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Major Severe Weather Outbreak November 17

Hoosier

By Hoosier,
in Weather Forecasting and Discussion

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Memphis Weather

Memphis Weather

Posted
Posted

I think as the growing Lakes/OH Valley thread would indicate, this is a threat that's mostly going to be centered in that area, which is a pretty substantial shift from about 24 hours ago when it looked like AR/Ozarks could be the target. While the GFS is an outlier and likely too progressive, all models are speeding up the system and the best dynamic/instability combo to support either a sustained QLCS and/or initial/later embedded supercell structures look to fall across the KY/IL/IN/OH area. 

 

To the south of there, while the threat is not zero it seems by the time convection is able to develop, the front has already cleared the more unstable areas in the lower MS valley and is quickly pushing toward the Nashville-Huntsville corridor where thermodynamics are much less favorable (not to mention dynamics now pulling away). Again, this is a pretty substantial shift in modeling in the last 24 hours, so it's far from clear cut but as we're now within 72 hours the chances for additional major shifts does lessen. 

 

So while Tony's concerns earlier about this threat covering multiple subforums seemed right on, today's data would indicate that the GLOV thread is where the action will be. It's quite possible this could be a decent repeat of the Halloween event in terms of areal extent, with the ceiling of wind/tornado strength a bit higher as well.

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extremewx52

extremewx52

Posted
Posted

It appears that 11/10/02 is actually #1 and then #3 is 11/22/10, the day of a high end EF-2 near Rockford IL and 2 EF-1 tors in southeast Wisconsin. There's several long track tornadoes amongst the 93 tornado reports in the top analogs.

 

Northern Indiana looks to be in the bulls eye of that plot you are referring to. 

 

post-8696-0-45865600-1384458143_thumb.pn

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RCNYILWX

RCNYILWX

Posted
Posted

It appears that 11/10/02 is actually #1 and then #3 is 11/22/10, the day of a high end EF-2 near Rockford IL and 2 EF-1 tors in southeast Wisconsin. There's several long track tornadoes amongst the 93 tornado reports in the top analogs.

 

Northern Indiana looks to be in the bulls eye of that plot you are referring to. 

 

post-8696-0-45865600-1384458143_thumb.pn

Many of those occurred on 10/24/01, which is also one of the top analogs. The IWX CWA was hammered by several strong tornadoes.

Sent from my SCH-I535 using Tapatalk

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Gilbertfly

Gilbertfly

Posted
Posted

FWIW....

 

 

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
134 PM EST THU NOV 14 2013

VALID NOV 14/1200 UTC THRU NOV 18/0000 UTC

12Z NAM/GFS EVALUATION...INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NO SIGNIFICANT INITIALIZATION ERRORS WERE SEEN ON THE NAM OR GFS.


UPPER TROUGH EVOLVING OVER THE WESTERN U.S. ON SAT...WITH THE AXIS
REACHING THE UPPER MIDWEST SUN EVENING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z ECMWF/12Z UKMET/12Z CMC
CONFIDENCE: A LITTLE BELOW AVERAGE

THERE HAS BEEN A TREND TO SWING THE UPPER TROUGH AXIS THROUGH THE
PLAINS QUICKER COMPARED TO GUIDANCE FROM WED. THE 12Z GFS IS
QUICKEST WHICH MATCHES THE FASTER GEFS ENSEMBLE MEMBERS...BUT
THERE IS A DISTINCT SEPARATION BETWEEN THE QUICKER GEFS MEMBERS
AND SLOWER EC MEMBERS. THE CMC ENSEMBLE MEMBERS SHOW MORE SPREAD
BETWEEN THE TWO CAMPS...BUT THE MEAN OF THE LATEST SPAGHETTI
HEIGHTS IS SOMEWHERE CLOSE TO THE 00Z ECMWF AND 12Z UKMET/CMC
MODELS. THE 12Z ECMWF HAS MADE A SUBLTE SLOWER/WESTWARD ADJUSTMENT
FROM ITS 00Z RUN. HOWEVER...GIVEN SMALL FASTER ADJUSTMENTS SEEN IN
THE 12Z UKMET/CMC...PERER NOT TO GO SLOWER LIKE THE 12Z
ECMWF...AND STICK WITH A BLEND INCLUDING THE OLDER 00Z ECMWF WITH
THE 12Z UKMET/CMC.
 

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tornadotony

tornadotony

Posted
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Even the faster GFS would pose a significant severe threat around Chicagoland as long as it doesn't speed up even further. Pretty good CAPE exists at 18z Sun.

Yeah this detail is getting lost in the thickets.  The GFS is still a major event, probably from I-40 northward.  But the GFS timing has not been nearly as consistent as the Euro, which has basically been a rock now for days.  I know the Euro has had a few issues on a couple systems recently, but I gotta trend toward it.  Either way, this looks pretty brutal.

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Hoosier

Hoosier

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Yeah this detail is getting lost in the thickets. The GFS is still a major event, probably from I-40 northward. But the GFS timing has not been nearly as consistent as the Euro, which has basically been a rock now for days. I know the Euro has had a few issues on a couple systems recently, but I gotta trend toward it. Either way, this looks pretty brutal.

The wind profiles with this thing are something. How often do you see such strong upper level winds (300 mb winds of 125+ kts) punching into the warm sector and not lagging behind the cold front.

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nwohweather

nwohweather

Posted
Posted

It appears that 11/10/02 is actually #1 and then #3 is 11/22/10, the day of a high end EF-2 near Rockford IL and 2 EF-1 tors in southeast Wisconsin. There's several long track tornadoes amongst the 93 tornado reports in the top analogs.

 

I've been thinking this since Day 1. The setup is eerily similar except it wasn't totally warm up towards Toledo, only hit a high of 67

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Indystorm

Indystorm

Posted
Posted 
Then, on Sunday, with south winds screaming aloft and gusty at ground level, the moisture return from the Gulf will be palpable, with 3 standard deviations above normal. As the cold front slams into the warm air mass Sunday afternoon (timing not in stone yet!), strong lift, aided by intense wind shear and moderate instability will fuel rotating thunderstorms known as supercells. Significant tornadoes and damaging straight line winds are possible, as it appears right now, from parts of Illinois, Indiana, Ohio, Michigan, Kentucky, Tennessee, and Arkansas. It is still unclear whether or not we have a risk: the GFS model says it will be from I-57 eastward; the NAM model says everybody from Freeport to Galesburg and eastward, look out. There are way too many differences yet and with the system still partially offshore this morning, I want to wait two more model runs before or if I assign a severe risk. Suffice it to say, however, this does have potential to produce the entire gamut of severe: hail, high winds, tornado, and even localized flooding in areas that get hit with the strongest storms. Due to very strong winds aloft, any severe thunderstorms will be moving very rapidly, probably at 60 MPH or even faster. Thus, if warnings are issued, you won't have much time to react. Give me one more day to try to pin this down better,but if you have plans from Saturday late afternoon through Sunday evening, be prepared for thunderstorms, which have at least some potential to be severe. Look for highs on Saturday and Sunday to be in the 60s, with lows Sunday morning to be in the 50s.

From Gil Sebenste on Thursday

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Minnesota Meso

Minnesota Meso

Posted
Posted

The model disco here has been interesting to read.  I know the Euro swung and missed with the east coast storm and it was a good win for the home team. Having said that, the Euro has been very consistent with this system vs the US model. When I see this much difference 72 hrs out with the placement of the surface low between the Euro and the American models I go hunting to see what kind of support the Euro has.  Based on the 11/14 12z runs of the models I find plenty of it at 12z Sunday morning.  The op Euro has the surface low in Iowa and has strong agreement with the UKMET.  One other operational model has it as well and that is the JMA (which I only use for comparison reasons, never for a deterministic forecast.)  Looking further yet I see the Euro ensemble means shows it as well.  So lets dig deeper and look at where the surface low is forecast to be from the ensemble members of the GGEM and GFS.  A quick look for Sunday morning shows 13 of the 20 members from the GGEM agree roughly with the Euro operational as to the location of the low with differences as to how strong it will be.  When it comes to the GFS 12 of its 20 members show it over IA as well.

 

I haven't looked at details such as cape and dews and where they intersect with the upper wind fields, so I can't say where the best threat is.  However I do feel that the prudent way to go at this time is to weight the forecast 70/30 in favor of the Euro verifying.

 

Edit:  BTW I used this to view the ensemble members not the e-wal site from Penn State:

 

 

http://meteocentre.com/models/models.php?run=12&map=na&mod=gemglb〈=en

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Minnesota Meso

Minnesota Meso

Posted
Posted

The NAM is a big Debbie downer. Not liking this trend. I hope its just the NAM being the NAM.

 

 

Living up here in fly over country, the one thing that I have noticed over the years is that the NAM is much better in the warm months than the colder months, as a matter of fact, most times I ignore the snowfall forecast that it shows, even 6-24 hours out.  I have no idea why but it has problems in the cold season months up here.  At any rate it's not a global model and we have to wait until the trough is fully on shore.

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weatherwiz

weatherwiz

Posted
Posted

When it comes to the NAM at this range, you never want to look at the NAM for face value purposes, you just want to see how it's handling the evolution of the pattern and how it's handling the key features that are of importance.  The NAM still shows a fairly impressive and large warm sector with temperatures having the potential to get into at least the lower 70's and dewpoints which may reach the lower to mid 60's as far as north as southern IL/IN.  Along with impressive shear overspreading the warm sector, including a very potent MLJ/ULJ, the NAM has all the pieces the Euro/GFS are showing as well but it's just a matter of timing with the NAM which I wouldn't worry about at this stage.  

 

Needless to say, some models are showing an impressive amount of dry air working into the mid-levels...this might be lagged a bit but as long as this wouldn't mix down to the surface and screw with the dews, this could really help enhance the damaging wind threat.  

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