5/24/2005 FCST: High/Central/Southern Plains

[Justin Walker]

Well once again, another marginal setup for May. Many things looking good across eastern Ok and western Ar. Helicity will be through the roof with values of 500 m2s2. Cape values of 2500-3500 J/Kg, possibly higher in locations. 850 Mb flow is weak out of se but 700 mb wsw at 25knts. 500 mb flow fairly strong with 45knts from sw. 250mb even weaker though, 25knts nw...ugh!!
The Cap is not as strong for tuesday. 850mb 19C and 700mb 9C. Still strong, but we have been getting close to breaking it across this region the last few day(except today, I don't think we were close).

We will have good mid level support for tuesday, upper level little weak, as well as 850. Lots of turning with height. So this forecast definately has holes in it. We will have to just wait and see! :roll:

EDIT: Lamont 00z sounding still 238 CIN...Not even close to breaking today

 

[Mike Johnston]

Agree, Justin; there are some factors to like for an E OK setup on Tuesday. Besides those you point out, note the negatively tilted surface low, extending from center in extreme SW KS, southeastward across OK. Proximity of warm front and forecast surface moisture convergence suggest we may have a real surface boundary at work. Deep layer shear of 35 kts out ahead of the boundary is decent (at least relative to recent days this far south.) I also like the way weaker lid strength, low LCL's, and theta-e ridge is forecast to be oriented out to the right of the surface boundary.

Southern extent of cloud cover during the day from overnight convection forecast to the north of target area may be a limiting factor. I agree that cap looks breakable. Now somewhat dated SPC day 2 outlook bifurcates the discussion into a western high plains setup and a second setup AR to Miss Valley. However, I would not be surprised if the next version brought more focus towards E OK - perhaps areas just south and east of OKC.

 

[Jeff Snyder]

I'll await morning data before posting a more detailed forecast... However, I did just want to mention that I think tomorrow's potential in OK is nearly entirely dependent upon the movement of the MCS in western Kansas right now. Given the very slow movement, there is a very signficant possibility that the cooled, dried outflow air from tonight's convection could overspread OK and pretty much squash any real severe possibility tomorrow afternoon/evening.

 

[Ryan McGinnis]

Day's not looking terrible on the plains, either. The usual problems of this year exist -- moisture, for one, with a 20F+ degree dewpoint depression forecast on the NAM for western NE & KS. The cap is an issue, with 700mb temps around 10C; even higher as you go south. Looks like a shortwave is progged to kick through over the 18-0Z period. The LLJ isn't too exciting, but it's butting under a pretty nice NW flow, with 45-55kts of shear between 18Z and 0Z on the NAM. NAM progs some 250mb diffluence above south-central Nebraska. If anything pops in Nebraska and Kansas, it looks like it'll be high-based hailers, but even that's better than nothing this year. I don't know if I'll chase tomorrow (I'd have to take a day off of work, which are limited), but if I did, I'd probably start the day out in Kearney, NE and move south and west of there. The cap gets weaker further north, so I'd suspect storms would fire in extreme southern Nebraska/northernwestern Kansas first, if they do.

**(disclaimer: poster is rather new to forecasting. If anything I say makes no sense, let me know. )**

 

[Kiel Ortega]

Originally posted by Jeff Snyder
I'll await morning data before posting a more detailed forecast... However, I did just want to mention that I think tomorrow's potential in OK is nearly entirely dependent upon the movement of the MCS in western Kansas right now. Given the very slow movement, there is a very signficant possibility that the cooled, dried outflow air from tonight's convection could overspread OK and pretty much squash any real severe possibility tomorrow afternoon/evening.

What sucks is the 12Z OUN sounding is contaminated...though the 12Z LMN doesn't look too appeasing for Oklahoma. Looks like CO again for today...lapse rates on the 12Z DNR sounding look great for hailers again. I'll go with Ryan's and the SPC's forecast of hailers (kinda surprised didn't see larger hail reports yesterday)...at least there's been some consistency in the past two days...unlike the TX Panhandle where it was a lot more finiky (spelling?) a couple weeks ago.

 

[Tom Dulong]

This from NWS Boulder early morning SWO...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL COLORADO.

.DAY ONE...TODAY AND TONIGHT

SEVERE THUNDERSTORMS ARE EXPECTED ACROSS NORTHEASTERN COLORADO THIS AFTERNOON AND EVENING. THE COMBINATION OF MOISTURE ...DAYTIME HEATING...AND MODERATE WIND SHEAR WILL PRODUCE AN ENVIRONMENT WHICH IS PARTICULARLY FAVORABLE FOR LARGE HAIL. SUPERCELL THUNDERSTORMS WITH DAMAGING WINDS AND TORNADOES MAY ALSO DEVELOP ON THE PLAINS DURING THE LATE AFTERNOON AND EVENING.

So your best bet is same area in high plains that got hit yesterday...xcpt shear, helicity, and potential instability to be a little better today. Also, ACCAS over the CO Front Range this morning...a good sign

 

[Jeff Snyder]

I'm wondering about the supercell potential in eastern Oklahoma within a few hours. While the surface winds are rather disorganized, Tds in the upper-60s to low-70s east of OUN with temps in the upper-80s are yielding (according to SPC mesoanalysis) CAPEs in the 2000-3500 range. Additionally, both the Purcell and Haskell profilers are showing strong mid-level flow across the area, with Purcell showing 35kt 500mb, and Haskell showing 40-45kt midlevel flow. Continued insolation should help weakend the cap further and increase the potential instability. Current satellite showing cu developing / persisting along and east of an Edmond to Hugo line. Currently mesonet obs and satellite showing an OFB/front sinking southward across northern OK, located mainly along a line from Edmon to Broken Bow, and east-northeast from there.

Again, weak southwestery flow south-southeast of OUN is yielding little helicity, though more backed surface flow exists farther into east-central and southeastern OK. Profilers showing a nice veering wind profile above the surface, so low-level shear is still sufficient for supercell, despite the pitiful near-surface shear (0-1k). I'd say supercells are possible, though the poor near-surface shear would likely diminish much of a tornado threat.

I may head out just east of here in the couple of hrs if it looks like storms are going up.

 

[Kiel Ortega]

Originally posted by Jeff Snyder
I'm wondering about the supercell potential in eastern Oklahoma within a few hours. While the surface winds are rather disorganized, Tds in the upper-60s to low-70s east of OUN with temps in the upper-80s are yielding (according to SPC mesoanalysis) CAPEs in the 2000-3500 range. Additionally, both the Purcell and Haskell profilers are showing strong mid-level flow across the area, with Purcell showing 35kt 500mb, and Haskell showing 40-45kt midlevel flow. Continued insolation should help weakend the cap further and increase the potential instability. Current satellite showing cu developing / persisting along and east of an Edmond to Hugo line. Currently mesonet obs and satellite showing an OFB/front sinking southward across northern OK, located mainly along a line from Edmon to Broken Bow, and east-northeast from there.

Again, weak southwestery flow south-southeast of OUN is yielding little helicity, though more backed surface flow exists farther into east-central and southeastern OK. Profilers showing a nice veering wind profile above the surface, so low-level shear is still sufficient for supercell, despite the pitiful near-surface shear (0-1k). I'd say supercells are possible, though the poor near-surface shear would likely diminish much of a tornado threat.

I may head out just east of here in the couple of hrs if it looks like storms are going up.

18Z LMN sounding doesn't look so good, but maybe farther south it's a bit better...SPC mesoanalysis seems to correspond okay to the sounding at LMN. I agree with you that the tornado threat is null as the BL winds are complete crap.