TornadoFan
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Svr Wx threat April 1-April 2 2024
- Thread starter KevinH
- Start date
TornadoFan
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Latest HRRR run.
KevinH
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SPC expands ENH risk further south
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Tue Apr 02 2024
Valid 021630Z - 031200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR CENTRAL/EASTERN KY...SOUTHEAST IN...SOUTHERN OH...AND FAR WESTERN WV...
...SUMMARY...
A severe weather outbreak is possible through this evening over the Ohio Valley with the broader severe weather risk including parts of the Southeast. Strong and potentially long-track tornadoes are possible from Indiana and Ohio southward into the Mid South. A threat for strong tornadoes may focus this evening into tonight across parts of Alabama and Georgia.
...OH/TN Valley area through this evening...
Complex scenario late this morning with ongoing convection across WV, trailing outflow to the west across KY, and another cluster of storms moving into the trailing outflow zone across TN/KY. The lead storms have produced damaging winds (up to 92 mph measured), though this line of storms should weaken near or just after midday as it encounters the remnant cool air wedge close to the WV/VA border.
The storms farther west will move along the remnant outflow zone, where surface temperatures are in the low-mid 70s with dewpoints of 65-70 F. A couple of the storms will likely become persistent supercells capable of producing tornadoes (some of which could be strong/EF2-3) given the already strong wind profiles/long hodographs with effective SRH of 200-300 m2/s2.
Uncertainty is relatively high for areas north of the ongoing TN-KY-WV convection. The storms approaching middle TN and southern KY will tend to reinforce the earlier outflow, which will likely interfere with/limit destabilization this afternoon toward parts of OH (especially eastern OH). The corridor of richer low-level moisture from northeast AR into southeast MO (immediately west of the TN storms) suggests that air mass recovery will occur toward southern IL and southern/central IN by late morning into early afternoon, and southwest OH this afternoon. Strong deep-layer shear/long hodographs associated with an amplifying midlevel trough/jet and a deepening surface cyclone will support the potential for fast-moving supercells capable of all severe hazards, including strong tornadoes where sufficient low-level warming/moistening occurs in the wake of the morning convection. As previously mentioned, the northeastern extent of the primary severe threat into OH is more uncertain given the ongoing convection to the south, but will trim the northeast edge of the MDT risk area and expand south some to account for the outflow corridor enhancing the tornado threat on the mesoscale across KY.
...Eastern AL/western GA overnight...
In response to the amplifying midlevel trough/deepening cyclone over the MS/OH Valleys, deep-layer flow and low-level moisture advection will increase tonight across AL/GA. A surge of upper 60s boundary-layer dewpoints and strengthening low-level shear both appear supportive of supercells/tornadoes overnight in a broken band ahead of the synoptic cold front. An isolated strong tornado or two will be possible.
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Tue Apr 02 2024
Valid 021630Z - 031200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR CENTRAL/EASTERN KY...SOUTHEAST IN...SOUTHERN OH...AND FAR WESTERN WV...
...SUMMARY...
A severe weather outbreak is possible through this evening over the Ohio Valley with the broader severe weather risk including parts of the Southeast. Strong and potentially long-track tornadoes are possible from Indiana and Ohio southward into the Mid South. A threat for strong tornadoes may focus this evening into tonight across parts of Alabama and Georgia.
...OH/TN Valley area through this evening...
Complex scenario late this morning with ongoing convection across WV, trailing outflow to the west across KY, and another cluster of storms moving into the trailing outflow zone across TN/KY. The lead storms have produced damaging winds (up to 92 mph measured), though this line of storms should weaken near or just after midday as it encounters the remnant cool air wedge close to the WV/VA border.
The storms farther west will move along the remnant outflow zone, where surface temperatures are in the low-mid 70s with dewpoints of 65-70 F. A couple of the storms will likely become persistent supercells capable of producing tornadoes (some of which could be strong/EF2-3) given the already strong wind profiles/long hodographs with effective SRH of 200-300 m2/s2.
Uncertainty is relatively high for areas north of the ongoing TN-KY-WV convection. The storms approaching middle TN and southern KY will tend to reinforce the earlier outflow, which will likely interfere with/limit destabilization this afternoon toward parts of OH (especially eastern OH). The corridor of richer low-level moisture from northeast AR into southeast MO (immediately west of the TN storms) suggests that air mass recovery will occur toward southern IL and southern/central IN by late morning into early afternoon, and southwest OH this afternoon. Strong deep-layer shear/long hodographs associated with an amplifying midlevel trough/jet and a deepening surface cyclone will support the potential for fast-moving supercells capable of all severe hazards, including strong tornadoes where sufficient low-level warming/moistening occurs in the wake of the morning convection. As previously mentioned, the northeastern extent of the primary severe threat into OH is more uncertain given the ongoing convection to the south, but will trim the northeast edge of the MDT risk area and expand south some to account for the outflow corridor enhancing the tornado threat on the mesoscale across KY.
...Eastern AL/western GA overnight...
In response to the amplifying midlevel trough/deepening cyclone over the MS/OH Valleys, deep-layer flow and low-level moisture advection will increase tonight across AL/GA. A surge of upper 60s boundary-layer dewpoints and strengthening low-level shear both appear supportive of supercells/tornadoes overnight in a broken band ahead of the synoptic cold front. An isolated strong tornado or two will be possible.
Last edited:
TornadoFan
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The MDT risk was also expanded further into Kentucky.
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After this convection in IN and KY passes through the risk area, there's a large clearing where the air is warming and moistening.
OhOkayThen
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A lot more clearing than I anticipated going on in Southern Illinois and Western Kentucky.
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Exactly. There's a strong recovery behind this convection.
Even if the the warm front doesn’t make it as far north into Ohio as originally thought, I think the southern half of the state could still very much be in play. Could be one of those threats that hugs the OH/KY border. If that’s how it pans out, it could spell bad new for the Cincy metro, which spills way farther south into northern Kentucky than I think most people realize.
wx_guy
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Interesting. So looking at the latest SREF (9z, the 15z should be coming out shortly), there are some intriguing insights:
So the ingredients that get factored into the "Significant Tornadoes Ingredients" measure are ML CAPE, ML LCL, 0-1 km Helicity, 0-6 km Shear, and 3-hour probability of 0.01 in of precipitation.
For ML CAPE, there is a small (6-ish hours) window of 70% chances of > 500 ML CAPE in the Ohio MDT risk, but much larger CAPE chances further south:
For the ML LCL, the Significant Tornadoes Ingredients looks for the probabilities of it being lower than 1.5 km...this is basically 100% across the entire area.
For 0-1 km Helicity, at 21z today (the time I'm looking at), it is near 100% chances in the Ohio/Kentucky areas, and it becomes ~100% in the Alabama area in the following hours.
For 0-6 km Shear, it is also nearly maxed out at 100% for being over 40 knots:
For the final ingredient - precipitation -- this is maxed near 100% chances of 0.01 in or more in 3 hours in the Ohio/Kentucky area and subsequently maxes over AL/GA at near 100% later in the evening. (Here it looks linear, but in subsequent frames, it becomes a large area over AL/GA).
So....it looks like the Southern area has near-primed ingredients for Significant Tornadoes (based solely on the index/algorithm), and the Ohio/Kentucky area has great parameters for significant tornadoes as well -- but it's more iffy on the ML CAPE at 70%...if the CAPE doesn't get high enough, you may not see SIG tornadoes.
Definitely a high ceiling for whatever can occur! I'd be remiss not to show the results, the actual significant tornado ingredients index. I'll show first at 21z and then a little later in the South:
So the ingredients that get factored into the "Significant Tornadoes Ingredients" measure are ML CAPE, ML LCL, 0-1 km Helicity, 0-6 km Shear, and 3-hour probability of 0.01 in of precipitation.
For ML CAPE, there is a small (6-ish hours) window of 70% chances of > 500 ML CAPE in the Ohio MDT risk, but much larger CAPE chances further south:
For the ML LCL, the Significant Tornadoes Ingredients looks for the probabilities of it being lower than 1.5 km...this is basically 100% across the entire area.
For 0-1 km Helicity, at 21z today (the time I'm looking at), it is near 100% chances in the Ohio/Kentucky areas, and it becomes ~100% in the Alabama area in the following hours.
For 0-6 km Shear, it is also nearly maxed out at 100% for being over 40 knots:
For the final ingredient - precipitation -- this is maxed near 100% chances of 0.01 in or more in 3 hours in the Ohio/Kentucky area and subsequently maxes over AL/GA at near 100% later in the evening. (Here it looks linear, but in subsequent frames, it becomes a large area over AL/GA).
So....it looks like the Southern area has near-primed ingredients for Significant Tornadoes (based solely on the index/algorithm), and the Ohio/Kentucky area has great parameters for significant tornadoes as well -- but it's more iffy on the ML CAPE at 70%...if the CAPE doesn't get high enough, you may not see SIG tornadoes.
Definitely a high ceiling for whatever can occur! I'd be remiss not to show the results, the actual significant tornado ingredients index. I'll show first at 21z and then a little later in the South:
KevinH
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Well damn!
Any lurkers out there please join the forum. The more ground truth the better!
HazardousWx
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Lurking and waiting to see what we get later. Edit: See we lost all the member data. I joined in 2002 and had a lot more messages than the number listed.
Tomcats Forever!
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Yeah, I think I read a timing product wrong.
Tempestas Tonitrua
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Got a couple of smaller storms firing up west of Paducah tracking into Illinois
TornadoFan
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Yes! They see it. It's 70 degree with a dew in the mid to upper 60s in this area.
TornadoFan
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Yeesh.
Austin Dawg
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Thank you guys for all the information we're getting. I'm gonna be in and out going to my doctor this afternoon but I will check back in as soon as I return I have a feeling it's gonna be an active afternoon into the evening