Forecast Blogs

Showers and Thunderstorms Possible Later Today, Uncertainties Remains

  


Flood Advisory Continues for the Stones River

We still have a flood advisory in effect for Davidson County due to the Stones River.

We still remain above the action stage, hence the advisory remaining in effect. Any additional rainfall we see today through the weekend will likely cause us to stay above the action stage. If you come across a flooded roadway, turn around don’t drown.

Another Round of Showers and Thunderstorms Today?

Uncertainty is the key word for today. There are still a lot of variables at play, which will determine when and the type of storms that we see today.

*Update as of 3:30 PM our atmosphere has remained “capped” so far today. Our local NWS launched a special 19Z balloon that confirmed our “capped” environment thus far. This is great news for everyone that has afternoon plans. While we still are not in the clear, the longer storms hold off, the better off we will be. Our local NWS had this to say in this afternoon’s discussion:

“Well all eyes are absolutely 100% glued to the radars located in Hopkinsville and Nashville as forecasters and weather watchers alike squint to see if that “little blip” will turn into something…or anything. But alas, the waiting game continues which makes this forecaster very happy. The longer these storms wait to develop, the better off we are here in Middle Tennessee.”

They additionally go onto say: “IF (and a BIG IF) these storms can get going, we`ll be dealing with all severe weather modes as there is quite a bit of dry air aloft favoring downbursts and large hail as well as enough wind shear to favor possible tornadoes. But for now, we praise the cap but continue to watch.”

We are still not in the clear yet by any means. Continue to stick with us on Twitter @NashSevereWx as we will be watching the radar and let you know if any storms begin to develop.*

Timing: Now Until 9 PM

The timing of today’s showers and thunderstorms continues to be difficult. For this morning, our atmosphere remains “capped” which means no showers or thunderstorms have the ability to develop. If and when this “cap” breaks, we will see showers and thunderstorms develop rapidly.

One of our short-range models, the HRRR, wants to bring heavy showers into the mix around the early afternoon.

UPDATED Model Run as of 12:00PM CDT

Another key issue with today is where the severe storms will develop. Those to our northwest do appear to have the greatest potential, however, we are close enough to this area that we need to keep a very close eye on any showers and thunderstorms that do develop.

As can be seen in the image above, showers and thunderstorms look to stay to the north of I-40. One of our other short term models, the NAM3km, wants to keep the majority of showers and thunderstorms confined to our northwest…but it also wants to sneak in a renegade cell south of I-40 around mid-afternoon.

The models are not agreeing with how today and this afternoon will happen. For this reason and many others, uncertainty remains.

 UPDATED: Slight Risk of Severe Weather for Davidson and Williamson Counties

The Storm Prediction Center has updated today’s severe weather outlook. They moved the higher-end “Enhanced Risk” further north towards the KY/TN state line. Does this mean we’re out of the woods today? Not at all, but it’s an improvement. In fact, most of Williamson County is now only in a “Marginal Risk”.

As for the probability breakdown of each severe weather factor, we sit on the border for a lot of our severe weather probabilities. All this means is that we need to keep a close eye on these storms, if they shift southward at all, our severe weather potential could go up.

DOWNGRADED: 5% Probability of Damaging Winds Within 25 miles of your location (15% sitting just to our north)

15% Probability of Large Hail Within 25 miles of your location (30% sitting just to our north)

2-5% Probability of Tornado Within 25 miles of your location

Main concerns from our local NWS office appear to be damaging winds and flooding. However, large hail and an isolated tornado can not be ruled out.

Takeaways:

  1. Models are not perfect. We could see showers as early as the lunch hour or as late as the afternoon to early evening.
  2. Damaging winds and flooding appear to be the main concerns, but large hail and an isolated tornado can not be ruled out.
  3. There appears to be a fine line between seeing showers and thunderstorms and not seeing any at all. Most models are trending for the majority of showers and thunderstorms to skate across the I-40 corridor.
  4. There is the possibility that the storms miss us entirely to the northwest, hence even more uncertainty.

This is an evolving forecast that will likely change in the hours to come. Be sure to stick with us on Twitter @NashSevereWx throughout the day for the latest on timing and overall severe weather potential.

Saturday AM Looking More Promising, Could See a Pop-Up Thunderstorm in the Afternoon

Good news for those planning to run in the St. Jude’s Rock ‘N’ Roll Nashville Marathon, models have been trending towards a dry start and morning. You may still want to have a good rain plan just in case. Humidity will be high. Hydrate!

With the race times being pushed back, temps should be in the low 70s when the race begins. Temps will quickly climb through the day, possibly reaching the upper 80s to 90s as our high. Additionally, we could see heat index values reaching the 90s by the afternoon.

Additional Note: The record high for April 29th is currently set at 90° which occurred in 1894. We will see if we break that record tomorrow or not.

Hourly Weather Forecast Graph

Top Box: Temperature (Red), Dew Point (Green), Heat Index (Gold) | 2nd Box: Wind Speed and Direction (Purple), Wind Gusts (Blue) | 3rd Box:  Relative Humidity (Green), Precipitation Potential (Brown), Sky Cover (Blue) | 4th Box: Rain Potential | 5th Box: Thunder Potential 

Saturday should be a very enjoyable, summer-like day as long as we can keep the showers away. We do have the potential to see some pop-up showers and thunderstorms in the afternoon. If we do, don’t be surprised if we get a severe thunderstorm in the mix. Main concerns with any of these thunderstorms would be damaging winds, hail, and heavy rainfall if this occurred.

Another Chance of Severe Weather Comes Sunday Into Sunday Evening

General Timing: Late Afternoon Through Sunday Night

While the GFS and Euro have been in range for quite some time now, we do have a few of our short term models coming into range, which will hopefully provide some more insight into the timing for Sunday.

Right now, it appears that we will make it through the majority of the daytime hours on Sunday free of any showers. By the late afternoon, our first shower/thunderstorm chances appear.

One of our short-range models, the NAM3, wants to bring showers into the area in the early to mid evening hours.

NAM3 Loop Sunday 4 PM Through Monday 10 AM

This is just what one model is thinking. When looking at the GFS and Euro, both models are trending towards this late afternoon to evening time frame. With any potential severe weather event 3 days out, there lies uncertainties. We will continue to keep an eye on the models and let you know of any timing changes as more models become available.

Main Concerns: Damaging Winds, Heavy Rainfall, and Flash Flooding

We are currently in the “Marginal Risk” category by the Storm Prediction Center which translates into a 5% probability of severe weather occurring within 25 miles of your location.

With this outlook, damaging winds, heavy rainfall, and flash flooding appear to be the main concerns.

To go along with the heavy rainfall and flash flooding potential, the Weather Prediction Center currently has us in their “Marginal Risk” category which translates to their being a 2% – 5% probability risk of rainfall exceeding flash flood guidance.

While these are the main concerns, large hail and an isolated tornado can not be ruled out at this point either.

Next Week – A Dry Start, More Showers Possible By Wednesday

By the beginning of next week, expect for a short break from the showers/thunderstorms trend. Monday and Tuesday look to be fantastic days with mostly sunny skies and highs in the high 60s to low 70s. By Tuesday night, shower chances look to return as another system wants to bring showers and thunderstorms back into the picture by Wednesday.

5-Day Pollen.com Forecast


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