6/5/08 FCST: TX/OK/KS/NE/MN/IA/MO

[Mikey Gribble]

I really haven't done much in the way of forecasting today, so I can't post a forecast at this time, but I did just throw together a quck paragraph on my blog on the setup for tomorrow. I'm feeling lazy so I'll just copy and paste that.

A tornado outbreak is looking likely on Thursday. Extremely strong wind shear will combine with moderate instability ahead of the dryline over potions of central Kansas, creating an extremely favorable environment for tornadic supercells. Long curved hodographs in the lowest 3km, 1km SRH >250, and 5km near 20kts will all be favorable for a strong tornadoes across the entire state. Right now I like the area from Pratt, Kansas to the Oklahoma border for a target. Discrete storms should come off the dryline in the late afternoon. Initially high LCL heights may limit the tornado threat, but as storms move quickly into the warm sector they should encounter better moisture and LCL heights will drop below 1000m. At this point the tornado threat will increase and cyclic tornadic supercells capable of strong tornadoes appear likely.

As Mike mentioned storm motions are going to be a *****. I am guessing 45mph for any good surface based storm, but that is right at the top of the range that you can keep up with. Another thing worth noting is that anvil level winds ahead of the dryline should be above 40kts, so we will likely be dealing with classic supercells at least until late evening, when a transition to HP may happen.

 

[Chris Lott]

For what it's worth, NWS in Norman says parts of OK could go under a moderate risk for tomorrow, and I could even see it possibly down into parts of NW TX. Once a storm fires on th dryline and gets into the juice it could go nuts.

 

[Heidi Farrar]

Yep, Day-2 Moderate all the way into Central OK with a (mostly 45%) hatched area from southern MN extending into north Texas!

http://www.spc.noaa.gov/products/outlook/day2otlk.html

I've been hitting the Skew-Ts pretty hard and have noticed how the northern target is seeming much more favorable for tornados on today's runs, as opposed to yesterday's. Yesterday this time, Lincoln, NE (NAM) had EHI in the 1-2 range, western IA wasn't much better, and the hodographs looked pretty disgusting. Now KLNK is at 4.4 EHI, SWEAT > 500, and the hodograph is big and loopy at 03Z. http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=klnk

Just a rough sampling of Iowa (KDMX, KFOD) looks pretty big, too. The hodographs aren't looking like western KS did back before the late May high risk, but they're definitely looking "tornado-y." EHI > 3 and SWEAT > 400 stretch at least to KMSP in Minnesota.

EHI & SWEAT are higher on average the farther south one looks, generally in the 5-7, >450 range from northeast KS all the way to Lawton, OK.

I've been considering chasing southern Kansas, but with the way things are looking for storm motion/speed, numbers of chasers, etc., I am not sure I want to throw myself into that kind of situation on my first official Plains chase. Think I'll hold off & try for southern MO on Friday; it's closer anyway.

 

[Joe Acord]

12Z data indicates that sfc low is expected slightly south of I40 across western OK at 00z Thursday night. SFC winds are showing se-ly 20 in the OKC metro area during that time. 850 winds from the sw at 50-60 knots. 550MB winds from the west at 80-85 knots. 2500 j/kg CAPE. 65-70 deg DP's.

Anyways, according to the basic data above, I am guessing that Central OK may get the undercard to the main event that everyone is thinking is going to happenng in nw-ern MO and SW-ern Iowa. I am pretty skeptical that things are going to play out that far north.

I want to thank Glenn Rasmussen for catching my typo...

just wanted to repost this since my theory about CENT OK coming to life tomorrow is looking eminent. I do think think that the area between Lawton to Alva is going to be reallly active tomorrow. Any isolated cell that pops on the dryline is going to rock-n-roll. When comparing the cap values earlier this week, the data is indicating that little to no cap is expected over the OKC area.

 

[mark plate]

just wanted to repost this since my theory about CENT OK coming to life tomorrow is looking eminent. I do think think that the area between Lawton to Alva is going to be reallly active tomorrow. Any isolated cell that pops on the dryline is going to rock-n-roll. When comparing the cap values earlier this week, the data is indicating that little to no cap is expected over the OKC area.

I agree, and am not sure cells will be all that isolated. I expect we'll see a high risk eventually somewhere tomorrow, and certainly believe the high risk could extend at least as far south as central Oklahoma including the OKC metro.

 

[Jonathan Whitehead]

Basically looking at data from the local WFO, appears tomorrow is an all-go with supercells firing along the dryline in central and south-central KS tomorrow at peak heating. H85 winds will be rather strong for early June at 50kts mid morning. H50 winds will be SWTRLY at 80kts. Also helicities are approaching "off the chart" values at 400m2/s2 along and east of the dryline in KS. The jet dynamics and forcing with this system is totally unheard of for this time year, more like April. So storm motions will be on the order of 50-60kts. CAPE values of 3000-4000 J/kg are progged with sfc dews in mid to upper 60s and temps in the 88-91 range. Now that does make for large dwpt depressions but the insane vorticity will more then make up for it. I also look for morning stratus in the Kansas Turnpike in the morning which will mix out rather quickly around noon. So categorically speaking, im going HIGH RISK tomorrow along the KS/OK state line from I-35 NWRD to SLN to OMA.

EDIT: This is a PARTICULARLY DANGEROUS SITUATION. I do hope the local TV mets are taking this seriously and that local EMAs are preparing for PDS event. I am concerned about a wedgefest event tomorrow, particularly with high populated areas in the threat region.

 

[Paul Redmond]

For what it's worth, NWS in Norman says parts of OK could go under a moderate risk for tomorrow, and I could even see it possibly down into parts of NW TX. Once a storm fires on th dryline and gets into the juice it could go nuts.

Roger that, recent Unysis NAM AND GFS runs indicate some dryline activity in north central and western texas (perhaps the last gasp in texas) on thursday around 22 CDT. Things could be interesting in north central TX untill the loss of daytime diurnial.

 

[Shane Adams]

Ironically, the h7 temps were killing much of this forecast by being too high a few runs ago, now they're almost too low. I'm not sure I dig the more-than-breakable h7 temps being advertised, along with those linear VV and precip fields. As of now, IMO, tomorrow looks a lot like what 5-3-99 almost was, a bunch of intense but linear storms all junked up together. I keep searching for some sign of where a storm might deviate more to the right, or perhaps be more isolated from the rest of the convection. The WRF CIN is depressing, if you buy into it, considering what it would mean to such a potentially-awesome chase setup. The GFS is more stingy with CIN, and more generous with surface veering. As weird as this is to say, I actually prefer the GFS solution currently.

 

[Warren Faidley]

Agree with a few others about taking the southwestern most options. I'm really tired of low hanging, rain-wrapped tornadoes in the HP super juice near fronts. (Like today in Colorado). Nice if you get there for the early initiation, but afterwards it's a pain to route between massive cells only to see insane wall clouds scraping the ground only to be fouled by cold outflows and inflows.

I suspect tomorrow will be a dryline event. Thank goodness.

A Perryton, Woodward, ICT line would be great.

W.

 

[Bill Schintler]

Chase Target for Thursday, June 5

Chase target:
Bee, NE (just NW of Lincoln).

Timing and storm mode:
Supercell storms will initiate at 4 PM CDT, with all forms of severe weather likely.

Synopsis:
The WRN CONUS trough will deepen through the period, and a lead H5 wave now over NERN NEB will be followed by a broad region of large-scale assent on Thursday. A broad area of severe convection is underway, extending from ERN CO into CNTRL IA, where a long-lived supercell has been a prolific tornado producer this evening.
The WRF is not entirely believable with regard to anticipated overnight convection trends across IA tonight. Current reasoning is that a large convective complex will move across the state, and this is supported by ongoing convective trends as well as the FCST nose of a 60kt LLJ which will transport copious amounts of moisture into IA between 04Z-10Z. Latest models have trended increasingly S with the synoptic SFC features.

Discussion:
As has been the case lately, the uncertain evolution of several elevated overnight and early morning MCSs will complicate the FCST picture. One storm complex, associated with a lead vort max, will track from WRN IA towards ERN IA and into SERN MN through 14Z. Storms will continue to train for several hours tonight near I-80 in ERN NEB. Additional elevated development should take place over SERN SD between 17-19Z owing to isentropic lift north of the WF. By 20Z, an OFB should exist along I-80 in ERN NEB, where it will intersect the synoptic WF near Lincoln. The WF will extend SW to low pressure centered SW of Grand Island; and then a CF will extend SW though CNTRL NEB and KS. Strong instability will develop in SERN NEB with afternoon heating, while recovery will be slower in SWRN MN and IA where cloud cover persists. Subsidence in the wake of the aforementioned lead wave will suppress SFC-based convection until late in the day when an H3 fanning diffluent pattern overspreads NEB and SD, leading to strong large scale assent. By 22Z, SFC-based convection should initiate first along the WF and intersecting OFBs, and should quickly become SVR given the magnitude of instability and shear. Deep-layer shear will increase to AOA 60kts as the H5 speed max ejects from the trough base, while a strengthening LLJ will result in increasing hodograph curvatures along and just N of the WF/OFB. SPC SREF suggests SFC-1km SRHs to 300m2/s2 in this area.

Feel free to PM me for nowcasting.

-bill
10:21 PM CDT, 06/04/08

 

[Brandon Sullivan]

Will be leaving here around 6 AM CDT..

Current Target (Based On 0z) Is around Topeka, KS maybe just a touch SW..

Winds appear to back pretty good in the area around 00z and CAP holds for a good part of the day.. CAPE and helicity values are impressive...

Basically all the parameters are in my liking, I cant really find anything huge to whine about... EXCEPT 65 MPH storm Motions!!! woo, move it or lose it!!!

 

[David Toner]

I agree with Warren. Aiming for a Enid, OK target to start with.

I am concerned that the supercells with how long the supercells will remain discreet before forming into a line.

Other than that and the fast moving cells this looks to be a very good chase day.

Good luck to everyone!

 

[Dustin Wilcox]

One thing I like about tomorrow is that the target area is vast, so hopefully we won't have a zillion chasers on one storm. Provided I really need to go to work tomorrow, I'm biased to E NE, though I'm not so sure that’s not where I would want to be anyway. Per the 12KM a nice 850 low and subsequent triple point sets up just to the NW of Columbus. Provided this is on the nose of the 50kt LLJ underneath a 60-70kt 500mb wave that will likely be my target, though current ongoing convection and overnight activity, sfc features are likely to change, any ofb's or differential heating boundaries will likely be huge in finding where Tornado potential will be enhanced, I do have some concern over storm mode as many models (including 4km WRF) are pretty aggressive with forming a convective cluster, though provided forecasted wind shear I’m not fretting.

My Target....
http://grib2.com/animate/nam218nojava.php3?fcsthour=24&type=ATMOS_BRF&region=C-PLAINS

EDIT: Again flooding will be a major issue across much of the target area, esspecially where storms are training tonight, many county roads are still washed out, throw tonights rain on things and by morning it may be quite nasty....

 

[mark plate]

I agree with Warren. Aiming for a Enid, OK target to start with.

I am concerned that the supercells with how long the supercells will remain discreet before forming into a line.

Other than that and the fast moving cells this looks to be a very good chase day.

Good luck to everyone!

I think we may see discreet supercells for quite some time down here in Oklahoma. The cap is stronger to the east, and I think will help keep storms somewhat discreet longer than areas further north.

My "gut" feeling is that initial supercells, which may produce violent long-track tornadoes, will weaken rapidly as they near U.S. Highway 75 in Oklahoma later in the evening and likely entirely dissipate before reaching U.S. Highway 69. More linear convection will develop back to the west around that time as stronger forcing arrives in that area.

Oklahoma City is at great risk...storms may weaken just in time to spare Tulsa...close call there though.

 

[afischer]

Bunker's motion 50-60kts for tomorrow? Are you kidding me? *checks calendar* I think a few significant/long track tornadoes are more or less a guarantee... just not sure how chaseable they'll be. Pack your rocket fuel...