5/23/06 FCST: KS / NE / SD

[Matthew Havin]

Echoing some of the chatter in the "Future of the Season" thread, I'd like to formally welcome back severe weather potential to the Plains for Tuesday. It's about time!

A 500mb shortwave will eject out of the Rockies Tuesday morning, supporting a 995-1000mb surface low by 21Z Tuesday somewhere between NC KS and central NE (according to the 12Z and 18Z Sat runs of the NAM). The GFS has a northern low in SD and a southern low in KS...which will likely become better resolved as a few more runs pass. Dewpoints in the 64-68F range will be possible in central/eastern NE supporting 2000-2500+ CAPE, coupled with 0-3km helicity in excess of 150-250m2/s2 across E NE.....supporting supercells with storm motions less than 30 mph.

Better resolution will of course come in the days ahead, but for those making plans, good launching points for Tuesday in my mind will be from Grand Island to Lexington NE (I-80), and down to Salina to Hays KS (I-70)(Kansas only a good idea if models revert to more southerly low as what 12Z NAM had).

 

[samuel stone]

I too would target south central nebraska if the NAM verifies with its forecast of the surface low. Temps drop
off a little from 95 or so to 85 north of the warm front (which nam bassically proggs on the ks ne border) this should result in better LCL's along and north of this front and of course more backed flow, so I wouldnt want to target too far south into kansas as storms may tend to be higher based in that area, not to mention cap could be a problem in kansas. If the gfs verifies with its place ment of the southern surface low, I would probably target the frther south like oh say concordia/ clay center/ Abilene, ks area.

I am a little intrigued by the morning precip the nam puts out, maybe a little outflow boundary in favorable orientation to storm motion set up?

probaly some of this difference in surface low placement will resolve in later runs so its best to just sit and watch those models.

 

[Stan Rose]

Tuesday definitely shaping up to be an interesting day...interesting enough for me to start checking mileages on my one day off work! 00Z NAM even more favorable and breaks out isold precip all the way to TX along the dryline by 03Z. LCLs are pretty high south though. If you buy the NAMs moisture transport, the best parameters would actually be up in SD where helicity is maximized thanks to the low, and there's lower LCLs too. But that's too much driving for me, so im hoping S Central NE holds up since that's at least within range. decent LL moisture remains the key. mid and low lev jets intersect at the KS-NE border at 60 and 40 kts respectively. Ill definitely be watching the progs for the next 48 hours

 

[samuel stone]

Yeah, 0z NAM definently moves the warm front and associated backing winds north in south dakota, while 12z NAM had it around ks ne border. I wont be heading all the way to south dakota though since I have Finals and dont get out of school untill 11 am here in Hutchinson, so I will definently be playing the southern target as well.

Edit: after looking at the 500-300 MB winds I think southcentral nebraska is still the way to go. upper level wind especially 300 mb, veer considerably more in southern nebraska and kansas while in northern nebraska and southern south dakota 500-300 mb winds remain southerly. I dont like the prospects of chasing in that wind profile. At this point I would target Red Cloud, Nebraska. This all based off NAM, hoping GFS hops on the band wagon.

 

[Tim Marshall]

Time to dust off the cameras once again and head to KS on Tuesday. This mornings ETA shows nice jet max across the area west of I-135. The system has slowed since last nights run. I am concerned about all that precip it breaks out in the morning which kills the CAPE. I may have to adjust my target southward from HLC to DDC if that occurs. Will continue to monitor. TM

 

[Adam Atkins]

Lovely kinematics, plenty of lift and gorgeous storm country make this an enticing chase opportunity. Tornadic events are more probable with backed surface-850 flow and there is a nice SSE low level jet all day long on Tuesday. I'm concerned the high temperatures and shallow moisture will mix out the higher dewpoints near the dryline which could hurt initiation possibilities, but there may be some uplope in the western KS/NE/SD to compensate (?). (This occurs a lot in the west TX panhandle and E Colorado) The lack of baroclinicity weakens the mid-level shortwave during the day but 40-50 kts at 500 mb is quite adequate for chaseable supercells. I'd look for moisture pooling where the strongest backed flow is just along and north of the warm front somewhere near the NE/SD border.

 

[mikegeukes]

12Z Run, differences in the models of the placement of the 500 mb low
Reading AFDs, local WFO's are saying the NAM is the outlier.

GFS: Western SD
http://weather.cod.edu/forecast/GFS/gfsUS_500_spd_60.gif

NAM: Northeast CO, Western NE
http://weather.cod.edu/forecast/ETA/etaUS_500_spd_60.gif

ECMWF: Northern NE
http://weather.cod.edu/forecast/ECMWF/ecmwf_500_spd_72.gif

UKMET: Northern NE/Southern SD
http://weather.cod.edu/forecast/UKMET/ukme...00_avort_60.gif

Canadian: Has a trof into Western SD, extending into NE
http://weatheroffice.ec.gc.ca/data/model_forecast/622_50.gif

NAM X: Northern NE/Southern SD
http://wwwt.emc.ncep.noaa.gov/mmb/mmbpll/e...mods.500z60.gif

Mike
http://mgweather.blogspot.com Weather Data and Forecast Models Links

 

[Dustin Wilcox]

I really enjoyed the fact that the ETA 0Z run pushes the low farther East then previous runs, making it a lot closer chase for myself. If tonights ETA where to verify I will be targeting the area between Grand Island and Norfolk, where CAPE is forecasted to be 3500 with dewpoints forecasted by the model to be 65 with a small area of 70 dewpoints pooling in NE KS, wind profiles also look favorable for good storm structure and a possible risk of tornadoes with decent backing winds at the surface and favorable SW winds at 500mb
Just wanted to throw this out there Sean McMullen a stormtrack memeber and his wife Katie were married yesterday (It was a fun night!!!) anyhow they are now on there chase vaction honeymoon so if you see them out wish them luck!!!

 

[nickgrillo]

I'm still leaving tomorrow around noon for Grand Island, NE and then go from there on Tuesday (will probably be headed south/southwest from GRI). The NAM and GFS still make a decent chase day out of Tuesday... With the NAM showing 2500-3000j/kg of mlCAPE by the mid-afternoon -- with shortwave ascent effectively cooling and removing the layer of CINH ahead of the boundary. I took a look at a few forecast soundings... I don't really like the LCL heights progged across a lot of the area (e.g. 1500-1800m AGL) but low-level lapse rates approaching dry adiabatic from the surface on up to 2 km combined with some low-level CAPE (the GFS shows a lot more CAPE below 3km than the latest NAM) could help things a bit.

For instance, the 21z forecast sounding for KHSI (Hastings, NE) shows about ~2000j/kg of mlCAPE (ascent from the lowest 100mb) with very steep low-level lapse rates within the boundary layer. CINH is also reduced to near zero by that time, assuming a parcel of 85/59F. So, increasing the Td to 62F increases CAPE to 3000j/kg, but still doesn't do much for the LCL, with the unmodified sounding showing the LCL at ~750mb, which is pretty high, and will probably tend to mitigate tornado potential a bit (and increasing the td those few degrees only brung the condensation level down to ~775mb). There is some decent low-level curvature (although the hodograph isn't particularly large) given the low-level veering -- with 0-3km SRH around 150-175m2/s2 across a lot of southcentral NE -- with enough 0-6km shear to support supercell structures, given sufficient flow at all levels, with a solid 30-40kts aloft at 500mb across southern/central NE.

I'm chasing (and will be out chasing through Day 10 quite possibley) regardless, just hoping we get regions of enhanced moisture pooling to locally lower LCL heights.

 

[Mike Peregrine]

Haven't had time to take a very detailed look at how things are setting up tomorrow yet, but something worth watching for KC area chasers who are working and unable to make a full day of it - -

Will be watching later runs today, but currently the 36hr NAM and GFS both like to break out precip in NW Missouri by 0z tomorrow under a significant CAPE target and great curvature on the forecast hodos. Anything that can break out in NE Kansas/SE Nebraska/NW Missouri during this time frame currently looks to be quite chaseable. Sig tor index also makes a significant jump in this target area at 0z. Something to keep an eye on, anyway.

Here is a current link to the KEAX 36hr forecast (note that this is subject to change as models update). As a possibly quicker option tomorrow, I'd at least stay in touch with what is going on in the STJ to Mound City, Missouri areas.

 

[Fritz Kruse]

Right now I am targeting the Hastings NE area, like many others, for
initiation of supercells because of the good turning from surf to 500mb
with shortwave trough, low level waa and jet.

I don't care for the GFS mid level winds, they look way to low for such a
vigorous shortwave and prefer the NAM winds around 40kts.

Timing of the shortwave trough will be critical for figuring out just where
to be, and adjustments will likely be made after 12z Tuesday.

Cannot rule out a few tornados with this much shear and instability around
2000 J/kg, and the LLJ may help toward dark?

 

[mikegeukes]

Negative thing I see for Tuesday is the inverted-v soundings.
Quick look at some 12z NAM forecast soundings, for late Tuesday (00Z Wed)
across portions of Nebraska and Kansas, show a lot of inverted v soundings,
which favors damaging winds and some hail than tornadoes.

Forecast Soundings for Selected Cities in Kansas and Nebraska can be found here:
scroll down a bit, there near the bottom of the blogs.
http://mgweather-kansas.blogspot.com/
http://mgweather-nebraska.blogspot.com/

Mike

 

[Jason McKittrick]

After looking at this mornings models and this afternoons observations I am somewhat encouraged. Although I have seen better moisture fields in past years, as far as this year is concerned a 5PM Dpt of 70 at EMP is impressive. We will need all the moisture we can get if we are going to get anything significant going tomorrow given very warm temps aloft 700mb T 9-12C. I feel that Dpts in the mid to upper 60s maybe achievable in SC Neb tomorrow. The northern end of the dryline looks like the place to be, however if anything can initiate along the warm front there would be tremendous shear and instability available there. My feeling is that the cap will be a sufficient along the warm front to preclude any development during the daylight hours since all the forcing seems to be associated with the SW trough moving across C and W Neb tomorrow afternoon. I would hate to drive all the way to Aurora only to have storms go up tomorrow afternoon along the warm front where there will most certainly be better instability and shear.

My name is Jason and I am a chase aholic. It has been 15 days since my last chase and now only 18 hours and counting til my next chase.

 

[Mike Hollingshead]

http://www.wxcaster2.com/CENTRAL_MESO-ETA_...NDSBLI_30HR.gif

Interesting flow in sc now on the meso-eta. We'll see if tonights run does anything similar. I think a lot of tomorrow will hinge on if there is indeed a decent sfc low in NE or not. The shear doesn't look all that great unless you can get the sfc to back like it is on the meso-eta.

http://www.wxcaster2.com/CENTRAL_MESO-ETA_...HSWEAT_30HR.gif

Even with it being as weak as it is you can see what that does to the helicity. A sub 1000mb sfc low in sc NE tomorrow sure would be nice.

Edit: Well so much for that happening. I guess it is be on tail end charlie or stay home. With southerly flow along the sfc trough stuff to the north might have some issues.

Check out the moisture on TOP's sounding tonight HERE
The wonders of moisture pooling.

 

[Tim Marshall]

TARGET: HEBRON, NE Drove up to Salina, KS last night. Looks like I'm pretty close to where I want to be. Current (9am) target is within 60 miles of Hebron, NE. PROS: Ample surface flow, dryline progged to head east. Morning ETA and RUC show nice westerly winds at 500 MB over target. CONS: Quality moisture is a concern. No strato-cu around. I am also concerned about the low being progged farther north than expected, thus, upper winds (above 500) stay in northern NE and SD. This uncoupling of the jets has me concerned. Then, there is the cap. With 25C temps progged in northern KS, this may limit southward development. Lots of uncertainties today, but I am here to chase. TM