5/1/08 FCST: KS/MO/OK/AR/TX/NE/IA

[Jeff Miller]

Could be quite the interesting set up in and around the Sioux City area later today. MikeH seems to have caught on to this a little earlier today, and the SPC now has raised the tornado threat in the SD/NE/IA Tristate area from 2 percent to 5 percent.

Earlier today, the idea was temperatures wouldn't be able to make it past the mid 60s. However, steady dew rises and temperatures now heading into the mid 70s in this region will be interacting with a stationary front draped right on this region. Once any storms cross this front, again near the SUX area, they have the risk of becoming tornadic with impressive shear differentials looking at 0-2km and 4-6km (SR) winds. Also, hail parameters look somewhat better too with deeper moisture and higher temperatures interacting with strong lapse rates.

On a personal opinion, I think that the local office here has totally downplayed the situation and nearly dismissed the potential. They actually reduced the threat here for precipitation in the mid-morning update. I'm not sure why they aren't buying the dynamics. I expect one or two supercells in this area to cross the front.

In a nutshell, SUX to Vermillion, SD could be a great northern target player this afternoon.

 

[George Grant]

Nonetheless I woke up today with a migraine after securing a day off yesterday (of course), so my chase target will remain 50-100 miles west of my home in Ames, probably around Jefferson, Iowa, to play the warm front if I don't get sicker.

After the disappointing coolant-leak trip to McCook last week, the water pump has been replaced. Although I've now contracted the worst case of the flu I've had since I received a flu shot at Fort Benning 18 years ago. So, I'll go chasing anyway.

60 degree Tds have finally made it to S Iowa & Nebraska. LLVL winds look to be a little more backed over in W Iowa and back into NE Nebraska. The RUC breaks out precip in that area by 0Z. And, it reveals a small corridor of SRH in this area. Looks like I'll keep it close to home and try US59 between Harlan & Denison. Although, the northeast Nebraska quadrant also looks intriguing. Maybe I'll follow a couple pros and head up US275 towards Wayne closer to the triple point...

Geo

 

[Dave Winslow]

Northern Target

I'm just about to complete our noon weathercast in Sioux City and after earlier targetting Columbus, NE, I am thinking that staying right here may be the way to go. I think Mike H. picked Sioux City as a good northern target in an earlier thread, and in a rare stroke of fate I may not have to move anywhere. The OAX sounding is pretty disheartening with 10 C at 700 mb, but with a dry slot moving into SE Nebraska right now and eventually maybe towards Sioux City, things could get interesting along the Misssouri River by the evening. RUC shows storms forming right on top of Sioux City along the cold front/warm front occlusion and riding northeast on the edge of some good helicity. ESE winds here are around 18 mph and skies are still overcast. But I think this location for people who can't and don't think it's worth the gamble to race into Southeast KS could see something.

One lacking point is the lighter 500 mb winds....30-40 kts at best if RUC is correct by 7 pm. The good shear is at lower levels along warm front.

 

[Jeff Miller]

Dave,

I agree with you on the lacking 500mb winds... however, I feel that any front-riders will be able to interact with enough low level helicity to accomplish decent rotation. It's going to be interesting to see exactly how this plays out and develops, thats for sure. Now, the sticky point is trying to figure out time of initiation along the northern target.

 

[Derek Weston]

Seriously considering a NW Iowa target now. Could be in Topeka or Sioux City by 5ish. Seems as though we have a better shot at seeing *something* up north. Would like to see the clouds leave, but along the WF up there looks interesting. I've already seen this sort of setup close to the low play out a few times in Iowa this season ... maybe again?

 

[mark plate]

My "sleeper" target from yesterday is awakening...with more people jumping on the northern (specifically NW initially) Iowa target. U.S. models coming around to what the EURO models showed yesterday in that area with warmer temps/higher Tds/stronger 500 winds. Current obs support this as well.

Temps may push 90 along the dryline in the Pawhuska to Stillwater area late this afternoon? Will this be enough? Maybe. It may take temps that warm to get a storm before dark. Dryline retreats by 00Z, so if a storm doesn't go by then, it may be closer to midnight before they get going. High LCL's liable to be a problem down here anyway for tornado genesis...hence the relatively low 5% SPC tornado probabilities.

 

[Mark Blue]

My wife and I will be setting up shop in Chanute KS after driving to Colby KS from Denver last night. I like this target because the dewpoints will be in the 63-64 range by 0Z and the secondary low that is forecast to develop along the OK and KS border in response to the upper air energy ejecting out later today. I think the strong surface heating in the general SE KS region is also going to aid in a severe outbreak later on today. If you're in Chanute and you see a red VW GTI with Colorado plates come on by and say hi!

I also like every paramater I'm seeing here including the hodogaph.

http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=RUC&STATIONID=kcnu

 

[Chris C Sanner]

The Due W 850 winds have helped me make up my mind to stay put here in Norman and just hope that the WRF was onto something. Right now the moisture at 850 has been shunted well E of the Dryline and I'm not quite sure I really care to sit under blue skies again like I did last week. I might as well invoke the Moore rule. It IS the first week of May after all. Scientific in my approach? Well....no. But it sure beats a blue sky cap bust...I'll either get a great storm or I'll finish some important homework. Win/win

As far as meteorological stuff goes, the CAPE is already 4000 down in SC Oklahoma and I have a feeling we will be seeing extreme Cape over a lot of Oklahoma. Will that be enough? If the 850 winds back nearly 90 degrees then we would definitely have a shot. I hope everyone that is taking the risk gets rewarded...but I'm just gonna have to sit this one (mostly) out.

 

[Edward Ballou]

NWS is saying the CAP will be too strong this evening. The clouds will definitely affect heating. Some of the parameters look pretty decent, but it seems like a very difficult recipe to put it all together for a show this evening. I'd love to see some pops, but I just don't have the confidence in this setup. Perhaps it's the gas price that's affecting my decision too.

How's that for the first forecast of the year? (yuck, no reply needed)

The WRF is popping a few cells by the Brookings area - I think I will stick around and try to get the car wet.

 

[Josh Richardson]

I've been torn between the Sioux City and SW IA areas all day, ended up driving to Creston and have decided to target around here. RUC seems to break out precip inv of the dryline in SW IA and at that same time creates a nice tongue of 0-1 km SRH. Guess I'll just stick it out in SW IA and see what happens.

 

[Chris Lott]

I know a lot of people are doubting the cap right now, but I believe it erodes over parts of C. OK. in the late evening. As stated, the 850mb winds aren't helping right now, but some soundings in the area suggest it's gone in late evening. Not good as far as viewing is concerned, but at this point I would take what I could get. I agree the I-35 corridor in C. OK. and south where the better tongue of CAPE will be. It would be nice to get a chunk of energy down here, where it looks like much of N. Texas could blow up with a little "umph".

 

[mark plate]

I know a lot of people are doubting the cap right now, but I believe it erodes over parts of C. OK. in the late evening. As stated, the 850mb winds aren't helping right now, but some soundings in the area suggest it's gone in late evening. Not good as far as viewing is concerned, but at this point I would take what I could get. I agree the I-35 corridor in C. OK. and south where the better tongue of CAPE will be. It would be nice to get a chunk of energy down here, where it looks like much of N. Texas could blow up with a little "umph".

I don't think anyone is doubting that the cap will break by late evening...that's never been in doubt as storms will definitely initiate by then when the cold front impinges on the dryline and starts kicking everything east. These storms should be linear and mainly a wind and maybe hail threat. However, these are not the storms the chasers are interested in. The cap may be killing the pre-dark tornadic supercells we're all hoping for.

 

[Kenny Drake]

For those southern plains chasers... Cu field going up north of ADM thanks to terrain-induced forcing. Diff Vort. Advection is still off to the west so I'm not holding high hopes for the Cu field to sustain itself once the dryline mixes either east or west of the area. Definitely worth keeping a watch on though. Mesonet showing nice sfc dewpoints in the area (mid 60s). Sig. Tor parameter is maximized in that area too. ~4000J/Kg CAPE and <25J/KG CINH.

 

[David Wolfson]

Currently heading east on US54 from El Dorado, KS, after recalibrating. The late RUC, confirmed by my eye with the vis. sat. is now discouraging of development much to the north per the northerly targets due to capping. The satellite seems to show the mid-level push sweeping aggressively east into MO and southwest IA, already to Omaha. Secondary low over south-central KS develops through late afternoon into evening as NE low occludes. Best forcing seems to shift south and stick at southeast KS border through 03Z.

Anticipating traveling east to Ft. Scott, then south on US69 through the afternoon, with (hopefully!) initiation around 22Z.

 

[beaudodson]

The Springfield, Missouri - NWS Office is thinking that discrete cells may not develope. They have written an excellent discussion this evening. You may view the discussion here:
http://kamala.cod.edu/mo/latest.fxus63.KSGF.html

Quote "THE POPULAR QUESTION FOR THIS
AFTERNOON REGARDS WHETHER OR NOT DISCRETE SUPERCELLS WILL DEVELOP
ALONG THE DRYLINE PRIOR TO SUNSET.
MY GUESS IS NO...UNLESS IT OCCURS UP IN NW MISSOURI OR FAR NE
KANSAS. THE AIRMASS OVER EASTERN KANSAS AND OKLAHOMA HAS TOO GREAT
OF A DESERT INFLUENCE...CREATING A VERY STRONG CAP."


The current maps from SPC are showing that CAPE has reached 3000-4000 across much of central and eastern Oklahoma then stretching into southeast Kansas. Satellite is showing some CU trying to form over Kansas. Not sure if this is going to be enough though to overcome the extreme cap - as the Springfield, MO Office has noted. It could be fairly late in the evening before thunderstorms are able to generate.

RUC pops numerous storms across Kansas and Oklahoma/Missouri. Problem is that the RUC is overdoing dew points. Looking at the current surface obs and coming them to the RUC forecast - they appear to be overdone. Not sure which model has a complete handle on the moisture return. This appears to be throwing off the QPF.

The Tulsa Office believes that the CU field forming over Oklahoma will break the cap as the wind fields increase over the next few hours. Yesterday the NAM forecasted a decrease in CIN across most of eastern Oklahoma after 4 pm today - a rather dramatic decrease. Tulsa has noted that CIN is decreasing over southcentral Oklahoma at this time.

Edit: A 20Z BALLOON FROM KOUN WILL BE RELEASED SHORTLY