April 1st-4th Severe Weather Thread

[andyhb]

Wouldn't recommend using the RAP at this range.

[alexanderhall]

Wouldn't recommend using the RAP at this range.

 

Could find similar evidence on the 0z NAM, though not quite as pronounced. 

[brettjrob]

Peeking at the 06z NAM before bed, and it's slightly earlier and more pronounced with the convective signal in N OK. The environment over which the convection tracks (roughly END-PNC) is jaw-dropping and more reminiscent of a noteworthy May event. It would be foolish to discount the convection-allowing models entirely, but I'm leaning a little more than 50/50 in favor of discrete supercell initiation 22z-00z along the DL which would have the potential to yield SigTors.

 

One possible fly in the ointment would be the WF failing to lift near/past the OK/KS border. This NAM run continued a southward trend, placing the triple point around WWR. If for some reason the WF ends up draped from Elk City to Ponca City or something like that, I can see the greater displacement between the warm sector and upper energy tipping the scales toward a cap bust, but I doubt that will happen.

[andyhb]

So yeah...a sounding I pulled from the 06z NAM at 06z in northern OK has an EHI of 14.6.

 

It's not as strongly capped as you would think either.

[thewxmann]

Why I think there is a greater chance of initiation than not, despite the output of the high-res models:

 

-All the models I have seen depict no CIN and an eroded inversion at 0Z.

 

-The "source region" of the EML is not thermonuclear in nature, i.e. not from deep old MX, owing to the relatively broad-based nature of the trough. Sometimes if the "source region" is very hot the models will underdo the WAA in the mid-levels.

 

-There is more reason for initiation tomorrow -- richer moisture, more upper air support, sharper dryline -- than there ever was today... and we got supercells today.

 

-Most of TX will be near the favorable right-entrance region of a jet streak and in the left-exit region of the STJ. The jet orientation is going to be favorable for lift.

 

-All the globals -- the GFS, Euro, CMC, UKMET, etc. indicate some form of initiation. Actually the GFS is the most bearish of the group.

 

-Models clearly indicate a subtle disturbance embedded in the STJ coming from MX and nosing into the warm sector by 0Z, and actually the latest runs are trending stronger with this feature. As exemplified in events such as 4/15/12 and 2/5/08, these can shift the scales towards initiation in marginal situations. Given the sparse data network in MX, the high-res models might not be picking up on this whereas the globals might be better at assimilating the various other sources of data... who knows.

 

Of course, this is all low-confidence and I could be totally be wrong, but I would personally lean a little more bullish for tomorrow than I would normally.

[Disc]

OUN 12z sounding from this morning:

[OUGrad05]

Capping is a concern in latest SPC guidance. This is a tough call. Any cells that can go up will be supercells with a tornado threat especially after 6pm. But the cap could prevent initiation... Reminds me of a couple other past events (both producing and busts)

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[tornadotony]

Capping is a concern in latest SPC guidance. This is a tough call. Any cells that can go up will be supercells with a tornado threat especially after 6pm. But the cap could prevent initiation... Reminds me of a couple other past events (both producing and busts)

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The main difference is that the caps on the bust days are usually stronger than the cap on the 12z Norman sounding.

 

I kinda alluded to this last night, but I'll echo Jim...I think at least one or two BFD supercells is/are going up late afternoon/early evening.

[tornadotony]

Also, the HRRR (3-km, convection-allowing) initiates in both cntl OK and N TX.

[Ed Lizard]

18Z soundings being ordered anywhere?

[Superstorm93]

 

 

NCEP Operational Status Message Wed Apr 2 14:03:40 2014 GMTNOUS42 KWNO 021403

ADMNFD

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE

NWS NCEP CENTRAL OPERATIONS COLLEGE PARK MD

1402Z WED APR 02 2014

A CRITICAL WEATHER DAY IS POSSIBL DUE TO A SPC FORECAST OF

MODERATE RISK AT DAY 2.

SHRUELL/SDM/NCO/NCEP

 

 

HRRR has the focus in KS today

 

[brettjrob]

Leaning firmly in favor of CI along the dryline, though obviously it's not a total slam-dunk. Obviously, many things favor significant severe provided CI. A couple of the caveats I see:

 

- The 12z NAM (which I'm taking much more seriously than morning runs of the RAP/HRRR, after yesterday) shows a pronounced flow weakness around H7, leading to the dreaded hodo kink over much of OK (worse with southward and westward extent). How real is this? It could be a major fly in the ointment if it's as bad as modeled.

 

- W OK is in severe drought, and has received virtually no significant precipitation this winter. Mixing is likely to be an issue and I fully expect dew points to verify lower than the NAM/GFS forecast, especially right along the DL. This should be less of a problem as storms approach I-35, though.

 

Otherwise, the ceiling is very high and I think it will at least be approached, pending those issues. With a surface low deepening to 994 mb by early evening, this is a rather classic setup and one which favors low-level shear strengthening more rapidly than models indicate. I sort of got burned by taking the low-level model wind fields too literally last year on 5/19, so I won't make that mistake again. There are a lot of similarities to that setup, though ultimately being early April with severe drought, LCLs will certainly not be as favorable (over a wide area) as that day.

[tornadotony]

The 12z GFS just kicked up the threat to another level tomorrow.  Instead of major early initiation/widespread warm sector convection (some of which would likely still be tornadic), it holds off the vast majority of initiation until 21z or later, with much lower QPF values indicative of far more discrete convection.  This is in line with the OP NAM and the 4-km NAM run, the latter of which has a potent supercell signal by 00z across AR and LA.  I think MO will have a decent tornado threat, but unidirectional profiles up there may favor a linear mode with widespread wind damage and QLCS tornadoes for the most part.  If the GFS and NAM trends continue, though, I'd almost expect a high risk eventually from far srn MO through much of AR and into N LA.

[JoMo]

Well the warm front has pushed through here, and has made it into SE KS. It looks like the HRRR/NAM want to light up the warm front this evening and keep storms mostly along and north of that. Unless there are some right turners, I'm hoping things will be quiet here today.

[Stebo]

OUN 12z sounding from this morning:

Wow this is an incredible sounding from this morning.

 

18Z soundings being ordered anywhere?

I would imagine we will see some today.

[Stebo]

The 12z GFS just kicked up the threat to another level tomorrow.  Instead of major early initiation/widespread warm sector convection (some of which would likely still be tornadic), it holds off the vast majority of initiation until 21z or later, with much lower QPF values indicative of far more discrete convection.  This is in line with the OP NAM and the 4-km NAM run, the latter of which has a potent supercell signal by 00z across AR and LA.  I think MO will have a decent tornado threat, but unidirectional profiles up there may favor a linear mode with widespread wind damage and QLCS tornadoes for the most part.  If the GFS and NAM trends continue, though, I'd almost expect a high risk eventually from far srn MO through much of AR and into N LA.

 

Yeah the GFS is downright scary across AR for tomorrow and I completely agree on the high risk, I wouldn't be shocked if we saw one in a little over an hour.

[Stebo]

The new day one added 30% hail risk along the KS/OK border but also trimmed the 5% tornado risk from parts of eastern OK and western AR/MO.

[Hoosier]

Just some context about the April 3 date.  Everyone remembers it for the Super Outbreak but over half of the years since 1950 have had at least 1 tornado on that day.  1956, 1957, 1968, 1989 and 2012 had 20+ tornadoes.

[1900hurricane]

Right now, I'm leaning towards a local chase if things look good tomorrow. Getting out of a test at 18Z is really going to hamper my range, but that should leave me enough time to fly north to somewhere between Groesbeck and Corsicana and catch some of the southern action (hopefully).

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[tornadotony]

Other 12z high-res output also leave the warm sector fairly clean through 21z tomorrow.

[Superstorm93]

Day 2 outlook remains virtually unchanged 

 

 

 

...REGIONAL SEVERE WEATHER OUTBREAK POSSIBLE THURSDAY AFTERNOON AND
EVENING FROM SRN MO AND AR INTO THE WRN OH/TN VALLEY... 

 

[LocoAko]

FWIW (which is probably not much), 15Z HRRR seems to have a nice track of updraft helicity immediately east of OKC at 00Z. 

 

[Chicago Storm]

Just left Norman. Going to head north and sit in N-C. OK.

[Ed Lizard]

Seems a little early, but looping satellite centered on AUS and ICT, cu field already looking a little agitated West of ABI

[wxmeddler]

Dew point is an astonishing -2°F in Pampa,TX. Gotta think if this sharpens up a bit more then chances of CI along the dryline goes up.

[Thundersnow12]

Models are doing a pretty piss poor job right now with sfc wind direction across west-central OK compared to 18z progged directions. Winds already backing to due south now or even some SSE winds (OJA/KIN2/CHK). 

[brettjrob]

Models are doing a pretty piss poor job right now with sfc wind direction across west-central OK compared to 18z progged directions. Winds already backing to due south now or even some SSE winds (OJA/KIN2/CHK). 

 

Yeah, and the SPC Mesoanalysis H85 winds are a lot more backed than most of the guidance had indicated for 18z. Also, just to reiterate, the RAP/HRRR are pretty useless right now with regard to BL thermodynamics. The 16z HRRR forecast for 19z put the 60 F isodrosotherm roughly along I-44, such that El Reno should have a reading in the mid-upper 50s right now. In reality, Clinton (50 miles farther W) is still at 63 F.

[JoMo]

Tornado Watch Likely.

 

http://www.spc.noaa.gov/products/md/md0248.html

[Thundersnow12]

Eh

 

[NTXYankee]

So not sure how reliable Euro is in short range, but has been pretty consistent last day or two with not bringing front/dryline through DFW Thursday. Basically parks it just west of region, then brings it through after 0z. Others have pulled it completely through to the east. Of course could be reading it wrong, used wundermap for the first time.