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Severe Severe weather threat April 17-19

Thinking it'd be possible to chase two areas within a quick drive: Around Ennis, TX and in the RR Valley near Durant. Tight window though.
 
Stp is very high across the gulf coast, could see a strong tornado or two if a cell becomes semi-isolated. Damaging wind from a squall line or bow echo's also look plausible. PDS sounding from mobile county 2019041618_NAMNST_059_30.64,-87.34_severe_ml.png
 
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Zander98al said:
Stp is very high across the gulf coast, could see a strong tornado or two if a cell becomes semi-isolated. Damaging wind from a squall line or bow echo's also look plausible. PDS sounding from mobile county View attachment 19091
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This sounding has some* VBV, I’m not really decided on that subject as there’s some proof that it doesn’t do much but some proof that it can, IDK lol, but the nam 3km has very messy storms modes right here, more of a QLCS, still need watch for any storm that can manage to fire out ahead the line
 
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Myfrotho704_ said:
This sounding has lots of VBV, I’m not really decided on that subject as there’s some proof that it doesn’t do much but some proof that it can, IDK lol, but the nam 3km has very messy storms modes right here, more of a QLCS, still need watch for any storm that can manage to fire out ahead the line
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Fwiw, this LR NAM sounding near Charlotte Friday night is just insane lol. Convection fires right underneath the surface low which tracks up the I-85 corridor leading to a very favorable environment for tornadoes. ???

Obviously long ways to go w/ this event and wind is most likely gonna end up being the primary threat but still if the surface low forms east of the mountains and backs the surface winds, then we could be in bad shape.

nam_2019041618_081_35.14--80.68 (1).png
 
Webberweather53 said:
Fwiw, this LR NAM sounding near Charlotte Friday night is just insane lol. Convection fires right underneath the surface low which tracks up the I-85 corridor leading to a very favorable environment for tornadoes. ???

Obviously long ways to go w/ this event and wind is most likely gonna end up being the primary threat but still if the surface low forms east of the mountains and backs the surface winds, then we could be in bad shape.

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Yeah I was just looking at that, a lot of SFC winds coming from the SE in parts of NC, worried already lol, sweetgum in my backyard has been making a weird sound and it’s root system is exposed, last thing it needs is damaging windsECEFCB70-92FD-4516-BE67-2DDD5985F5B2.png
 
This can’t be good.

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BHS1975 said:
This can’t be good.

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Yeah just looking at the nam sim reflectivity it has all kinds of things going on friday. Starts with a few shallow rotating cells early in the day with the S flow off the atlantic to a couple of isolated supercells in early to mid afternoon to the main show in the evening. Then Saturday looks like one of those days with scattered showers and a few thunderstorms around that produce a lot of small hail

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long range HRRR has a lone supercell in a environment by itself tomorrow. In a pretty high STP zone. If
a supercell or two gets by itself might produce a strong tornado over texas
HRRRSE_prec_radar_026.png
 
So, why hasn't the title of the thread been changed? This looks like more than a one day threat.
 
Our threat for severe in GSP area, is going down due to the timing of the frontal passage being in the morning, per local mets, rainfall not looking that heavy either. Widespread.5 or less.
 
Reading mhx it doesnt sound like its gonna take much to get those LLJ winds to the surface. It sounds like it's a situation where the stronger the shower or storm the worse the wind but any shower or storm will get the winds down.
 
metwannabe said:
Already SPC has enhanced for Friday.... oh boy
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Lol the NAM 3km near CLT, gets a hail threat mixed in there aswell, wind whipped hail ?! Also has little backing of SFC winds from the SE aswell, promoting a tornado threat, that high PWAT is gonna help drag down stronger winds from that LLvL jet 559149F7-1F08-4594-9047-2A6782360F44.png
 
Thanks for the thread title change. This might be the biggest threat for NC since the April 2011 tornado outbreak.

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Sounds like some meteorologists here in alabama are worried about convection forming ahead of the line. Wbrc fox 6 put a moderate risk for tornadoes and big area of alabama is in spc enchanced area. Itll probably be mostly embedded supercells and some spins ups although spc has a hatched significant severe threat in west alabama.
 
Spc has 10% tornado risk with chance of significant tornadoes. As well as 30% wind damage with possible significant wind damage.Screenshot_20190417-073904_Samsung Internet.jpg
 
We had better hope the 3km NAM is wrong with it's depictions of dewpoints in the upper 60s to 70 across the Carolinas and CAPE of 2,000-3,000 across most of the area in advance of the best dynamics or else there will be a nasty severe weather outbreak of wind and tornadoes. The SIM radar at hour 60 shows individual supercells popping up in the areas with solid instability and a line also appears to be forming a bit further to the west. This could easily be a scenario where supercells pop in front and then a line of strong winds moves through with the best dynamics and shear later in the afternoon/evening hours.

CAPE at 18z Friday

3km.jpg

SIM radar 18z Friday

3km sim radar.jpg
 
NoSnowATL said:
Has the threat in Georgia diminished due to the arrival time over night?


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For now I would say so, the 3km NAM has the storms weakening quite a bit by the time they make it to Georgia... But with all the dynamics involved I would still watch this one as the line could hold together better than it's showing. It appears though the highest threats will be west and east of Georgia. The Carolinas and Louisiana/MS/AL look like the target areas right now.
 
snowlover91 said:
We had better hope the 3km NAM is wrong with it's depictions of dewpoints in the upper 60s to 70 across the Carolinas and CAPE of 2,000-3,000 across most of the area in advance of the best dynamics or else there will be a nasty severe weather outbreak of wind and tornadoes. The SIM radar at hour 60 shows individual supercells popping up in the areas with solid instability and a line also appears to be forming a bit further to the west. This could easily be a scenario where supercells pop in front and then a line of strong winds moves through with the best dynamics and shear later in the afternoon/evening hours.
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SPC write up had a interesting tid bit....

...Synopsis and Discussion...
Deep upper trough extending along the MS Valley early Friday morning
is expected to continue eastward, maturing into a well-formed
mid-latitude cyclone centered over the southern Appalachians by the
end of the period. Very strong flow aloft will exist throughout the
base of the upper trough, with the strongest flow developing within
its eastern periphery Friday afternoon and continuing into Saturday
morning. 500-mb flow could exceed 100 kt, which is near record
values across the Carolinas and into the mid-Atlantic based on SPC
sounding climatology. In contrast to these impressive dynamics,
overall thermodynamic environment will be marginal. Given that ample
low-level moisture will be in place (i.e. dewpoints in the mid 60s
to low 70s and 100-mb mean mixing ratios over 12 g/kg), the modest
instability is largely a result of warm temperatures aloft and
consequent poor lapse rates.
 
snowlover91 said:
We had better hope the 3km NAM is wrong with it's depictions of dewpoints in the upper 60s to 70 across the Carolinas and CAPE of 2,000-3,000 across most of the area in advance of the best dynamics or else there will be a nasty severe weather outbreak of wind and tornadoes. The SIM radar at hour 60 shows individual supercells popping up in the areas with solid instability and a line also appears to be forming a bit further to the west. This could easily be a scenario where supercells pop in front and then a line of strong winds moves through with the best dynamics and shear later in the afternoon/evening hours.

CAPE at 18z Friday

View attachment 19108

SIM radar 18z Friday

View attachment 19107
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It's hard for me to buy the NAM's long range stability predictions. I have seen them bust high so many times. That said, the dynamic nature of the system and the wind energy upstairs raises the concern level. We'll have to see how things are looking from a completely overcast vs. broken sky standpoint as we near Friday. That will likely be the difference between spotty to numerous severe weather reports and a widespread outbreak.
 
snowlover91 said:
For now I would say so, the 3km NAM has the storms weakening quite a bit by the time they make it to Georgia... But with all the dynamics involved I would still watch this one as the line could hold together better than it's showing. It appears though the highest threats will be west and east of Georgia. The Carolinas and Louisiana/MS/AL look like the target areas right now.
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But wont this be occurring tomorrow night for AL which would diminish the threat ?
 
SoutheastRidge said:
But wont this be occurring tomorrow night for AL which would diminish the threat ?
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The storms would likely be moving through in the evening hours to early overnight which will allow them to still hold together especially with the dynamics involved. As you get further east into Georgia the models are indicating the storms moving through at the most stable time of the night, the 2-8am period so that's why the threat there will likely be lower. Still could change though and it all depends on how quickly this storm ramps up and where.
 
Rain Cold said:
It's hard for me to buy the NAM's long range stability predictions. I have seen them bust high so many times. That said, the dynamic nature of the system and the wind energy upstairs raises the concern level. We'll have to see how things are looking from a completely overcast vs. broken sky standpoint as we near Friday. That will likely be the difference between spotty to numerous severe weather reports and a widespread outbreak.
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Yeah it seems a bit high to me but I noticed that the GFS and other globals are showing high temps Friday in the upper 70s to near 80, the main difference being the GFS and some other models have dewpoints in the 63-66 range whereas the NAM is 67-72. That can make a big difference this time of year when temps are in the 70s. We'd better hope the NAM is wrong with the instability it's showing or else it is going to be a VERY active day Friday across our area. Even the weaker instability of the GFS and other models would pose issues due to the strong LLJ and 925mb winds of 50-60kts across Central and Eastern NC.
 
Downeastnc said:
SPC write up had a interesting tid bit....

...Synopsis and Discussion...
Deep upper trough extending along the MS Valley early Friday morning
is expected to continue eastward, maturing into a well-formed
mid-latitude cyclone centered over the southern Appalachians by the
end of the period. Very strong flow aloft will exist throughout the
base of the upper trough, with the strongest flow developing within
its eastern periphery Friday afternoon and continuing into Saturday
morning. 500-mb flow could exceed 100 kt, which is near record
values across the Carolinas and into the mid-Atlantic based on SPC
sounding climatology. In contrast to these impressive dynamics,
overall thermodynamic environment will be marginal. Given that ample
low-level moisture will be in place (i.e. dewpoints in the mid 60s
to low 70s and 100-mb mean mixing ratios over 12 g/kg), the modest
instability is largely a result of warm temperatures aloft and
consequent poor lapse rates.
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And they are banking on weak instability. If the instability turns out to be higher than they are thinking that will just add more fuel to the fire here.
 
snowlover91 said:
And they are banking on weak instability. If the instability turns out to be higher than they are thinking that will just add more fuel to the fire here.
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Any SE surface winds combined with what the NAM shows ( 2000-3000 jkg ) is dangerous, tornado threat hinges on whether SFC winds can manage to back from the SE
 
snowlover91 said:
Latest 3km NAM has a broken line segment and multiple individual cells across parts of GA and the Carolinas.
View attachment 19117
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Soundings supports tornadoes all over central NC with sfc winds coming out of the SE, there is VBV in this sounding but I’m honestly ignoring it, this sounding anyways supports damaging winds with dry air aloft between 850 hPa and 500 hPa and decent PWAT which would allow for water loading, and plus that LLVL jet, this sounding anyways supports more low topped convection
B7A529E1-1E28-42BF-A0A1-CF11EC16A498.png
 
Myfrotho704_ said:
Soundings supports tornadoes all over central NC with sfc winds coming out of the SE, there is VBV in this sounding but I’m honestly ignoring it, this sounding anyways supports damaging winds with dry air aloft between 850 hPa and 500 hPa and decent PWAT which would allow for water loading, and plus that LLVL jet, this sounding anyways supports more low topped convection
View attachment 19118
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Yeah I think the main deal with this system is going to be damaging winds, especially if a line forms they could be pretty widespread with the LLJ forecast. Any cells that can develop ahead of the main line will be the ones to watch for a supercellular structure and possible tornadoes. A lot will depend on the position of our system and how quickly it cranks up, right now the LLJ really explodes just offshore. If it cranks up a bit faster than that would be even worse.
 
And the preceding shortwave ridge should keep clouds at bay longer.


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GFS sounding for Eastern NC in the band of enhanced 850mb winds. Not much instability but look at the winds... 60kts at only 1,000 feet above the ground. It sure won't take much to get that to the surface even in gusts with some of these storms.

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Rain Cold said:
It's amazing the NAM and GFS are always so different with their CAPE depictions. NAM seems to always be so much higher. I guess it's just the same as it is in winter...crappy.
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Normally in between happens, GFS underdoes CAPE sometimes by a 1000 jkg while the nam will spit out to much (500-1000jkg more than verification)
 
Beginning to worry a little about south MS/AL tommorow STP is extreme. And simulated radar shows supercells ahead of the line. Screenshot_20190417-115717_Samsung Internet.jpgScreenshot_20190417-115702_Samsung Internet.jpg
 
May end up like a bust like last event but if it isn't the environment is very volatile tomorrow. No wonder spc has a significant hatched area for tornadoes tomorrow.
 
Myfrotho704_ said:
Normally in between happens, GFS underdoes CAPE sometimes by a 1000 jkg while the nam will spit out to much (500-1000jkg more than verification)
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Yeah, that's true. I'd probably lean closer to the GFS than the NAM. In this case, warmer air aloft and cloud cover should save us. The dynamics are going to be very good, and some decent wind should mix down. But I am still on the fence about a widespread, long-duration severe wind event. Heavy rain is almost certain, and I imagine even sub-severe winds will be able to more efficiently bring down trees, given the soil conditions.
 
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