3/29/05 FCST : Plains

Looks like the Plains are in for a beating come next Tuesday. I did some looking on the long range on the GFS and it looks like a major storm is coming in. Temps are predicted to be around 65 degrees for most of eastern Kansas with Td's coming into the 60's in the same area. This is my first attempt to make a target area post for a date that is far in advance, I'm still a freshman meteorology student, so correct me if I am wrong!

I also noticed the KC/Pleasant Hill NWS HWO mention this in their outlook for Tuesday:

UPDATED PORTION...BY MID WEEK NEXT WEEK...A PATTERN CHANGE SHOULD BE
TAKING PLACE THAT MAY RESULT IN A MORE WIDESPREAD OUTBREAK OF SEVERE
WEATHER. WITH THE TIMING AND EXACT TRACK OF THIS SYSTEM STILL VERY
UNCERTAIN...
 
Tuesday is still a long way off, but it is looking good so far. Here is a quote from Wichita NWS,
IF WE CAN GET DECENT MOISTURE RETURN INTO THE PLAINS TUESDAY
AND THE BIG ASSUMPTION THAT THE ECMWF IS GOING TO PAN OUT, TUESDAY
COULD BE AN INTERESTING DAY.
 
The big problem with this low will again be meager surface moisture. With 30-40kt northwesterly flow across the Gulf on the heels of this weekend's low, it's going to be dang tough to get any significant moisture into the Plains, even modified continental air, much less true tropical air. The kinematics look just fine, but the thermodynamics are going to be difficult to get in order (which isn't uncommon for this time of year)...
 
I glanced at the GFS for this posted date just now. I don't like what I see with the models showing no real low-level focus in the form of a low.

The moisture looks hosed for this time period - with a dirty big anticylone over the northern Gulf sure to send the moisture return screwy if it verifies. It has dewpoints in the low 50s progged for the norhtern Gulf by 0Z Wed 30th.

However, this all may be because this system/trough is trying to hold off until Wednesday 30th until pulling out onto the Plains - which would give us perhaps a little better chance at moisture return. I will look at this - and if it seems feasible, will start another FCST thread in here for Wed March 30th.

KR
 
Yeah I just verified the GFS and it appears that the system is moving slower. 12Z GFS also has the L at 1001, so we will see if this storm will pan out, if possible.

Pleasant Hill still mentions of severe weather, but has the weather further south than Kansas City, rather in the southern Plains, and this storm would happen on Wednesday, rather than on Tuesday as this date was set. I have enclosed part of the Forecast Discussion that the Pleasant Hill NWS put out at 3 this afternoon:

Originally posted by Kansas City Forecast Discussion

THE
MEDIUM RANGE MODELS ADVERTISE STRONG FORCING AND IMPRESSIVE WIND
SHEAR, SO A SEVERE OUTBREAK MAY BE IN THE CARDS, ESPECIALLY FOR
PORTIONS OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY.
 
Originally posted by Ben Prusia
Pleasant Hill still mentions of severe weather, but has the weather further south than Kansas City, rather in the southern Plains, and this storm would happen on Wednesday, rather than on Tuesday as this date was set.

LOL - don't sound so down about the possibility of storms being further south - that's what I (and a lot of people!) are hoping for at this time of year, I think you'll find.

I'm not really bothered about what all the WFOs are thinking right now......I'm trusting my own interpretation of the models to see what's supposed to happen.

I am awaiting some newer models runs before seeing if a date change/new FCST thread needs to happen for this event next week. I'm still not impressed with moisture return signatures so far, but I don't think the GFS has a good handle on any of it, right now.

KR
 
For those that look at this before 0z Sat. The gfs has been trending negatively on the system mentioned(last 3 runs anyway). Even at that it still does manage to bring some >60 TDs up into the central plains by 132hr(with weak sfc reflection too). It is kicking out a positive tilt trough which of course no one wants. I found this interesting difference between the eta and gfs at 84hr. I would think the jet orientation off the nw coast would stand a better chance at kicking out a more neutral to negatively tilted trough than the gfs is showing at the same time. Is there any truth to this? To me the 84hr jet on the eta says neg tilt to follow more-so than the 84hr gfs. It looks to allow something to dig more. Just an ob.

http://www.rap.ucar.edu/weather/model/eta8...4hr_300_wnd.gif

http://www.rap.ucar.edu/weather/model/gfs0...4hr_300_wnd.gif
 
It's also interesting to note that the ECMWF provides a considerably different solution than the latest GFS... The European still has a strong (989mb I think) low in the central plains, rather than the washed-out trough solution that the GFS has trended towards. Regardless, I still feel that the 30-40kt northwesterly 850mb winds across the Gulf from late sunday to late Monday will wipe out any significant moisture available, especially if the GFS verifies, as it pushed the front all the way through the Gulf and into the northearn Carribean area! UGH! The ECMWF, however, would provide more optimism for chasing since it shows a strong low-level jet from the western Gulf / eastern TX northward, which would give us the best chance of getting any sort of real moisture up into the plains...
 
This fish still looks too small to keep to me. I'd throw it back in and wait for the next system that should come out a few days later. A much more impressive storm is progged to come out around the 31 st in the latest series of medium range guidance - so +/- a day or so. The system on the 29th has looked progressively worse with time, of course the next system always looks better in long-range forecasts.

Glen
 
Interesting setup for western Central KS today. Very impressive shortwv trough will be over the panhandles by afternoon with deep sub 990mb sfc low in western KS. Strong mid level CAA of -20C / 2C at H5/7 respectively means that only marginal moisture return is necessary for positive area on the sounding... about 800 J/kg of SB CAPE in a background environment of very strong upward vertical motion...should be enough to allow high-based supercell hailers. Some of the veterans like to call these types "Vacuum cleaner" supercells. High based, very photogenic most of the time, on the leading edge of the synoptic dry intrusion... target is Great Bend down to Medicine Lodge. Will finalize by noon when I wake up after recovering from this morning's mid shift.

Mike U
 
Moisture is the obvious enemy today, though the 50 Tds have crossed the Red River, heading northward. Overall, it would have been nice to not have to be worrying about moisture yet again, since this sytem, along with the past couple, could have been quite good for chasers had we had enough moisture. That said, I guess I shouldnt' complain too much since that's what's often the limiter this time of year:

WERE IT NOT FOR THE LACK OF DEEP LL MOISTURE AND AN OVERABUNDANCE OF CIRRUS...THIS WOULD BE A CLASSIC SETUP FOR A PLAINS SEVERE WX OUTBREAK.
 
Interesting scenario - as it seems the high cirrus shield has prevented deep boundary layer mixing and allowed the shallow but modest moisture to make good progress northward today. Coupled with the further south than expected track of the low - there is some posssibility of mid 50's dewpoints overlaid by nearly dry adiabatic lapse rates. Question then becomes if sufficient moisture pooling can occur ahead of the front to support convective initiation, and if the cloud cover limits heating too much to overcome the cap. So, perhaps a rogue high-based cell or two can get going in KS later today.

Glen
 
I don't know so much about today. Latest RUC pretty much nullifies CAPE today, with a pretty good capping inversion in place across much of the heartland. Of course I could be wrong since I'm unfamiliar with what values (as far as CIN goes) sugests a strong cap. I just don't like what I see. ETA also aggrees that CAPE is nil.


The dewpoints are looking good with 50's creeping up even into southeastern Nebraska (yay me). 60's in southeastern Kansas. Near 70's in parts of Oklahoma and Texas. GFS is a little more aggressive in respect to dewpoints for my area, putting it around 60.

LI's in the latest RUC aren't anything to write home about, unfortunately. Things look interesting on the 30th around 0z in northwest Kansas as far as LI values, but that's another discussion.

My limited understanding of all things forecast related tells me to bet conservatively and say nil on severe weather. At best I expect to see a few surprise severe cells, but even that's a wager I wouldn't put money on.
 
The Dewpoints across northern Oklahoma are making me wonder... I glanced over Dupage and saw the models still keeping Dewpoints under 50 in Southern Kansas, but as the 19z SFC obs are showing, Tds in some places are already flirting with 50 if not over it already. Even a 57 in Northern Oklahoma is looking healthy; better than either tthe ETA or RUC have been. Some of those 50s keep climbing northward a bit on the weak SFC winds from the south, you may see SPC jumping a SLIGHT RISK for the area. Some of those winds are crawling out of the southeast a bit, so ya never know. A moisture tounge is evident, and everything else seems alright, so I wouldn't be surprised to see a few severe in the area of Southern Kansas, Northern Oklahoma. I'd be tempted to play the Hwy 160 stretch near Medicine Lodge if you're in the neighborhood and see what happens in the next couple hours.
 
Dewpoints are rising pretty rapidly accross N OK/S KS the last few hours. Latest SFC indicates near 50 td's as far north now as Salina, KS. A quick glance at OK Mesonet indicates upper 50 td's beginning to show up along the Red River, however 60's are still in deep south TX. I feel the RUC has a pretty good handle on evolution of the moisture this evening with 52-54 td's becoming common accross S KS/N OK. As Glen said in a previous post, farther south track of SFC low than expected is encouraging as well.

Main concern for me remains the high amount of CIN and very marginal values of 300-500 J/KG sbcape by initiation. Main question remains if enough moisture can arrive prior to dark to help remove capping inversion and intiate convection by 0z. Shear profiles are very supportive of elevated supercells, and mid-level temps remain supportive of marginally severe hail.

Pratt appears to be a decent starting point for now. SFC moisture should be maximized in this area in the 21-0z time frame.

Im still sitting in ICT watching data.. i'll probably depart by 2:30.
 
Convection is now finally ongoing across Southern KS. A couple svr warnings have been issued by DDC and ICT (earlier) for the convection just west of ICT at 9:30. A few marginal hail reports have been reported per SPC storm reports. Fairly strong/severe storms are also ongoing in western NE.

Dewpoints across the area are now in excess of 52 or so accross S KS with 55-58 in N OK. Had we had an additional 5-10 hours of moisture return earlier today, a much different situation would likely be ongoing right now.. oh well.. it is March!
 
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