2012-04-09 FCST: KS/OK/TX

[Warren Faidley]

Looks a rare, May like pattern setting up next week, offering multiple day chasing in favorable regions.

Monday looks to be a potential sleeper, but worth an early deployment for me. The specifics are covered in detail, re: SPC Day 2, DDC, AMA and KOUN AFD's / HWO's.

Models are forecasting 60+ DP's with around 2k J/KG CAPE and favorable jet dynamics and directional shear. This has the makings of a classic sneak attack, along with similar possibilities on Tuesday, Wednesday and Thursday, before a more dynamic system moves in over the weekend, which could produce a "big" show.

Regardless, nice to have non-overly dynamic setups in April with somewhat slow moving storms... initially.

Someone may want to initiate threads for Tuesday onward.

Good luck to all, be safe.

W.

 

[brice.coffer]

Just finished looking over the morning models. I agree about Monday being a potential sleeper. While not great, CAPE and helicity are sufficient enough for supercells, and 0-6km bulk shear should not be a problem either. NW flow will keep storm motions at June-like conditions, however it won't provide much upper-level support for lift. The combination of surface heating and weak confluence along a diffuse dryline, will most likely allow for convection in NW OK/SW KS, in my opinion.

I think the main threat seems to be large hail and winds. The hodographs are nicely curved in the low-levels but pretty straight overall. If convection can form and mature, splitting supercells seem likely, which will only increase the SRH. If that happens and storms can find themselves in an environment of low LCLS, then I think we'll see some tornadoes tomorrow.

I saw the Mapleton tornado last year on April 9th, so I'd love to see another one tomorrow to make it 2 years in a row.

 

[Stan Rose]

12Z NAM shows some enhanced helicity along the warm front near the OK-KS border by 00Z, if there's gonna be anything that's probably the place to be.

 

[Jesse Risley]

The 12z/07 models (ECMWF/NAM/GFS) do seem to be coming into better agreement about tomorrow's potential in OK and KS and TX. Taking a look at the upper-air pattern, there seems to be consensus that a perturbation will approach from the west, embedded in the NW flow, with NAM being slightly more bullish on wind speeds and a more pronounced vorticity maximum nosing into W OK between 18z/07 and 00z/08. By midday, it looks like an area of low pressure will be sitting right near far western TX/OK panhandle region, with a warm front gradually pushing well north of the Red River Valley during the day, progged to orient itself from NW-SE, likely from near Woodward, OK to Ardmore, OK and points SE, while a cold front approaches from the north, drifting southward towards the KS/OK border region by mid-afternoon.

The NAM and GFS are slighly more bullish with moisture pooling behind the warm front, with both showing Td profiles </= 60 degrees reaching NC OK by 18z; on the contrary, the ECMWF is showing this higher moisture return still down near the Red River Valley at the same time, though all models seem to show better Td profiles </= 60 degrees moving well into WC OK by 00z/08. This is all related to there being some sizable differences in how the models are handling SBCAPE profiles, with the GFS and the NAM showing far more magnanimous values over a much broader region than the ECMWF is, with the NAM being the most bullish of the MAF trifecta. Nevertheless, there is a good consensus that at least parts of the far NE TX panhandle, NW OK and SW KS should realize SBCAPE profiles AOA 1,000 J/KG by late Monday afternoon. SFC-500 mb bulk shear profiles on the magnitude of 35-40 kts should support the maintenance of supercells and, as Stan noted, some of the forecast Skew-T, Log-p diagrams on the GFS/NAM/ECMWF are noting ESREH values >150 m2**s2 INVO the warm front across NW OK/far SW KS, with very respectable hydrolapses between H7 and H85 and WB0 levels around 7k - 9k feet.

Given these aforementioned forecast Skew-T, Log-p profiles, large hail, some significant, and damaging downburst winds look quite plausible, though I believe we'll see a few TOR reports tomorrow as well, especially near the front, where 0-1 km shear profiles will likely be maximized INVO progged LCLs <750m. Ahead of the primordial forcing for ascent, I'd expect to see convective initiation somewhere ESE of a (approximated) Liberal, KS - Perryton, TX - Pampa, TX corridor after 18z, with convection spreading ESE into Texahoma and overspreading the Red River Valley region overnight as the frontal boundary sags southward.

 

[Jacob Ferden]

Not a whole lot to add to Jesse's post, but am looking at a preliminary target of Woodward, OK by 20z. Thinking as others do that the primary mode here will be splitting supercells eventually organizing into a convective system moving off to the SE by sunset. Thinking the best chance of a tornado or two will be right near the triple point where 0-1 km EHI is maximized, and early on (first one to two hours after initiation) before storm modes become less favorable.

 

[Jeff Snyder]

I'm still on the fence for today, but I'll need to make a decision within the next 15 mins if I want to give myself enough time to get up to far NW OK and make adjustments from there. Current obs show widespread 60-61 F Tds across western OK with temps near 70 F. There appears to be a weak dryline in the extreme eastern panhandle, with Tds in the low 50s and temps in the low 80s; a weak cold front is located a little farther west (temps in the low-mid 70s, Tds in the 30s and 40s with weak winds). Upper-troposphere flow is out of the west-northwest, with southerly or south-southeasterly sfc winds in the "moist sector". Clouds have been eroding across western OK, but present vis sat imagery shows clouds hanging tough in southwestern OK. Current sat and radar indicates some mid-level cloudiness and showers in the central TX panhandle westward into parts of eastern NM. Fcst hodos from the 12z NAM show nice low-level curvature as winds veer from SSE to W from the sfc to near 3 km AGL. The vertical shear vector does change direction of rotation (from clockwise with height to counterclockwise with height) near 4ish km, which may jumble up the vertical perturbation pressure gradients (refer to the linear term of the perturbation pressure eqn) and, therefore, the potential for storm motion that deviates from the mean wind. At any rate, this is a minor concern for me. I'm eyeing the area around Fort Supply, but I'm open to adjustments depending upon what happens with the junk in the C TX panhandle and what happens with the cloud cover in W OK.

 

[Tim Vasquez]

I haven't followed the spotter or chaser reports, but I have seen the radar through the afternoon. Northwest flow supercells producing a series of tornado warnings in the area south and southeastward of Woodward. The tornadic circulations all appear to show a southeastward track (140 deg). The main storm weakened considerably at 2356Z... it looks to have been seeded by a new storm that is now becoming dominant further west near Camargo and definitely is showing significant gate-to-gate shear on all of the low-level elevation cuts. Unfortunately it looks like the Canadian River will be causing a lot of navigation problems, but I suspect over the next 20 minutes we'll see this circulation moving into south central Dewey County near Rhea.