4/5/10 FCST: NE,KS,OK,IA,MO

[Joel Wright]

Monday's starting to look pretty damn good to me over central IL, back through northern MO, and southeast IA. Latest GFS largely agrees with the NAM, in respectable surface instability in this region. The warm front should help pool the surface moisture just south of front. GFS is probably a little overdone with the 65+ dews Monday afternoon, but 60+ seems pretty doable to me with the above mentioned moisture pooling. Excellent turning with height, with a pretty potent mid-level jet punching in by later in the day.

These warm front setups are obviously very tricky to forecast, and it's a bit early, but at this point I'm really liking west-central Illinois like some others have mentioned.

 

[Danny Neal]

I like the last runs from the NAM and GFS for obvious reasons . I guess what raises a red flag to me is this is the first time I have seen this advertised for this region. I was initially writing off Monday as a cap bust in the C Plains as I have discussed with others via private IM's but now my attention has been grabbed in a big way further east. I want to see a little more consistency before I lay my cards down, but it is definitely worth watching. Right now I am concerned with the possibility of "crapvection" (See: ILLINOIS) and that sfc winds are generally weak in the area of interest. Nevertheless, I will keep a close eye on Monday and possibly Tuesday.

 

[Joel Wright]

I like the last runs from the NAM and GFS for obvious reasons . I guess what raises a red flag to me is this is the first time I have seen this advertised for this region. I was initially writing off Monday as a cap bust in the C Plains as I have discussed with others via private IM's but now my attention has been grabbed in a big way further east. I want to see a little more consistency before I lay my cards down, but it is definitely worth watching. Right now I am concerned with the possibility of "crapvection" (See: ILLINOIS) and that sfc winds are generally weak in the area of interest. Nevertheless, I will keep a close eye on Monday and possibly Tuesday.

One thing I've recently noticed is a little wave of low pressure in Iowa Monday afternoon. This may help enhance the low levels, especially in southeast Iowa. I'm not too concerned with winds at the surface, since just off the surface wind velocities go up in a hurry. By mid afternoon winds as 925mb are forecast to be over 30kts, with a few pockets pushing 40kts.

 

[Eric Sipes]

VERY generalized cut and paste forecast from my website.

Location: A 500mb trough, characterized by 65-70kt WSW flow over the plains, will be centered over Utah by 00z 4/6. At the surface, a warm front will extend from Southern NE to Southern IA, Northern MO, and IL. A dryline will extend South from the warm front in SC NE through C KS and W OK, E TX Panhandle.

Discussion: Initial SVR weather threat will be over N MO and IA. Storms could be on-going in the morning with the possibility of marginally SVR hail. Later in the afternoon, storms will redevelope along the warm front in IA and possibly SE NE where a strong cap will be in place. Given mod instability and strong SRH, supercells containing large hail, strong winds, and a few tornadoes will be possible. Later in the evening, storms will grow upscale into an MCS as they move into W IL.

Further S and W along the dryline, a strong cap will be present throughout the morning and early afternoon hours. Later into the afternoon/evening, boundary layer warming should be sufficient to weaken CINH enough to allow for at least isolated storm developement. CAPE values upwards of 2000-2500J/kg and dewpoints ranging from 60-65F will likely be common across the warm sector. This coupled with 0-3km SRH of 300-350 m^2/s^2 and EHI levels greater than 4.0 means that any storms that do develope will likely be supercellular in nature. Large hail, strong winds, and tornadoes will all be possible if storms can develope.

-Eric​

 

[Ryan Wichman]

I have made a forecast at convectiveaddiction.com. I can't copy over much of the discussion because I have included a lot of pictures and soundings, but Monday is looking very good across SE Iowa area. Many of the models and especially the SREF is really picking up on this.

There are still a lot of little things which inherently cannot be picked out this far out i.e. where on-going storms will be and how they will mess up the atmosphere. By far the best looking like the best day thus far (Tuesday doesn't count!)

 

[Tony Laubach]

I think part of the reason that the models aren't picking up on a lot of precip is because the trough axis is still progged to be over Nevada and thus leaves virtually NO vorticity over the target areas from Kansas through Illinois. The 12z NAM keeps it mostly dry across the entire length of the front from Kansas to Illinois.. sorry Iowa. I don't think the lack of precip is completely due to capping issues as the 700mb temps are expected to be in the 6-8C range with a little bit of CIN, but not enough IMO to hamper development, at least on its own. The lack of upper level support across the region seems to be the biggest player which combined with the cap may yield issues, but given the surface conditions and convergence along the dryline and front, I expect a few storms to develop and hopefully take advantage of the enviornment.

The area I am liking at the moment from a KS standpoint is either the triple point or the dryline bulge being picked up by the models. I have a more detailed analysis going up on my blog here in a bit as the 12z GFS comes in to do a comparison with the two.

BTW, in case the newbies are wondering.. a good spelling lesson for you to keep in mind... to spell bust, you do it I-O-W-A!

 

[Mike Hollingshead]

BTW, in case the newbies are wondering.. a good spelling lesson for you to keep in mind... to spell bust, you do it I-O-W-A!

Yeah if it is July lol.

http://www.twisterdata.com/data/models/gfs/3/maps/2010/04/03/12/GFS_3_2010040312_F60_WSPD_850_MB.png

GFS is insistent on taking a little surface wave through eastern NE into western IA by 0z, leaving veered flow behind it and keeping any cape to the south.

http://www.twisterdata.com/data/mod...4/03/12/GFS_3_2010040312_F60_CAPE_SURFACE.png

It's been showing up real well on the cape progs. That is with precip over central and northern IA.

Just annoying how different that is than the NAM's surface ideas. Evidently just some differences with that lead wave going across SD? Not a huge difference but GFS flattens the 500mb height lines more across SD/nc NE with that than NAM and just a little bit earlier with that. Even NAM shows some issues with that low level flow. Oh well, guess we'll see Monday lol. I don't think either plan to change their thoughts there anytime soon as is often the case with such details between them.

 

[Andrew Pritchard]

I like the last runs from the NAM and GFS for obvious reasons . I guess what raises a red flag to me is this is the first time I have seen this advertised for this region.

It's actually not the first time this setup has appeared further east, it's just the first time the NAM has brought it into range so people can see pretty colors on composite maps like EHI and such.

I actually told someone a couple days ago that if you really wanted to believe the GFS that you really had to be thinking about the warm front near the IA/MO border during a brief conversation. It caught my eye as a possibility a few runs ago, but I don't like getting too excited about warm front days too far out as they like to be pretty finicky.

The best areas I can see playing right now are right near the triple point if you live in the plains, and right near the IA/IL border if you live in the midwest. Based on this morning's runs I am not as impressed. I think the GFS is a little too fast lifting the warm front into Minnesota and Wisconsin by evening, and the NAM just looks too diffuse. I checked very briefly last night's run before heading to bed and it just screamed tornadic supercells riding the warm front across southeast Iowa and western Illinois but per this run I'm not seeing it. Time for it to revert back on future runs, but I continue to focus on Tuesday for the more widespread, albeit likely more difficult to chase day.

Similar to the phrase "when it is May, you chase", the number one rule in Illinois is "when there is a warm front in Illinois, you chase."

 

[Jeff Piotrowski]

Sunday-Tuesday

The new 12Z NAM has slowed the trough now looks like it emerges into the plains late Tuesday. The 18Z SPC just put up a Slight for KS on Sunday late in afternoon. Look at the 36hr CNU sounding looks good. http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=KCNU.

Monday now looks like the area around OMA-GRI late in the day on WF and low level jet over the WF SE/NE.

Tuesday-now looks to be a double play. The first area is the triple point around 18Z near OMA-moves toward DSM by 0Z. The DL looks to be from OMA-ICT-LTS line at 0Z. The first storms go mid afternoon in IA then back build down the DL toward TOP.

Now the magic happens the main upper support and the bottom of trough central NM. Pressure falls in the afternoon in the across TX Phndl with new surface low forming SW of CDS. The winds back in WC/OK to the SE with temps upper 80's and DP of 60-65 a head of DL capes over 2000 J/KG. The DL looks like it will break the cap over WC/OK at around 0Z with moderate shear in place expect significant severe weather event to unfold Tuesday night across OK.

 

[Adam Lucio]

Monday will be a tough choice for sure.

The latest nam brings even more CAPE along the dryline situated across KS. The soundings show a nasty inversion layer around 850...not sure if that will be able to break or not. IF it does though, given the profile in the area any storm that goes up will go absolutely insane. I don't know the magic cap-cape-breaking numbers.

The warm front play along the I-80 corridor seems a good bet for storms, and these storms will have the potential to rotate and produce severe weather, although its not as pronounced as the area under the stronger cap. Where surface flow is better backed, it is also weaker and where flow is veered it is stronger...frustrating.

Right now I'm torn between the triple point and hanging back and playing the warm front. As Pritchard already mentioned, IL warm fronts are notorious for producing big events that are hard to see coming. Monday could be such a day.

 

[Chris Vagasky]

The new 12Z NAM has slowed the trough now looks like it emerges into the plains late Tuesday. The 18Z SPC just put up a Slight for KS on Sunday late in afternoon. Look at the 36hr CNU sounding looks good. http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=KCNU.

Change that to KCSM and take a look at the 60 hour forecast (00z Tuesday)...that sounding and hodograph had me drooling.

If you want to take the easy way, I've posted the image here:

http://i39.tinypic.com/jagewm.jpg

A very breakable cap, 3000+ CAPE, nearly 300m2/s2 SRH. If that image actually happens, I think I'm going to be coming down with a case of the supercell flu, and won't be showing up to work.

 

[Mike Smith]

Newton, KS

While we are shopping for soundings, take a look at Newton, KS (KEWK): http://beta.wxcaster.com/cgi-bin/parse_skewt_trace_all.cgi?model=NAM&STATIONID=KEWK

At 7pm Central on Monday, the cap has virtually broken with SRH of 196 and 2300+j of CAPE.

Especially if Kansas gets pre-dawn thunderstorms, Monday's dry line activity looks very "promising."

 

[jamesmseitz]

Change that to KCSM and take a look at the 60 hour forecast (00z Tuesday)...that sounding and hodograph had me drooling.

A very breakable cap, 3000+ CAPE, nearly 300m2/s2 SRH. If that image actually happens, I think I'm going to be coming down with a case of the supercell flu, and won't be showing up to work.

I also saw in the last GFS run that it has the system slowing down and not flying on the Canada. This is truely beging to look like 2 very good chase days indeed. Theat Net has been turned on and explorer is ready for 2 days of fun indeed .... Now the fun part... where and how to play this one. I love Weather

 

[Mike Hollingshead]

Well if we want to post good looking forecast soundings, these two work well...

Concordia KS 7pm

Hebron NE 7pm

NAM needs to be right on this one so bad.

Scary shear in se IA....FFL whatever that is.

 

[Derek Weston]

Southern Iowa along the WF has some very nice shear. Right here at home in Iowa City looks like a decent play perhaps. Most interesting area, though, is south central Iowa where the NAM projects a nice bulge of CAPE. If we're seeing CAPE >2000, with a lifting WF and the sort of shear profiles we're seeing now... hard to ignore that play. Sig tornado parameters are great in this area... where I'd play if I was going for the warm front.

The DL has me spooked. However, last few runs by NAM have had cap erosion in South Central Nebraska near the triple point... breaks out isolated precip in SE Neb around 0z.

Sort of day where I might be able to play in-between on I-80. Maybe hang around Omaha. If the ingredients look to come together further west near the triple-point, slam west. (however, we're probably looking at a waiting game out there) If the WF appears likely to light up further east into Iowa... could play that easily. (and this will go sooner than the western option) Risky deal about the warm front, though -- where does it end up? Northern Missouri is quite a bit different than Iowa near I-80.

Tough day.