5/22/08 FCST: NE, KS, TX, MO, OK

[Mark Farnik]

Call it a gut feeling, but I think the models are getting a little ahead of themselves by initializing the dryline and warm front a little too far south and east from where they will actually wind up on Thursday. Right now the target area appears to be Hill City/WaKeeney/Dodge City corridor, but I'd bet money when we get closer to the event itself the target area will shift back to the west about 50-75 miles from where the models currently depict it and the main show will occur in the Atwood/Oakley/Garden City corridor. As of now, my preliminary target for Thursday is Colby, KS, from which I can play south along the dryline or north along the warm front with ease.

EDIT: I'm not sure why the NAM is depicting a MCS trekking eastward along the warm front Wednesday night... the atmosphere east of a line from Julesburg, CO to Merriman, NE will be firmly capped through Wednesday evening, and any convection that forms in eastern WY and the NE Panhandle is going to rapidly lose intensity as it moves further east into the capped, stable air over west central Nebraska. I'd hedge my bets that the warm front is also going to make more northward progress than currently anticipated, and while I don't expect it to penetrate more than the southernmost tier of counties in Nebraska, I wouldn't be surprised to see it hanging out right on or on either side of the Kansas/Nebraska state line. The farthest north I would expect to see the warm front according to the models would be the Highway 34 corridor, and the farthest south I would expect to see it would be the Highway 24 corridor, so I'll split the difference and guess the warm front will be somewhere in between, roughly parallel to the Highway 36 and the Atwood/Oberlin/Norton corridor.

 

[Shane Adams]

When is the moisture return gonna start for this event? I've been watching the OK mesonet for the past 24 hours and the dewpoints in S Oklahoma have fallen 10 degrees over the past 12 hours, with NE flow dominating across the entire state. Kinda worries me about this Thu-Fri

 

[Brett Roberts]

When is the moisture return gonna start for this event? I've been watching the OK mesonet for the past 24 hours and the dewpoints in S Oklahoma have fallen 10 degrees over the past 12 hours, with NE flow dominating across the entire state. Kinda worries me about this Thu-Fri

With 68-73 F Td's already widespread over southeast Texas, I'm not too worried at this point. We currently have northeast surface flow over most areas N of I-20, but models forecast return flow to begin in earnest by tomorrow afternoon as the strong surface cyclone develops over the central High Plains. Hopefully, that will give us more than enough time to advect the good stuff as far north as NW KS/SW NE by showtime Thursday.

 

[Van DeWald]

I agree Robert, the moisture is there across eastern Texas, it's just waiting to get tapped. By Wednesday afternoon, there's a pure fetch straight out of the gulf. Open the floodgates and let it ride north for the next 24 to 36 hours on brisky southeastly winds.

Van

 

[Mikey Gribble]

With the LLJ cranking at 40kts overnight on Wednesday I think we'll see the moisture make some serious progress. I'm not too worried about it, but the moisture along the Texas coast was pretty shallow this morning. I would think deeper moisture is close by though and 36 hours of a strong LLJ should be sufficient time to get low to mid 60's to northern Kansas.

 

[Chris Hayes]

I too am worried about storm motion speed, but I think the storms will be going at a bit more of a chaseable speed in the warm sector at the triple point and south along the dryline.

 

[Mikey Gribble]

Here we go again with the NAM and GFS being half a state away from each other with their placement of surface features. If you go with the NAM I would target up around Norton to Hill City area. If you go with the GFS I would target South of Hays. Both of them have some fairly big differences that would have a significant impact on the chase too. Below is a NAM forecast sounding for Hill City and a GFS sounding for Hays.

Hill City - http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=_KHLC

Hays - p://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=GFS&STATIONID=_KHYS

Both solutions are supportive of tornadic supercells, but the Hays hodograph is a thing of beauty with a significant tornado paramater nearing 13. The NAM keeps 10km SR winds above 50kts, which would favor classic supercells, while the GFS keeps them much lower in the 30kt area, which would favor HP supercells. LCL's are lower with both models this run thanks to lower surface temps, so this eases up the need to stay on the warm front IMO. I really like the NE corner of the dryline bulge, which is kind of hard to place with an arcing dryline, but it is basically the Hays or Norton area, depending on whice model you go with.
Still a lot of details to be ironed out, but lower surface temps in the latest run is certainly a plus for the tornado potential IMO.
edit the hodograph is not so beautiful any more with the dryline being farther east. Go over to Salina though and it looks better with the 00Z run. It isn't as good as the 12Z, but as long as it is supportive of tornadic supercells I am not going to complain.

 

[Van DeWald]

48 hours out and the Nam has been very consistent on my target. Still sticking with a McCook, NE to Hill City, KS target here for the best tornado potential. By 00z 5/23, Nam progs the 0-1km EHI bullseyes around 8, with 40 kts of 0-1km shear with an H70 dewpoint nearing 7 degrees. LCL height about 1200. Maybe something right on the KS/NE border, up to 10 to 30 miles north of the warm front, wherever that sets up. Storms will probably fire down the dryline, but the above spot will most likely provide the best show I think. Just make sure the gas tanks are full at the beginning of the chase, as noted, it will be moving north northesat at possibly 40kts? Personally, am thinking the GFS may be too far east with the dry line which places the best energy between Hill City and Concordia. To far east, and too far south IMO.

Van

 

[Chris Wilburn]

Well not much has changed based on the latest 00z run of the NAM. Target is still a general area in extreme NW KS into extreme SW NE. Very deep surface low of 983mb should be located in the area of eastern CO with very backed surface winds around 20kts and backed 850mb winds near 40kts to create some nice low level shear. 700mb winds and 500mb winds are roughly due south. It would be nice to see the 500mb winds to turn slightly south/southwest, but we should be ok anyway. CAPE is forecasted near 2,500-3,000 J/kg and dews should reach near mid 60's in the afternoon. The warm front should be draped along the KS/NE border with the sharp dryline trailing from western KS into SW OK. I just did a forecast sounding for Hill City, KS based on the 06z NAM and it shows very low LCL heights by 00z on the order of 600 meters which is nice. LFC heights are roughly 1,200 meters. The thing I am concerned with on the WF play is storms quickly moving north/northeast into more stable air and thus hindering the tornadic potential. I prefer to chase the dryline in extreme NW KS where storms should remain in more instability as they move north/northeast. Previously mentioned forecast sounding for Hill City shows greater than 300 0-1SRH and greater than 400 0-3 SRH with an EHI of 6 and CAPE near 2,500 J/kg. Still a couple model runs left to go but you have to be encouraged by the run to run consistency of the NAM. Just to mention really quick the GFS does have the dryline a bit further east in KS along I70, but either way we should be good. I will be in Salina, KS Wednesday night and we should depart there towards the target area in the morning. General target along I70 in NW KS which will change I am sure. Hope to see everybody out there!

I just looked at surface obs. in TX and it looks like mid 60 dews are located in eastcentral TX and low to mid 70 dews are located along the gulf coast. Surface winds have began to back in southern and central TX and with a strong 850mb LLJ and 36 hours of moisture return left I think we should be in good shape as far as moisture is concerned.

 

[Paul Knightley]

We're in Hays at the moment - will stay here tonight as well. Looking at somewhere around Colby to Atwood, KS, for tomorrow at this stage, close to the dryline-front intersection. My worry is that heading much further north will bring the 850 flow too much around to the east, reducing low-level veering with height. Supercell motions shouldn't be too bad, especially if something can root onto the front.

 

[Paul Knightley]

Latest WRF seems to be shifting everything a little SE - obviously will have to refine tomorrow morning, but new data suggesting south of I-70 IMO, perhaps around Dighton, KS.

 

[Bill Hark]

Very impressive parameters coming together for Thursday. With a low in NE Colorado, warm front across Kansas that will lift slowly northward toward the Kansas/Nebraska border, surface winds will be backed across Kansas. Even the 850 winds will be backed. The 12 Z WRF and GFS shows strong SW winds (50-60) for most of western Kansas and the Oklahoma/Texas panhandles though more southerly in NE Colorado. Dewpoints around 65. The WRF shows the best CAPE (2500-3000) just east of Dodge City southward to I-40 but CAPE will be sufficient (about 1500) closer to the warm front in northern Kansas. Helicities will be about 200 but much higher along the warm front. Currently, I see two target areas. The southerly one is from Dodge City to Greensburg ahead of the dryline. The northerly one will be around Oakley, KS close to the triple point. I'll wait until later today to decide based on more data and where I end up chasing today.

Bill Hark

 

[Mike Johnston]

Latest WRF seems to be shifting everything a little SE - obviously will have to refine tomorrow morning, but new data suggesting south of I-70 IMO, perhaps around Dighton, KS.

Yes. As we see so often, the latitude of the lee surface low is shifting on these last few model runs leading up to the event. NAM now has it at 986 centered in far SE CO, while GFS has it at 984 over E Central CO. Apex of theta-e ridge looks to be bending around south of I-70 now. Actually, if you go purely on a parameters bullseye, the 12z NAM suggests a target invo Dodge City now.

 

[Jim Bishop]

Really wish I could chase this event. If I could I think I'd choose the southern target in Northwest Oklahoma.

I like the move veered 700-500mb flow, allowing the storm motion to be more toward the northeast than north north-northeast like it will be further north. Also the storm motion should be a bit slower and more chaseable in Western OK.

Regardless there will be tornadic supercells from I-70 to I-40, more isolated in Western OK, much more widespread near I-70. Big tornado day coming together for tomorrow...

 

[Jonathan Whitehead]

Thursday def still coming together to be classic high plains chase day.
A quick glance at models, specifically NAM, shows 60-70 sfc moisture return this afternoon and overnight. That would be my only reservation however with this setup-moisture return. Something that will def have to be monitered. For that reason Im keeping tomorrow a SLT with potential upgrade to MDT for the 06Z SWODY1.
I havent yet nailed down a target as I havent had time to pick thru everything but anywhere along a Hays to DDC line I think would be a nice place to be, someplace with good N/S/E/W road options.

Heres a glance at the NAM sounding for ICT.:
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=NAM&fcsthr=030&STATIONID=KICT

EDIT: New Day2 is out, MDT