Re: Fall Severe Weather Thread

by **Stovepipe** 2012-09-12, 8:29 am

Wow, that does look pretty wild. Bring it!

by **Toot** 2012-09-17, 6:44 pm

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Tropical like tornado threat

by **Stovepipe** 2012-09-17, 8:42 pm

by **Toot** 2012-09-17, 8:48 pm

Lmfao

by **tennessee storm09** 2012-09-26, 10:05 pm

guess as we get into october, thats normally our driest month of the year... so i expect it startiing quite and tranquill... hopefully towards end of october into november things will ramp up some... seen some nice outbreaks in novemeber before... guess i am just impatient for a big event near... i havent gotten a nice event since super tuesday 08.... when i got a good chase on a f4 just 10 miles from my house...

by **Toot** 2012-09-27, 4:32 pm

Starting to see a decent signal for a powerful storm system around the second week of October. This is based on GFS ensemble guidance... as many members show significant lowering of heights over a short period of time in the central and eastern parts of the US.

Of course the smaller scale details are still very unclear but I would watch this timeframe for something more organized in terms of severe weather.. along with the chance of a significant cold front!

The culprit for this change seems to be related to the EPO in the bigger picture.. as it quickly trends back to negative from positive territory. The EPO (Eastern Pacific Oscillation) currently seems to be in control of the longwave weather pattern over North America as the dominance of this feature is clearly seen in the data.

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by **Toot** 2012-09-28, 10:11 pm

The strong storm system I mentioned yesterday continues to stand out amongst guidance products. This system and its associated cold front will likely carry an organized severe weather threat in the eastern united states during the October 5-8th timeframe. It also looks like some locations may see the coldest air of the season in wake of this system!

The image below is taken from the latest run of the GFS valid for October 5th.

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by **Dyersburg Weather** 2012-09-28, 11:45 pm

Toot wrote:The strong storm system I mentioned yesterday continues to stand out amongst guidance products. This system and its associated cold front will likely carry an organized severe weather threat in the eastern united states during the October 5-8th timeframe. It also looks like some locations may see the coldest air of the season in wake of this system!

The image below is taken from the latest run of the GFS valid for October 5th.

I agree. Maybe this pattern will continue. This looks like a storm we would see in November.

by **tennessee storm09** 2012-09-30, 11:12 am

looks like this will be a pretty potent surface low riding across arkansas into western tennessee.... it should bring us abundant rains in the order of 2 to 4 inches with iso higher amounts... best chance for severe weather will remain well to our se. especially parts of alabama... were a iso tornado cant be ruled out. its a fairly dynamic system, but the lapse rates look weak at best to our se.

by **Toot** 2012-09-30, 12:00 pm

A well organized storm system is slated to drag a strong cold front through the eastern united states next weekend. The severe weather threat remains a concern as a shortwave troff begins to take on a negative tilt while deepening an already strong surface low. At this moment in time..the shaded areas below seem to have the best chance for severe weather.

After the cold front passes through.. a (Strong for October) cold advection regime will dominate for a couple of days with widespread low temperatures in the 30's and 40's... from the TN valley northward! Ready or not...colder weather is on the way and it may stick around a while this time!

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by **tennessee storm09** 2012-10-01, 7:05 pm

the 18z gfs has brought back my OHIO VALLEY SCREAMER my friends... the first part of the second week in october... the slp looks to be sub 1000 also, stay tuned

by **andyhb** 2012-10-01, 11:48 pm

Not seeing it.

by **tennessee storm09** 2012-10-02, 5:36 am

andyhb wrote:Not seeing it.

ozgfs did loose it... but i like the time frame for a system, larry cosgrove also spoke about that in his saturday nite newsletter... 13th to 15th october ..

by Vanster67 2012-10-02, 8:45 am

Well, I hope not as the wife and I are planning a trip to Horshoe Southern Indiana for a little fun!! Severe weather can hold until I get back! smartass

by **tennessee storm09** 2012-12-02, 5:52 pm

i am going to bring up a old thread... because the system around 10th11th december mite just be a legit threat... deep trough diggin in the southern plains with a amped up pattern coming up... just saying threat is worth watching this time frame... with a se ridge in the mix going by the 18z gfs at least... should shunt the system off to our north... behind it mightjust be our first snowflakes of the season... now lets see if the euro can amp this thing up some also

by **andyhb** 2012-12-02, 6:26 pm

Yeah, I'd have to agree with you on that one, while it is far out, the 18z GFS/12z Euro verbatims would be potentially significant with an intense s/w migrating around the base of the larger scale l/w and inducing strong sfc cyclogenesis in TX/the Arklatex and then moving NE. The moisture return looks solid for this far out with 60s dews to the OH River and 65+ getting well into MS and AL, although I'd like to see more consistency before really getting into more detail. This would hold a lot of potential though, I'll go as far as saying that.

by **Eric** 2012-12-03, 4:39 pm

Isn't this interesting...we finally have a severe weather threat worth discussing. As Andy mentioned, ALL of the 12z GFSe members have the trough energy in some shape or another, but they all want to do different things with it after hour 180. Synoptically speaking, the 12z GFSop plants a ~1000mb SLP over N AR with a closed ULL and a 110kt jet max ripping overhead, putting the mid-Mississippi Valley in prime position for some "interesting" weather.

With that being said, the 12z Euro slaps the 12z GFSop, and tells it to get with the program. The Euro picks up the storm, but nearly 48 hours earlier. This has critical implications as the later the energy takes in getting here, the better quality of the warm sector. This *shouldn't* be a problem as the entire SE will be under a SW flow regime for several days previous thanks to the sub-tropical high parked off the GA coast.

What we will need to watch for is which global is more consistent with the storm strength and track, since this appears to be a low CAPE, high shear event and timing of arrival will be critical (12z GFS brings her in in the wee hours of the morning). Definitely something to watch, for sure.

by **andyhb** 2012-12-03, 4:59 pm

Good post Eric. Something in me tells me the timing will be somewhere in between the GFS and the Euro, I think the trough may have a bit more time to dig than the Euro forecasts, but I also think the GFS may wait too long given the suppressed ridging to the east of the incoming jet streak/vort max.

One of the big alarm bells, like with some of the greats in recent years (both severe weather, snow and otherwise), is that all the models have come aboard more or less, pretty far out.

by **Eric** 2012-12-03, 5:09 pm

andyhb wrote:Good post Eric. Something in me tells me the timing will be somewhere in between the GFS and the Euro, I think the trough may have a bit more time to dig than the Euro forecasts, but I also think the GFS may wait too long given the suppressed ridging to the east of the incoming jet streak/vort max.

I'd buy that, but I'm not at all impressed by the strength of the ridge. The base of the trough wants to put itself in the NW sector of the circulation and one would think that should hasten it's progression eastward...I don't know, but you're right, there's definitely something hinky going on...the globals shouldn't be THAT far apart.

by **jmundie** 2012-12-03, 6:43 pm

Eric wrote:
andyhb wrote:Good post Eric. Something in me tells me the timing will be somewhere in between the GFS and the Euro, I think the trough may have a bit more time to dig than the Euro forecasts, but I also think the GFS may wait too long given the suppressed ridging to the east of the incoming jet streak/vort max.

I'd buy that, but I'm not at all impressed by the strength of the ridge. The base of the trough wants to put itself in the NW sector of the circulation and one would think that should hasten it's progression eastward...I don't know, but you're right, there's definitely something hinky going on...the globals shouldn't be THAT far apart.

When the globals are on completely different pages, you always defer to the Euro (which is unfortunate... I feel like we're owed some severe weather given these ridiculous temps we're dealing with in December) the GFS is just a bad model. Sometimes spectacularly bad. The gfs is normally more progressive too. which is strange.

I've been watching the ensembles pretty closely, especially in the long range, and the gfs has been really invested in repeatedly holding low pressure over the rockies. I don't know why - but I wonder if there's a kink in the coding causing that.

by **andyhb** 2012-12-03, 7:01 pm

jmundie wrote:
When the globals are on completely different pages, you always defer to the Euro (which is unfortunate... I feel like we're owed some severe weather given these ridiculous temps we're dealing with in December) the GFS is just a bad model. Sometimes spectacularly bad. The gfs is normally more progressive too. which is strange.

I'd tend to refer to the ensembles more than individual model runs at this juncture. Sure the Euro is a bit farther north but it doesn't take that much of an adjustment to change that (especially within the pattern leading up to the trough's development).

by **Toot** 2012-12-03, 7:07 pm

jmundie wrote:
When the globals are on completely different pages, you always defer to the Euro

One has to know the biases of each operational model..if the GFS and Euro are disagreeing on different aspects and this is due to a known bias of the euro...it would pay you not to defer to the euro just because it disagrees with the GFS. This will work both ways though..im just saying its not wise to defer to the euro simply because the GFS disagrees with it...you have to look further into model biases.

by **tennessee storm09** 2012-12-03, 8:04 pm

personally after looking at latest gfs 18z... looks like a nice severe weather pattern for most of this month... se ridge isnt bulgin. for this upcooming system gfs has the ohio valley screamer vs the euro lakes cutter... i thke the in the middle approach now... this is going to be interesing

by **jmundie** 2012-12-03, 8:48 pm

Toot wrote:
jmundie wrote:
When the globals are on completely different pages, you always defer to the Euro

One has to know the biases of each operational model..if the GFS and Euro are disagreeing on different aspects and this is due to a known bias of the euro...it would pay you not to defer to the euro just because it disagrees with the GFS. This will work both ways though..im just saying its not wise to defer to the euro simply because the GFS disagrees with it...you have to look further into model biases.

I know the model biases - the euro has a tendency to over amp low pressures, the gfs is too progressive, et al.

The gfs is often too northern stream dominant as well. I just have a hard time believing the gfs over the euro outside 5 days on something like this, just because of data input. We're talking about vorts that are somewhere in the northern pacific now.

by **tennessee storm09** 2012-12-03, 9:32 pm

ole henry marguisity has a vid on this upcoming system... saying a possible nasty severe outbreak over the lower mid miss valley

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