Discussion (May 18-19-20-21) Moore Tornado EF-5 from NWS

[cycloneye]

No big changes at 16:30z update. (Moderate Risk / 15% chance of Tornadoes) Go here to see the SPC update

[wx247]

This snippet from Tulsa is pretty telling in my opinion of what "could" develop later today:

ALL SIGNS CONTINUE TO POINT TOWARD SIGNIFICANT SEVERE WEATHER LATE
THIS AFTERNOON AND EVENING PRIMARILY ACROSS NE OK. STORMS MAY BE
JUST AS INTENSE FURTHER SOUTH AND EAST ACROSS EAST CENTRAL OK INTO
NW AR HOWEVER THEY ARE LIKELY TO BE REDUCED IN NUMBER WITH
EASTWARD AND SOUTHWARD EXTENT. LESS DEEP MOISTURE AND A STRONG
CAPPING INVERSION CONTINUE TO SUPPORT MUCH LOWER STORM CHANCES
TOWARD SE OK.
FORECAST WIND PROFILES SUPPORT A WINDOW OF FAVORABLE SHEAR
PARAMETERS FOR STRONG TO VIOLENT TORNADOES. WHETHER THIS IS
REALIZED WILL DEPEND LARGELY ON EVENTUAL STORM/S/
EVOLUTION...HOWEVER UNDERSTANDING THE POTENTIAL EXISTS IS
NOTEWORTHY.

[TwisterFanatic]

Storms that fire on the dryline will be INTENSE. Dryline is very, very pronounced. 70 degree dewpoints ahead, mid 30 degree dewpoints behind it.

[CrazyC83]

Tornado watch coming out soon. It might be a PDS, but at least should have big numbers.

[wx247]

New Mesoscale Discussion indicates a Tornado Watch should be out for E KS shortly. The MCD mentions the possibility of a few strong tornadoes.

Edit: I see CrazyC83 beat me to the punch with his post. I am not sure it will be PDS, but I agree that the probability numbers will be high.

[WeatherGuesser]

I know the air is thick here, but it will be Tuesday night into Wednesday before the system gets here and so far, no risk area posted.

[CrazyC83]

I would go 80/50 for the tornado numbers personally, but hold off on PDS for now at least. That is unless the WFOs want it...

[CrazyC83]

A bit of a surprise to see the Tornado Watch (180) for MN/IA. No real warning and not exactly a tornado-prime atmosphere. But they see something I don't...

[EF-5bigj]

So when are the storms expected to start firing?

[CrazyC83]

So when are the storms expected to start firing?

Mid to late afternoon.

[wx247]

Something to be concerned about beyond the tornado risk... it looks like we could see some monster hail reports today.

[Bunkertor]

So when are the storms expected to start firing?

SPC says 20z which is in 1,5 hours

[RL3AO]

A bit of a surprise to see the Tornado Watch (180) for MN/IA. No real warning and not exactly a tornado-prime atmosphere. But they see something I don't...

Yeah. I was surprised when the weather radio woke me up for that...

[CrazyC83]

Tornado Watch 181 coming out. Also another one likely soon in central/western OK (slightly lower numbers perhaps).

[cycloneye]

From Jim Cantore:

Jim Cantore‏@JimCantore3 m
Looks very capped in OK so when storms go they will explode this afternoon. #OKwx

[CrazyC83]

Probs 70/30 on WT181. Since it does not include any of Oklahoma, 182 may have higher numbers.

[wx247]

Probs 70/30 on WT181. Since it does not include any of Oklahoma, 182 may have higher numbers.

I would imagine that if we were going to see a PDS watch, it would have happened with the KS one. The probabilities are higher there. Dynamics are impressive further south, but I just don't think they will pull the trigger. I have been wrong before and may be again.

[CrazyC83]

Probs 70/30 on WT181. Since it does not include any of Oklahoma, 182 may have higher numbers.

I would imagine that if we were going to see a PDS watch, it would have happened with the KS one. The probabilities are higher there.

Well, that only takes up a small part of the MDT risk area for tornadoes (i.e. the 15% area). But to go from 30% to 60% sig-tor in a small area with a slight difference would be a huge change. I'm thinking around 40-50% sig-tor, not quite PDS.

[TwisterFanatic]

I think the Oklahoma watch could have higher probs, storms will stay discrete much longer in OK than in KS.

[Ntxw]

I would watch the Red River valley area onwards into eastern Oklahoma for big discrete cells this afternoon. Shear is very good and anything that pops up there will likely spin quickly if and when that cap is broken.