Severe Weather Threat 4/15/16 KS/CO/OK/TX/NM

[Jim Martin]

 

Looking like a severe weather threat for Friday out in the Southwest... mainly high based storms from what have seen and read...

[brettjrob]

High-based supercells are a near-certainty Friday afternoon on the High Plains, and I'm not very optimistic about tornado potential.

That being said, as a benchmark for what's possible in these situations, it's important not to forget the 21 April 2007 outbreak along I-27. So many people were writing that off all the way up until showtime. Comparing current progs for 2 m dew points against the observations that day, we're looking at a fairly similar situation: mainly low-mid 50s, with crappy trajectories and nothing much better upstream for hundreds of miles.

I don't like the look of this trough nor its timing quite as much as that day. More importantly, the Panhandles have regressed to short-term drought over the cold season (vs. having been deluged for a month prior to the 2007 event), which I think is ultimately what limits the probability of a multi-storm daytime tornado event Friday to 15-20%. Absent the vigorous PBL mixing we're almost certain to see by mid-late afternoon, I would be more on-guard for an overperforming day.

[Chicago Storm]

Probably should extend this thread through Monday.

Moisture quality, wind profiles and a lack of EML are all sig issues.

Can't say I'm enthused for chasing prospects.

[andyhb]

Pretty depressing reading these threads.

[thewxmann]

Pretty depressing reading these threads.

 

[Stebo]

It is mid April, if it was mid May the complaints would be valid. I do think though the heavy rains from this event will pay dividends later on in the season with respect to moisture transport.

[Quincy]

It is mid April, if it was mid May the complaints would be valid. I do think though the heavy rains from this event will pay dividends later on in the season with respect to moisture transport.

This.

 

I would much rather trade a slow April for knocking out the short-term drought. That will hopefully set us up for better success down the road.

 

As for the season, yes, April has been generally slow so far, but we got "spoiled" with one of our busiest months of February in quite some time. Even if we flatline on the tornado reports for the next two weeks, we'll still be ahead of where we were going into the final days of April in any of the past three years.

 

With that said, Friday has some potential. The setup synoptically isn't incredibly different from 4/21/07. I am absolutely not calling for a repeat, but even the GFS, despite its issues with boundary layer moisture, indicates some severe potential in the High Plains. While it may not be worthy of a long-distance chase, if I was out close to the area and the forecast doesn't significantly change, it would absolutely be worth chasing. (some picturesque storms appear likely and will probably be free of the chaser convergence you'd see with a more "typical" April event in the heart of Oklahoma)

 

On a more personal note, April chases (for the most part, but not entirely) have been junky over the past couple of seasons. I sat out Sunday/Monday, thankfully, and will be saving time, money and effort for better threats down the line.

 

Also, I've heard complaints from chasers about a late first chase this year. What about the events earlier this year? There have been chaseable tornado events in Dixie this year and not to mention the NE OK/KS tornadoes on March 30th. It's easy to get impatient, but it's very much early in the season.

[brettjrob]

This.

 

I would much rather trade a slow April for knocking out the short-term drought. That will hopefully set us up for better success down the road.

 

As for the season, yes, April has been generally slow so far, but we got "spoiled" with one of our busiest months of February in quite some time. Even if we flatline on the tornado reports for the next two weeks, we'll still be ahead of where we were going into the final days of April in any of the past three years.

 

With that said, Friday has some potential. The setup synoptically isn't incredibly different from 4/21/07. I am absolutely not calling for a repeat, but even the GFS, despite its issues with boundary layer moisture, indicates some severe potential in the High Plains. While it may not be worthy of a long-distance chase, if I was out close to the area and the forecast doesn't significantly change, it would absolutely be worth chasing. (some picturesque storms appear likely and will probably be free of the chaser convergence you'd see with a more "typical" April event in the heart of Oklahoma)

 

On a more personal note, April chases (for the most part, but not entirely) have been junky over the past couple of seasons. I sat out Sunday/Monday, thankfully, and will be saving time, money and effort for better threats down the line.

 

Also, I've heard complaints from chasers about a late first chase this year. What about the events earlier this year? There have been chaseable tornado events in Dixie this year and not to mention the NE OK/KS tornadoes on March 30th. It's easy to get impatient, but it's very much early in the season.

 

On the topic of a crappy March-early April: having watched the Plains season very closely since 2006, I have to say that this year's early season is much worse than average. Looking back further in an historical context, this is undeniably true, too. In fact, the March 1-April 15 period has been pretty much useless for four straight years now on the Plains, and that isn't historically common. It may not be exceptionally rare, but it's not something you'd expect year after year, either. Usually, we can muster at least one decent event (i.e., something worthy of 10% hatched tornado probabilities) during that 45-day window.

 

This doesn't count events well east of I-35. When veterans say they've never gone this late without chasing, it's because they're from an age when people didn't waste their time dinking around in the Ozarks and Southeast. And ultimately, that's what most chase efforts there are: a waste of time. I don't begrudge anyone their right to chase there and enjoy it, but there seems to be a new trend among chasers in recent years to proclaim anyone uninterested in it as a "snob," and/or to talk about how Plains chasing is "too easy" (I know you're not doing this at all, but I've seen it elsewhere). Whereas, from my perspective, it's completely reasonable not to bother "counting" setups in that area toward the health of the season. Endless Arklatex and Dixie tornado setups = worthless chase season, to a large contingent of chasers, and it's not really about irrational snobbery.

 

I totally agree with you in that April chases are junky at a far higher rate than May/June ones. If one half of the season is going to be awful on the Plains, it's far better for it to be March-April - it's not even close (similar to comparing Alabama chase setups against western Kansas ones ). At the same time, the two halves of the season being active aren't mutually exclusive, so there's no silver lining to how crappy the season has been so far - it only means late April through June will now need to be above-average, rather than just average, to make this a good year.

 

Finally, I fully agree with you and Stebo that if the consensus QPF for Fri-Sun verifies, it will be a game-changer for any southern Plains setups over the next 20-30 days (at least). It's frustrating that the rainfall can't come before Friday's setup, but hopefully, it will be worth the wait.

[Chinook]

Yeah, remember when we had day-2 high risks and day-2 moderate risks?

 

https://upload.wikimedia.org/wikipedia/commons/thumb/7/7a/Evolution_of_SPC_Forecasts_Leading_to_April_14%2C_2012.png/800px-Evolution_of_SPC_Forecasts_Leading_to_April_14%2C_2012.png

[nrgjeff]

I agree.

...When veterans say they've never gone this late without chasing, it's because they're from an age when people didn't waste their time dinking around in the Ozarks and Southeast. And ultimately, that's what most chase efforts there are: a waste of time. I don't begrudge anyone their right to chase there and enjoy it...

 

While it makes perfect sense to travel to the Plains to chase, it makes little sense to travel to the South to chase. When I lived in the Plains I never considered travel to Dixie Alley. Now I live in the Southeast so of course I will chase Dixie Alley, but only as a local chase not travel. I also plan a trip to the Plains each May to visit friends and family, and of course chase storms. My Plains trip is considered my main chase event.

[mfgmfg]

Looking like a severe weather threat for Friday out in the Southwest... mainly high based storms from what have seen and read...

 

Please use an image url that doesn't dynamically update, such as the following. Causes less confusion when looking at the thread on a future day or in months/years.

[brettjrob]

There's been a slight uptick in the moisture progs for Friday, with an increasing consensus for mid 50s on the Caprock northward into E CO. Forecast hodographs are pretty gorgeous along the dryline by 00z. It's probably going to look just good enough to sucker many of us out for a long drive, only for PBL mixing to mitigate the tornado threat. However, if the "background" (prior to vigorous mixing) surface moisture indeed verifies as mid-upper 50s dew points, the threat is non-zero and there may be a more legitimate window around 00-02z. Overall, my thoughts remain similar to yesterday, but hedging a bit more towards impressive long-tracked supercells that could put down a tube or two somewhere along the great expanse from east-central CO to the South Plains.

[andyhb]

I want to believe the 4 km NAM with mid-upper 50s dews and ESRH pushing 500 m²/s² along the expanse of the dryline with weak capping from 00z through 03z (some of the soundings it is putting out there are ridiculous), but I really can't seriously considering its performance with most things regarding moisture this year. With that said, the GFS looks a little silly with its degree of mixing early on, nothing else shows that level of dryness.

 

Euro gets the mid 50s+ dewpoints fairly far north although they aren't quite pushed right up against the dryline like you might want to see.

[Chinook]

Those 55+ dew points will happen a lot more often W of I-35 -after- this whole rainstorm is over. The storm will reduce drought in KS and OK. You are probably right in doubting the 60 dew points on the 4km NAM in the threat zone.

 

I think Friday should be an active day. Perhaps the day-2 or day-1 slight outlook will be extended to western Nebraska.

[nrgjeff]

Friday I favor southeast Colorado. While one really can't take the Palmer Divide off the table yet, I like Arkansas River Valley north of Raton Mesa better. Northeast Colorado may battle a cool surge. Meanwhile southeast Colorado looks to stay on the warm side of the east-west boundary. Morning showers may track from southeast Colorado to southwest Kansas. I would track the outflow from those.

 

Upper level shear is a little better where the Panhandles meet New Mexico; however, I favor the low level shear in southeast Colorado still under enough deep layer shear. Southeast Colorado has the geographic features and/or forecast outflow boundary noted above. If the boundary sinks south one would have to consider it. Cells forming near the dry line and outflow intersection will need some time to get into the modest moisture for a tornado, but the hail should start early and often.

[andyhb]

I am pleased to see that the Euro is not caving to the GFS' mixing degree. CAPE increases to over 1500 J/kg across parts of the Panhandle and E NM by 03z with a pretty nice WSW 300 mb left exit region reaching the area by that time. Would have to think the forcing for ascent from that would help overcome nocturnal capping. This is likely the type of setup where some morning + early afternoon rain/cloud cover would help a lot in terms of maintaining more quality BL moisture.

[brettjrob]

HRRRx and NSSL WRF look awfully tasty for tomorrow invof the N TX PH and OK PH. It will all come down to moisture, as we've known all along. Current obs and soundings are not the most encouraging, so I remain skeptical. On the other hand, the NSSL WRF has rarely been grossly overdone on moisture (that I've seen), and it progs LCLs well under 1000 m by early evening. Given 54-55 F dew points in this region by 00z, I think tornadoes are increasingly likely, as the incoming jet and the kinematic profiles are very nice. I'd put the probability of actually seeing that at maybe 40%, though, until looking at obs again in the morning.

[Chicago Storm]

HRRRx and NSSL WRF look awfully tasty for tomorrow invof the N TX PH and OK PH. It will all come down to moisture, as we've known all along. Current obs and soundings are not the most encouraging, so I remain skeptical. On the other hand, the NSSL WRF has rarely been grossly overdone on moisture (that I've seen), and it progs LCLs well under 1000 m by early evening. Given 54-55 F dew points in this region by 00z, I think tornadoes are increasingly likely, as the incoming jet and the kinematic profiles are very nice. I'd put the probability of actually seeing that at maybe 40%, though, until looking at obs again in the morning.

Recent HRRR...

[brettjrob]

Yeah, pretty remarkable CAM agreement on the scenario today ever since the event starting coming into range yesterday morning. I would've expected more uncertainty from a setup with significant thermodynamic flaws. We can add the HRRR, NCAR Ensemble, and SPC 4km WRF to the list supporting intense supercells streaking across much of the TX/OK PHs between 21-02z.

 

The instability axis is not all that wide, so it currently looks unlikely that storms will survive too late into the evening, limiting any long-track nocturnal tornado threat (probably for the best). Vis sat shows plenty of stratus across the target zone this morning, and model soundings suggest this will keep mixing under control, as andy mentioned yesterday.

 

Overall, I think this will be a triumph for convective-scale modeling: it's giving us high confidence in intense supercells late this afternoon into the early evening, where large-scale models would've left more uncertainty regarding the intensity and longevity of dryline storms, given such a limited east-west window of instability. The UH signal across CAM families is impressive, and I expect at least one or two tornado reports by dusk.

[Chicago Storm]

If chasing today I'd probably be sitting in/near Dumas, TX and then take things from there.

[Typhoon Tip]

This.

 

I would much rather trade a slow April for knocking out the short-term drought. That will hopefully set us up for better success down the road.

 

As for the season, yes, April has been generally slow so far, but we got "spoiled" with one of our busiest months of February in quite some time. Even if we flatline on the tornado reports for the next two weeks, we'll still be ahead of where we were going into the final days of April in any of the past three years.

 

With that said, Friday has some potential. The setup synoptically isn't incredibly different from 4/21/07. I am absolutely not calling for a repeat, but even the GFS, despite its issues with boundary layer moisture, indicates some severe potential in the High Plains. While it may not be worthy of a long-distance chase, if I was out close to the area and the forecast doesn't significantly change, it would absolutely be worth chasing. (some picturesque storms appear likely and will probably be free of the chaser convergence you'd see with a more "typical" April event in the heart of Oklahoma)

 

On a more personal note, April chases (for the most part, but not entirely) have been junky over the past couple of seasons. I sat out Sunday/Monday, thankfully, and will be saving time, money and effort for better threats down the line.

 

Also, I've heard complaints from chasers about a late first chase this year. What about the events earlier this year? There have been chaseable tornado events in Dixie this year and not to mention the NE OK/KS tornadoes on March 30th. It's easy to get impatient, but it's very much early in the season.

 

not that it has much hope of verifying but ...wouldn't the convective crowd like the D9 oper. Euro!?  

 

flyin' saucers all over the Plains that day - wow what an appeal

[Quincy]

not that it has much hope of verifying but ...wouldn't the convective crowd like the D9 oper. Euro!?  

 

flyin' saucers all over the Plains that day - wow what an appeal

There's been a consistent signal over the past few runs from multiple model suites (EC/EPS/GFS/GEFS/CFS) about some enhanced (no pun intended) severe potential beginning next weekend and potentially lasting for a string of days. Things are looking up, with today being a good day and even a couple of lingering days coming up. A quick break, then we really start to light up the season?

[andyhb]

Great mesoscale update from AMA, posted for posterity.

 

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE AMARILLO TX
212 PM CDT FRI APR 15 2016

.MESOSCALE UPDATE...
...SEVERE WEATHER LIKELY THIS AFTERNOON AND EVENING...

CURRENT OBSERVATIONAL ANALYSIS, INCLUDING A SPECIAL 18Z KAMA SOUNDING
REVEAL A POTENTIALLY CONCERNING PICTURE FOR THIS AFTERNOON AND
EVENING AROUND THE PANHANDLES.

SYNOPTICALLY: A LARGE UPR LOW SPINNING TO OUR WEST WILL SEND A WAVE
OUR DIRECTION LATE THIS AFTERNOON. THIS WAVE WILL OVERSPREAD A
SHARPENING DRYLINE IN THE VICINITY OF THE TX/NM BORDER AROUND 20-21Z
THIS AFTERNOON. BELIEVE THAT THE UPR WAVE, ALONG WITH CONVERGENCE
ALONG THE DRYLINE WILL BE SUFFICIENT TO SPAWN ISOLATED TO SCATTERED
THUNDERSTORMS BY MID TO LATE AFTERNOON. THE MOST FAVORED LOCATIONS
FOR INITIAL ACTIVITY SEEM TO BE FROM ROUGHLY HARTLEY TO DALHART TO
BOISE CITY.

AT THE MESOSCALE: THE 18Z KAMA SOUNDING SHOWS AN INTERESTING
THERMODYNAMIC PROFILE WITH LOW LEVELS STRUGGLING TO MIX OUT BENEATH A
SHARP INVERSION CENTERED AROUND H8. SFC OBS REFLECT THIS AS MOST
EVERY LOCATION IN THE TEXAS PANHANDLE REMAINED BELOW 70F AT 1PM.
DEWPTS ARE FAIRLY HOMOGENOUS IN THE LOW TO MID 50S. WITH CLOUDS
FINALLY MIXING OUT BETWEEN UPR WAVES, EXPECT TEMPS TO REACH THE MID
70S THIS AFTERNOON. WITH MID LEVEL COOLING OVERSPREADING THE WRN
PANHANDLES, A NARROW CORRIDOR OF MLCAPE VALUES OF 1500 TO 2000 J/KG
WILL LIKELY BE NOTED LATE THIS AFTERNOON/EARLY THIS EVENING. VALUES
OF 0-3 MLCAPE SHOULD INCREASE TO 75-100 J/KG FROM 00Z-03Z.

IN ADDITION TO THE AFOREMENTIONED UPR WAVE, SEVERAL OTHER FACTORS
CAUSE INCREASING CONCERN EARLY THIS EVENING AS LOW LEVEL WIND
PROFILES BECOME QUITE CONDUCIVE TO LOW LEVEL MESOCYCLONES AND LCL
HEIGHTS FALL BELOW 1000M. 0-1 AND 0-3 SRH VALUES INCREASE
SUBSTANTIALLY JUST BEYOND 00Z AS CONTINUED COOLING ALOFT COUNTERACTS
SOME MINOR LOSS OF DAYTIME HEATING TO PROVIDE A LOW LEVEL ENVIRONMENT
RIPE WITH TORNADIC POTENTIAL FOR ANY ONGOING/DEVELOPING SUPERCELLS.
FAVORABLE LOW-LEVEL WIND FIELDS WILL BE NOTED THROUGH MOST OF THE
NIGHT, WITH INDICATIONS THAT THE THERMODYNAMIC ENVIRONMENT MAY BOUNCE
BETWEEN SFC-BASED AND ELEVATED ALL THE WAY THROUGH AROUND MIDNIGHT.

THREATS AND TIMING: ALL SEVERE WEATHER THREATS APPEAR POSSIBLE THIS
EVENING WITH A CONCERNING WINDOW FOR TORNADOES FROM AROUND 00Z-05Z,
WHERE A TEMPORAL AND SPATIAL OVERLAP OF FAVORABLE INSTABILITY AND LOW
LEVEL SHEAR EXISTS. SHEAR PROFILES WILL FAVOR MORE DISCRETE STORM
MODE THIS AFTERNOON AND EVENING BEFORE A SLIGHT SHIFT TOWARD A BIT
MORE STORM INTERACTION AND UPSCALE GROWTH LATER IN THE NIGHT AS MID
LEVEL FLOW BACKS AHEAD OF THE (SLOWLY) APPROACHING UPR LOW. LARGE
HAIL WILL BE A THREAT THROUGHOUT THE EVENT, ESPECIALLY GIVEN EXPECTED
SUPERCELL STORM MODE AND GENERALLY DRY MID LEVELS. THE SEVERE THREAT
WILL GENERALLY BEGIN IN THE NW PANHANDLES AROUND 4 PM LIKELY CONTINUE
IN ONE FORM OR ANOTHER THROUGH AT LEAST THE FIRST HALF OF THE NIGHT.

LOCATION: THE WESTERN HALF OF THE COMBINED PANHANDLES WILL BE FAVORED
FOR SUPERCELLS THIS AFTERNOON/EVENING. THOUGH THE ENVIRONMENT IN THE
EASTERN PANHANDLES WILL BE MUCH LESS FAVORABLE, THE "INERTIA" OF
MATURE SUPERCELLS MAY BE ENOUGH TO ALLOW A FEW SUPERCELLS TO CHUG
INTO THE ERN PANHANDLES.

ALL-IN-ALL: A PRETTY FAVORABLE SETUP FOR SEVERE STORMS IS IN THE
OFFING WITH THE POTENTIAL FOR SEVERAL SCATTERED SUPERCELLS TO AFFECT
THE PANHANDLES THIS EVENING AND TONIGHT.

ELSENHEIMER/SIMPSON

[Chinook]

already a svr-warned storm with a hook shape near Las Animas CO

[Chicago Storm]

Tor wanrned supercell SW of Eads, CO. Nearby OBS site is 73/50.

[KSWx]

Strong couplet on that one.

[Chinook]

tornado reported near that location

[Chicago Storm]

Via Scott Longmore on Twitter...

[thewxmann]

not that it has much hope of verifying but ...wouldn't the convective crowd like the D9 oper. Euro!?  

 

flyin' saucers all over the Plains that day - wow what an appeal

 

It looked bad a few days ago, but yeah, latest runs of GFS and Euro are lighting it up a week+ out.

[Chinook]

supercells developing near Dalhart TX