4/23/06 FCST: TX/OK/KS/MO

Jason Boggs

SPC day 3 has most of Kansas and Missouri in a slight risk as of right now. Models are hinting at a dryline near DDC with moisture values in the upper 50's to low 60's east of the dryline. Forecast CAPE values of 2000-2500 near the Great Bend area look fairly doable. Models are suggesting a 700mb temp of near 10C, but I think the combination of daytime heating and moisture should erode the cap by late afternoon. Directional shear looks ok but I'm not too overly impressed with the speed shear as of right now. If the scenario pans out, I look to be targeting the area along highway 281 from Pratt to Great Bend.
 
I think the warm front dryline intersect could be the area to play. Once cap breaks storms should initiate near triple point and begin to tap into locally increased helicity and LCL's along warmfront thus increasing their tornado potential as opposed to storms further south along dryline which may have higher LCL's and
more veered surface winds compared to East/Southeast winds along warm front, However as stated by Jason directional shear in this area looks good but speed shear leaves somthing to be desired.

Since it is in my backyard I am sure Ii will be chasing. Target: Wherever DL WF intersect sets up.
 
I was worried about the lack of deep layer shear after the 12Z yesterday, but with as good of directional shear as the NAM continues to show, I don't think we are going to have a problem with deep layer shear. I really like the setup for central Kansas. The biggest problem IMO is that I don't see us getting the dewpoints that the NAM is forecasting. Overforecasting dewpoints has been a problem with the NAM all year and I don't think this setup is going to be the exception.
Storms should track NE into an area of backed winds and lower LCLs and as long as the 850mb winds back as forecast, I think tornadoes are likely East of the triple point. As far as picking a target goes, it is the easiest forecast of the year IMO.
 
I'm a little surprised that there isn't more discussion regarding the chase potential in KS tomorrow afternoon and evening... Perhaps the gas prices are gettin' to some folks... :lol:

As it stands now, my primary concern is moisture recovery. Regardless of what the models indicate, the true 60F isodrosotherm is still way down in Texas (Fort Stockton to near San Angelo back down to near San Antonio). There were a few more 60-65F tds showing up farther north into central TX around 2-3pm, but those have seemingly mixed out, which also makes me concerned about moisture depth. With a high along the central Mississippi, the air entering eastern TX is just dry cP air being circulated from the eastern US. So, it looks like much of the moisture hopes for tomorrow will have to take the west Texas scenic route up into the target area. Fortunately, the models are forecasting a 30-45kt southerly LLJ from southwestern TX into southern KS tonight. The 12z DRT sounding showed a relatively deep moist layer up to nearly 800mb, so that'll help. (Note that 12z BRO sounding had a rather shallow moist layer of only ~30mb deep) There is the possibility that an organized MCS may roll across western and central Texas overnight, with any organized cold pool and OFB acting to severely disrupt moisture return.

IF we can really get >63F tds into the area tomorrow, then we'll have to deal with my secondary concern -- weak flow aloft. As has been advertised for a while now, the stronger 500mb flow will stay in the southwestern US until the trough kicks out Monday. Fortunately for us, strongly backed low-level flow will aid in offsetting the marginal flow aloft to yield deep-layer shear profiles that are still supportive of supercells. Hodographs from model forecast soundings (which really need to be taken with a grain of salt since they were 36hr forecasts) indicated quite nice curvature for tornadoes. The overall magnitude of the winds isn't impressive, but any supercells will likely intensify that (at least in the inflow layer / low-levels) given the relatively strong CAPE progged. LCLs may be another issue, but less so as one heads farther north from the warm front (also into progressively more stable air). I see that the 18z NAM run now keeps the low a little farther southwest. Overall, it looks like I'll be making headway towards Salina or Great Bend tomorrow. Obviously, I'll have more confidence in a target area when I see the surface obs tomorrow morning.
 
Chase target:
Rush Center, KS (20 miles west of Great Bend).

Timing:
A broken line of storms will initiate through 6 PM CDT along a Ness City to Great Bend to Hutchinson line. These storms will reach severe limits in the Great Bend area at 7 PM with the first SVR warnings probably issued for Rush and Barton counties at this time.

Comments:
The primary severe threat will be supercell storms capable of golf-ball size hail; however, a tornado threat will also exist near the DL/WF triple point where interaction with an old outflow boundary left over from early morning convection should take place. Storms will remain discrete and limited in overall aerial coverage during the daylight hours. Storm motion will be to the NE at 15 mph, resulting in excellent chasing conditions with good overall visibility and impressive storm structure.

Discussion:
Tonight, an MCS is advertised to develop in ECNTRL KS at the nose of a 45kt LLJ. Tomorrow morning, this complex and shift E of the area while leaving an OFB along or just W of I-135 by the time storms initiate. By early afternoon, a WF will be located along US-96/US-56, or along a GBD to EMP line. The DL will surge EWRD as a compact mid-level H7 vort max/H5 40kt streak approaches the area through 00Z. Mesoscale forcing resulting from these features should be sufficient to overcome convective temperatures in the 95F - 100F range. This capping is a positive feature on Sunday’s setup, as aerial coverage of convection will be limited to a few cells.

Low confidence with MDLs ATTM, with most guidance continuing to flip-flop on timing and track of key features and SFC moisture. NAM and UKMET are in good agreement of QPF and SFC moisture, as well as track and timing of the mid-level disturbance, although the new (00Z) NAM is now weaker with the SHWV strength. Both MDLs are overly ambitious with the amount of SFC moisture available for convection and are also are too early on timing of convection as they are underestimating CIN as a result of the moisture FCST. GFS and NGM MDLS both place best forcing a bit further west while delaying timing of convection. SFC moisture verification has been a problem over the last month and this event is no exception. The 00Z DDC sounding is exceptionally dry, indicating SFC dewpoints in the mid-30 degrees F. Meanwhile, the OUN sounding indicates a 100mb deep moist layer with dewpoints in the 11C range through this layer. The 00Z NAM initialized 5F too warm on SFC dewpoints S of the developing WF in KS. The EWRD motion of the DL should be much more rapid then advertised by the NAM given the depth of the moist layer in SCNTRL KS (only 30-50mb deep) by late afternoon. This model also is not forecasting the veering SFC flow W of the DL, which should verify given the H85 flow and the rapid mixing that will occur there.

After adjusting for discrepancies in anticipated SFC moisture, expect a narrow axis of MLCAPE’s of about 1200 J/kg. Immediately NE of the DL/WF, expect decent deep-layer shear to 40 kts under the aforementioned H5 streak; while SRH (0-3km) will locally exceed 300m^2/s^2 with a 30kt H85 streak on top of the backed SFC flow of 10mph.

- bill
 
Hi,

My target if I decide to head to Kansas is in the vicinity of the W winds perhaps northwest of Great Bend. I am not as happy with the upper flow though a sharp right mover could do the trick. Moisture may be a concern as well - we'll see how the recovery goes.

I'll decide in the morning.

Regards,

Jimmy Deguara
 
Got a room in Dodge City. Not very happy with latest model runs. I knew the dewpoints were over forecasted but still hoped for something better as it stands now. I'd write more but gotta go to bed. If you see me tommorow I'll be in a black toyota paseo with AZ plate, hope to see some chasers out. Good luck.
 
Agree with the latest model runs, esp. with moisture showing 55-60 dewpoints. I will likely chase anyway as I really having nothing going on tomorrow. Will head towards Woodward in the morning and go further east from there to around Liberal give or take 40-50 miles. Hope to see you out there Robert. I will be driving a brown/beige Nissan Altima with Oklahoma tags. Need to get some sleep for tomorrow.
 
This event seems to remind of the Hoisington f4 event back in on April 21, 2001, there are of course differences, Hoisington event featured slightly higher dewpoints and lower temps and thus lower LCL's (700 mb temps were lower too so the lower surface temps did not result in stonger cap), also Deep layer wind fields were stronger. So basically the problems with this set ep weren't as significant of problems on April 21, 2001, but similarities are still prevalent however.
 
Even if moisture return is adequate, I'm not convinced the deep layer shear will be supportive for *nice* supercells. While the ETA derived hodographs in KS look nice (cyclonically curved), weak 500mb winds may lead to updrafts that rain out quickly. Storms will certainly be moving at a snail's pace ;)

ATTM, the setup is too marginal for me to chase, but I'll throw in the obligatory 12z data check tomorrow before any final decision is made.

Aaron
 
Another virtual chase lining up!

Have had a peek at this...2 areas of possible interest, neither especially great! 1st is around Dodge City, or just to the north of there, ahead of a forecast dry-line bulge, and close to the DL/WF intersection. 2nd area is Childress-Turkey. ECMWF breaks out heavy precip across the cap rock here, and although shear is marginal for severe storms, there seems to be enough for isolated supercells. However, there is some convection down there at the moment, and this could limit surface heating. However, it could also throw out some boundaries.
 
Looks to be a very marginal chase at best. Deep layer shear will be at the very mininum for supercells today. Overall wind speeds are very weak but there is very excellent veering with height. However, with the winds being so weak and storm motions of 10-15knts, cold pools should rush out fairly quickly and cut off supercells causing to line out. Moisture is another major concern today, Td's will only reach 56-60F today near the triple point and with the sfc temps reaching upper 80's, this will lead to very high LCL's.

The tornado threat will be very slight today given all the negatives that this system offers. However, I missed the Beatrice tornado because I decided it wasn't worth the trip given the margional moisture. So with that said, I will probably chase because I don't want to get kicked in the butt again missing a tornado. :rolleyes:
 
I've been watching the OK mesonet for the past 90 minutes and the dewpoints are already higher than forecast on both the RUC/ETA. A nice nose of 60-62 has been working its way from NW TX across the river into SW OK and continues to spread north. Not saying this turns the day around, but you have to like seeing moisture being UNDERforecast this year. A check of local temp forecasts across the DDC CWA shows mid-upper 80s along and just south of the I-70 corridor. If the current moisture tongue can continue its pace throughout the day, there is a chance we could realize 60-62 dewpoints in a narrow axis near the TP for dewpoint depressions in the 20-25 range, just over the borderline for tornadoes. Might be a longshot but it's certainly possible. Someone's gonna get an awesome storm and maybe a tornado today, might as well be me.
 
Yeah, definately a bit discouraged to see the day slip a bit more into the marginal category, but stranger things have happened. TDs in the mid 50s in Souther-Central Kansas hopefully indicate a rise to near 60 or more. While I think the LCLs will be the big concern today as temps fly into the upper 80s to low 90s, I'm hoping the warm front will allow us a brief chance along and near I-70 for storms. Flow isn't as great as one would like to see, which also leads me to think the precip will rain into the updrafts. The opposite side is that storms will be moving slow enough today which is a far cry from everything else I chased this year.

Logistics are also playing a role as we have 8 people split among two vehicles, so a Sunday chase so close to home split among 4/car is hard to pass up in itself. We'll be heading out from Denver and be on the road by 9am.

I've seen stranger things happen, especially in this area of the country. I'm not sure I'm ready to write the day off yet, so I'll at least venture out and give a hoot before I call no joy. We'll see how conditions change over the next few hours and see if there's a small area someplace along that front which could offer some hope.
 
No go for me. With very marginal shear, weak wind fields, high background pressures, and an upper ridge sitting right over the target area, along with the marginal moisture situation, I don't expect much to write home about.
 
I'd be heading for Burlington, CO this afternoon except for one reason: the community band I play in is having a concert at 7 p.m. tonight, so I can't chase today. Hopefully we'll get a nice storm or two back towards my area (Fort Morgan/Sterling) but it looks like the most interesting storms will be in far eastern CO/western KS today, and I couldn't make it back in time if I drove to Burlington or points further east. Besides, with gas being the way it is, I can't afford to chase a marginal situation like this. I'll just sit this one out, hope for at least a nicely structured non-severe storm within 50 miles of my house, and wait until an event with more significant potential comes along to go out chasing farther east. If I have to wait a couple of weeks for it, so be it.
Just my $0.02 worth.
 
Ryan McGinnis and I are sitting looking at data in Hays, KS on a very marginal day (but hey, it's Sunday!).
Storms firing around Dodge City are moving NE and expected to hit some higher CAPE air at about the same time the cap is expected to erode according to the ETA for 0Z Monday. I'm guessing this will occur somewhere around NE of Great Bend (perhaps the Lyons, KS area)*. This is the same area that multiple earlier experimental parameters identified, which is hopefully more than coincidence.

*(but then I'm a real rookie at this)
Wishcast out.

Darren Addy
Kearney, NE
 
I think we're going to go east here a bit towards Salina. There are some CU starting to materialize on the last few sat shots, and that's more than I can say for where we are sitting. The Tds are a bit better east, too.
 
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