Severe WX Severe Weather Threat 4/5/17-4/6/17

Fred Gossage said:
The 00Z NAM and 00Z UKMET (which does about as well with synoptics as the Euro) say a slower solution is right. We'll see. The op GFS has been the faster model on other runs too... even of its own ensembles. Pretty much, every scrap of guidance that's not the op GFS... would have to speed up for the op GFS to be right with its timing.
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Thanks Fred, this goes to show I really shouldn't try to look at and analyze model guidance when I'm dog tired :)

Either way, this looks to be a long next few days with two legit severe threats in the next 96 hours or so
 
The 00Z Euro has managed to come in even more volatile than the previous run. There are greater height falls into the heart of the warm sector during peak heating... and the low-level jet continues to trend even more organized, wider, and stronger. Because of this, we're now talking about having 0-1 km SRH at face value this run of over 300 m2/s2 and 0-3 km SRH over 500 m2/s2 juxtaposed with some very high CAPE. This has caused the 3 km EHI to now max out at 10 ahead of the dryline in central AL at 7 pm Wednesday on the Euro... and a 1 km EHI as high as 6.
 
Fred, is the worse of this gonna be south of Gadsden? or, are we in the middle of it. Really couldn't tell,
but it looked to me that the enhanced risk was pretty close to Gadsden:(
 
Scott, we're not talking about on Monday, where there is an Enhanced Risk. This is a discussion about the threat for Wednesday.... which may be a threat that encompasses the entire state of Alabama, and a large part of Mississippi, Tennessee, and parts of Georgia... at the least. Monday, despite the Enhanced Risk near by, will probably be south of you... but this discussion is not about that threat.
 
WOW Its already on the day 3 for Tuesday Night including my area!

day3otlk_0730.gif

...Central Gulf States...
Deterministic guidance appears more bullish than the ensemble output
(particularly the NCEP SREF) suggests concerning low-level moisture
return and potential for vigorous thunderstorm development prior to
12Z Wednesday. If this occurs, it will probably do so in the
presence of strengthening shear supportive of some severe weather
potential, including a risk for supercell development.
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Fred Gossage said:
The 00Z Euro has managed to come in even more volatile than the previous run. There are greater height falls into the heart of the warm sector during peak heating... and the low-level jet continues to trend even more organized, wider, and stronger. Because of this, we're now talking about having 0-1 km SRH at face value this run of over 300 m2/s2 and 0-3 km SRH over 500 m2/s2 juxtaposed with some very high CAPE. This has caused the 3 km EHI to now max out at 10 ahead of the dryline in central AL at 7 pm Wednesday on the Euro... and a 1 km EHI as high as 6.
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That's pretty crazy to hear of those changes in the EURO from one run to the next. It's not often that you'll see the EURO spit out such high EHI #'s. I'm not sure that even happens once for us in most severe seasons. Regardless, I'd like to see more GFS ensembles come around to increase confidence. There are still a fair amount that are far less bullish. Though, there's clearly a high ceiling for this system on a good many as well.
 
Sorry Fred, i should have payed more attention. With us having bad weather every few days i lose track of what days
we are having severe weather. Thank u for all that u do on here!
 
Taylor Campbell said:
That's pretty crazy to hear of those changes in the EURO from one run to the next. It's not often that you'll see the EURO spit out such high EHI #'s. I'm not sure that even happens once for us in most severe seasons. I'd like to see more GFS ensembles come around to increase confidence. There are still a fair amount that are far less bullish. But regardless there's clearly a high ceiling for this system.
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It really wasn't a big increase from one run to the next. The 12Z Euro had a 3 km EHI max of 9 in north central AL for the same timeframe.
 
Fred Gossage said:
It really wasn't a big increase from one run to the next. The 12Z Euro had a 3 km EHI max of 9 in north central AL for the same timeframe.
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I'm speaking more in terms of the 0-1km EHI. Earlier today you said it was at 4, but now at 6. I consider that a pretty significant increase.
 
I think it is a pretty good bet that there will be an outlook area on day 4!

Edit @3AM-Just checked my local forecast for Tues night and it say Partly Cloudy-SPC says marginal risk for severe LOL things changing too fast for even NWS to keep up!
 
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6z NAM is hands down the strongest environment I've seen in years for AL/MS. Sbcapes close to 4000 by 18z Wednesday with a very deep boundary layer and strong EML overtop. Even with the windfields the NAM gives you still have helicity values around 300 and STP close to 5. Knowing the NAM at this range, that isn't good.
 
Dang! We all of course made the day 4 SPC Outlook--with possibillity of upgrade! I could see somebody under a tornado warning for the 4-3 event but in their safe place while looking at the models for this event LOL
 
Fred Gossage said:
The 00Z Euro has managed to come in even more volatile than the previous run. There are greater height falls into the heart of the warm sector during peak heating... and the low-level jet continues to trend even more organized, wider, and stronger. Because of this, we're now talking about having 0-1 km SRH at face value this run of over 300 m2/s2 and 0-3 km SRH over 500 m2/s2 juxtaposed with some very high CAPE. This has caused the 3 km EHI to now max out at 10 ahead of the dryline in central AL at 7 pm Wednesday on the Euro... and a 1 km EHI as high as 6.
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Very scary Fred! EHI at 10 is in the extreme danger zone. I just hope and pray folks are alert and prepared.
 
wow the 6z nam just leaves you hanging at the end of the run...impressive EML and shear Wednesday early afternoon. Will be interesting to see if the NAM speeds up the front or if the GFS slows down. The nam looks more credible and is backed by the euro.
 
ARCC said:
6z NAM is hands down the strongest environment I've seen in years for AL/MS. Sbcapes close to 4000 by 18z Wednesday with a very deep boundary layer and strong EML overtop. Even with the windfields the NAM gives you still have helicity values around 300 and STP close to 5. Knowing the NAM at this range, that isn't good.
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We're seeing thermos to the level of 4/27 here. There is still too much run to run inconsistency with the GFS. If that falls in line with the Euro/UKMET/NAM, there is potential for long track, violent tornadoes as stated in the BMX AFD.

This should have EVERYONE'S attention.
 
Kory said:
We're seeing thermos to the level of 4/27 here. There is still too much run to run inconsistency with the GFS. If that falls in line with the Euro/UKMET/NAM, there is potential for long track, violent tornadoes as stated in the BMX AFD.

This should have EVERYONE'S attention.
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Haha you said it and I didn't have too. :P
 
I didn't realize that BMX already had it "Enhanced" risk with a confidence factor of 3. When was our last big outbreak or significant threat. I keep thinking 4/27-28/14, but that one fell flat for the most part.
 
ARCC said:
I didn't realize that BMX already had it "Enhanced" risk with a confidence factor of 3. When was our last big outbreak or significant threat. I keep thinking 4/27-28/14, but that one fell flat for the most part.
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I wouldn't say 4/28/14 fell flat. It turned out to be the 4th largest outbreak in AL history (23 tornadoes), but the potential on the third day (4/29) was limited due to the occluded nature of the trough and the stalled MCS. It could've been much worse, but it wasn't a slouch.

But the deep layer shear on 4/28/14 wasn't favorable for long track tornadoes. We had them cycling every 10-15 miles, which limited the strength. The deep layer shear here supports longer tracked supercells....
 
Kory said:
I wouldn't say 4/28/14 fell flat. It turned out to be the 4th largest outbreak in AL history (23 tornadoes), but the potential on the third day (4/29) was limited due to the occluded nature of the trough and the stalled MCS. It could've been much worse, but it wasn't a slouch.

But the deep layer shear on 4/28/14 wasn't favorable for long track tornadoes. We had them cycling every 10-15 miles, which limited the strength. The deep layer shear here supports longer tracked supercells....
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4/27 was a complete Forecasted Convective Amplification Deficiency outside of the mayflower/vilonia monster. When we're talking about a 3-day outbreak and only one of them is qualified as a non-Forecasted Convective Amplification Deficiency, I think we can safely call the event as a whole a Forecasted Convective Amplification Deficiency. It was literally 2 highs and a moderate.

Is it just me, or is the SPC day 4 outlook a bit east of most model guidance (outside of the GFS)?
 
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