November 5th, 2017 Severe Weather Event

[HillsdaleMIWeather]

6 minutes ago, Chicago Storm said:

Na, south/weaker trend continued.

?, 12Z kept the warm sector south of I-80, 18Z gets it back North of the border 

[Hoosier]

Just now, HillsdaleMIWeather said:

?, 12Z kept the warm sector south of I-80, 18Z gets it back North of the border 

Warm sector did come farther north out your way.  Actual surface low track did not shift north though.

[HillsdaleMIWeather]

Just now, Hoosier said:

Warm sector did come farther north out your way.  Actual surface low track did not shift north though.

Duh, I was looking at the wrong map. Apologies 

[Hoosier]

18z GFS is farther south.

[Hoosier]

It does look like the surface based severe threat could commence somewhat early, perhaps prior to noon.  Should already have good instability by then and enough lift, at least near the warm front.

[Hoosier]

I wonder if we will get the SPC outlook an hour early tomorrow night with daylight savings time ending.    Technically it doesn't end until 2 am though and SPC is in the central time zone.  

[Chinook]

This is definitely worth following, as long as the NAM has the SRH values in these ranges: 0-1 km SRH > 150 m2/s2 and 0-3km SRH > 250 m2/s2. If we continue to see that on tomorrow's models, then I would say we might get 1-5 tornadoes out of this situation, plus 20-50 wind reports. It might be in the general region of Van Wert OH, which had that disastrous tornado in 2002 at this time of year. 300mb winds in the range of 70 kts may help a few of these storms become supercellular, amongst the other parameters.

by the way, the SPC has added in a new tool

http://www.spc.noaa.gov/exper/href/index.php

[tornadohunter]

4 minutes ago, Chinook said:

This is definitely worth following, as long as the NAM has the SRH values in these ranges: 0-1 km SRH > 150 m2/s2 and 0-3km SRH > 250 m2/s2. If we continue to see that on tomorrow's models, then I would say we might get 1-5 tornadoes out of this situation, plus 20-50 wind reports. It might be in the general region of Van Wert OH, which had that disastrous tornado in 2002 at this time of year. 300mb winds in the range of 70 kts may help a few of these storms become supercellular, amongst the other parameters.

by the way, the SPC has added in a new tool

http://www.spc.noaa.gov/exper/href/index.php

Where is the outrage over this mention of Van Wert? Why isn't he being attacked like I was? 

 

 

Lmao. 

[andyhb]

6 minutes ago, tornadohunter said:

Where is the outrage over this mention of Van Wert? Why isn't he being attacked like I was? 

 

 

Lmao. 

Comparing the actual setups is a whole different ballgame. Don't be obtuse.

Like literally all you initially said was "Van Wert OH, that is all" and then justified it with "it's a tornado prone area and the parameters are pretty good", even though they really weren't (and still aren't) that impressive.

[Chinook]

Oh boy. Well, November 10, 2002 was a much better overall surface low, with tornado parameters in place across the Southeast, and then it was a surprise getting so many tornadoes with low CAPE in Ohio and Indiana. I'm sure the models at the time didn't pick up on enhanced CAPE in Ohio and Indiana about a day beforehand. But that situation was a much more synoptically-evident severe outbreak and it produced many tornadoes in the Southeast as well as (almost) near me in Ohio. The shear was better in 2002, for sure.

[Hoosier]

Just looking through the 18z runs a bit more.  NAM got quite a bit more unstable... even some pockets of 2000+ J/kg CAPE, similar to what the Euro has been showing.

[homedis]

Haven’t commented in a while but I’m now in Champaign, IL for school so I am definitely interested in this set up as it looks like I’m in a great location.

[high risk]

3 hours ago, Chinook said:

by the way, the SPC has added in a new tool

http://www.spc.noaa.gov/exper/href/index.php

       There was an implementation of HREF Version 2 earlier this week.   it's effectively the operationalization of the popular SPC Storm-Scale Ensemble of Opportunity (SSEO), aggregating the current and previous runs of the NAM nest, Hi-Res Windows, and NSSL WRF.       It overall scores better than any other hi-res ensemble system (HRRRE, NCAR...)     SPC's web site is pretty slick.

[Stebo]

SREF trended SE on the 21z run with the bulls eye of best parameter space. Looks a bit faster too with frontal passage in the MSLP field.

[Hoosier]

Doesn't look like the 00z NAM will make a drastic move.  Maybe a creep north.

[HillsdaleMIWeather]

4 minutes ago, Hoosier said:

Doesn't look like the 00z NAM will make a drastic move.  Maybe a creep north.

Warm sector extent is a tiny bit north

[Hoosier]

Does continue to trend toward slightly higher dews.  Now there are widespread 66-68 values south of the warm front.

[Stebo]

Just now, Hoosier said:

Does continue to trend toward slightly higher dews.  Now there are widespread 66-68 values south of the warm front.

There should be moisture pooling along the boundary as well especially with strong advection in the warm sector. So even if these values are a bit high in some places, along the WF they may be close to correct.

[Jim Martin]

Aside from the severe weather risk, still looking like some healthy rain totals by 7 AM EST Monday in Northwest Ohio.

[Hoosier]

Near Lafayette, IN

[Hoosier]

Nice CAPE for September, I mean November

[HillsdaleMIWeather]

0Z GFS also gets warm sector further north

[Central Illinois]

Haven’t commented in a while but I’m now in Champaign, IL for school so I am definitely interested in this set up as it looks like I’m in a great location.

Yeah I think were in a good spot for this one. The Lincoln 3pm update sounded pretty good for areas along and east of I-55


Sent from my iPhone using Tapatalk

[Hoosier]

This was put out by LOT earlier, and seems pretty reasonable at this point.

Looks like some areas could get multiple rounds of severe wx.

For anyone out chasing, don't forget about the earlier sunset time.

 

 

[RCNYILWX]

0Z GFS also gets warm sector further north

The important thing on the GFS is the trend and it continues to adjust south. At this point, I feel comfortable more heavily weighting forecast toward the NAM solution, along with Euro. Another factor I'm seeing on the NAM is that much of the precip appears to be post frontal and although the parameter space is still impressive in the warm sector it indicates more of a surging front scenario that could undercut surface based convection.

Sent from my SM-G935V using Tapatalk

[Hoosier]

34 minutes ago, RCNYILWX said:

The important thing on the GFS is the trend and it continues to adjust south. At this point, I feel comfortable more heavily weighting forecast toward the NAM solution, along with Euro. Another factor I'm seeing on the NAM is that much of the precip appears to be post frontal and although the parameter space is still impressive in the warm sector it indicates more of a surging front scenario that could undercut surface based convection.

Sent from my SM-G935V using Tapatalk
 

To me, the most sure threat at this point looks like hail, and some of it could be fairly large given the steep lapse rates/strong shear.  Tornado potential looks intriguing especially with anything riding near the warm front. The undercutting issue does look like it could be a concern with time.

[RCNYILWX]

To me, the most sure threat at this point looks like hail, and some of it could be fairly large given the steep lapse rates/strong shear.  Tornado potential looks intriguing especially with anything riding near the warm front. The undercutting issue does look like it could be a concern with time.

Also, not necessarily applicable to the severe risk theme but some concern as well for a flooding risk. Top of the charts pwats nearing 1.5", with areas just north of sagging boundary likely having more than sufficient mucape for robust convection tapping into those pwats. Models (NAM in particular) also showing very strong moisture convergence in 925-850 level from east central IL across parts of Indiana.

Sent from my SM-G935V using Tapatalk

[Quincy]

3 minutes ago, Hoosier said:

To me, the most sure threat at this point looks like hail, and some of it could be fairly large given the steep lapse rates/strong shear.  Tornado potential looks intriguing especially with anything riding near the warm front. The undercutting issue does look like it could be a concern with time.

The front looks generally quasi-stationary through late afternoon, outside of areas to the W/SW of central Illinois. There does seem to be a rapid surge closer to 00z. The warm front and triple point areas seem to be the most intriguing with respect to severe potential. Storm motions suggest that cells could ride along an effective warm front, but low level lapse rates continue to be a glaring concern. The 3km NAM also merges cells into a QLCS by early afternoon.

No major changes from earlier thinking that this looks like a spotty hail event with a few isolated tornadoes possible. Also concur that early day storms could be possible prior to midday, especially in vicinity of the warm front.

[Hoosier]

Here's something.  Since 1950, there are zero reports of hail larger than golf ball size in November in the LOT/IWX cwas.  Let's see if that is put to the test...

[IllinoisWedges]

SPC not backing down.