4/21/10 FCST: CO/KS/NE/TX

[jamesmseitz]

I have been watching this feature for awhile now and starting to really believe that this system will be the beginning of a possible 3 day event.

GFS has been picking a strong Low Pressure ejecting of the Rockies on about the 21st of April. Moisture looks to return better after the 21st, but growing up in Colorado if there is any upslope into the Front Range those days seem to be fairly good. This Feature along with the terrain there could be some great storms that roll of into the plains. With the upslope winds flowing into the Rockies and Upper level winds coming out of the southwest this is the ingredients for Supercelluar devotement in the area. Dew Point do not need to be has high in the area (50's usually does the trick) because of the natural lift with the higher terrain.

I know the days to come hopefully will be better but I believe it will start that evening and wanted to start the discussion.

 

[jamesmseitz]

I looked at the models this moring and they are starting to look even better. The main event will be the 22nd and 23rd I know but if you look the low eject over the front range and creates a fairly good upslope. I remember these days in Colorado being pretty good days. Being in MInnesota I am looking to start on the 21st and enjoy the days to come. Finally it looks like a great pattern change so let the fun begin.

 

[PeteMcConnell]

I see what you're talking about James. At this point the GFS is definitely showing a large trough ejecting from the Rockies with some decent CAPE,low LCLs, marginal dewpoints and veering winds that appear adequate for a severe weather event on the 22nd and beyond. Still time for things to change, but something should develop with these dynamics coming together. Have a safe trip out from Minnesota.

 

[Skip Talbot]

I've been reluctant to get too excited about this day (and especially the following days) as the GFS has been bouncing around quite a bit from run to run. The last few runs have been pretty consistent with the upper level pattern however. It looks like we are going to have a cut off upper level low sitting over the southwestern states. Its position on Wednesday leads me to believe that speed shear is going to be a problem for this setup. The trough is not forecasted to eject until at least a day later. The area I'm most interested in is the TX panhandle. The GFS is indicating a dryline setting up here with modest instability. The easterly surface flow might be enough for initiation on the upslope across the Caprock. However, with the trough not ejecting yet, mediocre surface winds, and lack of strong low level jet, we're looking at really weak speed shear. Both 500 mb winds and bulk shear look like they could be in the vicinity of 20 knots. This may not be enough for sustained supercells. While we could see initiation from the upslope flow, the storms may die off early or transition into a more linear mode as they will be unable to maintain updraft/downdraft separation in the weak flow. If the GFS slows the system down as it has a tendancy to do, the lack of shear will be an even bigger problem. Slowing the system down might help the following days in terms of moisture return and putting the trough into phase, but that's for another thread and for when the models lock onto a solution.

 

[Chris Wilburn]

I can't chase this day so I haven't looked into it much until now. Based on the 00z GFS I really like what I see for those that head out. 992mb surface low in the northwest TX panhandle with a dryline basically cutting the TX panhandle in half from east to west. Surface dews forecasted mid 50's to upper 60's, but from what I have always heard you can actually have lower dews in the caprock area. Hodographs for both the northeast TX panhandle and NW TX look very impressive. CAPE is close to 2,000 J/kg and it does show some CINH left to be burned off at 00z, but nothing too dramatic. 850mb winds look very nice out of the south and even southeast as you move into the northern portions of the TX panhandle. The best 500mb winds don't look to overlay the dryline until late afternoon and close to 00z, but that still gives time for things to kick off. The 500mb winds are only forecasted in the 40kt area so slower storm speeds will be welcome for all I am sure.

I would say anywhere from Pampa to Shamrock to Childress would be a nice start and adjust from there. I guess the only possible negatives are moisture return and moisture depth. I only mention that because if the models are overdoing moisture by 5 degrees or so that can create a problem. If the models are right with mid to upper 50's things are good to go. Also, if there is any slow down on the 500mb winds than forecasted now that could hamper things as well. Speed shear doesn't look the greatest and storms may have trouble to get going. Still some uncertainties, but looks good. The NAM should be on board at the 84 hour at 12z later this morning so that will give something to compare to the GFS.

 

[Chris C Sanner]

Complicated sfc pattern is taking shape over the panhandles region for tomorrow. Models won't handle the many mesoscale boundaries and whatnot very well, but am expecting at least one very good area to emerge tomorrow. 500s are in the 30kt range with Bulk Shear values very adequate for supercells. Hodos look fine too, especially factoring in likely storm motions. 4km WRF initiates plenty of precip all up and down the panhandle, so this looks like an interesting day off of many's radar right now it seems. More detailed forecast on my site at the link in my sig.

 

[Jason Boggs]

If yesterday dropped a tornado in the TX panhandle, today won't have a problem at all. I'm really excited about today. Plenty of moisture, High CAPE upwards of 3000, and decent upper level support will give us supercells again today. Today we have a warm front to play with and possible outflow boundaries from yesterday. My initial target as of right now is Happy, TX about 30 miles south of Amarillo. Storm direction will be SE so I'll just set up and let them mature and come to me.

 

[jeremy wilson]

I agree Jason. The dynamics are better today than yesterday and the boundaries should make things interesting. Myself and Brandon Sampson are gonna head to Childress and decide where to go from there. By the way if anyone knows of any decent motels at decent prices in Childress then shoot me a P.M. Gonna hole up there for some two day panhandle magic!

 

[Bart_Comstock]

I would say use priceline.com or that other one with the gnome. I wish I was the chaser that had money for hotels and >1 day adventures.

Good luck and stay safe!

Don't book through the website just shop prices with them. Once you have found a cheap hotel call them and say you were going to get a room with them on <insert website name here> and then ask if they can do cheaper. They will say yes. The way those sites work is they get unsold rooms on hotels that are at a low capacity that night.

At the hotel I work at we charge 159 a night. If we have a slow night we will have website rooms available. Those rooms will be sold to priceline at a 60-70 dollar discount. They will then sell the room back to the public for 20-40 bucks more than they got it from the hotel. The hotel then has to pay a commission to the site if the room sells. The hotel can save you 20 bucks and in turn save them from having to pay the commission. It is a win win for you and them and you will get your room at the price that the website would pay for it.

If the front desk clerk says they can't lower the price ask to speak to the sales manager and explain it to them and they will get you the cheaper rate.

That said, I really am thinking today is going to be more a day of good positioning like yesterday was than anything else. I am still going to skip today in favor of chasing the next two days but If I had to pick a spot I'd say head towards Tulia and then do a supercell dance and hope for the best. There will be probably one or two good storms but I am saving the days off and gas money for a better day.

 

[Bill Schintler]

Chase Target for today, April 21

Chase target:
Clarendon, TX

Timing and storm mode:
Storms will develop between 6 and 7 PM CDT. All modes of severe weather are possible, including an isolated tornado or two.

Discussion:
15Z analysis indicates low pressure centered INVOF Simms, TX; with an outflow-enhanced WF extending towards the SE. Analysis of visible satellite imagery indicates this boundary has essentially stalled out along an AMA/Silverton/Matador line in the panhandle, or along the eastern extent of the Caprock Escarpment. This orographically-enhanced boundary will serve as the focus for renewed convection by late afternoon.

Instability will increase during the period as moderate mid-level lapse rates and an EML, as indicated by upstream 12Z EPZ and ABQ soundings, overspreads LLVL dewpoints in the low 60’s F along the Red River valley. SFC-6km shear will remain weak until early evening when an H5 40kt compact jet ejects from the main WRN CONUS low. Additionally, low-level hodographs will increase between 00-03Z as an increasingly veered LLJ strengthens over backed SFC flow.

- Bill
11:15 AM CDT, 04/21/10

 

[Jay McCoy]

I wont rehash all the parameters that look so good today. I will talk about the one that has me concerned right now and that is with the upslope flow right now we are having a hard time buring of the low clouds and fog and the temps are stuck in the 50's which means the instability is lacking compared to foecasts for much of the risk area. It is slowly buring off from SW to NE and also from NE to SW but in the middle it is solid and thick. We still have 3-4 good hrs of heat to destabilize. Lets hope it clears.

 

[Mike Johnston]

Looks like a boundary is visible on radar from just east of Cannon AFB, NM to west of Lubbock to south of Lubbock. The way its moving, could very well be an outflow boundary from last night's convection. Close enough to area of favorable developing parameters this afternoon - might be a focus for initiation in the hours ahead.

 

[Richard Dickson]

Sitting in Happy, TX right now and almost all of the clouds have burned off. Winds are still light out of the SSE, but have picked up a little in the past few minutes. I also see some CU building on radar SW of here in N.M. I think I'll be sitting here for a while longer and see what the radar brings later on. I may be overly optomistic, but I think today will have some success.

 

[Jeff Snyder]

I wasn't really planning on chasing today, but, after looking at the 12z runs, I made a quick decision a little before noon that this setup was worth chasing. As such, we're a little behind the ball in terms of positioning, which affects our target area. Right now, my eye is on the boundary S of CDS, evidenced by NE or ENE winds at the TX Mesonet sites between Silverton to N of Paducah. Obs south of this boundary are largely characterized by SE-SSE winds, mid-70s temps (73 @ Floydada increasing to 77 near Paducah), and Tds in the 59-60 F range. We won't be able to make to the storms initiating on the DL from Clovis to Big Spring considering the slow storm motion. VWPs from LBB and AMA are a bit disconcerting in that they're showing only 15-20 kts of flow from the sfc to 5-6 km AGL. The RUC and NAM have 500 mb winds strengthening a bit by 00z, but we're still in the middle of the ridge, for the most part (see 500mb temp progs as well). Without much large-scale ascent aloft (and even indications of large-scale weak subsidence aloft across much of the panhandles), we'll probably need to hit the Tc along that boundary SW of CDS to initiate (assuming sfc convergence is still strong enough to push sfc parcels to the LFC). Sites on the Paducah to Silverton area...