10/26/2010 FCST: IN/MI/OH/IL/KY/TN/MS/AL/GA/PN

[Robert Dewey]

Wind gust potential via 4km WRF: http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/nmmwrf.gust_animate_1h.html

Look at that circulation around the low (time sensitive)!

 

[George Widener]

Quite the impressive storm, and its already making headlines around here. I hope people actually take it seriously though...
Seeing as how I'm sitting in the middle of it, and have this week off from work...I guess I'll be forced to tote the camera around and see what kind of images I can capture. I'd consider driving over to Lake Michigan but I think the real wave action will be offshore based on wind directions (at least on the Wisconsin side).
Going to be crazy for sure.

 

[Jeff Piotrowski]

Storms over night

The new 12Z 4KM has storms going by 9Z in the MO valley area.
http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/

The new 18Z ruc has storms pop over NW-SW MO by 5Z then back build into eastern OK.

http://wxcaster.com/CONUS_RUC_1000-500_SLPPRPTHK_11HR.gif


I would expect the slight risk may have to be moved back westward if convection starts as far west as the latest models suggest.

Update: Mike the precipitable water is now over 1.0 over eastern OK heading for SE KS. The nose of the 1000 cape is west of FSM heading NNE toward SW/MO and extreme eastern OK.

I would think a couple of severe storms not out of the question tonight.

 

[Mike Smith]

Jeff,

Note that SPC has extended the 10% general thunderstorm line quite a bit father west in the 17Z and 20Z convective outlooks.

While there is no CAPE, precipitable water over the Flint Hills and eastern Oklahoma is around 0.8" which is above normal for the time of year. It would not surprise me if, as you suggest, the LLJ gets cranking after SS and we see a few thunderstorms from around ICT east in southern KS given the strong forcing.

Mike

 

[Bob Hartig]

Found a hi-res WRF run (5km) from NWSFO MQT, mainly centered across the northern Great Lakes. It pretty much sums up my thoughts on the convective aspect of this system. The system strength is slightly deeper (~2mb) than the NAM, but it shows healthier CAPE (750j/kg) with insane bulk 0-6km shear values of 100knts... & 70-80knts in the first KM!

Well, that's just plain scary. Not only have we got embedded supercells, but this thing also shows discrete cells popping out ahead where 1 km helicities are 300-plus.

I don't know what to do with this setup--or maybe I do and I just hate to accept it. It just doesn't look chaseable. Looks like I just sit in my car at the edge of Caledonia with this one, watch the radar, and wait to get clobbered.

 

[Jesse Risley]

Moderator Note
​

Given the unusual nature of this one particular system, coterminous with the references to the Armistice Day Blizzard, and considering that this system is also expected to bring damaging gradient winds from a non-thunderstorm, synoptic scale event, meteorological forecast discussions about the system itself, absent the specific severe weather parameters, are going to be allowed to continue here in the TA thread. The thread from the Winter weather discussion forum has been merged here.

 

[Jeff Piotrowski]

KS/MO/OK

The 21Z Ruc now has storms going by 3Z over SE KS this looks good with the western edge of the 60 DP are now slowly backing NW across NE/OK the nose is headed for SE/KS.

The 700mb temp around 10C over the target area but 5C of cooling is now along the I-35 corridor rapidly moving east approaching the moist axis over far SE KS by 3Z.

SPC: Upgraded to Moderate DAY 1. http://spc.noaa.gov/products/outlook/day1otlk.html

Also the 2% into OKLA & 5% tornado risk has been moved back west to SW/MO. Tulsa 64 DP and going up CF now PNC expect storms to fire from NE/OK-MO by 4Z.

 

[Mark Blue]

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[Glenn Rivers]

Differences from Nov 1940

The pressure with this system may end up being lower than Nov 1998 and Nov 1940, but the wind fields do not seem as impressive. This particular system seems very wide, and it is not hemmed in by high pressure on any side. By contrast, with the Armistice Day storm of Nov 11,1940 (if memory serves me correctly) there was very high pressure over Quebec of over 1030 mb, and very high pressure of almost 1040 mb over Alberta when the storm was at its deepest. The pressure gradient looked more extreme, and I would guess that if todays numerical guidance was available back then, the NAM would show an 850 mb prefrontal jet streak of 90-100 knots, and a large area of 80+ knot post frontal 850 mb winds. Probably, the GFS would show 80-90 knots with the prefrontal 850 mb jet, and a large area of 70+ Knot post frontal 850 mb winds.

Getting back to the NAM, the Armistice day storm would probably be progged to be almost encircled by 30+ Knot surface winds, with a large streak of 40+ Knots in some of the post frontal areas from South IL to North MI (over land). Over water, the 10 km grid would probably forecast some 50+ knot surface winds over Lake Michigan.

To sum up this is an impressive storm, especially considering it is only October, but the pressure gradient and wind fields seem weaker than would typically be the case for a 960 mb event in the upper Great Lakes. The forecast wind fields at 850 and at the surface seem much weaker then 1940, and somewhat weaker then 1998.

 

[Mike Smith]

SPC at 01Z has upped the day one convective outlook to moderate risk along the Missouri-Illinois border.

A strong rise/fall couplet has developed over Kansas in the last few hours near the front. Given the MUCAPE now extends from TUL to SZL and is surging north, they may well be correct.

 

[Zack Hargrove]

I am torn whether or not to chase this or not. I am here in North Carolina and myself and a partner are debating on whether or not to make the journey to North/Central TN/KY tomorrow. I am afraid that it may not be worth the 5-6 hour drive if things just end up staying completely linear. I would be banking on the bottom of the convection being a little more discrete out in front of the line this far south. The other thing that concerns me is the cloud cover and the limitations of instability. If there is any substantial instability at all, North/Central TN/KY could be a pretty big activity zone. Terrain also could be a bit of a problem, but I've managed through worse.

At this point, I am thinking it may not be worth it to skip class for this one, but I suppose I will wait for the 2 AM SPC update. Anyone else have any views about the situation in TN tomorrow? Timing also concerns me a bit.

 

[Robert Dewey]

The pressure with this system may end up being lower than Nov 1998 and Nov 1940, but the wind fields do not seem as impressive.

It's not too dissimilar. I pulled up some surface maps of the Armistice Day storm, which does in fact show a 1041mb high over WA, and a +1026mb high over ME. The current system should interact with a developing 1027mb high over OR and a 1028mb high off the NE coast (fairly similar to the Nov10 1998 event actually). If the current storm deepens as expected, it will be 10mb deeper than the Armistice Day storm, which would yield a fairly similar pressure gradient.

FWIW, the GRB sounding from Nov10 1998 featured 70knts at 850mb during the height of the storm... Again, not too dissimilar to the current event.

 

[Chip Redmond]

Absolutely torn on this system. Will it be worth going anywhere or not? That is the question I can't seem to get out of my mind. However, there is a good chance history could be made tomorrow with the low and perhaps it's impact on the United States and I fully plan to be a part of it!

Initial instinct tells me to go south towards TN/KY. Much more instability with more chase-able storm motions (still super fast) and a better chance at isolated storms developing ahead of the linear mess. However, this may be the most substantial cloud cover I can personally remember over the entire United States and I know that will limit convection from the Gulf to the Great Lakes. With such strong forcing and shear along the front, their is guaranteed to be a squall line, capping and cloud cover aside. For only a few hours away, where we can get to flat land that will yield the strongest winds, I am taking the Ohio option.

As of right now, I plan on intercepting the squall line once (maybe more if a miracle occurs) along US70 around Dayton around 2pm. I hope to intercept the strongest winds I have ever encountered. It will be dangerous, but with proper planning and bracing for impact at the proper location could make a very exciting intercept. It's October and I need some extreme nature darnnit! This SDS is getting to me.

Chip

 

[Rob Gardner]

Storm motions are surprisingly slow right now, presumably because of the low topped thunderstorms. Contemplating a break of dawn chase if storms can stay discrete long enough. the latest RUC has storm motions slower over Illinois by dawn. If storms can initiate in southern illinois central illinois could be a hot spot come early AM. Just don`t know if there is enough instability for discrete cells to move that far east....

Rob

 

[Cody Pryor]

I am starting to be a little concerned for my local area. I was looking at the 00z NAM and the front will be just entering Indiana at 15z. I looked at the cape and there is a nose of 500-750 jkg of cape there in southwestern part of the state all the way up to Terra Haute. I will certainly be keeping a close eye on this one.


at 15z front position:
http://www.twisterdata.com/index.ph...nding=n&output=image&view=large&archive=false



at 15z Cape (Max 0-70mb AGL)
http://www.twisterdata.com/index.ph...nding=n&output=image&view=large&archive=false#