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Severe Threat May 15-16, 2025

Grand Poo Bah said:
I think they're doing decent because

1. SPC forecasts are more for local meteorologists than regular citizens, and the messaging has been pretty detailed about the current level of uncertainty and potential ceiling. It's up to the local mets to communicate the range of possible outcomes to their regions.

2. Once the SPC is locked into a higher risk forecast, it's impossible to dial it back. It was pretty clear to meteorologists 24 hours before the April 27th event that nothing too serious was going to materialize in a large portion of the hatched area, but they had already communicated the 15-30% hatched risk.

Even finding a way to communicate the floor and ceiling of events would be tough, because sometimes even when conditions end up being perfect, something unforeseen stops it from reaching its true potential. The SPC has an impossible job because any amount of over confidence can erode public confidence when it doesn't pan out. I expect they'll upgrade the risk area even more if things keep trending more confidently in a bad direction. They still have two more updates before things kick off.
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Right, but that's exactly my point. Currently the SPC has no way of factoring in highly conditional threats where the outcome is likely to be a high-end event, or nothing.

The forecasters have to work within this framework and do the best they can. I'm suggesting the framework is flawed and should be revisited for these types of setups.
 
lake.effect said:
Right, but that's exactly my point. Currently the SPC has no way of factoring in highly conditional threats where the outcome is likely to be a high-end event, or nothing.

The forecasters have to work within this framework and do the best they can. I'm suggesting the framework is flawed and should be revisited for these types of setups.
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Who going to tell them their method is wrong.
 
I like the 12z RRFS and 18z RRFS for Saturday morning. Severe line of storms moving thru North MS between roughly 5am thru 7am Saturday morning. We'll see what the 00z HRRR has. Both RRFS runs further hint at redevelopment late Saturday afternoon/evening which I can't disagreed with, but it depends on what the early morning round does.
 

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UncleJuJu98 said:
I'm just gonna take a gamble and say the RAP is being wonky lol. Also has 3km EHI of 10-11 over Mississippi.
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Looked at 21Z RAP and spit out my drink. Likewise, NAM 3km shows a very concerning parameter space out ahead of a nasty MCS making its way southward through TN into AL/GA/MS. Wanna see more consistency on this as the time frame gets a little better in-range on the CAMs, but it certainly gives me cause for concern. The presence of a weakening cap out ahead of the MCS could also allow for storms to retain greater intensity.
CODNEXLAB-FORECAST-2025051421-RAP-SE-con-3kmehi-33-51-100.gifCODNEXLAB-FORECAST-2025051418-NAMNST-SE-prec-radar-36-60-100.gif
 
Clancy said:
Looked at 21Z RAP and spit out my drink. Likewise, NAM 3km shows a very concerning parameter space out ahead of a nasty MCS making its way southward through TN into AL/GA/MS. Wanna see more consistency on this as the time frame gets a little better in-range on the CAMs, but it certainly gives me cause for concern. The presence of a weakening cap out ahead of the MCS could also allow for storms to retain greater intensity.
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Eagerly awaiting 00z HRRR lol
 
lake.effect said:
Right, but that's exactly my point. Currently the SPC has no way of factoring in highly conditional threats where the outcome is likely to be a high-end event, or nothing.

The forecasters have to work within this framework and do the best they can. I'm suggesting the framework is flawed and should be revisited for these types of setups.
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I think it's safe to assume that this is one of those events where if the SPC could initiate that 5% hatched for tornadoes, they definitely would.
 
00Z HRRR continues to show the cap breaking and ILX/IWX getting storms. However, this time it forms into a semi-organized line of storms that sweeps this. The question now I believe comes down to, will this be a broken line of supercells, or will it turn into a semi-organized line? I think both are on the table due to CIN numbers around ILX/IWX being -10 to -30, some even being lower. If this turns into a broken line of supercells, obviously the threat turns to tornadoes (including significant) and very large hail (baseballs plus). Obviously if it's a line, we're talking mainly large hail, damaging winds, and embedded tornadoes due to shear numbers being around 40 - 50 knots. Obviously that drops the significant tornado risk.

I wouldn't be surprised if the SPC moves the 10% hatched down south into ILX/IWX for a conditional threat of tornadoes (some strong). However, I also wouldn't be surprised if they stuck with the 5%.
 
US_Highway15 said:
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Took this sounding from the north central IN/MI border. NAMNST is only the model that really pays respect to tomorrow's ingredients and has the cap breaking (although that's the usual I feel like from the model). Although I would vew this as the *worst case scenario* (peep the Moore 1999 tornado analog). In all, HRRR/NAM/GFS/RAP kind of just laugh tomorrow off and have the cap remain in place.

I'm going to be honest, I kind of give the IWX area a 20-30% of anything occuring. I'm with the NWS IWX MET's on this event in terms of confidence.
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i see one glaring issue with this sounding
 
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