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

Posted on Wednesday, April 2, 2014 @ 9:11 pm by Mysterious Meteorologist

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

Current Radar Loops

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

Tonight – Rain/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:

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.

We remain excluded from tonight’s tornado probability outlook:

Thursday – Off/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:

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 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: