2016-03-30 EVENT: KS/OK/TX

[James Gustina]

Definitely not a perfect setup by any stretch but it looks like it may be the first major chase day outside of Dixie and the Midwest. A high amplitude, neutral trough is progged by most members of the SREF to begin nosing onto the Great Plains Tuesday evening. By Wednesday, moisture return looks to be uninhibited ahead of a sharpening dryline that will slowly move into Central Oklahoma. Low-60s have looked probable across the warm sector on most models sans the GFS, which is still sticking to it's faster solution. Right now the biggest discrepancy, as is tradition with these March setups, is timing. I tend to lean towards the ECM/NAM solution of a gradual ejection of the jet streak between 21-00Z due to the consistency of their synoptic setup over the previous few runs but that also might just be blind hope.

 

[Greg McLaughlin]

This setup is very interesting. Sunday's cold frontal intrusion into the Gulf doesn't appear to have affected the reservoir of deep moisture across the Gulf basin. In fact it looks like the front has become quasi stationary. This bodes well for quality moisture return. Assuming we end up with a north/south dryline which is what is being depicted in some fashion by most models, I expect storm mode to favor supercells with typical nocturnal upscale growth later in the evening. There has been some evidence of veer back shear profiles, especially in earlier runs, but the trend has been for a more favorable veering profile. This appears to be shaping up to be the first real setup in the Alley for 2016. Right now it looks like I will be doing a backyard chase.

 

[Greg McLaughlin]

One significant potential caveat with regards to overall severe weather potential is possible early/mid day MCS development across southern OK. Such a scenario could cut off moisture advection to the north. Having seen the 00z Euro and GFS it appears that while the NAM paints a much more ominous picture WED, the GFS/ECMWF are more in line and show a less favorable severe weather setup.

 

[James Gustina]

The degree of capping really is riding on how well that EML gets advected east on Tuesday. The NAM has been painting a much rosier picture but it also has picked up on a wide open atmosphere by 21Z. That with the late enhancement of the low-level shear relative to the time of day might do this one in.

Sent from my XT1080 using Stormtrack mobile app

 

[Jeff Duda]

It sure seems like this season is taking its dear sweet time getting into full swing. This setup looks to be another step along the way of better looking setups this spring, but still doesn't look that great. My thoughts:

Dislikes

• consistent disagreement between mesoscale/regional (i.e., NAM and its flavors) and large scale/global (i.e., GFS and FIM) with the latter indicating a more progressive trough and veered flow...generally not conducive towards a likely severe weather event in favorable chase terrain. So with that said, this pretty much becomes a wishcast based solely on the NAM.

• Not the greatest lapse rates over the warm sector in response to notable warming at 500 mb in spite of height falls. Could be related to a subtle lead impulse that passes over the southern Plains early in the day.

• While mid-level flow is pretty good, it seems the shear is concentrated mostly at and below 700 mb. That could tend to favor a faster upscale development, i.e., less time for discrete storms.

• Despite CIN eroding fairly early in the afternoon, the model doesn't break out storms until right around 00Z, and it looks like the main part of the show could be after dark.

Likes

• Decent moisture quality for the time of year

• Decent heating (i.e., it doesn't look like the warm sector will be totally socked in by clouds all day)

• Dryline forcing (not a sweeping cold front)

• Sufficient CAPE and shear for supercells and tornadoes, assuming storms form and don't interfere

 

[Royce Sheibal]

Based on latest NAM and 4KM models, we may want to add NE/IA/MO to the headline. Solid DPVA close to the low and positioning on the left exit region of a nasty jet makes me think a decent risk will be there even with sub-60 dewpoints. Soundings in SE NE are looking solid for cape/cin/shear and have probably the best low-level lapse rates that you'll find on Wednesday.

Last week we had some nice supercells forming on the border of a 75F/35F warm front and dropping 1" hail in Omaha. With temps on the cold side of the warm front near 55F this time around and better moisture, TORs are going to be more of a factor as long as we see some sunshine in the warm sector again.

NAM Forecast soundings from around Eagle to Wahoo, NE are "all red" for STP indicators. Keep in mind they are "all pink" down in Eastern KS, so that would still be my prime target to chase if I were ya'll, but SE Nebraska moving into IA and MO overnight seems moderately chasable.

 

[James Gustina]

Looks like the cold front from this previous weekend has finally washed out in the northern Gulf right near the coast. Return flow is taking the long way around but it looks like most of the deeper moisture wasn't touched. Doesn't affect a whole lot in the grand scheme of things given the main issue is the timing and overall synoptic setup, but I'd doubt just-in-time moisture with winds already beginning to turn out of the south across the Coastal Plains of Texas.

 

[samuel stone]

I honestly still remain rather confused by this setup.. however here are my current thoughts.

Atleast based off the 0z NAM, to me the best combination of moisture, SRH and lapse rates appears to be transitioning from southeast to eastcentral Kansas from 21z to 0z respectively. In fact the NAM has continued to improve this area over the last few runs with sup composite and sig tor now spiking around 14 and 4 respectively. NAM forecast sounding from around Emporia, KS looks pretty damn good but man what if we had some better lapse rates?? Also an apparent weakness on the forecast soundings winds don't increase much at all with height from 850 to 700 leading some S-shaped hodos. Regardless I see some definite potential for a few tors in east central or southeast Kansas between say 6-10pm. (Or maybe even later if mode holds out, there are holes in the CIN as late or later than 06z)

In addition, SREF guidance appears to be relatively in line more with the NAM.

To me the biggest concerns are are:

Is the NAM to be believed over the GFS, this also includes how prolific will early day convection be to the south with subtle impulse.

Weakness between 850 and 700mb

We appear to have a very late backing/uptick in SRH response in the lowest few Km..

Mid-Level Lapse rates are still weaker than desired and its really holding down the potential..

Pretty fast storm motions some right bunkers above 45kts

Preliminary Target: Emporia, KS (East of Emporia is good chase territory, west until about Marion or southwest towards El Dorado.. not so much.)

 

[Jeff House]

Might be a good day to keep it simple and target just east of the surface low in northeast Kansas. Warm front could make it as far north as Iowa. Morning rain in western Missouri may add an outflow boundary to work with in eastern Kansas. I favor the OFB intersection with dry line. Eastern Kansas should have more instability than points farther north. Moisture return may be impacted by rain farther south, and lingering clouds could delay instability. Still deep layer shear should be adequate though not robust; and, low level shear is forecast to improve somewhat late day. Finally the dry line should not be impacted by the cold front, a nice change.

 

[Tom Dulong]

Here is the latest projection via the CIPS from top analogs of previous events per the 12Z 3/29/2016 NAM 36-hr fcst for tomorrow evening.

 

[Ben Holcomb]

I've been doing a good job at keeping away from looking at events until a day or two out lately, and finally got to take a look here around 18Z today. The Water Vapor loop this afternoon isn't too bad, showing a big bowling ball trough/low spinning over Utah, becoming negatively tilted. The NAM and GFS both collapse that and eject a positively tilted trough out into the plains tomorrow. Lapse rates on the 12Z soundings looked pretty good, with -30C temps observed in Las Vegas at 500mb. Whether or not those translate east will be interesting to see.

Unfortunately both the GFS and NAM want to keep the winds mostly veered tomorrow, and both are departing the best 850 winds about storm time (21Z). Instability is good and moisture is good but instability appears to be kind of slim, and behind the departing 850s. I would say for myself, I'm going to probably predict a null chase for me tomorrow, so that is my target: null chase.

 

[James Gustina]

Just another brief note on moisture: pretty substantial lee cyclogenesis over the course of the day and it looks like the excellent moisture is already pretty far north into Texas. Given the strength of the low-level jet overnight as it transitions east of the High Plains, I'd bet we'll be waking up to low-60s across most of Oklahoma. Whether or not the northward advection into Kansas gets stunted by morning/early afternoon garbage remains to be seen.

 

[Ben Holcomb]

Looking at the 00Z observed soundings - WOW! A lot is in place and I really think tomorrow looks better than I was expecting earlier. 170kt jet streak observed at el paso at 200mb, Lapse rates are very good, even on the 00Z OUN and FWD soundings. AMA, MAF, EPZ, ABQ, etc all showing lapse rates >= 8.

FWD showing pretty decent moisture, and LCH is saturated to 700mb.With 60 degree sfc dewpoints already to the red river, I don't expect moisture to really be a problem.

The 2 things in my mind are how positively tilted will this trough be and how much convection does lead shortwaves kick off? Hoping the NAM trends of less positive tilt and more southerly 850 flow hold up. The 00Z NAM is the most bullish so far, with almost due south 850 winds here in Central Oklahoma.

I may have changed my mind from null chase above, and am thinking/considering Central Oklahoma around 4pm.

 

[Brian McKibben]

I was intrigued that the NAM had been trending further west with the DL in the Tues model runs. I then glanced at the 12z 4km SPC WRF and saw that it was even further west with DL and had a Supercell over central OK at 00z Thur. Definitely not a slam dunk but the forecast has been trending more favorable for chasers. New Wed 00z 4km NAM now shows the DL over I-35 and a few cells actually popping up. Tomorrow morning runs will be interesting to see. 850hPa winds increase pretty dramatically from 00z to 03z and thus the STP increases as well.

This looks like a clean out the shelter type chase for me. Good luck to all.

 

[Andy Berrington]

This has been one of the most challenging systems to forecast for that I can remember in awhile. Very poor model agreement that seems to have been lasting until hour zero along with potentially cascading effects from previous convection on both days. Current observations as Ben outlined seem to be leaning more on the bullish side, although I'm a bit leery that the ascent from the incoming sub-tropical jet could lead to a washout tomorrow morning/afternoon and decrease the chances for destabilization. Important to note that with the LLJ initially out of the SSW/SW, there will be a chance for moisture to move north in behind whatever morning stuff is there unless we get a big cold pool.