4/22/10 FCST: TX/OK/KS/NE

[Mike Hollingshead]

http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/tcolc_f27.gif

I've learned to really hate drives to the Texas panhandle this time of year. Seems I'm real good at doing so on days that get screwed by morning convection and stuck or sinking cold airmasses. The 12z 4.0 KM WRF-NMM radar forecast doesn't make me feel any better, blowing up convection at 8 a.m. in the southern TX panhandle and hanging that out east along the Red River most of the day. A good setup can be trashed just like that, and problem is I'd be a good chunk into the drive before I could be for sure. Just doesn't make me feel real well about anything north of Lubbock. Starting to prefer Nebraska on Friday puts a fork into being as far south as Lubbock Thursday. Course I stay home and the GFS will be right, giving much of western KS a good looking play.

http://www.emc.ncep.noaa.gov/mmb/mpyle/cent4km/conus/12/today_6h_f30.gif

That for 7am to 1pm precip compared to...

http://www.wxcaster2.com/CENTRAL_ETA_1000-500_SLPPRPTHK_30HR.gif

Arrrgghhh.

http://www.wxcaster2.com/CENTRAL_MESO-ETA_1000-500_SLPPRPTHK_24HR.gif

18z NAM comes in nicer than both. Seems trending towards GFS. Those two back to back early April systems the GFS did better on sfc features fwiw. Insisting on that dry puch/sfc wave going through se NE then while NAM pretty much had no such thing. It nailed both days further out and better than NAM was. If I remember correctly.

 

[Mikey Gribble]

I agree with Mike that morning convection and cloud cover lingering over the warm sector is the huge question mark on tomorrow. It is always a scary proposition when you have to pull the trigger before it becomes clear whether or not that is going to ruin your day. There's nothing I can do about that though. The setup is good enough for tornadoes that I'll pull the trigger and hope for the best.

I think the highest tornado threat for tomorrow is going to be in the area north of I40 up into the far southern portion of Kansas. The main reason I like this area best is because with both the GFS and NAM low level shear is a little more favorable in this area for tornadic storms, albeit for different reasons. The NAM has low level winds backing strongly across this area. The GFS on the other hand has the surface low farther north than the NAM, so 850mb winds aren't backing here, but it does show stronger wind speeds (850mb around 35kts). Both models show 0-1km SRH >150m2/s2 over this same area. One other lesser reason I prefer the northern portion of the panhandle is because I think the timing on convective initiation may be a little better up there.

If the warm sector can clear and crapvection doesn't ruin the day, then I think the environment will be favorable for tornadic storms. Any storm firing along the dryline should pose a tornado threat. The greatest tornado threat IMO is going to be with storms forming along the Canadian to Liberal corridor (east or west of there depending on the dryline location). I think that we could see a cyclic tornado producer tomorrow, but I don't think the setup is real favorable for strong tornadoes. I'm not saying one or two strong tornadoes isn't possible, I just don't think it's likely. Regardless, there should be a solid tornado threat if we get good insolation and it's definitely worth chasing.

My initial target is probably going to be in the Guymon area. That may change by tomorrow morning, but as of now I plan on stopping there to forecast and fine tune my target.
I posted a forecast and map on my blog if anybody is interested http://loadedgunchasing.com/blog1/

 

[Mark Blue]

My choices aren't as wide open as some, based on the amount of leave I have in the bank and chasecations already planned for in May and June. Therefore I will be leaving work at 2 pm tomorrow and blasting east on I-70 towards east central Colorado or slightly south of there. At this juncture I'm planning to position myself just east or slightly northeast of the surface low in order to see what happens. I see a nice bulls eye around Holly CO for shear and instability (EHI = 2.25) and helicity seems to be maximized in that same general area as well (250). The dewpoints (hopefully low 50s) aren't near as nice as those who are planning to chase the dryline further south, but I have to work with the hand I've been dealt. It appears a nice narrow corridor of 1250 J/kg of CAPE will work it's way into this same general area as well and lift does not appear to be a problem. I just hope the sun comes out and heats things up as that could be the one fly in the ointment at this point.

Here are some links to substantiate my numbers above:

http://bit.ly/8Z9ypT

http://bit.ly/bHtnyv

http://bit.ly/daNdaq

http://bit.ly/aw0CbE

http://bit.ly/cUsVNU

Best of luck to those who will be chasing and perhaps I'll see you under the meso!

 

[Bill Schintler]

Chase Target for Thursday, April 22

Chase target:
Parnell, TX (22 miles west of Childress)

Timing and storm mode:
Isolated supercell storms will develop after 6 PM CDT, with storm motion towards the northeast at 20 mph.

Discussion:
Two periods of convection will take place. First, elevated convection will track across the ERN TX panhandle and then WRN OK in association with a retreating WF during the early afternoon hours. Partial clearing will take place in the wake of this precipitation, allowing for insolation and destabilization. Low- to Mid-level clouds are a concern for insolation. SC and AC will persist along and E of US-83 in TX; however, seasonably strong heating should take place in the Panhandle with SFC temperatures rising to 75-80F. NAM model soundings suggest a TC of 75F. An area of CI will approach the WRN TX panhandle after 21Z, signaling the arrival of large scale assent in association with the approaching trough/ULVL low. Initiation will take place near Childress along a DL bulge with assistance from orographic enhancement within the Red River valley. Convection will later back build along a SW/NE-oriented line towards the Big Spring area between 3 and 6z.

Deep layer shear will increase to 60 kts by mid-evening as the jet streak ejects from the ULVL low. Hodograph curvatures will also increase after 3z as the BL begins to decouple and a LLJ increases to 30-40 kts. The SPC SREF indicates the significant tornado parameter increasing to 3 after 00Z. SFC-100mb MLCAPEs should locally increase to 2000J/kg despite modest dewpoints in the high 50’s F and mid-level lapse rates of 6.5 to 7 C/km. A strengthening LLJ will aid in the maintenance of a large storm cluster during the overnight hours.

- Bill
KD0DJG
www.twistertoursusa.com
9:50 PM CDT, 04/21/10

 

[Mikey Gribble]

Well the 00Z NAM has trended towards the GFS with the location of the surface low. It is now farther north in the vicinity of east central Colorado by 00Z. The dryline arcs to the east before turning south over west central Kansas. I still like this area along the arcing dryline in Kansas (just used to be in the NE panhandle with the 12Z run). I think the highest tornado probability tomorrow will be ahead of the dryline where low level winds back. That looks like it might be in the Garden City to Scott City to Tribune area tomorrow and on back to the surface low. 0-1km SRH is pretty decent across that area. Dewpoints in the mid to upper 50's is a disappointment. I was really hoping we could hit 60 degrees where the low level shear gets better, but I don't think that's going to happen. Mid upper 50's will be adequate though.
I think the tornado potential is slightly better with the 00Z NAM. I am concerned about how the models are portraying convective evolution through the afternoon. The WRF simulated radar showed a whole lot of nothing coming off the dryline over Kansas. I would think we'd get a few storms off the dryline in Kansas, so I'm a bit surprised to see that.
I plan on leaving town around 8am for Garden City. I'll work on my forecasting there and pick my final target, which will probably be northwest of there.

 

[Paul Knightley]

Just looking at this now - the KS target certainly has a few good looking ingredients: nice backed surface flow; good lift as the exit region of the approaching trough; proximity to the warm front. However, I'm tempted by the TX Panhandle - lift there should not be as strong, at least initially, so cells may be more discrete...with current activity moving away, outflow boundaries should be in place. An initial target of Childress, I think, to then be refined with obs/radar/sat pics through the day. Activity will continue well into the night in the CDS area, so some nocturnal lightning shows possible too! The only worry is the dry-line/cold front will start to surge eastwards through the evening, which will bring a line of storms, probably a squall line, swamping the more discrete activity. The front will slow down, though, as the LLJ kicks in overnight, providing ample low-level lift to keep the storms going through the night.

 

[Jacob Ferden]

Chase target: Shamrock, TX

Will be leaving Norman for the eastern Texas panhandle shortly. Plan is leave both options to the north and south open, so will take advantage of the US 83 corridor. I still really like the area just to the west of Childress, TX, so will be ready to drop down to that area if storms fire there. Expecting several supercells to go up on the dryline, with the hopes that one or more can take a right turn and produce.

 

[cdcollura]

Good day all,

Checking data in Wheeler, TX at this time and I am measuring a dewpoint of 62 with about a 20 MPH SSE wind. Clearing has taken place behind sparse elevated convection over W OK moving rapidly off to the NE. Scattered agitated Cu overhead with blues skies peeking through ant temp of 74.

Upper shortwave and dryline should impinge on this area during mid afternoon and onwardf, also bullseyed now by hatched 10% tor probs as per SPC. Incredible divergent / difluence noted as per RUC over this area at the H5 (500 Mb) and 250 Mb levels.

 

[Jeff House]

outflow boundary

Southwest Kansas has excellent backed winds near the synoptic warm front; however, the Panhandle will have higher CAPE. Morning convection in the Panhandle left a weak boundary intersecting the DL, breaking the tie in my mind. Believe the Panhandle boundary will create locally backed winds to go with the CAPE. Too bad it will be only a virtual chase from work.

Believe today will be the best chase day of the bunch thanks to good terrain, slower moving cells, less "other" convection, and better low level wind directions. This paragraph for those with only enough political capital (work/home/etc) to pick one day to chase. Morning rain ejecting away from the target zone today. Look for the low clouds to break up by mid-afternoon and sups to go on the DL. Would look for the one near the DL outflow boundary intersect. Though today should be the best chase day, agree with SPC that Friday might be the bigger concern for the non-chasing public.

Target: Currently at 18Z the boundary is near US-287 but should lift north of I-40 by later this afternoon. I'd head in the direction of AMA up to about US-83 or perhaps TX-70 at the farthest west. Then evaluate as I approach. I like the chances of a sup at the boundary DL intersect.

Chase safe and good luck!