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Author Topic: April 5th Severe Weather Threat  (Read 15859 times)

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Offline wfrogge

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Re: April 5th Severe Weather Threat
« Reply #150 on: April 05, 2017, 08:10:45 PM »
Verification is important. If you just always warn of potential, and then what happens is decidedly not as severe, the public stops paying attention. We're not just saying there's a potential for severe storms, we're giving probabilities and those probabilities are without a doubt, super incorrect.

Fact of the matter is, modeling crapped the bed again. As it has repeatedly recently. It seems like maybe some additional conservatism is in order. If you don't go high risk with a hatched area, and then the extreme storms start happening, it's a lot easier to start warning than it is to stop the hype train.

The probabilities were correct given the data we had with 24 hours to go.  If you know different there is a job at the SPC with your name on it :)

Offline WXHD

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Re: April 5th Severe Weather Threat
« Reply #151 on: April 05, 2017, 08:11:09 PM »
Verification is important. If you just always warn of potential, and then what happens is decidedly not as severe, the public stops paying attention. We're not just saying there's a potential for severe storms, we're giving probabilities and those probabilities are without a doubt, super incorrect.

Fact of the matter is, modeling crapped the bed again. As it has repeatedly recently. It seems like maybe some additional conservatism is in order. If you don't go high risk with a hatched area, and then the extreme storms start happening, it's a lot easier to start warning than it is to stop the hype train.

I have to respectfully disagree.

I think you and I are privy to the nuances of forecasting, model hugging and wish-casting that eludes the vast majority of people. For you and I and most everyone else on this forum, weather is at the least a hobby and likely a passion.

Forecasters did not tell us that there was a 100% chance of tornadoes happening. The forecast and maps showed a a smaller chance of such horror happening. To that end, the forecast was nearly perfect. How individuals chose to interpret that is no fault of the people responsible for giving their best effort to alert the public to the potential for significant weather. We are very fortunate that nothing extreme panned out. However, you and I were both watching the models, radar and reports until the last moment. We both know that had things positioned themselves just a few miles in a south west direction things could have brought a very different outcome. Everyone I know was aware of the weather and the potential for tornadoes. To that end, I feel like the forecasters did their job exceptionally.

I'm mobile so there's likely some errors, sentiment remains. As does my respect for you and your ability to read and interpret models Justin.
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Offline cgauxknox

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Re: April 5th Severe Weather Threat
« Reply #152 on: April 05, 2017, 08:12:17 PM »
Lightning visible to the west now as the line of potent storms approach.  Only warned storm is in the far southern valley for now.  Nevertheless, the storms approaching Knoxville look like they pack a punch.

We've had plenty of thunder and some rain here in West Knoxville over the last 30 minutes or so but nothing severe yet.  I don't know we'll have any excitement but am grateful for the rain.

Offline dwagner88

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Re: April 5th Severe Weather Threat
« Reply #153 on: April 05, 2017, 08:19:19 PM »
I thought for sure I was going to see some hail as the line came through (nearly 70 DBZ returns). It was all torrential rain. Got 1.1" in about 15 minutes. Nothing severe verified here thankfully.
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Offline StormNine

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Re: April 5th Severe Weather Threat
« Reply #154 on: April 05, 2017, 08:43:45 PM »
The southern IN through KY/TN portion of the threat didn't do that bad as far as verification goes especially considering that the HRRR and the NAM overestimated the dewpoints by 5 to 8 degrees. Not sure what happened down in GA but overall the threat underperformed pretty significantly although there were some tornadoes down that way. With this coming off the heels of last Thursday and a somewhat underperforming High Risk back on the 2nd, the SPC will feel the criticism. I am more concerned about the continued failure of radars during severe weather events and the fact that our computer models are not making the progress that they should than I am about the SPC's risk areas.

With that being said it appears that the SPC is in a rough patch similar to where it was during the spring of 2005 and 2009 where it kept making forecast errors due to complex systems. A lot of the underperforming events of those years were due to gulf convection allowing for the blockage of sufficient moisture return. Spring 2005 was an extreme example that saw one of the biggest High Risk busts ever and several Moderate Risk busts.

Offline Dyersburg Weather

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Re: April 5th Severe Weather Threat
« Reply #155 on: April 05, 2017, 08:47:07 PM »
I interrupt this discussion to say it's colder than ****. Carry on.

Offline andyhb

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Re: April 5th Severe Weather Threat
« Reply #156 on: April 05, 2017, 09:32:57 PM »
Verification is important. If you just always warn of potential, and then what happens is decidedly not as severe, the public stops paying attention. We're not just saying there's a potential for severe storms, we're giving probabilities and those probabilities are without a doubt, super incorrect.

Fact of the matter is, modeling crapped the bed again. As it has repeatedly recently. It seems like maybe some additional conservatism is in order. If you don't go high risk with a hatched area, and then the extreme storms start happening, it's a lot easier to start warning than it is to stop the hype train.

Eh, I'll respectively disagree with the bolded. It's hard to get people's attention at the last minute when they have already made prior plans/etc. since they didn't expect a high magnitude event. They are basically equally tricky situations.

A multitude of things today, primarily as a result of the southern stream vort max that passed through the warm sector this morning, prevented a larger scale event from a seemingly favorable synoptic setup. Without going too far into detail, the lack of stronger low level flow through much of the afternoon was the #1 cause of the underperformance. For starters, it meant that the cold pool laid out by the morning storms basically saw no modification over E AL/GA.

This weak flow was a result of the aforementioned vort max leading to the primary low level jet axis being shifted into GA/etc. (in response to localized pressure falls). Here, bulk shear was comparatively weaker, the column was more saturated leading to HP/outflow-dominant storms and surface winds grew increasingly veered with time. Moisture return further north was hampered by the lack of stronger low level flow, as was hodograph curvature (lack of turning between 850 and 500 mb was also an issue further south into AL). Once the storms in E AL and TN reached the backed low level flow near the boundary, they had very little residence time before reaching stable air.

Post Merge: April 05, 2017, 09:41:23 PM
without a doubt.... ::)

Bruce, if half of the events you called for a week out verified, most of this forum would probably be in the ground with engraved blocks of granite sitting atop them.
« Last Edit: April 05, 2017, 09:41:23 PM by andyhb, Reason: Merged DoublePost »
Dynamic upper level troughs with adequate warm sector instability™


Offline BRUCE

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Re: April 5th Severe Weather Threat
« Reply #157 on: April 05, 2017, 10:59:08 PM »
well... its time to dig into the models n see when we have a next chance of opportunity... you have a great night andy... ;)
Come on severe wx season...

Offline skillsweather

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Re: April 5th Severe Weather Threat
« Reply #158 on: April 06, 2017, 12:51:08 AM »
Man bummed to not got any storms here. It really felt like it would storm today earlier. The air felt perfect for storms but guess other things messed it up.. I miss spring days with back to back storms like one each week at least.
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Offline justinmundie

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Re: April 5th Severe Weather Threat
« Reply #159 on: April 06, 2017, 06:42:48 AM »
Eh, I'll respectively disagree with the bolded. It's hard to get people's attention at the last minute when they have already made prior plans/etc. since they didn't expect a high magnitude event. They are basically equally tricky situations.

A multitude of things today, primarily as a result of the southern stream vort max that passed through the warm sector this morning, prevented a larger scale event from a seemingly favorable synoptic setup. Without going too far into detail, the lack of stronger low level flow through much of the afternoon was the #1 cause of the underperformance. For starters, it meant that the cold pool laid out by the morning storms basically saw no modification over E AL/GA.

This weak flow was a result of the aforementioned vort max leading to the primary low level jet axis being shifted into GA/etc. (in response to localized pressure falls). Here, bulk shear was comparatively weaker, the column was more saturated leading to HP/outflow-dominant storms and surface winds grew increasingly veered with time. Moisture return further north was hampered by the lack of stronger low level flow, as was hodograph curvature (lack of turning between 850 and 500 mb was also an issue further south into AL). Once the storms in E AL and TN reached the backed low level flow near the boundary, they had very little residence time before reaching stable air.

Post Merge: April 05, 2017, 09:41:23 PM
Bruce, if half of the events you called for a week out verified, most of this forum would probably be in the ground with engraved blocks of granite sitting atop them.

Maybe I'm a bit hyperbolic... but I spent most of my evening trying to explain to people who were critiquing the weather service and local mets how difficult forecasting is, which is frustrating. But it's hard to justify when you can't even lean on the probabilities being even close to right. I also haven't seen anyone mention how models were essentially useless yesterday.

I realize I'm alone, but even when we have an enhanced risk, people are paying attention. I feel like we're going to have a much greater problem in the future when people start ignoring moderate and high risk events, and that's certainly going to happen the more often those events turn into nothingburgers.

Offline Thundersnow

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Re: April 5th Severe Weather Threat
« Reply #160 on: April 06, 2017, 08:26:40 AM »
At the risk of beating a dead horse about the current risk scale... people, in general, don't really understand it.

"Enhanced" sounds worse than "moderate." If I didn't know better, I would think the same.

I heard someone on the radio yesterday actually confuse the two. The news person said something about an "enhanced risk" around Chattanooga, but "moderate" everywhere else.  I think a numeric "category" scale might actually make more sense... most people seem to understand the 1-5 scale (in terms of severity) with regard to tornadoes and hurricanes. Why not do something similar for severe risks?

Offline StormNine

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Re: April 5th Severe Weather Threat
« Reply #161 on: April 06, 2017, 09:22:24 AM »
At the risk of beating a dead horse about the current risk scale... people, in general, don't really understand it.

"Enhanced" sounds worse than "moderate." If I didn't know better, I would think the same.

I heard someone on the radio yesterday actually confuse the two. The news person said something about an "enhanced risk" around Chattanooga, but "moderate" everywhere else.  I think a numeric "category" scale might actually make more sense... most people seem to understand the 1-5 scale (in terms of severity) with regard to tornadoes and hurricanes. Why not do something similar for severe risks?

I use the numbers when I discuss severe weather threats and I'm noticing more news outlets and even the NWS start to get on board with calling it a Level 3 risk instead of an Enhanced. I usually put the category name in parathesis so those used to seeing understand better. I think it is time to shed those sometimes confusing names and go numbers (using High Risk for a Level 5 would still make sense though). This is why the Tor Con works so well with the public is because it is a simple 1 to 10 measurement.

The non-weather caring public operates on the KISS principle. The simpler and more concise the weather information is the better. At the end of the day, all they want to know is how concerned they should be about seeing severe weather at their precise location. Unless it is a bar filled with Earth Science/Meteorologist fanatics, you don't have to worry about a full on bar brawl being started over whether Georgia should be in a Moderate or High Risk.


Offline BRUCE

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Re: April 5th Severe Weather Threat
« Reply #162 on: April 06, 2017, 09:33:10 AM »
Maybe I'm a bit hyperbolic... but I spent most of my evening trying to explain to people who were critiquing the weather service and local mets how difficult forecasting is, which is frustrating. But it's hard to justify when you can't even lean on the probabilities being even close to right. I also haven't seen anyone mention how models were essentially useless yesterday.

I realize I'm alone, but even when we have an enhanced risk, people are paying attention. I feel like we're going to have a much greater problem in the future when people start ignoring moderate and high risk events, and that's certainly going to happen the more often those events turn into nothingburgers.
truth is think we all have a bit of hyperbolic in us... if we didnt, we wouldnt all be in this forum posting about weather... its a passion we all have... weather it be winter storms or severe weather... no one wishes devastation or destruction on no one... but seeing a violent long track tornado is such a adrenaline rush cant explain...
Come on severe wx season...

Offline Curt

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Re: April 5th Severe Weather Threat
« Reply #163 on: April 06, 2017, 10:16:11 AM »
One thing I'm learning from severe weather events is how much the warm front or morning convection plays a huge role in making or breaking the event. I know in April 2011, the morning MCS played a huge role in tipping the event into epic proportions. However, the same MCS or convection event yesterday IMO played a role to lessen the event. In north GA, it actually created a huge cool pool for much the Atlanta metro north, thus instability was almost zero by the time the event could have gone gangbusters. This was WELL forecast 24 hours in advance by CAPE modeling on the short term NAM and HRR- and most offices did not account or at least believe this in those areas. I'm not sure if the rest of the event was lessened overall by its impact of lack of recovery time for instability as a whole over the region or lack of recovery time for moisture- who knows. It appears to the green person that I am- that these pre event thunderstorm clusters might be the key to the overall puzzle.
« Last Edit: April 06, 2017, 10:23:09 AM by Curt »

Offline BRUCE

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Re: April 5th Severe Weather Threat
« Reply #164 on: April 06, 2017, 11:28:27 AM »
One thing I'm learning from severe weather events is how much the warm front or morning convection plays a huge role in making or breaking the event. I know in April 2011, the morning MCS played a huge role in tipping the event into epic proportions. However, the same MCS or convection event yesterday IMO played a role to lessen the event. In north GA, it actually created a huge cool pool for much the Atlanta metro north, thus instability was almost zero by the time the event could have gone gangbusters. This was WELL forecast 24 hours in advance by CAPE modeling on the short term NAM and HRR- and most offices did not account or at least believe this in those areas. I'm not sure if the rest of the event was lessened overall by its impact of lack of recovery time for instability as a whole over the region or lack of recovery time for moisture- who knows. It appears to the green person that I am- that these pre event thunderstorm clusters might be the key to the overall puzzle.
100 percent agree... great post
Come on severe wx season...

 

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