonight (meh), Updated Info On Late Week Storms

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

Current Radar Loop

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

TonightWarm, Slight Chance of Rain – 10PM Low 60s!!!

A light shower may arrive late tonight. Short term models think so.

I had to double check to see if the approaching precipitation seen in the models will actually make it here. Below is a vorticity chart showing the presence of “spin” in the atmosphere needed to produce precipitation. The more vivid the colors the more “spin” we have in the atmosphere.

This shows a small amount of vorticity advection into Middle Tennessee, which causes “lift” in the atmosphere. It’s not all that impressive, like it is in the Mid-West, but agrees with models to roll through late tonight…So our rain chances are still set at “meh”.

For the record, “meh” means “not much.”

Any rain should be gone in the morning.

TuesdayPartly Sunny – Wake Up 53, Afternoon High 76

high

WELCOME BACK SPRING!!

Later This Week

extended

We are currently not technically outlooked for severe weather by the Storm Prediction Center. This may change. Check out the forecast location of the low pressure center “L” Friday morning:

Remember, we would prefer that “L” to be further north, which would decrease our strong/severe weather concerns.

Right now, the best thinking on the timing for any strong/severe weather is Thursday night/overnight Friday/Friday morning.

Most of the severe weather should stay west of the Mississippi River.

Poor Arkansas! ;(

WxNerds will enjoy this run of the GFS model, showing dew points in the upper 60s (!!) early Friday afternoon, as the cold front sweeps west to east:

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The storm system should clear out by Friday night, but not before we see 1″ to 2″ of rain, falling mostly Thursday night and Friday:

The weekend looks nice, with high temps in the 60s. There is a mention of isolated showers Sunday, with another round of storms possible Monday. If you want your May flowers, then, well, it needs to rain in April.

This website supplements @NashSevereWx on Twitter.

Lunch Update on Rain Tonight (meh), Late Week Storms

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

Current Radar Loop

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

TonightSunny, but a Few Showers Possible Late70s today, 60s tonight

A light shower may arrive late tonight. The RAP thinks that’ll be after midnight:

Any rain should be gone in the morning. It’s unlikely to be enough to rain anything out Tuesday.

Tuesday – Volcanic Eruption with Lava, Global Superstorm, Godzilla – AM Low 56 : 350 PM High

Wait, sorry, that was for Virginia.

For us:

TuesdayPartly Sunny – AM Low 53 : 76 PM High

Later This Week

We are currently not technically outlooked for severe weather by the Storm Prediction Center. This may change. Check out the forecast location of the low pressure center “L” Friday morning:

Remember, we would prefer that “L” to be further north, which would decrease our strong/severe weather concerns.

Right now, the best thinking on the timing for any strong/severe weather is Thursday night/overnight Friday/Friday morning.

WxNerds will enjoy this run of the GFS model, showing dew points in the upper 60s (!!) Friday afternoon, as the cold front sweeps west to east:

The storm system should clear out by Friday night, but not before we see 1″ to 2″ of rain falling mostly Thursday night and Friday:

The weekend looks nice, with high temps in the 60s. There is a mention of isolated showers Sunday, with another round of storms possible Monday. But, first storms first : )

This website supplements @NashSevereWx on Twitter.

Spring! (But Severe Weather Possible Late Thu/Fri)

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

Current Radar Loop

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

Sunday Night – Chilly & Clear

Monday – Cool Morning, then Sunny; Tiny PM Rain Chance – Morning Low 36 / Afternoon High 72

With high pressure off to our east, “return flow” begins (that’s wxspeak for warm air arriving from the south).

Return Flow:

There is a tiny chance of rain Monday night as a weak, dissolving shortwave approaches.

Tuesday – Partly Cloudy Warm – Morning Low 53 / Afternoon High 74

Beautiful!

Official Extended NWS Forecast:

Screen Shot 2014-03-30 at 4.04.18 PM

Severe Weather Outlook

The severe weather concern remains. What looked like a Thursday event appears to be evolving into a Friday event. That’s not good news.

Why?

Because the nefarious low pressure center (the “L”) and associated cold front will have more time to strengthen. It also means more time to pump storm-fueling warm and humid air into Middle Tennessee, like throwing more dry brush into a forest fire.

The current outlook from the SPC (Storm Prediction Center) does not include us … yet. The only reason is that we have not reached at least a 30% chance of severe weather happening within 25 miles of us. Places well to our west have reached that limit, and are under the threat of severe weather Thursday.

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The models are in pretty good agreement that we will have the high dew points (humidity), which fuels storms. What remains to be seen — and we won’t know until the day of the event — is how much fuel will be in the atmosphere for storms to work with.

The GFS model (below, showing Thursday 10 pm – Saturday 1 am) has one round of thunderstorms moving in Friday around noon, and another round redeveloping for Friday night. It’s too early – WAY TOO EARLY — to know if we will even have two rounds of thunderstorms.

The Canadian model (below, showing Friday 7 am – Saturday 7 pm) pushes a round of rain in Thursday and, unlike the GFS model, the Canadian sticks to only one round of rough weather Friday night. This is because the track of the “L” is much further north. Remember, the closer the “L” is to the north, the more potent the storms should be.

The European model (not pictured) is definitely the fastest of the models.  It predicts rain late Thursday, then a main line of storms Friday morning, with everything clearing out in the afternoon. Like the Canadian model, the Euro keeps the “L” further north into the Great Lakes region. The European model would be the best model scenario for us because it moves the system in the fastest, and keeps the “L” well to our north.

A lot can and will change between now and then. Stay tuned.

This website supplements info @NashSevereWx on Twitter.

Warming Up. Looking Ahead to Mid/Late Week Storms

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

Current Radar Loop

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

Saturday – Too Cold 10 PM 43

Winds will begin the taper off after sunset.

We’ll have to wait until tomorrow to see any meaningful sun.

Sunday – Cooler, Sunny – Morning Low 35 / Afternoon High 62

That’s better.

Monday – More Sunshine – Morning Low 40 / Afternoon High 72

Very, very nice.

Official Extended NWS Forecast:

Severe Weather Outlook

The concern for severe weather Thursday/Friday remains.

In Tuesday’s post we talked about how important the track of a low “L”pressure center can be. That’s one of several ingredients necessary for severe weather. It looks like the ingredients just MIGHT come together next week. The “L” may track through AR, MO, IL, which would be particularly concerning for Middle Tennessee.

What I’m about to go over are only two big ingredients needed for strong/severe storms. There is are more, but I don’t want to nerd this up too much.

All thunderstorms need “fuel.” That fuel is moisture, which is measured by the dew point (humidity). Dew points in the 60s (yellow and orange colors on the map) are enough fuel for big, bad storms.

GFS dew point model Thursday 1 am – Saturday 7 am:

Canadian dew point model Thursday 7 am – Saturday 1 pm:

The European model (not pictured) brings in more moisture further north. Not all three of models “agree” on the exact timing of the arrival of the 60s dew points, but they generally agree we’ll see dew points in the 60s late next week.

Ignition. That’s the low pressure system. Attached to the “L” is a dry-air-toting cold front, which will collide into the warm, wet air already in place. This will create instability, and set off the storms.

Remember, the closer the “L” moves to us (with it on the north side, us on the south side), the higher the severe potential.

Watch the tiny red “L” move on the maps below:

GFS model Thursday 1 am – Saturday 7 am:

The track for this low has been further south than some of the previous model runs, which would be more conducive for severe weather. It’s not the strongest low pressure in the world, but it’s certainly enough to cause problems. If the low actually ends up tracking a little further south, I’ll be more concerned about this possible severe weather setup.

Canadian model Thursday 7 AM – Saturday 1 PM:

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This model has the track of the low a little further north than GFS, but overall, the tracks are similar.

European model (not pictured) wants to push the worst of the weather in Friday morning, which would be the best news for us because the atmosphere would be most stable. The track of the low is almost a hybrid of the Canadian and GFS model.

The SPC (Storm Prediction Center) does not have anyone outlooked this far out because the models are not agreeing with each other enough for them to confidently outline an area:

Screen Shot 2014-03-29 at 8.28.51 AM

However, SPC expects they will reissue an outlook area if/when the models become more consistent.

This website supplements info @NashSevereWx on Twitter.

Rain & Thunderstorms Late Tonight/Overnight

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

Current Radar Loop

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

—–4:00 PMUpdate—–

Late Tonight – Rain & Thunderstorms – Afternoon High 70, 10 PM 60

At 3:30 PM, rain and storms were firing up inside a Severe Thunderstorm Watch box in Texas and Arkansas:

That’s the system coming our way, with an ETA late tonight.

Storms may be strong on arrival, but they’re not expected to be severe. We remain outside the latest Storm Prediction Center’s “Slight” Risk outlook for severe weather:

An additional 0.55″ of rain is expected.

The rain should be gone by noon Saturday:

Saturday looks much cooler (high in mid-50s), but by Sunday, temps will rebound. The beginning of next week looks awesome.

There is some concern about a severe weather pattern setting up in Middle Tennessee sometime next week. Right now, it looks like Thursday, but we are too far away to pin down what (if anything) we’ll see, and when. Stay tuned.

This will be the last post Friday. Find more/updated information @NashSevereWx on Twitter.

Rain and Storms Late Tonight & Late Friday Night

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

Current Radar Loop

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

Updated at 4:15 PM

The pattern we’ve seen over the past few weeks: north and northwest winds — which delivered below-average temps — has broken. South winds are taking over. This means warmer temps with rain/storms.

ThursdayWind Advisory, Rain Tonight – Low 60s/Upper 50s

Winds were already gusting over 30 mph this morning. Winds will strengthen this afternoon (Gusts – Dark Blue; Sustained Winds – Purple):

A 46 MPH wind gust will create problems for large trucks and high-profile vehicles during the evening commute. Be careful!

A Wind Advisory remains effective through 4 AM Friday:

from A Mighty Wind

Rain & Thunderstorms will continue to linger around Middle TN. Super-dry air near the surface has been preventing a lot of the rain from reaching the ground. You may see a few sprinkles (ProTip: the wind will LOL at your umbrella), but it’ll be nothing like what we see tonight.

Tonight, legit rain arrives. Here is the HRRR model from 7 PM until 4 AM:

Notice that squall line that comes through in the middle of the night. We’ll keep a close eye on that.

This rain will continue off and on (mostly “on”) into Friday morning. A few thunderstorms are possible, but severe weather is not expected at this time, We’re very curious to see how potent that wee-hour line of storms will be.

We aren’t sure exactly when the rain will stop, but the best thinking is before mid-morning. Rainfall totals will range between 0.70″ and 0.80″. That’s enough to rainout outdoor activities.

FridayRain/Storms – AM Low 55, PM High 68

After the morning rain/storms push east, most of the daylight hours should be rain free, although we could still see a shower or two.

All eyes are the weather Friday night.

Yesterday, the Storm Prediction Center included us in its “Slight” (think “elevated”) Risk area for severe weather. Today, SPC shifted that area out of Middle Tennessee.

Just because we are not included in the “Slight Risk”, does not mean we are out of the woods completely with this system. SPC still includes us in the 5% chance area of severe weather happening within 25 miles of you:

Screen Shot 2014-03-27 at 3.39.41 PM

Why the shift? One big reason is the forecast track of the surface low pressure center: if it goes north of us (and we get the southern side of it), we’ll see a good chance of severe weather.

However, we think the low pressure will still be developing and pass over/south of us, putting us on the northern (or “wrong”) side for severe weather. This is what the GFS/Euro models think will happen:

Hence the downgrade from a Slight Risk.

Another potential limitation on severe weather tomorrow will be any thunderstorms which may occur to our south: along I-65 and into the northern Gulf of Mexico. To get severe weather tomorrow, we’ll need an uninterrupted pipeline of south winds blowing in all that warm, wet air north from the Gulf. Any thunderstorms which develop along the way will block the pipeline and limit our severe weather chances.

Nevertheless, even if they aren’t severe, there will be rain and a few storms Friday night/overnight.

The Hi-Res NAM model delays the heavy stuff until 1 AM Saturday, maybe later:

The GFS agrees. Here it is at 1 AM Saturday:

Rain should end around dawn Saturday morning, but not before a grand total of around 1.5″ of rain will have fallen:

Friday night (especially early in the evening) may be relatively dry, but by Saturday morning, it looks like soccer/baseball/anything that requires a ball to roll on grass or dirt will be rained out.

A rain out looks likely at Rod Cook Field Saturday:

The cold front triggering all this rain will slice into temps a bit, but nothing like what we’ve seen the past few weeks.

Official Extended NWS Forecast: 

Screen Shot 2014-03-27 at 3.47.15 PM

This website supplements information found @NashSevereWx on Twitter.

Rain & Storms; Severe Weather Possible Friday Night

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

Current Radar Loop

Temp, Winds, Storm, & Rain Forecast: Next 36 Hours (auto-updating)

Wednesday Night – No Rain; Increasing Clouds, 42° by 10 PM

Clouds will be building tonight ahead of some rain. These clouds are a precursor to some very interesting weather setting up the next couple of days.

NOAA GOES East DATA - EASTERN US IR - Mozilla Firefox 2014-03-26 15.19.04

The above image is an infrared view of a low pressure center forming in the Plains, on the east side of the Rockies. This will be a major player in the rain and storms we expect Thursday.

ThursdayWind Advisory & Rain – Morning Low 37 / Afternoon High 61

Wind. A Wind Advisory is in effect Thursday:

As we remind you during all Wind Advisories: be sure to secure your 88 year old, 88 pound aunt. Winds may gust up to 40 MPH.

Rain. Weather models, including the RAP (below), suggest we may see a few early Thursday morning showers:

The daytime hours should be mostly dry; however, after dark, rain and a few thunderstorms (severe weather not expected Thursday) are forecast to arrive. By 1 AM Friday morning, it should really be pouring (at least according to the GFS model, below):

Expect 0.70″ of rain to fall through 7 AM Friday morning.

FridayMore Rain; Severe Weather Possible – Morning Low 55 / Afternoon High 71

Rain and Thunderstorms are likely Friday night.

The Storm Prediction Center puts most of Tennessee just outside the “Slight” category for a severe storm late Friday afternoon/evening.

Damaging straight-line winds are possible Friday night. This outlook and forecast will be updated several times over the next few days. Stay tuned.

Rainfall from Thursday night through Saturday morning will approach 1″.

Official Extended NWS Forecast:

This website supplements info @NashSevereWx on Twitter.

Review of Today’s Snow; Cold Wed Morning; Return to Spring

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

Current Radar Loop

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

Tuesday Night – Clearing Out

Several narrow bands of light to moderate snow moved through this morning and earlier this afternoon:

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Even though it was above freezing at the surface, some of the snow bands were intense enough to cause some light accumulation on some grassy surfaces.

Just before 12:20 PM, there was thundersnow just NE of Brentwood:

Roads and bridges were too warm to be threatened

Many of you tweeted us with amazing pictures of this #SpringFail:

Screen Shot 2014-03-25 at 1.19.27 PMScreen Shot 2014-03-25 at 1.10.17 PM Screen Shot 2014-03-25 at 1.12.52 PM

Strong winds this afternoon will dry up most of the wet surfaces before temps drop this evening, then winds will die down as we progress through the evening.

(Side note: This system affecting us today will merge with another weather system off the Carolina coast, creating a MONSTER STORM, which is forecast to ride up the East Coast. Cape Cod will be getting the worst of this system with a full fledged BLIZZARD. Major cities should be spared the worst, with just a dusting to a couple inches of snow.)

Wednesday – Cold AM & Sunny – Morning Low 23 / Afternoon High 46

Screen Shot 2014-03-25 at 12.37.48 PM

At least the winds will be dead. No need to worry about wind chills.

Wednesday night won’t be as cold as Tuesday night.

Thursday – Sunny, Windy Day; PM Thunderstorms – Morning Low 37 / Afternoon High 62

Our next system will be more spring-like. Winds will blow from the south, gusting up to 35 mph. A Wind Advisory may be issued by our NWS for Thursday. Will all those strong southerly winds, warm temperatures will arrive, hopefully for good.

The feeling of Spring in the air will give way to some Spring like thunderstorms.

The SPC (Storm Prediction Center) currently keeps severe chances well off to our west.

Storm Prediction Center Mar 25, 2014 0730 UTC Day 3 Severe Thunderstorm Outlook 2014-03-25 12-29-54 2014-03-25 12-35-16

We don’t think storms will be arriving until the overnight, but we are still too far away to be sure.

GFS model Thursday 7 pm – Friday 4 pm:

Friday looks like a washout, with a few showers lingering into Saturday morning.

Official Extended NWS Forecast:

Screen Shot 2014-03-25 at 3.16.21 PM

Severe Weather Outlook

Next week could — possibly — bring us as much as our first Spring Severe Weather Event, or maybe as little as garden-variety thunderstorms.

Models are coming together to show the big ingredients we need to have a chance of severe weather.

It’s a good time to review them:

#1 Warm & Humid Air (The Fuel)

There’s a lot of warm (temp) and humid (dew point) air to our south and in the Gulf of Mexico. How do we get it? South winds.

That looks to be happening next week. It takes a couple days for south winds to blow that good, deep Gulf of Mexico moisture in here — especially with all the dry air already in place.

This run of the GFS model (next Tuesday 1 PM – Friday 1 PM) shows dew point (humid air). To get severe weather, you generally dew points of at least 60 and up (yellow and orange colors) ahead of a cold front.

Here’s the GFS model (Monday 1 AM – Wednesday 7 AM), depicting the transport of warm air into Middle Tennessee from the south. This is courtesy of a ridge of high pressure.

Notice that a trough (in blue) shows up next Wednesday, kicking out the warm south air, replacing it with a north/northwest wind, its cooler temps, and drier air.

#2 Ignition (Match)

The match igniting the warm, humid air is a low pressure system and a corresponding cold front. The closer you are to that low pressure center, the better severe-friendly lift and spin you will have in the atmosphere.

Lately, our severe weather events have featured a low pressure center moving through the Great Lakes region. It was (thankfully) too far away to cause a bigger, more severe, problem.

If the center of a low pressure moves closer to us — further south, through Arkansas, Missouri, and Illinois — our severe weather chances increase dramatically.

Here is the GFS model, next week, Tuesday April 1st 7 PM – Friday April 4th 1 AM. Notice the location of the center of the low pressure.

Notice the low pressure system moving through the Great Lakes — this would give us a more linear squall line thunderstorm threat. If that low (the “L”) was closer to us, severe concerns would increase.

This is just one model and it’s really far out. Alot can, and probably will, change. We aren’t predicting severe weather for next week, at least not right now. We wrote this only to illustrate the things we look at when forecasting severe weather.

This website supplements info @NashSevereWx on Twitter.

Rain, A No-Worry-Flurry, & Cold

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

Current Radar Loop

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

Monday Night Slight Chance of Sprinkles/Flurries 

I could sit here and go through all the weather models with you, but reality is there is not a chance of any accumulating snow. The weather system is weak (many areas will see no precip), the roads are warm, and we’ll only barely, and briefly, reach freezing.

TuesdayWindy, Cold, & Slight Chance of Rain/Snow – Morning Low 31 / Afternoon High 45

The rain/flurries may linger through mid-afternoon.

The forecast wake-up wind chill is 28. Wind chill values aren’t forecast to get above 35 all day. All this is courtesy of strong north winds, gusting as high as 30 mph by the afternoon. #SpringFail

Maybe this will make you feel better. At least it always make me feel better — My parents moved to Montreal, QC, Canada from Oxford, MS. At least your forecast does not look like this…

Screen Shot 2014-03-24 at 3.45.13 PM

(Editor’s Note: I do not feel better, but I hope y’all do)

Wednesday – Sunny & COLD – Morning Low 22 / Afternoon High 49

Expect a Hard Freeze Wednesday morning:

This will be a shock to the system. Thankfully, a modest wind will only cut the wind chill down to 20.

We’ll warm up quickly Wednesday, then the pattern will shift from cold to warm.

Thursday’s winds will gust to 40 mph, but the high will be 61.

Official Extended NWS Forecast:

Screen Shot 2014-03-24 at 4.00.55 PM

Severe weather is not expected Thursday/Friday.

This website supplements info @NashSevereWx on Twitter.

#SpringFail - Tuesday AM No-Worry Flakes

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

Current Radar Loop

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

Monday – Mostly Sunny – Morning Low 27 / Afternoon High 54

The wake-up wind chill will be 23; however, we will rapidly warm up in the morning.

Clouds will increase Monday night.

Tuesday – Slight Chance of Rain/Snow – Morning Low 33 / Afternoon High 45

Our final blast of cold Canadian air will push through in the wee hours of Tuesday morning. As this happens, we can’t rule out early morning light rain or a few snowflakes. The NWS mentioned “scattered flurries.” No big deal.

No accumulation or significant travel impacts are currently expected.

Here’s the Hi-Res NAM model 7 AM Tuesday. You can see the snow (in blue) scoot by, mostly missing us:

Official Extended NWS Forecast:

This website supplements info @NashSevereWx on Twitter.