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Zander98al
Guest
The winde fields in those pictures are very high.
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4/11/20 - 4/13/20 Severe Weather Outbreak
- Thread starter Webberweather53
- Start date
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- Tags
- severe weather tornadoes
BHS1975
Member
All eyes are on the euro but I’m more concerned at the cmc and the gfs to a degree suggesting less than half inch of rain for NC. Maybe a developing drought/wildfire risk if only a few discrete broken supercells blast through. I was hoping for a washout like the euro shows but it still does not have much support as of 6z Tuesday guidance I just looked through .
Webberweather53
Meteorologist
The GFS is getting its butt handed to it on this upper trough over the southwestern US. Even inside 12-24 hours, it's been consistently verifying way too fast & progressive (surprise!) (notice the deeper blue (red) colors west (east) of the mean trough axis & green contours which indicates a statistically significant trend at that.
The GFS ensemble hasn't done much better.
The king is back!
The GFS ensemble hasn't done much better.
The king is back!
12z Icon for those interested. Definitely seems to be in the Euro camp.
12z GFS moving the surface low into prime position but continues with the idea of storms to the south. Gfs also is increasing instability in Alabama. So I would guess if You take those storms to the south away Alabama probably has some rough storms. ( I believe the gfs is the only one with storms to the south at this point)
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Zander98al
Guest
Any similar analogs to this upcoming severe threat in the southeast?
Webberweather53
Meteorologist
We're entering the most favorable phase (phase 8) of the Global Wind Oscillation (GWO), for tornadoes and tornado environments in the deep south, especially for Dixie Alley, this is consistent with the more recent NWP forecasts and growing consensus for severe next weekend.
Figure 5 from Gensini & Mariano (2015) Red shading = above normal sig tor parameter, stippling (harder to see)) denotes statistical significance & vis versa w/ blue. We're currently about to see a glimpse of the composite at the far bottom right.
Here's the current GWO forecast available via: https://atlas.niu.edu/gwo/
Each black box denotes forecast increments of 1 week in advance, thus the +7 in phase 8 corresponds to where the GWO is forecast to be a week from now when this potential bout of severe weather may be knocking on our doorsteps in the SE US
For a reminder/primer on what the GWO is (it's just Atmospheric Angular Momentum (AAM) + AAM tendency), I explained this in more detail here back in December: https://southernwx.com/community/threads/the-great-december-dump.650/page-120#post-221423
On a side note, I've always found it interesting how these seemingly random/stochastic subseasonal events like the MJO, whose e-folding scales are on the order of several weeks-few months, leaves its footprint in the global circulation pattern sometimes for months after it's long gone. This is a classic example of that. Here's a plot shared by Dr Ventrice of 200mb (tropopause/upper troposphere) zonal wind anomalies (red = positive >>> (anomalous) westerly winds, blue = negative >>> (anomalous) easterly winds). Notice the band of orange shading (positive AAM anomalies or anomalous westerly flow) starts out in the deep tropics in February. This +AAM/westerly flow was likely triggered by an MJO event coupling to the leftovers of an ongoing weak El Nino this winter, and watch how this anomaly persists and propagates poleward over a period of several weeks, eventually reaching us in the subtropics 2 months later to influence this upcoming bout of severe weather next week.
The residence time of these zonal wind anomalies in the context of the temporal scales of the phenomena that trigger them (i.e. I'm saying the zonal wind anomalies are persisting and potentially influencing the weather well beyond the lifespan of a typical MJO event) is truly fascinating to me and one of the big reasons why I've vested so much of my time and interest to studying climate dynamics and these poorly understood subseasonal phenomena.
Pretty neat huh?
Figure 5 from Gensini & Mariano (2015) Red shading = above normal sig tor parameter, stippling (harder to see)) denotes statistical significance & vis versa w/ blue. We're currently about to see a glimpse of the composite at the far bottom right.
Here's the current GWO forecast available via: https://atlas.niu.edu/gwo/
Each black box denotes forecast increments of 1 week in advance, thus the +7 in phase 8 corresponds to where the GWO is forecast to be a week from now when this potential bout of severe weather may be knocking on our doorsteps in the SE US
For a reminder/primer on what the GWO is (it's just Atmospheric Angular Momentum (AAM) + AAM tendency), I explained this in more detail here back in December: https://southernwx.com/community/threads/the-great-december-dump.650/page-120#post-221423
On a side note, I've always found it interesting how these seemingly random/stochastic subseasonal events like the MJO, whose e-folding scales are on the order of several weeks-few months, leaves its footprint in the global circulation pattern sometimes for months after it's long gone. This is a classic example of that. Here's a plot shared by Dr Ventrice of 200mb (tropopause/upper troposphere) zonal wind anomalies (red = positive >>> (anomalous) westerly winds, blue = negative >>> (anomalous) easterly winds). Notice the band of orange shading (positive AAM anomalies or anomalous westerly flow) starts out in the deep tropics in February. This +AAM/westerly flow was likely triggered by an MJO event coupling to the leftovers of an ongoing weak El Nino this winter, and watch how this anomaly persists and propagates poleward over a period of several weeks, eventually reaching us in the subtropics 2 months later to influence this upcoming bout of severe weather next week.
The residence time of these zonal wind anomalies in the context of the temporal scales of the phenomena that trigger them (i.e. I'm saying the zonal wind anomalies are persisting and potentially influencing the weather well beyond the lifespan of a typical MJO event) is truly fascinating to me and one of the big reasons why I've vested so much of my time and interest to studying climate dynamics and these poorly understood subseasonal phenomena.
Pretty neat huh?
Cadi40
Member
Perhaps it’s too early, but is it looking like this possible outbreak will not include N.C.?
Webberweather53
Meteorologist
Same ? different day.
The medium range GFS NW trend is finding more ways (& seasons) than one to screw us over. Instead of going from snow >>> cold rain, we trend from cold rain >>> severe.
Yay.
The medium range GFS NW trend is finding more ways (& seasons) than one to screw us over. Instead of going from snow >>> cold rain, we trend from cold rain >>> severe.
Yay.
Webberweather53
Meteorologist
Definitely not, at this stage anyone from the Gulf coast to TN & southern OH valley - mid-Atlantic is easily within the implied realm of error.
Just wondering but when was last time we had a big severe weather event occur on Easter? I can think of quite a few that have happened on Palm Sunday but I can’t think of one on Easter.
Is it too early to throw a gulf coast convection into the mix? Or us getting locked into a hybrid cad and pinning the warm front along I95. Good times
Webberweather53
Meteorologist
Webberweather53
Meteorologist
CIPS analog guidance day 5-7 all severe probabilities. Keep in mind that 15%+ (yellow shading) is equivalent to an SPC slight risk, 30%+ is the equivalent to at least an enhanced risk. This should give most an idea of what the general threat area is probably going to look like once it's outlined by the SPC. Anyone from Texas & Oklahoma to the Carolina is most likely to be impacted as it currently stands.
BHS1975
Member
I’m not all in with the euro. You can see on the icon some areas East of the foothills going into eastern NC will be hard pressed to see 1” of rain. Despite all the goofy red and orange severe colors moving in Monday morning. If there is bad timing (after midnight) I expect qpf could dry up even more with loss of heating. This could however bring the greatest threat to the mtns&foothills around or before midnight. Too soon for specifics but I’m rooting for a washout in what seems like a DRY pattern.
Webberweather53
Meteorologist
It definitely does, but it's also been an enemy, especially for those in the western piedmont (Charlotte- Greensboro) and is one major reason why there's a secondary maximum in tornado track densities near Charlotte & Winston-Salem.
Webberweather53
Meteorologist
Here comes another big Euro run, the 6th one in a row.
Sounding out of South-Central Mississippi in the early afternoon from the Euro.