5/10/10 FCST: TX / OK / KS / CO/ MO

[Dave Kaplow]

Wonder if anyone else is noticing the lack of QPF forecast along the dryline by this morning's runs of both the GFS and NAM? And what others might make of this? The NAM does seem to break out quite a bit between 0z and 3z, but along the warm front in SE KS, not along the dryline. Perhaps this tendency is enhanced by the potential for outflow boundaries from early a.m. convection to sharpen the warm front? That area is closer to home for me, but southeast Kansas is not very good chase territory.

So, I'm still up in the air on whether to chase this one. Positives are the great dynamics, of course, but from a chase standpoint, storm motion (if in fact the cap is broken), terrain, and hordes of chasers could make it quite difficult. And as always, there's the issue of just how far I want to drive and the relative weight of distance driven vs. potential for a successful chase.

I won’t be chasing this one but I have certainly been following the forecast as the event takes shape, and yes, it seems to me that the relatively small QPF currently being forecast is a real concern. While all the severe parameters do look fabulous, the fact remains that none of the models have been predicting much in the way of warm sector precip, especially along the dryline, certainly not what you would expect to see from the kind of high-end severe event this is increasingly being touted as. So yes, that would be a concern for me. Possibly relevant to this, the NAM is showing an extensive area of drying and subsidence in KS at 850mb, in a roughly linear area east of and parallel to the dry line. This occurs after 12z and shows most dramatically on the 18z map:

time sensitive COD link

Tds at that level really take a hit before rebounding somewhat by 24z. I am not a good enough forecaster to know exactly what to make of this feature, possibly it can be ignored - no other models seem to show anything like it, but it’s been there consistently on all the last day’s NAM runs, and I doubt it can bode well for widespread storm coverage along the dryline in KS and OK if it verifies.

 

[Trey Thee]

The 12Z 4KM show lots of morning convection across central and NE OK/SE KS before 18Z. This will leave a boundary at 18Z from FSM-PNC area.

All Models are further NW with primary surface low IE Goodland at 18Z tracking toward Salina at 0Z. The DL at 21Z will run from HYS-GBR-END-FSI. Storms will fire around 19Z near Hays SE toward OK/KS border by 21Z.

The more significant tornados will developed on the boundary/DL intersection over SC-KS/NC-OK around 22Z time frame.

Jeff that puts initiation in OK somewhere around 4pm. That is about 2hrs earlier than I had anticipated. You feel the boundaries will fire the storms that quickly? Care to elaborate just a bit? I may need to be in position by 3pm instead of 4 or 4:30 if thats the case.

 

[Stan Rose]

Picking a target today may be fun, but its pointless. There is a tremendous spread on how this system is going to take shape, depending on which model you're looking at. I can't chase, but if i were (and the strong dynamics certainly justify an attempt!) id just park myself at the KS/OK border and see what tommorrow brings--not like there's any rush with all the morning convection Jeff mentions. Interesting to note that the 4km WRF also fires up discrete cells along the dryline by the afternoon, only to kill them off later in the forecast. There's definitely some caveats with this event, but i certainly wouldnt stay home if i didnt have to!

 

[Brian Davidson]

Is there a reason no one is talking about Missouri with this storm?

"THERE IS ALSO THE POSSIBILITY FORSTRONG...LONG-TRACK TORNADOES TO OCCUR. THE MOST INTENSE ACTIVITY IS EXPECTED TO OCCUR ALONG AND SOUTH OF INTERSTATE 70 AND ALONG AND WEST OF HIGHWAY 65 IN MISSOURI." <NOAA <http://forecast.weather.gov/showsig...endence+MO&product1=Hazardous+Weather+Outlook


EDIT: Just saw that MO was added to the post title. Thanks!

 

[Jason Haller]

Is there a reason no one is talking about Missouri with this storm?

"THERE IS ALSO THE POSSIBILITY FORSTRONG...LONG-TRACK TORNADOES TO OCCUR. THE MOST INTENSE ACTIVITY IS EXPECTED TO OCCUR ALONG AND SOUTH OF INTERSTATE 70 AND ALONG AND WEST OF HIGHWAY 65 IN MISSOURI." <NOAA <http://forecast.weather.gov/showsig...endence+MO&product1=Hazardous+Weather+Outlook

I believe people are looking at this on a chase perspective and not the down the stream perspective. from what I can tell seems this storm will still be producing strong tornadoes well into the night down stream into the Kansas City area. Will be interesting to see how this evolves.

 

[Jeff Passner]

I supect that models think there's too MUCH shear... I know, that seems impossible but if the speed shear is too strong, the growing unpdrafts get sheared off. If the updraft can't overcome the shear then it can't be a storm. While I can't say this for sure, I suspect that might be happening. Also, the WRF and GFS are NOT the same as the 4-km WRF... I'm sitting this chase out because I think storm speeds will be too fast... It sounds weird, but this is not what I like... I see pure storm speeds at about 45-50+ mph. This is a highly dynamic system, with incredible speed shear and 500 hPa winds of 70 knots... Unless it rides some boundary, there is NO way the storms will be going 35 mph. The LLJ itself is far stronger than that. The main problem here is just getting an updraft to survive. Initially that will be a problem, but with the upper divergence and lifting, the updrafts will survive... That is why the storms south along the dryline are forecasted to die... The place to chase in this situation is Kansas-- where there will be lift and the storms can survive the LLJ.

 

[Brian Davidson]

I believe people are looking at this on a chase perspective and not the down the stream perspective. from what I can tell seems this storm will still be producing strong tornadoes well into the night down stream into the Kansas City area. Will be interesting to see how this evolves.

Yea, KC wont get anything "bad" until late evening to overnight. I have a personal rule of thumb not to chase after the sun goes down. I might head east into middle of Kansas and follow her home. Chase target for me would probable be Lawrence or east; starting at 3pm.

Please correct me by PM if I'm wrong on that. I'm still new to forecasting.

 

[Jason Bolt]

southeast Kansas isn't too bad of chase country. Its nothing like the chasers heaven that south central Kansas is, but its still relatively good when compared to some other places in the plains. The square mile grids kind of break down and are more skitish, but the terrain stays really flat for the most part.

I live in SE KS but please don't take this as a biased post; actually I believe the best play tomorrow will be the I35 corridor south from ICT. As far as the road network, having chased the panhandles, and western KS extensively one thing I like better about the road network in SE KS where I'm living now is most secondary roads here are river gravel, and I seldom if ever see the problems with these turning into muckety muck like many of the roads in the Hays-Great Bend-Pratt-Dodge area (my favorite chase area). I feel quite a bit safer getting off the main drag east and south of ICT. The road network is a little sparse just east of ICT south and north of 400, but a little further south like Ark City to Winfield I like it. It stays good all the way to MO.

There really isn't a lot more to be said forecast wise, but this setup reminds me of another (I think it may have been 4/26/09 I can't quite remember the date), where all models had the DL a little too far east. IIRC there was even a high risk area to the east yet the bigger play wound up along the southern end a trailing DL across the Enid area. I could sit here in my back yard and probably do ok, but I likely will be trucking for Ark City first thing in the morning. Really liking the best chances for a chaseable cyclical storm south of ICT.

 

[Chuck Robertson]

Another comment regarding the lack of QPF on the models along the dryline Monday afternoon. I am not allowing this to discourage me about the dryline for two distinct reasons:

1. I do not expect much accumulated precipitation from these cells as they will be moving very fast.

2. I do not expect much precipitation from these cells as they will likely be LP (low precipitation) in nature.

I have seen tornadic supercells in the past produce tornadoes, and barely even wet the pavement. In some situations such as this, tornadic storms are meant to tornado, not water the earth.

 

[Stan Rose]

Shear is not a problem i dont think, the bigger problem is the extremely large dewpoint spreads above 800 mb that both the NAM and WRF are showing in model soundings across srn KS/nrn OK. 2000 CAPE is plenty for an updraft, but lots of dry air in the mid levels can cripple a storm.

 

[Jeff Passner]

Chuck --- good points... The storms along the dryline will be more isolated and will be moving NE at 45+.... You are completely correct, they won't drop much rain on any one spot. The cores will be flying and with the excessive shear, the storms may be LP until they hit the LLJ later where they will get more moisture. The slightly veered 850 winds may also act to lessen the moisture depth on the dryline, thus the storms may actually be LP for the first 1-2 hours.

 

[Andrew Stoller]

Call me crazy, but if one wanted to roll the dice, I think there's a play further northwest in the extreme central/north east CO (early on) into northwest/central KS as the day progresses. Essentially playing the main synoptic triple point/east northeast of the surface low where moisture will pool. Seems like that area is always in play with these dynamic systems, where you can get a tornadic supercell in a relatively cooler stable environment. The Windsor CO event comes to mind. The NAM has been consistently breaking out QP in that area, with over 1,000 J CAPE as early as noon around Goodland. Depending on how I feel tomorrow morning, I may just try the main triple point. Initiation is more guaranteed and there won't be a chaser cluster %#$! to deal with.

The 18z NAM and GFS are in good agreement with breaking out precip south of Wichita and moving it east/northeast into southeast/east central Kansas. The shape of the 3 hour rain total even looks like a supercell by 00z according to the GFS.

 

[Jesse Risley]

Call me crazy, but if one wanted to roll the dice, I think there's a play further northwest in the extreme central/north east CO (early on) into northwest/central KS as the day progresses. Essentially playing the main synoptic triple point/east northeast of the surface low where moisture will pool. Seems like that area is always in play with these dynamic systems, where you can get a tornadic supercell in a relatively cooler stable environment. The Windsor CO event comes to mind. The NAM has been consistently breaking out QP in that area, with over 1,000 J CAPE as early as noon around Goodland. Depending on how I feel tomorrow morning, I may just try the main triple point. Initiation is more guaranteed and there won't be a chaser cluster %#$! to deal with.

We noted this in an updated forecast a short while ago. The warm sector dynamics ahead of the attendant dry line further south have been exhausted to death, and there is plenty of potential there, but the boundaries further north in Kansas will need to be watched too. Also, the 12z WRF is showing enhanced LI values all the way into SW NE.

 

[Michael O'Keeffe]

Not sure what to think of the new 0z NAM. I like the wider instability axis with 2000 j/kg of CAPE from I35 in S Kansas stretching to the Missouri border with over 4000 j/kg in C/E Oklahoma. But the NAM is showing widespread 70F dews into C Oklahoma. Seems like thats quite a stretch and the LLJ looks almost too good to be true! Helicity values are INSANE all along the dryline with over 300 m2/s2 at 0-1km over a large area. I'm not sure but that seems like too much. I also don't think the warm front will hang that far south in fact I wouldn't be surprised to see it move further north than forecast.

However if this model run is correct my goodness tomorrow looks very dangerous in fact downright scary over C/E Oklahoma and far S Kansas!

Edit: Even though the 0z NAM backed off bringing the warm front very far north into Kansas with all of the helicity and at least 500 j/kg of CAPE reaching I70 I wouldn't be surprised to see storms north of the front continuing to produce similar to the May 22, 2008 outbreak and when I say that I don't mean we will see that outbreak but we may see supercells track north of the front and continue to produce even when CAPE values are considerably lower than further south along the dryline.

 

[Buddy W Bradley]

Ok
. I pulled a few strings to get off of work at 3pm. Bryant Burrough and I Will be leaving Springfield for one of two targets. Independence Ks by 6pm or Lamar Mo by 5pm. Looks like the low level jet will be screaming making storms hard to keep up with and even dangerous if you are not very alert to the Changing conditions. My thinking on these two targets are of course dryline play in the Indepence area, and warm front play in the Lamar mo area. Also feel the second target will have less chaser convergence!! Shaping up to be possibly a HISTORIC day, May 10th, 2010!