tornadotony Posted October 4, 2013 Author Share Posted October 4, 2013 Just playing devil's advocate. It is early October, but you can't ignore the impressive setup that's modeled for mid-late afternoon. We'll see. The low-level jet is located behind that precip area and will eventually displace it as the cyclone strengthens and the the LLJ shifts N and advects the warm front/lift zone north. We may be focused a little farther south than we thought this time yesterday, but I'm thinking that with the moisture, shear, and instability that are already in place and, in the case of the last two, only need minimal advection northward, in addition to the forcing along the dryline that will be in place, this event is as close to sealed as possible at this point. Link to comment Share on other sites More sharing options...
Chicago Storm Posted October 4, 2013 Share Posted October 4, 2013 Nice looking structure to this weak cell near Deep River, IA. Link to comment Share on other sites More sharing options...
Chicago Storm Posted October 4, 2013 Share Posted October 4, 2013 Going to make a brief detour And check out this severe warned cell south of Grinnell, IA. Link to comment Share on other sites More sharing options...
Jonbo Posted October 4, 2013 Share Posted October 4, 2013 I'm wondering if a Holstein-Ida Grove-Cherokee area is a good starting point to see if things pop up there and then adjust as models update. Link to comment Share on other sites More sharing options...
Chicago Storm Posted October 4, 2013 Share Posted October 4, 2013 Going to make a brief detour And check out this severe warned cell south of Grinnell, IA. Cell had a clear slot an lowering for a time. Tons of cg's too. Link to comment Share on other sites More sharing options...
Chicago Storm Posted October 4, 2013 Share Posted October 4, 2013 Going to make a brief detour And check out this severe warned cell south of Grinnell, IA. Cell had a clear slot an lowering for a time. Tons of cg's too. Went through the core. Hail up around penny size. Link to comment Share on other sites More sharing options...
Quincy Posted October 4, 2013 Share Posted October 4, 2013 Don't get me wrong, I know this has serious potential, otherwise I would have turned back. Just under 2 hours from the eastern IA border now, been driving since before 6 last night. I'm pretty confident there are at least a few strong tornadoes today and hopefully those who are out chasing will get to see some good action. Link to comment Share on other sites More sharing options...
Superstorm93 Posted October 4, 2013 Share Posted October 4, 2013 http://youtu.be/tRUi630u49k Link to comment Share on other sites More sharing options...
tornadotony Posted October 4, 2013 Author Share Posted October 4, 2013 This is just absolutely a classic, prototypical Iowa violent tornado setup. Iowa seems to specialize in events with these fairly compact, deep lows, bulging drylines/sharp triple points, and numerous cases in the past have ended in spectacular results. The two cases that come to the forefront of my mind when looking at this setup are 5/27/95 (3 F4s, including the famous Stuart double vortex) and 4/8/99 (2 F4s, including a very large, >1 mi wide F4 that passed near Creston and Stuart (again)). And just because it's not April or May doesn't mean that the ceiling is automatically lower than those two events. The atmosphere doesn't care what date it is, and I think this setup is going to be another case that proves that. Link to comment Share on other sites More sharing options...
Ian Posted October 4, 2013 Share Posted October 4, 2013 I agree the date doesn't matter.. particularly in that region which has seen higher end events almost all year round. Well, it matters as far as not having daylight till 9:30. Link to comment Share on other sites More sharing options...
Stebo Posted October 4, 2013 Share Posted October 4, 2013 Yeah I think last night proved a few things, a decently strong tornado at night in October in that part of the world should dispels some of the worry that this system might not live up to potential. Link to comment Share on other sites More sharing options...
Quincy Posted October 4, 2013 Share Posted October 4, 2013 Yeah I think last night proved a few things, a decently strong tornado at night in October in that part of the world should dispels some of the worry that this system might not live up to potential.Tidbit: Even Connecticut had an F-4 tornado in October...10/3/1979. Link to comment Share on other sites More sharing options...
tornadotony Posted October 4, 2013 Author Share Posted October 4, 2013 I'm seeing a slightly disturbing trend in the RAP and HRRR models as the morning goes on. They seem to light up not only the dryline/cold front in wrn IA but also the warm front in ern IA/SW WI. Each RAP model increases the CAPE/decreases the sfc-based CINH more and more, and the HRRR has cells with intense updraft helicity west of Dubuque and Davenport. Link to comment Share on other sites More sharing options...
Stebo Posted October 4, 2013 Share Posted October 4, 2013 Tidbit: Even Connecticut had an F-4 tornado in October...10/3/1979. Oh yeah, October can be a sneaky good month for severe weather same with November, people tend to focus more on April/May but there have been very strong outbreaks in Oct/Nov in the last 20 years in the Plains/Lakes. Link to comment Share on other sites More sharing options...
Stebo Posted October 4, 2013 Share Posted October 4, 2013 I'm seeing a slightly disturbing trend in the RAP and HRRR models as the morning goes on. They seem to light up not only the dryline/cold front in wrn IA but also the warm front in ern IA/SW WI. Each RAP model increases the CAPE/decreases the sfc-based CINH more and more, and the HRRR has cells with intense updraft helicity west of Dubuque and Davenport. Given the 0-3km CAPE and the surface vorticity along the warm front projected around 20z, I am not surprised Link to comment Share on other sites More sharing options...
Ian Posted October 4, 2013 Share Posted October 4, 2013 Tidbit: Even Connecticut had an F-4 tornado in October...10/3/1979. I'm climo's biggest fan but it's not a good way to forecast an anomalous event. Maybe as far as historical potential etc, but otherwise.. meh. Link to comment Share on other sites More sharing options...
brettjrob Posted October 4, 2013 Share Posted October 4, 2013 I'm pretty much with Tony in the magnitude of expectations department, and will say I'm rather surprised at the morning SWODY1, honestly. There are ways for this to bust, but that's true of all but a few events per decade. In my mind, there's at least a 50% chance this day will be remembered decades from now. Currently in Council Bluffs trying to decide how long we can hedge between the warm sector/WF cells east versus the arcing front late. Link to comment Share on other sites More sharing options...
tornadotony Posted October 4, 2013 Author Share Posted October 4, 2013 I'm pretty much with Tony in the magnitude of expectations department, and will say I'm rather surprised at the morning SWODY1, honestly. There are ways for this to bust, but that's true of all but a few events per decade. In my mind, there's at least a 50% chance this day will be remembered decades from now. Currently in Council Bluffs trying to decide how long we can hedge between the warm sector/WF cells east versus the arcing front late. Something is biting at me, making it feel like climo is playing way more of a forecast role than it should. Link to comment Share on other sites More sharing options...
Stebo Posted October 4, 2013 Share Posted October 4, 2013 At first I wasn't believing the near 70 dew points for Iowa, but South of the warm front all over Eastern KS/ and Northern MO, there are dews in the 67-71 range. Link to comment Share on other sites More sharing options...
tornadotony Posted October 4, 2013 Author Share Posted October 4, 2013 It's always disconcerting when each successive model run ramps up the threat leading up to an event, and that's frankly what's happening right now. The 13z HRRR run is a nightmare for IA, with a cluster of violent supercells near Des Moines and then the string of pearls along the dryline. Link to comment Share on other sites More sharing options...
Superstorm93 Posted October 4, 2013 Share Posted October 4, 2013 12z HRRR focused on Sioux City The Comp Ref is very impressive alone, but the updraft helicity is rather telling of the potential that these cells have. Hopefully the SPC at least considers adding a 15% tornado region to portions of IA Link to comment Share on other sites More sharing options...
cyclone77 Posted October 4, 2013 Share Posted October 4, 2013 HRRR at 01z. Ouch. EDIT: Ahh Superstorm beat me lol. Link to comment Share on other sites More sharing options...
tornadotony Posted October 4, 2013 Author Share Posted October 4, 2013 If I were writing up the 1630z outlook, there'd be pink on it 50 mi either side of a line from Sioux City to Ottumwa. Link to comment Share on other sites More sharing options...
Chicago Storm Posted October 4, 2013 Share Posted October 4, 2013 Made it to Council Bluffs and will sit here for a while. Link to comment Share on other sites More sharing options...
JoMo Posted October 4, 2013 Share Posted October 4, 2013 Bit of a change on the new D1 Mdt area... still a 10% hatched tor where mod is. Link to comment Share on other sites More sharing options...
L.B. LaForce Posted October 4, 2013 Share Posted October 4, 2013 FWIW, here is an image from a custom WRF-ARW Model ran with level 2 radar assimilation, satellite, sfc obs, etc. Today it is being offered FREE as a trial due to some server technical difficulties that are out of our hands. Go here: http://hazardnotifications.com/custommodeling/ and use the following name/pass: Username:publicPassword:public123 Another run is currently scheduled for 17Z Link to comment Share on other sites More sharing options...
Thundersnow12 Posted October 4, 2013 Share Posted October 4, 2013 Link to comment Share on other sites More sharing options...
CUmet Posted October 4, 2013 Share Posted October 4, 2013 I'm pretty much with Tony in the magnitude of expectations department, and will say I'm rather surprised at the morning SWODY1, honestly. There are ways for this to bust, but that's true of all but a few events per decade. In my mind, there's at least a 50% chance this day will be remembered decades from now. Currently in Council Bluffs trying to decide how long we can hedge between the warm sector/WF cells east versus the arcing front late. I'm with you guys on this. The instability and shear parameters (both deep and low-level) are very impressive, and the HRRR has consistently put out a string of discrete supercells. The dryline stuff starting in eastern NE and heading into western/central IA I think is going to be the main significant/violent tornado threat, given the instability that's built up just ahead of it and the stronger deep-layer shear, although the warm front is a pretty decent play as well. Link to comment Share on other sites More sharing options...
Jonbo Posted October 4, 2013 Share Posted October 4, 2013 Looks like I won't have to go far then to see some activity now with it being in my back yard. Probably stay within a 50 mile radius of where I live to not go too crazy on the gas. Link to comment Share on other sites More sharing options...
Stebo Posted October 4, 2013 Share Posted October 4, 2013 6hr projection off the mesoanalysis ***time sensitive*** of the effective sig tor and 0-3km CAPE surface vorticity Pretty strong signals torward Western IA of any supercell having a very good potential of a strong tornado associated with them around 21 to 23z. Link to comment Share on other sites More sharing options...
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