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Severe Severe weather threat April 17-19

For Eastern NC, as the line approaches the Fv3 is also showing powerful 925mb winds, nearly 70kts just to the west of Wilson with widespread 55-60kts. Every global I've checked that I have sounding access to and every meso model all show the LLJ strengthening to 60-70kts over Eastern NC.

Fv3 925mb.jpg
 
HRRR shows broken line of supercells in south MS/AL where the hatched area for tornadoes are. going to be watching that area over night as well as central alabama for the pesky spin up tornadoes.
 
snowlover91 said:
For Eastern NC, as the line approaches the Fv3 is also showing powerful 925mb winds, nearly 70kts just to the west of Wilson with widespread 55-60kts. Every global I've checked that I have sounding access to and every meso model all show the LLJ strengthening to 60-70kts over Eastern NC.

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I’m not calling this a sting jet in anyways and these are 2 different things (sting jet on the backside of a bombing mid/high latitude storm), but it may be similar in ways, some mid level drying, some mixing of the winds to the sfc as the day progresses, strong winds at 925mb, any shower that taps into that could easily bring 40-60 mph winds to the sfc, very similar to a sting jet, I wonder with this system if your gonna be able to hear that roar above your head in eastern Nc/OBX
 
snowlover91 said:
For Eastern NC, as the line approaches the Fv3 is also showing powerful 925mb winds, nearly 70kts just to the west of Wilson with widespread 55-60kts. Every global I've checked that I have sounding access to and every meso model all show the LLJ strengthening to 60-70kts over Eastern NC.
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Yeah I cant really recall seeing that kind of wind speeds over head outside of tropical systems coming in lol....
 
Tornado warning near turkey creek, LA. Although i don't see rotation must have spun up and dissipated as quick as they pit out a warning.Screenshot_20190418-111616_RadarScope.jpg
 
Myfrotho704_ said:
I’m not calling this a sting jet in anyways and these are 2 different things (sting jet on the backside of a bombing mid/high latitude storm), but it may be similar in ways, some mid level drying, some mixing of the winds to the sfc as the day progresses, strong winds at 925mb, any shower that taps into that could easily bring 40-60 mph winds to the sfc, very similar to a sting jet, I wonder with this system if your gonna be able to hear that roar above your head in eastern Nc/OBX
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Yeah you have to wonder, if winds are 60-70kts only 1,000 feet above the ground that it shouldn't be that hard with any decent convection to mix some of that wind energy down to the surface in gusts. By the time it reaches the coast some models are showing 70-85kts 1,000 feet above the ground. One has to think that will mix to the ground more effectively in areas like the OBX, especially if any convection is involved. This is why I think the wind threat for areas in Eastern NC especially could be pretty high tomorrow. Certainly an interesting system, the last big wind event pulled the flashing off part of my house so I'm hoping I can escape this one without something else happening.
 
The hrrr even paints a potential tornado threat across upstate sc. don’t believe it but it handle the last event very accurately. So we will see


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Flurry said:
I think that's what a lot of these will be...Spin ups...Here one minute, gone the next...Gotta be on your toes
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Exactly there very pesky had a ef1 tornado hit near my college from the last event and only a severe thunderstorm warning was issued because it was so fast.
 
I know people say VBV doesn't have the impact people think it does on tornadogenesis but events like yesterday really make me doubt that. Wind fields just tore storms apart.

Whoever said that it would be like 4-26-16 made a great call. I chased that day and storms ahead of the line were just getting torn apart. I remember waiting on a cell in a good environment and that thing came NE on us, showing rotation and just fell apart by the time it reached our location.
 
snowlover91 said:
Eric, I noticed most models in soundings are showing winds in the 60kt range only 1,000 feet off the ground in portions of Eastern NC, some in the 65-70kt range. Apart from convection, is there a way to estimate how efficiently these winds could mix down to the surface in gusts? Here's an example sounding from the 3km NAM. Winds at 1,000 feet are right at 60kts but then at the surface they are sustained below 20kts. I would think in gusts 35-45mph could easily happen without the aid of any convection with a sounding like this?

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Winds at the surface vs 850 hPa just from boundary layer overturning can be in the ballpark of 80% of the top of the boundary layer (850 hPa). Obviously ignoring convection for a second, if there's a very sharp change in wind w/ height esp at the bottom of the BL, this estimation may be fraught w/ error and it may be a good idea to also analyze the mean wind in the BL. Even this sounding could support surface wind gusts of nearly 45-50 KT or so in the absence of any convection. I could definitely see the logic behind the SPC upgrading east-central NC to a MDT risk just for wind damage given what we're dealing w/
 
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Myfrotho704_ said:
I’m not calling this a sting jet in anyways and these are 2 different things (sting jet on the backside of a bombing mid/high latitude storm), but it may be similar in ways, some mid level drying, some mixing of the winds to the sfc as the day progresses, strong winds at 925mb, any shower that taps into that could easily bring 40-60 mph winds to the sfc, very similar to a sting jet, I wonder with this system if your gonna be able to hear that roar above your head in eastern Nc/OBX
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Given the spatial distribution of those winds and the type of convection we're going to be dealing w/ tomorrow, that really looks like projection of the rear-inflow jet from the ongoing QLCS onto the synoptic-scale flow regime.
 
Fwiw, the vast majority of the HREF members maintain & even reintensify the squall line as it enters central NC.

In fact all of the latest runs of each HREF member (NSSL, ARW, NMMB, HRRR, & 3km NAM) keep the squall line going into central NC which reinforces the idea that the large-scale conditions are favorable-very favorable for maintenance tomorrow.

cref_ps.ma.f03100.png
 
Rain Cold said:
Yeah, I don't see there being nothing. I don't see there being no severe storms. I'm kind of skeptical about a widespread event through central NC, though.
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Well, if it is anything like the past few years, it'll be a very isolated event with the severe storms. How often since the April 2011 outbreak have we had severe storm and tornado watches here, and talk of widespread storms, only for the storms to end up very isolated in nature?

Of course, this could end up different. Just have to wait and see. The models do look ominous.
 
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Forecast 500mb winds of around 105 KTS on the HREF tomorrow in GSO would be a record by a very wide margin for this time of the year & the latest in the year that 500mb winds > 100 KTS were observed, a true indication of how anomalous tomorrow's large-scale setup really is.


Screen Shot 2019-04-18 at 1.42.02 PM.png

500mb_mean.ma.f04500.png
 
Line that just crossed the MS River from LA is becoming more broken in nature

Edit: And right on que, more TOR Warnings in MS
 
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Webberweather53 said:
Winds at the surface vs 850 hPa just from boundary layer overturning can be in the ballpark of 80% of the top of the boundary layer (850 hPa). Obviously ignoring convection for a second, if there's a very sharp change in wind w/ height esp at the bottom of the BL, this estimation may be fraught w/ error and it may be a good idea to also analyze the mean wind in the BL. Even this sounding could support surface wind gusts of nearly 45-50 KT or so in the absence of any convection. I could definitely see the logic behind the SPC upgrading east-central NC to a MDT risk just for wind damage given what we're dealing w/
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I was just about to ask if they ever go MDT with wind damage events or only if it's an increased Tor threat. Seems I remember usually, MDT was for tor threat but then again as you/others have pointed out this is a very anomalous system with tons of wind energy potential.
 
metwannabe said:
I was just about to ask if they ever go MDT with wind damage events or only if it's an increased Tor threat. Seems I remember usually, MDT was for tor threat but then again as you/others have pointed out this is a very anomalous system with tons of wind energy potential.
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I don't think they will go with a moderate unless it seems the tornado prospects will increase. If they do upgrade it would probably be the day of based on what current obs/heating looks like as well as convection evolution. IF we get a good deal of CAPE to work with Friday I could see them going moderate with the noon update. The HRRR and 3km NAM runs tonight into tomorrow AM will be pretty important. My biggest concern is the powerful LLJ being modeled, every single model has it and I wouldn't be surprised if we see some gusts nearing 50mph apart from convection and maybe 60mph along the coast. It's going to be a rough Friday I'm afraid.
 
I feel bad for south alabama later because the HRRR shows it even more broke up than it is now. Screenshot_20190418-143347_Samsung Internet.jpgScreenshot_20190418-143407_Samsung Internet.jpg
 
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