April 24-30th Severe Potential

[OUGrad05]

This is perhaps the messiest "morning of" that I can recall.  Models still all over the place with convection mode and timing...honestly frustrating.  I haven't seen anything to warrant a high end tor threat despite some local chatter otherwise.  

We'll see what the 12Z NAM and GFS show and I'll continue to watch the high res models...hail seems to be the main threat.  SPC likely to upgrade the hail risk.  Hard for me to see them dropping the tor threat back from 10% or changing the hatched area with so many "unknowns" still floating around.  

If it becomes clear that storm mode will be primarily linear by 7 or 8pm then I would expect the hatched tor area, at least in OK to get carved way back or eliminated.  I think best chance for sig tors still remains within the first 90 to 120 mins of convection or if discreet cells are still around from 7pm to about 11pm...

Funny a few of you guys were talking about 4/26/09...That was a high risk bust that I was chasing on, but there were a few tors that day and a couple cells that had some nice rotation and were photogenic for awhile.  We had a scary moment that day chasing when we lost our sat uplink and had no cell coverage out in western OK.  We were out ahead of a storm, not in a good location and things got dead calm...within about 2 minutes the sirens in the small town started howling...at that point things were somewhat HP and rain wrapped and we hadn't had a radar update in some 35 minutes due to connectivity issues...needless to say on a high risk day it scared us pretty good, we were on the phone with the station there was a radar indicated tornado effectively on-top of us but there was so much precip we couldn't see anything...

Anyway, that wound up being a bust overall, we got some cool wall cloud pics with some mesa's in the foreground and background but that's about it...

[Jim Marusak]

It will be interesting to see to what extent the morning complex of storms plays into the overall setup this afternoon. Noticed an outflow boundary being kicked out across the I-70 corridor now and moving southwest. 

just saw that, as I just got home from work an hour ago and am catching up on the initializations real quick. any storm that bumps into that outflow boundary in eastern KS is gonna rotate and get nasty real quick. As well though, it might drag the warm front a bit further south, translating the north side convection zone a bit to the south.

[nrgjeff]

Warm front outflow boundary combo in northern Kansas offers locally higher SRH. Mid-upper level winds may force cells to cross, rather than ride boundary. With little chance of cyclical supercells, one could still look for one-and-done tornadoes. Perhaps more than 1-2 cells will perform as they cross this boundary. WF/OFB is my first target based on fundamentals, but two more are below.

 

Morning visible satellite and surface chart hint at a subtle east-west boundary on the KS/OK border, which should lift north slightly. Low clouds were noted KS side; mostly clear OK side. Surface winds kinked a bit in the area. Boundary extends all the way to Arkansas with the reverse visible satellite footprint. Both 00/06Z high-res NAM had small but intense supercells west of Wichita shooting north around 22-00Z. Perhaps the boundary is a gravity wave or other subtle feature quite separate from WF/outfllow farther north.

 

Finally a separate vigorous short-wave will eject across North Texas toward 00Z. Upper level winds will be slightly less parallel to lower levels down south. Storms may initiate later, but still with some daylight. Perhaps 1-2 supercells will get all alone, at least producing gorilla hail.

[Stebo]

Very impressive gravity waves over North Texas into OK right now. That is usually a very good sign on a severe weather day.

 

[ClicheVortex2014]

HRRR is pretty discouraging for tornadic supercell potential. It's showing a 2-3 hour period in Oklahoma where semi-discrete supercells reign, but they don't last much longer than that. There's also some high reflectivity in NE KS with some cells, but none are obviously long-lived.

 

[wildwestpb]

Very impressive gravity waves over North Texas into OK right now. That is usually a very good sign on a severe weather day.

What's causing the atmospheric jello ripple, and think it will end before the storms get going this afternoon?

[Stebo]

What's causing the atmospheric jello ripple, and think it will end before the storms get going this afternoon?

It is a signal that the trough is impinging upon the area of capped/stable air ahead of it.

[wildwestpb]

Just had a cell pop up just NW of me, already putting down nickel sized hail, and gusts to 40 mph. Moving NE@20.

And, just got warned severe as I was posting this. 60MPH winds, half dollar hail in the span of 6 minutes.
http://mesonet.agron.iastate.edu/vtec/#2016-O-NEW-KOUN-SV-W-0134/USCOMP-N0Q-201604261430

 

Live radar of it -

[SmokeEater]

Nam?

[ClicheVortex2014]

FWIW... SREF is picking up on a maximized tornado threat along the OK/TX border

 

[bdgwx]

NCAR's WRF ensemble has maybe one or two long supercell tracks in southeastern OK. 

[wildwestpb]

SREF and WRF ensemble is probably why NWS OUN updated it's HWO

TIMING...ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE THIS MORNING AND EARLY THIS AFTERNOON WITH LARGE HAIL BEING THE THREAT. THEMOST LIKELY TIME FOR ORGANIZED AND SIGNIFICANT SEVERE STORMSWILL BE AFTER 2 PM THROUGH THIS EVENING. THE MAIN STORM INITIATION AREA IS EXPECTED OVER SOUTHWEST OKLAHOMA AND WESTERNNORTH TEXAS. STORMS WILL MOVE QUICKLY TO THE NORTH AND EAST.IMPACTS...GIANT HAIL LARGER THAN BASEBALLS WILL OCCUR WITH SOME STORMS.WIND GUSTS TO 80 MPH AND TORNADOES ARE ALSO EXPECTED.RECOMMENDED ACTIONS...STORM SPOTTER GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSSTHE RISK AREA SHOULD PLAN FOR SEVERE WEATHER OPERATIONS THROUGH THIS EVENING.DISCUSSION...ISOLATED STRONG AND SEVERE STORMS WILL DEVELOP THIS MORNING ACROSS CENTRAL AND NORTHERN OKLAHOMA AS A DISTURBANCE MOVESQUICKLY NORTHWARD OVER CENTRAL AND NORTHERN OKLAHOMA. A MUCHSTRONGER DISTURBANCE WILL BE MOVING OUT OF WEST TEXAS THIS AFTERNOON AND ALLOW THE DEVELOPMENT OF NUMEROUS SEVERE STORMS.ALTHOUGH ALL STORMS WILL BE CAPABLE OF PRODUCING HAIL THE SIZE OF BASEBALLS AND LARGER...THE RISK FOR TORNADOES ISEXPECTED TO INCREASE LATE THIS AFTERNOON AND EARLY THIS EVENING.

[Stebo]

Nam?

4km NAM goes nuts with supercells across western Oklahoma between 21-00z very strong backing into the dryline there too.

[brettjrob]

Yeah, the NCAR Ensemble and SREF are honing in on the Red River, and that's my pick for today too. There should be at least a few tornadoes up in N KS/S NE, as well.

 

An analog I found with a very close H5 pattern match for the central US is 7 May 1995, which produced a cyclic monster from NW of DFW into Ardmore. The surface map had some important differences, but it's a bit more evidence in favor of the southern mode (N TX and possibly into S OK) today.

[1900hurricane]

Playing the southern target today too. Headed for Jacksboro now. I like it since 281 can get me N/S pretty easily.

Sent from my iPhone using Tapatalk

[wildwestpb]

Have another cell firing where the first one started, just NW of me.
http://cdnapi.kaltura.com/kwidget/wid/_557781/uiconf_id/13570192/entry_id/1_mv3sn31f

[Chicago Storm]

Agitated CU quickly developing along the DL in N. OK/S. KS.

[ClicheVortex2014]

Do I see more gravity waves in C OK?

[OUGrad05]

Do I see more gravity waves in C OK?

Yes you do

[wildwestpb]

Do I see more gravity waves in C OK?

Looks like - http://www.intellicast.com/National/Satellite/Visible.aspx?region=mko

[ClicheVortex2014]

Cap is letting loose. 4 cells now in OK

 

MESOSCALE DISCUSSION 0453
NWS STORM PREDICTION CENTER NORMAN OK
1009 AM CDT TUE APR 26 2016

AREAS AFFECTED...NRN/CNTRL OK...SERN KS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 261509Z - 261645Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AN ISOLATED HAIL THREAT WILL EXIST THIS MORNING ACROSS
PARTS OF NRN/CNTRL OK AND POSSIBLY INTO SERN KS. A WW IS NOT
CURRENTLY ANTICIPATED AS THIS THREAT SHOULD REMAIN LOCALIZED IN THE
SHORT-TERM...BUT TRENDS WILL BE MONITORED.

DISCUSSION...AN ISOLATED TSTM HAS DEVELOPED NE OF THE OKC METRO AREA
THIS MORNING...ALONG THE NRN PERIPHERY OF A RIBBON OF
MOISTENING/ISENTROPIC ASCENT NOTED IN WATER VAPOR IMAGERY. THIS
STORM IS LIKELY ROOTED NEAR 700 MB AT THE MOMENT...BUT WITH VERY
STEEP MIDLEVEL LAPSE RATES /NEAR 9 C/KM PER 12Z OUN SOUNDING/ A HAIL
THREAT MAY CONTINUE TO ACCOMPANY THIS STORM AND ANY ADDITIONAL TSTMS
THAT DEVELOP. HOWEVER...COVERAGE IS EXPECTED TO REMAIN ISOLATED
THROUGH THE LATE MORNING GIVEN THE RELATIVELY CONFINED AREA OF
ASCENT...AND THIS SHOULD PRECLUDE WW ISSUANCE IN THE
SHORT-TERM...BEFORE MORE WIDESPREAD TSTM/SVR POTENTIAL ACCOMPANYING
THE LARGER UPSTREAM TROUGH INCREASES LATER TODAY.

 

[Jonbo]

Could these morning storms around OKC set up an outflow boundary near the city and locally enhance the threat layer today?

[hurricaneman]

looks like that cell heading for Chandler has large hail and weak rotation, that cell may end up being the first of many tornado warned cells today

[wildwestpb]

Could these morning storms around OKC set up an outflow boundary near the city and locally enhance the threat layer today?

NWS OUN doesn't believe they will have an impact on weather later today according to their FB page, but if we get a lot, that may change.

Edit: Also, have other cells popping up SW of Norman and SE of Chickasha, OK.

[JasonOH]

The OKC storms appear elevated. They won't mess things up too bad, and may even create a better environment.

[Calderon]

It's pretty clear that the gravity waves crossing the area agitated the atmosphere enough to pop some decent elevated cells. 

 

They won't do a whole lot to the atmosphere and may lay down very subtle boundaries, if at all that aren't mixed out.

[boo radley]

Some of these statements are unwarranted. Large and extreme tornadoes? Carry on gentlemen, many of you are the reason I'm on the forum. That being said, Red river area looks to be very active for severe weather by mid afternoon.

[JasonOH]

If you are going to make a statement like that you better have some solid meteorological reasoning to back it up. Otherwise read more, post less.

This, if the VBV doesn't verify it could be possible, but I have my doubts that that would happen. Even if it did SRH would be meager at best.

[Stebo]

It's pretty clear that the gravity waves crossing the area agitated the atmosphere enough to pop some decent elevated cells. 

 

They won't do a whole lot to the atmosphere and may lay down very subtle boundaries, if at all that aren't mixed out.

Even these weak/elevated cells will add to the mix with boundaries.

[OUGrad05]

The scary thing is that these cells are giving that look and we havent even got to the best dynamics of the day. I expect some large and extreme tornadoes later when the cap breaks

Indicators are of a limited tor threat with possibility of a couple sig tors.  That is somewhat questionable unless storms interact with gravity waves and/or boundaries left by this morning convection.