5/18/2010 FCST: TX,NM,OK,CO

[Chuck Robertson]

Both the NAM and the GFS are saying Tuesday could be the "day before the big day" out in eastern NM, western TX Panhandle, and surrounding areas. Mid to upper level winds will just be starting to improve in advance of the approaching system for Wednesday, and will still be rather modest. It looks like there should be excellent directional shear from the ground up, with very well backed winds from the surface up through 850. Speed shear however may be a bit weak. Td's may approach 60 as far west as the western TX PH, and at 4000 ft elevation, that should be excellent, given that T-Td's should be quite low, yielding low LCL's. Even with the cooler temps in the northern TX PH and on into northeast NM, the models still initiate storms.

With the weak winds up top, there may be anvil ventilation problems, but at least the storms may enjoy a time window of opportunity of a few hours to have the chance to produce some interesting stuff.

 

[Bill Hark]

With the recent GFS and NAM outputs (init 00Z May 16), Tuesday is starting to show some potential. Both show the 500mb low shifting eastward a bit more quickly than previous runs. The NAM shows westerly 500 mb winds at 40-50 through eastern New Mexico and the Texas Panhandle. Dewpoints are marginal at 55-60 east of the dryline and a surface low forming in SE Colorado. There is a forecast tongue of 2000 CAPE pointing northward into the TX Panhandle. The GFS shows the surface low a bit farther south in northeastern New Mexico, wider area of 60 dewpoints, 30-50 500mb winds across the TX Panhandle that are more southwesterly. Although a bit early to define a target, I like the area between Amarillo and Dumas depending on the position of the surface low for best backing of the surface winds. I think pretty supercells are likely and maybe a tornado.

I am a bit annoyed because this came up a bit quicker than I had anticipated. I was planning on flying out on Tuesday to be ready for Wednesday and I may miss this opportunity if I can't find a way to fly out Monday afternoon.

Bill Hark

 

[Brandon Lawson]

Tuesday is looking more interesting with each new run of the GFS, which is coming more in line with the ECMWF and the placement of the shortwave trough at 72 hours out. While much of the mid-level forcing remains over New Mexico, both the NAM and GFS show some subtle shortwave energy (that's a dollar) overspreading low to mid 60's dewpoints in the Texas Panhandle. This, combined with a lifting warm front along the Kansas/Oklahoma border by 00z, should contribute to CAPE values of 2000-2500 J/Kg just east of a dryline in the Panhandle. This could be more or less depending on the quality of moisture return. Any storms that can develop in this environment will also be in favorable low-level shear with strong turning with height, and pose a threat for tornadoes. http://www.twisterdata.com/index.ph...ng=y&sndclick=y&sounding.x=434&sounding.y=406 *fingers crossed*

There is still plenty of time for things to change for better or worse, but it is definitely worth monitoring and could provide VORTEX2 with back to back tornado days next week.

 

[Chuck Robertson]

Yes indeed. This still looks like it could be evolving into a classic Panhandle setup, especially for west, southwest, and southeast of AMA. Still a little early to pinpoint, but an early guess might be Plainview, starting NW of there, and ending up east of there.

Speed shear is of some concern, but directional shear looks phenomenal! Both the NAM and the GFS show a thermal trough over the central and eastern TX PH, possible due to clouds and earlier precip. They also show a strong thermal ridge rising up into the western TX PH. This maybe a signal for an outflow boundary. If so, this could be a very interesting area to play, especially if we can get some cooking along such boundary. I like the area right on top of this thermal boundary to start. Perhaps there could be a sweet spot there, with say about upper 70 temps and T-Td spreads of around 15, with a strong SE upsloping wind.

BTW: Once again, the entire TX PH received tons of rain in the past few days. I just poured out 2.25 inches from my bucket. These kinds of rains really do add to the moisture content of the lower levels of the atmosphere here in the panhandles. The old saying around here is "Storms beget storms". These recent rains may prove beneficial in tornado production as well. They sure do help promote a greener panhandle, if nothing else.

 

[Brandon Lawson]

Models are breaking out a lot of precipitation on Tuesday with the arrival of the shortwave, which is hampering instability. This will be a wait and see day. It will all depend on if, when, and where convection occurs and whether or not it can clear off for some daytime heating. If the models are off on timing, good, if not, oh well.

EDIT: The difference in CAPE from last night's 00z run of the NAM to this morning's run is quite impressive. The difference is that it holds off on the convection. Meanwhile, the GFS has done the exact opposite and significantly decreased CAPE. I'm trusting in the NAM being better at handling precip. over the GFS.

 

[Adam Adkins]

I have been following this day very closely seeing as how it's right up my alley. The latest GFS runs have had CAPE around 1500 j/kg around the front range while the latest NAM runs have been significantly higher with about 2500 j/kg. Shear looks moderate so any supercells that get organized will have a shot at a weak tornado in this area. This setup reminds me a lot of June 4, 2009 where there were several short-lived supercells and funnels around the front range. I would love to get other's opinions though!

 

[Jacob Ferden]

Preliminary Chase Target: Dalhart, TX

Plan: Have a couple of issues currently ongoing, but assuming everything works out, will leave Norman around 9 AM CDT. Will reevaluate surface data in Elk City, and make final target refinements from there.

Reasoning: 18z GFS and NAM are in reasonably good agreement regarding tomorrow.

GFS shows two dryline bulges over the high plains, one near the NM-TX-OK intersection, and the other farther north into SE Colorado. Prefer the southern bulge due to the presence of CAPE aoa 2000 j/kg, which should be more than sufficient at this elevation. Cap may be more of an issue to the north and south, but GFS shows a hole in the cap over the target area. Shear profiles look good, with greater than 45 degrees of turning from 850 mb to 500 mb.

18z NAM shows a dryline bulge over the same area, but is less bullish on CAPE values, with only a small area above 2000 j/kg over the target area. Capping may be more of a concern with this solution, but EHI values are highest over the target area both from 0-1 km and from 0-3 km.

Expect storms to fire along the dryline and move to the ENE around 10 mph. Manageable storm motions and likely picturesque storms, along with the attendant tornado threat, could make for a potentially good chase day.

 

[Eian Greene]

Got my feet wet tonight on a storm near Falcon. While not severe, It was nice to get out and get a feel for the area again. Some storms that came through eastern El Paso county around 200-430Z have put down some moisture for tomorrow's action. Some model soundings out of KPUB are saying localized CAPEs of up to 3,200J/KG, which may be farther southeast near LAA.

I might see some local action if moisture and sufficient shear are present by about 21Z... I'm hoping to see some Front range action like Adam, a backyard chase scenario is indeed a good thing.

I'd target anywhere along and a 25 mi east/west of a line from LIC to LHX for today's setup, being more partial to the LIC area since I should stay close to home for today.

 

[Chris Wilburn]

I am actually very intrigued with todays potential. Dryline forecasted along the NM/TX border at 00z. Dew's in the lower to mid 60's with some areas forecasted over 2,000 CAPE. Hodograph south of Amarillo shows an almost perfect vertical wind shear profile. 30kts of shear at 850mb and 500mb at 40kts should create very chaseable photogenic supercells in the TX panhandle later today. Forecast soundings for the Amarillo area show 0-1 SRH close to 200 and 0-3 SRH over 400. Storm speeds forecasted right at about 30kts. Sign. Torn. Parameter maxed out just west of Amarillo by 00z with effective storm relative helicity close to 400 as well in this location. The main upper level energy doesn't arrive until the late afternoon. The CAP doesn't appear to be an issue and with slower storm speeds it should be a nice chase day. Tornado potential is definitely there and I wouldn't be suprised at all to see several tornado reports later on today. Preliminary target is Amarillo. This should be far enough west. From there it's just a matter of picking south or north based on surface obs. and visible satellite.

 

[Andrew Stoller]

The RUC is hinting at developing the surface low and potential dryline bulging a bit further northwest (placing it around Pueblo, CO by 21z-00z). Wouldn't be surprised at all if the SPC moved the 10% hatch a bit further northwest for the late morning outlook. That would place southeast CO/far northeast NM/OK panhandle region in a favored region of backed surface winds. Look for the east end of the Raton Mesa for possible orographically aided initiation. I'm looking at a line from Kim, CO to Clayton, NM. Maybe even a bit further northwest depending on the location of the surface low. Everything else looks to be great for a nice tornado day.

 

[Andrew Stoller]

The RUC and NAM are hinting at a secondary surface low forming in west central TX with a dryline/outflow triple point. Severe parameters are maximized Between Amarillo and Lubbock potentially. That will likely be the main show, but eastern CO, ahead of the main surface low, looks to be a good bet as well, if the low clouds can burn off and sufficient heating occurs.

 

[Bill Schintler]

Chase Target for Tuesday, May 18

Chase target:
Tulia, TX.

Timing and storm mode:
Storms will develop between 5 and 6 PM CDT, with supercells likely early in convective evolution. Storm motion will be towards the east at 20 mph. Intensification should occur as cells move off the Caprock, in areas just north of Turkey.

Synopsis:
A 50kt H5 streak will eject from the base of the WRN CONUS trough over the next 24 hours. MDLs are increasing the progression of the ULVL streak. Over time, a cutoff ULVL low will develop over the SRN Planes, which will set the stage for several days of active WX.

Discussion:
Low pressure will organize over NERN NM through 00Z. SELY, upsloping SFC flow will gradually increase during the afternoon. SFC convergence should be enhanced by orographic lift along the ERN extent of the Caprock Escarpment. Strong shear juxtaposed with MLCAPEs to 3000J/kG will be supportive of all modes of severe WX. SFC-3km SRH will locally increase to 300m2/s2 where backing flow exist along the ERN edge of the Caprock. Deep-layer shear will increase to 45 kts with the approach of the aforementioned H5 streak. During the evening into the overnight hours, storms will evolve into an MCS which will increase in coverage as the LLJ strengthens.

- Bill
KD0DJG
www.twistertoursusa.com
09:50 AM CDT, 05/18/10

 

[CZandbergen]

Complete forecast with hand analysis available at my blog. http://ke5zol.blogspot.com/2010/05/2010-5-18-forecast.html

The short version is I prefer the play into far SW KS due to what appears to be an OFB in the area.

 

[Rebekah LaBar]

Jeff Makowski and I are headed out to Amarillo today, and will readjust to probably somewhere between Dalhart and Dimmitt, depending on what's happening by the time we get into the target area.

We're currently west of Clinton, going west on I-40.

I expect we'll see some nicely structured supercells with hail; although I do not have high hopes for seeing a tornado, I would not rule it out. Although the setup may not be perfect, as others have mentioned, you don't need quite as high of dewpoints or instability to get nice storms up on the Caprock.

Let's go Panhandle Magic!

A full forecast/rehash of the setup can be found on my blog.

 

[Mike Johnson]

I am thinking of moving to Dalhart but am currently in Amarillo and my slow play it for a while. It looks to be in a favorable location late this afternoon as the stronger winds aloft overspread the region. Hope the supercells are photogenic early because once sunset approaches the LLJ will congeal this into one big mess I am afraid.