October Severe Wx possibilities

Toot wrote:The trend today with the system in the extended has been slower and weaker. I think this is all due to guidance forming secondary low pressure on the tail end of the cold front. Takes on more of a negative tilt also! Still keeping an eye on it though.

you wana a negative tilted system to produce good severe toot... i just got home from work... fixing to check out model data

tennessee storm09 wrote:you wana a negative tilted system to produce good severe toot... i just got home from work... fixing to check out model data

You don't have to have a negative tilt trough for good severe, case in point March 2nd.

Also this: http://www.americanwx.com/bb/index.php/topic/1062-violent-tornado-outbreaks-by-upper-trough-tilt/

yeah i knew the march 2nd event was positive titled, i mean i know you can get severe events without the trough not being negative titled... i just didnt realize there were that many significant events... i do remember fred gossage told me one time some of the best tornado outbreaks come out of the positive tilted type trough... i have been studying it some, but it still seems like to me the reall good ones come from a negative titled trough... thanks for sharing that info andy... nice reading material there

SPC has issued a slight risk for the mid-south with the first system.

Code:

DAY 3 CONVECTIVE OUTLOOK 
  NWS STORM PREDICTION CENTER NORMAN OK
  0220 AM CDT FRI OCT 12 2012
 
  VALID 141200Z - 151200Z
 
  ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE OH AND TN VALLEYS...
 
  ...OH AND TN VALLEYS/LOWER MS VALLEY...
  AN UPPER-LEVEL TROUGH OVER THE OZARK PLATEAU LATE SATURDAY NIGHT IS
  FORECAST TO DEAMPLIFY AND MOVE QUICKLY EWD ACROSS THE MID-MS VALLEY
  SUNDAY. AHEAD OF THE SYSTEM...A BROAD LOW-LEVEL JET IS FORECAST TO
  MOVE EWD ACROSS THE OH AND TN VALLEYS SUNDAY. AT THE BEGINNING OF
  THE PERIOD...THE MODELS SUGGEST A DECAYING LINEAR MCS MAY BE ONGOING
  ALONG THE WRN EDGE OF THE LOW-LEVEL JET FROM IL SSWWD INTO THE
  OZARKS. AS THIS LINE MOVES EWD AND SFC TEMPS WARM...REGENERATION OF
  THE LINE MAY OCCUR OR NEW CELL INITIATION SHOULD TAKE PLACE.
  ALTHOUGH THE GFS MODEL IS SLIGHTLY SLOWER WITH THE LINE THAN THE NAM
  SUNDAY...CONSENSUS PLACES A LINEAR MCS FROM IND AND OH SSWWD ACROSS
  WRN TN INTO NRN MS BY LATE SUNDAY AFTERNOON. THIS SQUALL-LINE SHOULD
  MOVE EWD ACROSS THE SLIGHT RISK AREA DURING THE LATE AFTERNOON AND
  EVENING.
 
  FORECAST SOUNDINGS AT 21Z SUNDAY ALONG AND JUST AHEAD OF THE
  SQUALL-LINE FROM INDIANAPOLIS SSWWD TO NEAR TUPELO MS SHOW MLCAPE
  AROUND 1000 J/KG WITH SFC DEWPOINTS IN THE LOWER TO MID 60S F. DEEP
  LAYER SHEAR IS FORECAST TO BE FROM 35 KT IN THE TN VALLEY TO AROUND
  50 KT IN THE OH VALLEY. THIS INSTABILITY AND SHEAR COMBINATION
  SHOULD BE SUFFICIENT FOR A SEVERE THREAT LATE SUNDAY AFTERNOON INTO
  EARLY SUNDAY EVENING. A THREAT FOR DAMAGING WIND GUSTS MAY EXIST
  WITH THE LINE MAINLY DUE TO THE STRONG LOW-LEVEL WINDS JUST ABOVE
  THE SFC. FURTHER NORTH AND WEST ACROSS THE LOWER OH
  VALLEY...ISOLATED LARGE HAIL MAY ALSO BE POSSIBLE DUE TO COLDER
  MID-LEVEL TEMPS AND STRONGER DEEP LAYER SHEAR PROFILES.

I notice NWS service, there thinking now it may be to the west of Chattanooga. We will see. Have a great day and and a great weekend everyone.

The 12z GFS continues to weaken the second threat and the secondary low it was forming on the tail end of the cold front is now a nor'easter like system in the latest run

Bruce is going to shit when he sees this..lol

Major disagreement among guidance models this afternoon concerning the system in the extended range (Oct 18 timeframe). The GFS has went to a southern stream gulf type low/Nor'easter...and the EURO has a weak northern stream dominant low along the US/Canada border.

Meanwhile the Canadian model has genesis near the Arkansas/Missouri border.. which rides due north.. but not before it becomes a serious bomb of a low pressure system.. and if it verified would be a MAJOR severe weather outbreak across the TN valley! This is similar to what the gfs showed just a couple of days ago.

I still have to stay true to the Euro and GFS right now, but enlighten me Toot, what is the success rate of the Canadian? I do not know.

Adam2014 wrote:I still have to stay true to the Euro and GFS right now, but enlighten me Toot, what is the success rate of the Canadian? I do not know.

I wouldnt stay true to any of them right now...the GFS has been all over the place. If I had to pick right now.. I would go with a blend of the Euro and Canadian. The CMC is not crazy..the gfs showed a similar system just a couple of days ago and a couple of the ensembles have the track of the CMC but weaker.

Anyways the canadian and the GFS (NCEP) are pretty close at day 5 in verification. The GFS is a little more accurate at this range

Day 5 (120-hour) forecast errors

Toot wrote:Bruce is going to shit when he sees this..lol

Major disagreement among guidance models this afternoon concerning the system in the extended range (Oct 18 timeframe). The GFS has went to a southern stream gulf type low/Nor'easter...and the EURO has a weak northern stream dominant low along the US/Canada border.

Meanwhile the Canadian model has genesis near the Arkansas/Missouri border.. which rides due north.. but not before it becomes a serious bomb of a low pressure system.. and if it verified would be a MAJOR severe weather outbreak across the TN valley! This is similar to what the gfs showed just a couple of days ago.

HOLYSHIT BATMAN! fixing to have to check out ensembles on that sexy thing... man if that were to even come close verifing...

Yeah, that has outbreak written all over it, but it is a outlier for now.

IMO the 18zGFS is looking pretty decent for SVR in western sections of the midsouth. Probably not much of a tornado threat.. but there seems to be some potential there for wind damage.



Of course the 18z is completely different with the second system..it has a system that is reminiscent of a Manitoba Mauler type low. Gets cold air involved with 989Mb Alberta clipper..lol but thats another thread

Toot, this is my thoughts on the upcoming storm system next week. First, there is a recurving typhoon around japan sending a strong pacific jet roaring across to the west coast with alot of energy involved. This will aid in a stronger storm system currently being modeled by the gfs and euro, or at least it should. The cmc is overdone with the intensity of the slp, but what that has told me in the past is USUALLY the other models should have a much stronger slp in future runs, but obviously not as strong as the cmc. Ive seen it more times than not, esp in winter when the cmc would show a 1060mb hp coming down, but it shows us that it was going to get cold for it being that strong to begin with

The best shot at severe with the first system looks to be in the western portions of the state where decent paramaters will be in place says the nam!

The gfs is a little stronger with the low..so keep that in mind


Shear


Lift


Ample amounts of energy too

Mrgolf wrote:Toot, this is my thoughts on the upcoming storm system next week. First, there is a recurving typhoon around japan sending a strong pacific jet roaring across to the west coast with alot of energy involved. This will aid in a stronger storm system currently being modeled by the gfs and euro, or at least it should. The cmc is overdone with the intensity of the slp, but what that has told me in the past is USUALLY the other models should have a much stronger slp in future runs, but obviously not as strong as the cmc. Ive seen it more times than not, esp in winter when the cmc would show a 1060mb hp coming down, but it shows us that it was going to get cold for it being that strong to begin with

Sounds reasonable to me!

Here we go again...Tell us again how the stormcenter is on the canadian border and there is no way such a system can produce here..lol Anyways...let the downplaying begin





Dont take my words too serious this morning..Ive had alot of Coffee

Toot wrote:Here we go again...Tell us again how the stormcenter is on the canadian border and there is no way such a system can produce here..lol Anyways...let the downplaying begin


Dont take my words too serious this morning..Ive had alot of Coffee

Not at all...SLPs often produce weather FAR downstream from the LP center...but the greatest area(s) of divergence (i.e. lift) is just SE of the storm center, especially if the mid-level jet is in a favorable position. These types of storm systems, however, are quite often very benign in terms of their effects on TN (except for the interactions of different mesoscale features - like Wednesday's event). Of course, all this could become irrelevant once the GFS spits out a completely different solution next week.

EDIT: The more I look at this, the more I think this could be a virtual carbon copy of Wednesday's event, minus the tornadic threat...synoptically they're very similar. QLCS arrives at the MS River around dinner time, weakening as it transgresses the state. Instability parameters look to be much weaker this episode, too, but kinematics can sometimes make up the difference. There is still time for a change, but with the wind structure(s) being the way they are, this could be a case where it looks like Tarzan, but plays out like Jane.

Eric wrote:
EDIT: The more I look at this, the more I think this could be a virtual carbon copy of Wednesday's event, minus the tornadic threat...synoptically they're very similar. QLCS arrives at the MS River around dinner time, weakening as it transgresses the state. Instability parameters look to be much weaker this episode, too, but kinematics can sometimes make up the difference. There is still time for a change, but with the wind structure(s) being the way they are, this could be a case where it looks like Tarzan, but plays out like Jane.

That wasnt really directed towards you Eric..just the general consensus that seemed to think the last system's stormcenter was too far north for organized severe weather to occur in this region and clearly that just wasnt the case. Systems that get that deep often produce severe weather here.. even though the storms center is thousands of miles away. As for the system above...it's too soon for me to make anykind of call on it..but if it keeps being progged in the 980's I will sound the alarm like I did with the last one

Toot wrote:

Eric wrote:
EDIT: The more I look at this, the more I think this could be a virtual carbon copy of Wednesday's event, minus the tornadic threat...synoptically they're very similar. QLCS arrives at the MS River around dinner time, weakening as it transgresses the state. Instability parameters look to be much weaker this episode, too, but kinematics can sometimes make up the difference. There is still time for a change, but with the wind structure(s) being the way they are, this could be a case where it looks like Tarzan, but plays out like Jane.

That wasnt really directed towards you Eric..just the general consensus that seemed to think the last system's stormcenter was too far north for organized severe weather to occur in this region and clearly that just wasnt the case. Systems that get that deep often produce severe weather here.. even though the storms center is thousands of miles away. As for the system above...it's too soon for me to make anykind of call on it..but if it keeps being progged in the 980's I will sound the alarm like I did with the last one

No worries...I didn't take it as such. The thing with MLCs that ride that northern stream is it's going to take a lot to produce organized severe weather this far south of the LP center due to the rising pressures/heights. Nearly all of the mid/upper level dynamics are circling the LP center and quite often, the moisture fetch isn't what we'd normally say with a typical spring-time MLC. But there is still plenty of time for a change, and just like with any system, the mesoscale features usually make or break an event.

Eric wrote:

No worries...I didn't take it as such. The thing with MLCs that ride that northern stream is it's going to take a lot to produce organized severe weather this far south of the LP center due to the rising pressures/heights. Nearly all of the mid/upper level dynamics are circling the LP center and quite often, the moisture fetch isn't what we'd normally say with a typical spring-time MLC. But there is still plenty of time for a change, and just like with any system, the mesoscale features usually make or break an event.

The latest runs are even further north..so if trends mean anything I would set on the side of not a big deal at this point! This looks more like an enforcer of a colder pattern to me.

The 18zGFS took a turn towards more of a situation as it develops a secondary low on the tail end of the front. Wind and moisture profiles would be much improved if this scenario were to play out. Verbatim would probably be pretty rocky in the western TN area!



That said..this is just one model run and previous runs haven't showed this.