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andyhb

May 7th-9th Severe Weather Episodes

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Yeah, I headed out real late, so I chose the area that would logistically lead me back to Norman as I chased. I likely would've jumped on the southern most left-turner had I been positioned before initiation. I didn't see anyone on 44 taking pictures at the time I was talking about, so I'm not sure I'll get to see the vantage point I was talking about. It was one of the few moments that I've chased in the past year where an Oklahoma storm wasn't insanely junky and had some sunlight in the background.

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This season YTD has been pretty much horrific on the Plains, after this debacle. Excepting the magic unicorn Colorado tornadoes on 4/15 and 5/7, there's been virtually nothing to show for several impressive troughs with seasonably rich moisture in place. If you take last week's systems and today's in combination, I'm not sure I've ever seen such a complete dearth of substantial tornadoes in the Plains this time of year from similar systems. All of these setups have been imperfect to varying degrees, but especially in May, flaws on the order of today's typically only serve to reduce the event from an outbreak to scattered tornadoes (one or two still being substantial/significant/long-lived). And from a chaser's point of view, even good structure - which can help compensate for tornado busts like today - has been very scarce.

 

Low level shear in the 21z-23z timeframe was definitely more anemic than forecast from a couple days out. Perhaps there was a gradual downward trend in that regard over the past 24-36 h that a lot of us overlooked, since it was a subtle detail -- the shear near and after 00z was going to be good either way. Shortwave timing must have been just a few hours off.

 

And to rehash a rant of mine I've been posting for years: today is W OK in a nutshell. Right smack in the middle of the U.S. climatological tornado frequency maximum, and it's been 15 years and counting since the last substantial multi-storm dryline tornado event (localized single-storm events have happened, of course, like Elmer last year and 11/7/11). For so many years, every single time W OK is the focus of a solid large-scale dryline setup like this, there's some major failure mode that creeps in. So many busts out there that I can't even keep track any more.

 

Yeah, it's frustrating. I think the majority of the issues have been related to wind profiles... this year's version of last year's junkvection failures. The Pacific Jet extension hasn't been very strong and there's been a lot of blocking in Greenland, which both contribute to bowling-ball-favored patterns. Bowling ball ejections (today) and ejections running into bowling balls downstream (today, 4/26) tend to have a higher probability of wind profile issues.

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Well tomorrow, after the vastly disappointing results of today, can only be better.

 

Great, you jinxed it. :P

 

But in all seriousness, the Quebec closed low moves a little more offshore tonight, which allows the 500mb closed low over the Front Range to open up, and a shortwave on the backend of the low to pivot forward and amplify over the southern Plains tomorrow. The net result is you get a nice open neutral-negatively tilted trough plowing into a now very moist warm sector.

 

We still fall short of an ideal configuration but it looks better at 500mb than any of the past three setups 24 hr out, and I'd think this is a MDT-risk caliber setup. (Then again, last few times I've said that haven't panned out, so take that last statement with caution.)

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Pretty significant couplet in Lucas, KS at the moment... I can't tell if CC is picking up a big debris signature or it's the 3" hail. Anyone else care to take a peek?

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Pretty significant couplet in Lucas, KS at the moment... I can't tell if CC is picking up a big debris signature or it's the 3" hail. Anyone else care to take a peek?

 

Definitely hail with some side-lobe contamination going on.

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Regarding tomorrow: after surveying the two NCEP WRFs, the NSSL WRF, and the HRRRx, the UH signal is not particularly impressive overall. Along the dryline, we once again see a scenario where storms initiate and attain UH, but weaken rather quickly. In the warm sector over the Ozarks/Ouachitas, there's definitely potential, but UH on the HRRRx and NCEP WRFs doesn't exactly scream outbreak.

 

I start my post with this because if I've had one takeaway from the past 3 weeks, it's that these CAMs are performing extremely well. Rationalizing away lukewarm UH output has not gone well on any day so far. Caveat: the open warm sector threat over E OK/AR is a bit different than the dryline setups, so I'm not as quick to trust the UH with sky high confidence.

 

Reverting to old fashioned meteorology, for whatever that's worth these days: deep layer shear looks like a possible issue roughly N of I-40, particularly back near the dryline. With the primary H5 trough axis sweeping across I-35 by 00z, it's no surprise that CAMs kill off afternoon dryline storms fairly quickly. S-shaped hodos, with a weakness centered around 3 km AGL, remain an issue on many forecast soundings throughout the warm sector. All that being said, I'd be surprised if there aren't several tornadoes, a few possibly significant, way out in the jungles. As for chasers, it's back to willing away Great Lakes/New England troughing on the long range GFS for whenever the next wave finally ejects from the Rockies mid-late month.

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Reverting to old fashioned meteorology, for whatever that's worth these days: deep layer shear looks like a possible issue roughly N of I-40, particularly back near the dryline. With the primary H5 trough axis sweeping across I-35 by 00z, it's no surprise that CAMs kill off afternoon dryline storms fairly quickly. S-shaped hodos, with a weakness centered around 3 km AGL, remain an issue on many forecast soundings throughout the warm sector. All that being said, I'd be surprised if there aren't several tornadoes, a few possibly significant, way out in the jungles. As for chasers, it's back to willing away Great Lakes/New England troughing on the long range GFS for whenever the next wave finally ejects from the Rockies mid-late month.

Sigh.

NWP will never, and I mean never in our lifetime, replace the human forecaster in severe convective forecasting. The obsession with hi res guidance and CAMs is bad.

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Still up here, 06z/short range guidance is certainly still supporting the potential for significant tornadoes especially INVOF the Red River into SW AR later on today. That cluster/MCS W of the metroplex looks to have a northward component of motion (and also doesn't look overly organized in terms of a cold pool/etc), which should allow this area to remain relatively untapped. Forecast soundings across the board by 00z show large hodographs with strong veering in the lowest 3 km and a LLJ of around 40 kts + great venting aloft.

 

Unfortunately, that Arklatex radar hole is likely going to reek havoc with monitoring this, but somewhere perhaps in the area affected by the 4/2/1982 tornado outbreak could get something nasty later on if things don't change substantially by then. Kind of interested to see how much Arkansas destabilizes as well up the I-30 corridor, since the wind fields look just as, if not more, impressive there.

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Wel the current trajectory of the MCS has taken it through the northwest half of the enhanced risk. The area you have mentioned has remained fairly untouched.

Still up here, 06z/short range guidance is certainly still supporting the potential for significant tornadoes especially INVOF the Red River into SW AR later on today. That cluster/MCS W of the metroplex looks to have a northward component of motion (and also doesn't look overly organized in terms of a cold pool/etc), which should allow this area to remain relatively untapped. Forecast soundings across the board by 00z show large hodographs with strong veering in the lowest 3 km and a LLJ of around 40 kts + great venting aloft.

Unfortunately, that Arklatex radar hole is likely going to reek havoc with monitoring this, but somewhere perhaps in the area affected by the 4/2/1982 tornado outbreak could get something nasty later on if things don't change substantially by then. Kind of interested to see how much Arkansas destabilizes as well up the I-30 corridor, since the wind fields look just as, if not more, impressive there.

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Sigh.

NWP will never, and I mean never in our lifetime, replace the human forecaster in severe convective forecasting. The obsession with hi res guidance and CAMs is bad.

Please review the multitude of professionals who swore on their lives that no way could we achieve dew points in the upper 60s because the Gulf coast dew points the day before were in the upper 50s.

Respect NWP or get left behind

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Please review the multitude of professionals who swore on their lives that no way could we achieve dew points in the upper 60s because the Gulf coast dew points the day before were in the upper 50s.

Respect NWP or get left behind

Anecdotal. Cool.

Just like you can point to cases where models failed..miserably.

NWP may outperform your average chaser/forecaster, but your specialist severe weather forecaster will never be replaced.

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Anecdotal. Cool.

Just like you can point to cases where models failed..miserably.

NWP may outperform your average chaser/forecaster, but your specialist severe weather forecaster will never be replaced.

And lol. "Respect NWP"

No one is saying replace the severe weather forecasters but this isn't the situation where we can go #LOLMODELS like we have years prior. NWP has grown by leaps and bounds in the last 10 years. Are there still hiccups, yes but they are less frequent.

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Anecdotal. Cool.

Just like you can point to cases where models failed..miserably.

NWP may outperform your average chaser/forecaster, but your specialist severe weather forecaster will never be replaced.

And lol. "Respect NWP"

 

 

Calling someone out for saying something anecdotal and then following it up with a gross generalization saying "never" will NWP outperform a severe weather forecaster is idiotic. You have absolutely no clue what NWP will be capable of 10, 20, even 50 years down the line, stop acting like you do. 

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Calling someone out for saying something anecdotal and then following it up with a gross generalization saying "never" will NWP outperform a severe weather forecaster is idiotic. You have absolutely no clue what NWP will be capable of 10, 20, even 50 years down the line, stop acting like you do.

Yeah it is a bit insulting to say what Sam said is anecdotal, he is one of the best out there and knows what he is talking about.

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DAY 1 CONVECTIVE OUTLOOK  

NWS STORM PREDICTION CENTER NORMAN OK  

1128 AM CDT MON MAY 09 2016  

 

VALID 091630Z - 101200Z  

 

...THERE IS AN ENH RISK OF SVR TSTMS OVER PARTS OF EASTERN OK AND  

MUCH OF AR...  

 

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CENTRAL  

PLAINS INTO THE MID/LOWER MS VALLEY...  

 

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS PARTS OF THE  

CENTRAL/SOUTHERN PLAINS AND MID/LOWER MS VALLEY...  

   

..SUMMARY  

 

SEVERE STORMS ARE EXPECTED FROM PARTS OF THE SOUTHERN AND CENTRAL  

PLAINS TO THE LOWER TO MID MISSOURI VALLEY...OZARKS AND ARKLATEX.  

TORNADOES AND VERY LARGE HAIL WILL BE POSSIBLE FROM EASTERN OKLAHOMA  

AND NORTHEASTERN TEXAS INTO CENTRAL ARKANSAS AND NORTHERN LOUISIANA.  

   

..CENTRAL PLAINS INTO LOWER MS VALLEY  

 

WATER VAPOR LOOPS SHOW A FAST-MOVING SIGNIFICANT SHORTWAVE TROUGH  

OVER SOUTHEAST NM. THIS TROUGH WILL RACE ACROSS THE SOUTHERN PLAINS  

AND INTO THE LOWER MS VALLEY TONIGHT. LARGE SCALE FORCING AHEAD OF  

THIS SYSTEM WILL RESULT IN SCATTERED SHOWERS AND THUNDERSTORMS FROM  

EASTERN KS AND MUCH OF MO INTO THE ARKLATEX REGION. MANY OF THESE  

STORMS WILL POSE A RISK OF SEVERE WEATHER.  

 

STORMS ARE EXPECTED TO INITIATE FIRST THIS AFTERNOON ALONG THE  

DRYLINE FROM EASTERN KS INTO CENTRAL OK. VERY STEEP MID LEVEL LAPSE  

RATES...MLCAPE VALUES OVER 2000 J/KG...AND FAVORABLE WESTERLY FLOW  

ALOFT WILL PROMOTE SUPERCELL STRUCTURES CAPABLE OF VERY LARGE HAIL.  

ISOLATED TORNADOES CANNOT BE RULED OUT...BUT THE MAIN TORNADO RISK  

APPEARS TO RAMP UP AS THE STORMS TRACK EASTWARD INTO EASTERN OK  

DURING THE LATE AFTERNOON...AND INTO AR DURING THE EVENING.  

FORECAST SOUNDINGS SHOW SUBSTANTIAL LOW LEVEL VERTICAL SHEAR OVER  

THIS AREA...SUGGESTING THE POTENTIAL OF STRONG TORNADOES. A  

CONSENSUS OF 12Z CAM SOLUTIONS ALSO SUPPORT THE IDEA OF INTENSE  

SUPERCELLS AFFECTING THIS AREA. THIS ACTIVITY WILL MAINTAIN A  

SUBSTANTIAL TORNADO RISK ACROSS MUCH OF AR BEFORE WEAKENING AS IT  

APPROACHES THE MS RIVER.  

 

..HART/GLEASON.. 05/09/2016  

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Hatched TOR includes Little Rock, AR... looks like the play would be in E OK early to W AR evening

 

 

Now we just sit back and hope "The Great 10% Hatched Curse of 2016" gets broken today lol.

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Greetings All; 

 

I've been reading this forum and others for several years now given my fascination with severe weather and have to say I've learned quite a bit by merely reading and observing. Given recent events, I thought this would be a good opportunity for my 1st post/question....

 

I'm curious if anyone knows the specific process the SPC and/or NWS Offices utilize for reviewing forecasts, the accompanying hits/misses and plugging that feedback back into the various models....in other words, what's the 360 Degree Feedback loop for each forecast?

 

Thanks in advance and if there is a more appropriate forum to post, I'd be happy to do so;

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Greetings All;

I've been reading this forum and others for several years now given my fascination with severe weather and have to say I've learned quite a bit by merely reading and observing. Given recent events, I thought this would be a good opportunity for my 1st post/question....

I'm curious if anyone knows the specific process the SPC and/or NWS Offices utilize for reviewing forecasts, the accompanying hits/misses and plugging that feedback back into the various models....in other words, what's the 360 Degree Feedback loop for each forecast?

Thanks in advance and if there is a more appropriate forum to post, I'd be happy to do so;

Verification numbers are always analyzed by the SPC. A lot of work is done with them and a lot can be learned based on how models performed based on certain scenarios. Models are always being improved, but the base of the models sometimes has bias. Most of the "loop" is finding which models do the best, and combining it with working forecast techniques.

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Wikipedia lists the tornado outbreaks of the year, and this web page shows there have been no EF-3s since February. I don't personally remember seeing any storm surveys of EF-3 or better damage since February.

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Now we just sit back and hope "The Great 10% Hatched Curse of 2016" gets broken today lol.

 

 

If I'm not mistaken those cursed ones you're referring to were a day 2 + hatched tor while this one is a day 1 with the 3rd outlook

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Wikipedia lists the tornado outbreaks of the year, and this web page shows there have been no EF-3s since February. I don't personally remember seeing any storm surveys of EF-3 or better damage since February.

 

I believe the Colorado one from Saturday was a high-end EF-2.  Not an EF-3, but pretty close.

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If I'm not mistaken those cursed ones you're referring to were a day 2 + hatched tor while this one is a day 1 with the 3rd outlook

 

There is no such thing as a hatched tor in a D2 outlook. Those are combined severe weather probabilities. The only ones that have the separate probabilities for tornadoes, hail and damaging wind are the D1 outlooks.

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There is no such thing as a hatched tor in a D2 outlook. Those are combined severe weather probabilities. The only ones that have the separate probabilities for tornadoes, hail and damaging wind are the D1 outlooks.

You're correct sir. However,  I was thinking about just the outlook in general.  Also, what I was referring to  was the strong/significant tornadoes that were mentioned in the early outlooks.  Plus the 10% hatched on the first outlook.  In other words, this outlook has a different look when forecasting the tornado probs than the previous ones (from what I can see, and remember.  I could be wrong, but just something I thought of.)

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Sigh.

NWP will never, and I mean never in our lifetime, replace the human forecaster in severe convective forecasting. The obsession with hi res guidance and CAMs is bad.

 

I don't want to beat a dead horse or regress, but in no way was Brett implying that hi-res NWP will/should replace forecasters. Not sure where you got that from. He was acknowledging how well CAMs seem to be performing this season, and that ignoring their consensus should be done at one's own peril (e.g., dewpoints in the 60s yesterday, characteristics of UH swaths from the past few threats, etc). 

 

Of course epic fails will still occur given the extremely nonlinear nature of convective initiation and the occasional failure of parameterization schemes to capture things like surface fluxes during droughts, etc. Observations are still crucial and nothing can really be substituted for forecaster intuition and experience, but IMO we are beginning to enter a time where hi-res stuff offers insight that you can't get otherwise. Once a model is spun-up and the physics adjust and balance, it's totally reasonable to expect these models to have represent extremely small scale features that models with lower grid spacings and especially our current network of observations can't capture. Of course if all models are showing a certain UH swath that comes to verify it can be a bit of a black box problem to determine what exactly they all honed in on to cause that. But given the relatively low density of our observing networks, and assuming proper analysis and quality control of the data fed in, I think one has to at least strongly consider the immense value that a model data assimilation system (that is, the optimal combination of both the observation networks and the model's physical constraints, carrying information from past assimilation cycles forward, and having a complete suite of physics (i.e. a soil model for surface fluxes, etc)) can offer as a forecasting tool.

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Watch the differential heating boundary near the Red River later on for enhanced tornado potential, RAP forecasts seem to not have this boundary indicated and thus low level shear/SRH may be underdone significantly. Would think any storm that tracks in this vicinity could keep going into AR for a distance too.

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