4/24/08 FCST: NE/KS

[Chad Cowan]

The latter profile would lead to the infamous hodograph "kink" that has been noted in conjunction with significant tornado events. So, not only are backed 850 winds great for moisture advection, they're also great for enhancing helicity.

A really good paper by Edwards & Thompson that mentions hodograph kinks:
http://www.spc.noaa.gov/publications/thompson/3may99/waf.htm

Don Giuliano and John Esterheld have an excellent presentation available on the 'hockey-stick hodograph' topic:

http://americium.gcn.ou.edu/presentation.ppt


To keep on the FCST topic, if I were chasing I would be around Medicine Lodge, KS at 10pm.

 

[Jeff Piotrowski]

OK/KS Target

The 17Z ruc says that the DL pops from west of ICT to west of OKC.
I like the area from ICT-END- to west of OKC. I would expect the Moderate to be pulled back south into Oklahoma on new update.

EHI over 9 NC OK at 0Z watch out.

 

[Alex Lamers]

Dryline is really sharpening up now. Hollis mesonet went to 92/29 at 1:50pm!

Profiler network over OK is beginning to show encouraging signs of winds trying to become more south-southwesterly. Lamont looks the best...850mb winds regularly ssw at 30-40 knots now.

New 18z RUC looks pretty exceptional for NC OK.

AJL

 

[John Hudson]

Loving the setup for WC Nebraska on 18Z RUC right now. Winds nicely backed, and good numbers on SRH at 40-50. Decent moisture returns at 1600 j/kg.

Going to target the area of Wallace, NE and wait for early evening for a good show.

Good luck for all.


John

 

[Fritz Kruse]

18z Ruc paints scary picture just northeast of Dodge City by 00z or 7 pm, but the CAPE and dewpoints look way too high based on current obs. Also it is suggesting much better mid level winds than previous.

I like 2 areas now, near Dodge City as the higher dewpoints wrap around and just north of a dry line bulge, then the north target near McCook.

 

[Mikey Gribble]

We are sitting in Pratt right now. I'm pretty comfortable with where we are at so I think we'll just stay put for the time being. I like the area ahead of the northeast portion of the dryline bulge. The dryline is pretty sharp (and tightening up) just across the border in Oklahoma. The moisture gradient is much wider just North of the border towards DDC where moisture kind of wraps back around towards the surface low. This should help to pull the mid 60 dewpoints along the OK-KS border northwestward towards Greensburg and just East of DDC. You also get a good overlay of higher temps and moisture tounge in this area (hence the CAPE tounge). I am banking on a storm firing between the border and DDC on the northern portion of the bulge (where the moisture gradient is sharper) and tracking into the Greensburg to Pratt area. As mentioned earlier the Lamont profiler shows low-level winds increasing and starting to back, which is great to see. As long as we can get a storm somewhere in this area I think we're in good shape once low-level shear increases towards dark.
BTW if anybody is going to be watching this unfold tonight and wouldn't mind posting pictures on the ST now thread for me send me an email at [email protected] with your email address. I have my blackberry on me so I can take pictures of the storm every so often and email them to you to be posted. I'll probably be pretty busy while I'm chasing, but I'll at least try to get some pictures sent out if there's good structure or a tornado.

 

[Donald Giuliano]

Wow, the OUN 19Z sounding is abysmal, with quality moisture only about 2" deep. I've been concerned about moisture return after yesterday's convection down in TX, but this is not good...we're effectively dealing with low 60s dewpoints at best over southern KS/northern OK right now.

The RUC appears to be significantly overestimating the amount of available moisture, with the SPC mesoanalysis valid 19Z having nearly 14 g/kg at 850 mb with 2000+ MLCAPE and a weakening cap over OUN...by contrast, the 19Z OUN sounding shows only 11-12 g/kg at 850 mb with <1000 MLCAPE and a huge cap. It looks like there might be some better moisture near the Red River trying to edge north, but with the strong daytime mixing occurring I have my doubts as to whether or not it will be able to make it to the dryline bulge forecast to set up near Vance AFB late this afternoon.

I'll be keeping an eye on things in case the situation improves, but am strongly considering staying put in Norman, as low 60s dewpoints will pretty much eliminate our chances of good convection in northern OK this afternoon.

 

[Geoff Manikin]

The RUC is having major problems this spring with moistening the layer just below the inversion. The precipitable water data is adding in a positive moisture increment that is being erroneously applied at some levels that are already fairly moist.

You can see an example of this on the parallel RUC web page:
http://www.emc.ncep.noaa.gov/mmb/ruc2/para/17z/
If you scroll the left side menu to the bottom and click on the first guess sounding comparison for OUN, you'll see the erroneously moist layer at 800 mb. This contributes to overly high values of best cape and possibly at least partially explains why the model is triggering convection along the dryline in OK late today. The bottom panel of that plot shows that the parallel doesn't have the bad moisture profile, and FWIW, this model is not lighting up the dryline south of Pratt today.

 

[Mark Farnik]

Currently sitting in the parking lot of the Hays Days Inn debating on what to do. I'm tempted to drop south to Pratt for potential isolated cells coming off the dryline bulge near Dodge City, but I'm a little nervous about the cap further south. Right now the northern target near the dryline/front intersection looks good. I'm contemplating heading north on 183 to Plainville, then back west towards Hill City on Highway 18. If you're out and about today and see a black and silver Subaru Forester with Colorado plates, that's me.

 

[Fritz Kruse]

Mdt to Towering? Cu near Ok border south of Medicine Lodge. Short Fuse composite paints around 3000 J/kg CAPE with weakening cap.

http://www.crh.noaa.gov/images/ddc/short/SFC2_latest.png
http://www.crh.noaa.gov/images/ddc/short/SFC1_latest.png

I am anticipating initiation around 6 to 7 pm along dryline just east of Dodge City to Med Lodge, then some supercells moving east toward Pratt.

 

[Mikey Gribble]

AS mentioned above CU is building back to the dryline just south of the Ashland to Coldwater area. This is the general area where I expect a storm to fire this afternoon if it happens.

 

[Donald Giuliano]

The RUC is having major problems this spring with moistening the layer just below the inversion. The precipitable water data is adding in a positive moisture increment that is being erroneously applied at some levels that are already fairly moist.

You can see an example of this on the parallel RUC web page:
http://www.emc.ncep.noaa.gov/mmb/ruc2/para/17z/
If you scroll the left side menu to the bottom and click on the first guess sounding comparison for OUN, you'll see the erroneously moist layer at 800 mb. This contributes to overly high values of best cape and possibly at least partially explains why the model is triggering convection along the dryline in OK late today. The bottom panel of that plot shows that the parallel doesn't have the bad moisture profile, and FWIW, this model is not lighting up the dryline south of Pratt today.

Interesting, thanks for the information. Do you happen to know why it is excessively moistening only the layer immediately beneath the cap?

 

[Fritz Kruse]

South Central KS

Cu evaporating...not looking good for area now...and what a waste of CAPE and shear! Now not sure if initiation will occur before dark??

 

[Geoff Manikin]

Interesting, thanks for the information. Do you happen to know why it is excessively moistening only the layer immediately beneath the cap?

It's actually not constrained to be immediately below the inversion; it can happen in any layer which is fairly moist to start. It just happens to be close to the inversion in some recent cases. It is good to know that the parallel looks much better, but that won't be implemented until late summer, so a crisis fix for the operational RUC is being considered.

To get back on topic, though, none of the recent parallel runs is showing initiation in Oklahoma this evening, and the signal even in southern Kansas is fairly weak. This contrasts the operational RUC which has some healthy precip signatures along the dryline over the next few hours. For the sake of those chasing, I hope that the operational RUC is correct; for the sake of the future of the model, I hope the cap holds.

 

[Ilya Neyman]

Cu is thickening up a bit in SCNTRL OK E of 44 right now, while its diminishing across the north. This may be due to backing low level flow coming up across the Red River, while 850's still veered up north.

Still a low chance of a storm developing in OK, but sig. severe if one does and sustains itself past the cap.