tennessee storm
Member
I want a very strong derecho....
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Pattern April Chasing ???⛈⛈⛈
- Thread starter TheBatman
- Start date
I’ll take a order of multicellular clusters developing off the lee side of the mountains and producing some insane shelf clouds as they travel SE
Webberweather53
Meteorologist
Wasn't entirely sure whether to post this in the main forum or here, but I've been working on this for a while in python.
This is a northern hemisphere 500 hPa anomaly composite of nearly 700 days for approximately four hundred winter storms (including both big & small events alike) that's struck NC since 1948. The -NAO stands out like a sore thumb, the -EPO is also fairly obvious. The +PNA is definitely there, just not the way many imagined, with near normal heights on the west coast and below avg z500 on the E coast = +PNA. We also have a slight, but non-negligible +WPO.
Neat.
This is a northern hemisphere 500 hPa anomaly composite of nearly 700 days for approximately four hundred winter storms (including both big & small events alike) that's struck NC since 1948. The -NAO stands out like a sore thumb, the -EPO is also fairly obvious. The +PNA is definitely there, just not the way many imagined, with near normal heights on the west coast and below avg z500 on the E coast = +PNA. We also have a slight, but non-negligible +WPO.
Neat.
ForsythSnow
Moderator
Would there be data for other states as well? Just wondering since different setups favor different storms for each part of the SE. Also, does this data cover for widespread winter storms or if the storm hits just one part of the state?
Webberweather53
Meteorologist
Something like that could definitely be done, as long as I have a list of dates to put into this composite it could work. I'm sure @GaWx would be the ticket for something like this. I also plan to divide this composite into Miller A, Miller B, and Hybrid/Overrunning cases, I generally have a feel for what they may look like based on the daily EPO, WPO, NAO, and PNA data from ESRL I've standardized. As for the composite, I included all storms that produced at least 0.1" or more of snow/sleet accumulation at either Charlotte, Raleigh, Greensboro, Wilmington, or Elizabeth City &/or were featured in a case study by myself, NWS RAH, or the NC State Climate Office. I binned just for larger storms (i.e. those that produced at least 4" of snow (NWS RAH winter storm warning criteria) or more at the aforementioned locations in NC or at least 0.1
at all the locations) and didn't note that much of a difference in the EPO, WPO, PNA, & NAO indices
+PNA has a higher correlation to cold further south of NC with highest correlation in the deep SE/FL. Also, since 1950, +PNA has been more frequent for major snow at Atlanta than -NAO as I’ve shown here.
This is neat. The NAO turns out as I expected, as does the EPO. The PNA ridge is farther west than I would have expected, but it kind of makes sense. My guess is that a strong PNA ridge farther east would probably influence the storm track farther south and east, keeping NC on the dry side of things.
Wow, very interesting. i don't know if python is some weather thing, or, i assume maybe you are using the python language to code this, but, either way, this seems to be the key to taking predictions to the next level. IE big data, AI, etc. I feel that increasingly now, we will be able to crunch an unfathomable amount of data and things are going to start sticking out. And using an amount of computation that would not have been possible even a few years back. But, the key is going to be people like yourself who know what to tell those systems to go off and compute on. I thought i heard about IBM using big data for weather, but, i just don't trust those big companies, I think it has to come from people like you. Anyway, not always sure what you are talking about, but I like the way you think.
Niceeee, this could be useful af when we get some sort of possibly next DJFM, the -EPO is a piece of the puzzle here in NC, but as we know we have lacked the -NAO, no wonder the storms we get is messy af as in snow/sleet/ZR/rain, maybe sometime we can get a -NAO to last a few weeks at least instead of big anticyclonic highs phasing through it in the matter of a day/few days, lol, also one reason why the PNA May be weak is due to the fact that sometimes the STJ undercuts it, making it more weakly + or neutral ?
Webberweather53
Meteorologist
Yeah a strong +PNA usually favors a colder/drier SE US.
Interestingly, when you look at storms that had only one favorable index (EPO, WPO, PNA, or NAO), the PNA was by itself the most frequently, about 50% of the time in fact when we had only one of the big four to rely on
Webberweather53
Meteorologist
To add to this, here's a lagged composite 3 weeks before and after the nearly 700 winter storm dates analyzed here.
The evolution overall is very interesting, a nice -NAO usually is present in the 1-2 weeks before big storms come knocking and conditions become stormy & cooler over the E US (likely helping to lay snow pack down to our north or even over us because many of these storms came in bunches). Near lag 0, a -EPO develops and a generally favorable pattern for wintry weather persists for a week or so thereafter, but it's eventually replaced by a -PNA at longer lags and the -NAO pattern progressively fades.
The color scale is the same for all images, I still haven't been able to get around to figuring out how to get the color bar to remain the same throughout.
(Nvm I eventually figured out the color bar issue)
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pcbjr
Member
You mean 92º with a 78% RH isn't your cup of tea ... at 8:00PM ... LOL ...
With you 110%, Larry ...
Webberweather53
Meteorologist
When I dissected the winter storms into "Miller B", "Hybrid/Anafrontal", & "Miller A" some interesting, yet generally anticipated results came about.
As I've always harped on here for the last few years, there are definitely distinct planetary-scale pattern differences between the two storm types, with Miller Bs often occurring in conjunction w/ big -EPO blocks and Miller A cyclones in NC favored w/ a predominant -NAO. These results are extremely significant, especially considering that both 500 hPa composites have about 200 days in them. Hybrid/Anafrontal type storms are essentially a blend of these two composites.
Unless there was an intra-hour high, 83*F looks to do it for today.
Notably more in the way of Cirrus clouds as well.
Notably more in the way of Cirrus clouds as well.
reached 84F here, this is waayyyyy better than thinking about a chance of snow that would possibly whiff, lol
pcbjr
Member
One thing you can count on ...
at least for months ...
another is, that 84º will seem like a cool day in about 45 to 60 from now ...
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Its a beautiful evening here. 69 and sunshine !
Ready to go fishing for some crappie tommorow, won’t be long before they start moving out over deeper parts of the water since water temps are rising
@BirdManDoomW
Hey Dude,
I would love your input on this study. I believe you're an untapped resource that is being underutilized. Thanks, in advance.
I guess we're screwed now since a -NAO does not exist in the winter anymore!To add to this, here's a lagged composite 3 weeks before and after the nearly 700 winter storm dates analyzed here.
The evolution overall is very interesting, a nice -NAO usually is present in the 1-2 weeks before big storms come knocking and conditions become stormy & cooler over the E US (likely helping to lay snow pack down to our north or even over us because many of these storms came in bunches). Near lag 0, a -EPO develops and a generally favorable pattern for wintry weather persists for a week or so thereafter, but it's eventually replaced by a -PNA at longer lags and the -NAO pattern progressively fades.
The color scale is the same for all images, I still haven't been able to get around to figuring out how to get the color bar to remain the same throughout.
(Nvm I eventually figured out the color bar issue)
pcbjr
Member
Being that I have been granted all the power in the world and beyond (LOL), I've unilaterally changed the name to -NAW ...
Carry on ...
I still say an official -NAO (as opposed to any Greenland block) prior to or during a MAJOR SE snow is overrated based on hard data from the last few decades, but I’ll save time and not list them this time. Regardless, it is good to be talking snow in late April. Looking forward to next winter!
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pcbjr
Member
NAWwww not yet; too early to be negative ... LOL
Another nice evening walk!
Snowflowxxl
Member
nice
Brent
Member
Seems like I'm missing quite the storm at home in Dallas
nam Shows a nasty multicellular cluster tommorow, soundings are supportive of it
Put out a second round of preemergent yesterday. Models go rainy friday. Win..... and then i look at the euro....nvm
Sent from my SM-G955U using Tapatalk
Sent from my SM-G955U using Tapatalk
Is it just me or did the NAM try to introduce the slightest chance of some severe here Friday? Correct me if I'm wrong but this sounding shows at the very least some downburst potential with that dry layer in the mid levels, even a curved hodo (of course it's the long range NAM so.....)
After a crisp 41 this morning, its warmed up to a comfortable 60.
That sucks! 82 here with a gentle breeze
Watch out for large chunks of ice falling from the sky.
Not the blue ice right?
B
Brick Tamland
Guest
I see SPC has gone marginal here now.... see how things progress over next day or 2
Hmmm...
...Carolinas through Virginia...
Models have converged on similar solutions regarding evolution of
synoptic environment. Southern-stream shortwave trough is forecast
to deamplify over the Carolinas and become absorbed within an
amplifying northern-stream trough. Moistening warm sector with
dewpoints in the low 60s F will advect inland resulting in marginal
instability, and storms may develop in warm sector as well as along
cold front as it advances eastward during the day. Strengthening
low-mid level winds will support sufficient vertical shear for
organized storms with damaging wind and a couple tornadoes the main
threats. A SLGT risk might eventually be needed over a portion of
this area, but due to lingering uncertainties regarding details of
the convective evolution, will introduce a MRGL risk category this
update.
Hmmm...
...Carolinas through Virginia...
Models have converged on similar solutions regarding evolution of
synoptic environment. Southern-stream shortwave trough is forecast
to deamplify over the Carolinas and become absorbed within an
amplifying northern-stream trough. Moistening warm sector with
dewpoints in the low 60s F will advect inland resulting in marginal
instability, and storms may develop in warm sector as well as along
cold front as it advances eastward during the day. Strengthening
low-mid level winds will support sufficient vertical shear for
organized storms with damaging wind and a couple tornadoes the main
threats. A SLGT risk might eventually be needed over a portion of
this area, but due to lingering uncertainties regarding details of
the convective evolution, will introduce a MRGL risk category this
update.
88 today...its hot
Sent from my SM-G955U using Tapatalk
Sent from my SM-G955U using Tapatalk
60 here with a light rain falling.
Z
Zander98al
Guest
18z nam showing a nasty setup for Thursday in alabama afternoon but the long range HRRR is in big disagreement. 
Today tied for the hottest day of the year, with a high of 85*F.