03/12/06 FCST: Southern Great Lakes to Western Gulf Coast

[Jeff Snyder]

Well, it appears that significant moisture (Tds 65-75) will move northward out of the Gulf starting tomorrow. With continued troughing in the west / Rockies, southerly flow should pump warm, moist air into at least the eastern sections of the southern plains. Model solutions are not in agreement very well, as the 12z NAM continues to show no organized cyclone in the Plains on Sunday, with a broad area of low pressure in sw KS, the OK/TX panhandles, and se CO. On the other hand, the 0z GFS and ECMWF show a ~990mb low in northern KS by 0z Mon (Sun evening), while the 0z UKMET has a weaker low (~1000) in central KS. Given the number of solutions favoring at least a moderately-strong cyclone in KS on Sunday, it's tough to buy the NAM forecast yet. Last night's NAM showed an elongated area of low pressure along the OK/KS border, with sw sfc winds across OK/TX/AR/LA; this morning's 12z does away with this, and brings S-SE winds across the warm sector. Nearby NWSFOs mentioned svr convection possible from se KS southward (OUN mentions possible in their eastern CWA), so it appears that they aren't buying the NAM solution.

I won't go into much more detail, since it is 72hrs out. I do hope moisture can work it's way westward a bit more, since I'm not a fan of chasing in NE TX or AR... However, spring break begins today, so I'm not too worried about being out late Sunday.

EDIT: Current Day 3 outlook outlines a high-end SLT event (30% hatched).

EDIT2: 12z GFS indicates the dryline will be located near a Dallas to east-of-Tulsa to east-of-Kansas City line by Sunday afternoon/evening. As it stands now, if the GFS verifies with it's more westerly moisture, I'll go. 500mb flow is progged to be very strong, with >80kts northwest of a Childress to Kansas City line, meaning incredibly fast storm motions, though it'll also translate into strong shear.

 

[Stuart Robinson]

Quick model round up for 18:00 CDT Sunday

03/11 00z GFS
Surface Low 994mb over Topika
100 knot plus 500mb winds across Tx Panhandle, South to North East Kansas. Quite well defined dryline, DFW to Joplin to East of Kansas City.
Dew points 65 plus along DL down in Texas to upper 50’s towards Iowa.

03/11 00z ETA
Surface Low 997mb over Great Bend, KS
80 knot plus 500mb winds across TX Panhandle, SW Kansas to NE Kansas
DL East of DFW to Springfield to further East of Kansas City
Dew points 60 plus along DL right up to North Missouri
750m2/2 !! of DLS over a wide area of Iowa.

In summary the ETA suggests that by 18:00 CDT the best flow will be out of phase with the instability – while the GFS says that it will be in phase.

Too far out to call anyway.

 

[John MacKay]

SPC throws out huge MDT risk out far the majority of MO/AR/IL/IN. Suggesting the potential is there for a tornadic outbreak. I won't look at the models in depth until Sat. evening, but looks like a great day, considering this system will usher in a more tranquil pattern (good news and bad news).

I may need a nowcaster on this one to give me adequate time (I'll edit this out after I get some responses).

I'll also need to look at the possible movement of storms after the 3/11 event.

Edit #1: Thanks to those with their input on the terrain in MO. I'll take that into consideration Sunday.

 

[Scott Lincoln]

One big thing that could throw a wrench into Sunday's severe..... a giant inversion. I've been looking at BUFKIT soundings for Kirksville, St Jo, and Burlington, and they all seem to have a huge inversion with CINS well in excess of 100. Almost everything else is very favorable, but the storms may not even form.... and if they do, right now i would see them only as elevated.
The best bet for low CIN looks to be near Kirksville from 4pm-6pm. The CINs lower to around 50 J/kg or so. Lets hope that the warm front gets some action and maybe tomorrow wont go bust.

 

[Matthew Havin]

12Z Canadian this morning has a 991mb low moving into NC/NE KS by 0Z Mon with precip between KC to Sedalia. Other models (NAM) have also slowed it a bit, so my thoughts are thinking for tornadic between KC and Columbia, with Saint Louis getting hit mainly during the evening as the line congeals and moves east.

This is starting to look a bit like a certain severe weather day...just a little weaker (that I will not name) in Missouri a few years ago. LIT has been talking about it in their AFD and mentioned it as well.

 

[Scott Lincoln]

Another problem with sunday... it doesn't look like the dryline is forecasted to move much through the day. It appears to me that the NAM keeps it in western MO until after dark when it could be overrun by the cold front, it then moves eastward reaching St Louis by around 6am.
Those are probably the two biggest reasons right now that the NAM is not forecasting dry line precip...

 

[Robert Dewey]

Tomorrow is looking very good for portions of the Midwest and Ohio Valley.

The warm front actually pushes up into southern lower MI SSUN night into early MON morning. T's increase to the low 60's with Td's not far behind, so LCL's will be pretty low. Directional and speed shear along the warm front will be very impressive as well...

As of right now, I would say the best TOR threat is along the warm front, as the GFS has SWerly winds all across the warm sector. Right now, it looks like the most active tornado areas will be around IA/MO eastward through OH around 00Z MON, spreading NEward into parts of northern IL/IN/OH and southern lower MI between 06Z and 12Z MON (with cold frontal activity later MON). GFS streams in decent SFC-based instability along and south of the warm front, even in the night time hours, so I'm not concerned about that.

 

[Robert Dewey]

One thing to note... I'd stay away from the NAM output. It is by far the odd man out, with ALL of the other models showing a single low pressure system dominating. In fact, the NAM solution would keep lower MI locked in near-freezing temperatures with ZR, where the GFS/GEM puts us into the 60's with a TOR risk!

I'd be very suspicious of the NAM's output.

 

[Mark Oerther]

NAM vs. GFS

Once again there is a conflict between the NAM and GFS. While the NAM has northeastern TX looking like a sure bet, the GFS counters that with showing less than or equal to marginal shear. I like the 65+ dewpoints and the directional and speed shear of the NAM, however with great differences in both model runs I would wait to see the RUC output. I think we will have a better idea of which forecast will be verified by the 00z run tonight and tomorrows 12z.

 

[nickgrillo]

http://www.wxcaster.com/modelskewt.php3?mo...&STATIONID=kirk

That forecast sounding for Kirksville, MO at 21z tomorrow pretty much says it all for the warm frontal zone across northern MO/westcentral IL -- with widespread 2000j/kg SBCAPE overlapping 250-350m2/s2 0-1km SRH by the mid-afternoon -- owed to very strong boundary layer veering, yielding the incredible hodograph curvature and the incredible storm-relative helicity. You won't often see large SBCAPE available in northern MO/westcentral IL in early MAR very often, that's for sure. Obviously, the biggest problem tomorrow will be the storm speeds -- with a solid 45-55MPH average.

But, this is not keeping me away... I'll be leaving for westcentral IL to start in a few hours... Peace.

* edited to correct mis-phrased

 

[Simon Brewer]

Absolutely incredible....could be a long track tornado in MO or IL tomorrow with those fast storm motions: 45-65 mph

 

[Alex Lamers]

HIGH RISK ISSUED...First of the year! I am issuing my outlook and will get back to you guys shortly. I am expecting long-tracked tornadoes and perhaps an event for the March record books.

 

[Tony Lyza]

Originally posted by Alex Lamers
HIGH RISK ISSUED...First of the year! I am issuing my outlook and will get back to you guys shortly. I am expecting long-tracked tornadoes and perhaps an event for the March record books.

Personally, due to expected tremendous shear, good instability, which leads to almost extreme EHIs, I would anticipate several violent tornadoes ala 3/1/97 only farther north.

 

[Scott Lincoln]

And they said it was going to be harder to issue high risks with the probabilistic criteria....

 

[Chris Foltz]

Backyard chase tomorrow. Don't know about you guys, but it's a double edged sword having a high risk over top of you. All of the pieces are falling into place for what could be a major outbreak tomorrow. GFS and NAM in fairly good agreement with the location and timing of initiation. Just hope any tornadoes that do form stay out in the open fields of northern Missouri. Thankfully, that area is mostly rural. Current plans are to head north to Macon and stage there to either run west on US 36 or north on US 63 both of which are four lane roads now, thankfully. Will obviously take a peek at the 12Z runs in the morning before heading out. Best of luck to anyone chasing tomorrow and prayers that no one is injured. Be safe!!!!!