Severe weather: 5/10-5/12 Plains/Midwest

[brettjrob]

Saturday through Monday all look to have severe potential, starting in the Plains and potentially expanding eastward for the latter half of the period. The ECMWF continues to advertise a potent, broad-based trough emerging from the Rockies by late Sunday, lending to a fairly classic May severe weather setup. It's showed this solution for almost a week now with only minor variations, an impressive coup over the other medium-range guidance.

Saturday (5/10):

Rich boundary layer moisture should be drawn into areas roughly along and E of I-35 in TX/OK/KS beneath relatively zonal, but moderately strong, flow aloft. While the dryline looks fairly diffuse, several models continue to indicate the potential for at least isolated convection by late afternoon and early evening. Low-level shear appears modest, but sufficient for at least a marginal tornado threat should supercells evolve. Overall, I'm expecting a typical SLGT risk day for early May centered over NE OK and E KS.

Sunday (5/11):

This has the most potential, but model solutions diverge rapidly through the course of the day, mainly regarding frontal placement and speed. As the longwave trough progresses through the Rockies, strong southwest flow will overspread most of the Plains by early afternoon. At the surface, the associated lee cyclone should deepen substantially during the day in the vicinity of E CO/W KS. A relatively tight baroclinic zone will extend NE from the sfc low into NE/IA; whether this acts as a quasi-stationary front during the day or a fast-moving cold front depends on which solution you buy.

The NAM is the most aggressive, crashing the front well into OK by 00z Mon, which seems partially a result of its more positive-tilt trough depiction. The ECMWF barely moves the front at all before dark, with the triple point near Colby at 00z Mon. The GFS roughly splits the difference. I'm generally favoring the ECMWF, but frontal placement in situations with cold air around is one of the few meteorological scenarios that make me at least pause and look at the NAM depiction at 84 hrs.

If the ECMWF is in the right ballpark, then Sunday could have high-end tornado potential, should mesoscale factors come together. The kinematic profiles along the dryline in W KS and NW OK are beyond impressive. If moisture is of sufficient quality and large-scale forcing emerges from the Rockies before dark, tornadic supercells appear highly probable. Neither of those are guarantees right now, though. Regarding moisture, it will be an interesting battle between drought/poor ET vs. potentially intense low-level advection (i.e., the ECMWF depicts H85 wind speeds of 40-60 kt.). As for timing, it looks just about perfect on the Euro, but any significant slowing could completely change things.

Additional storms are possible farther E along the front into NE/IA/MO, and there again, tornado potential could be very considerable. This mode will likely depend even more on frontal speed, unless open warm sector storms can develop.

Monday (5/12):

Broadly, the system starts to look more anafrontal by this time with somewhat more unidirectional wind profiles in the warm sector. Nevertheless, severe potential is evident anywhere from TX northeastward toward IL/IN/OH. The primary zone of concern varies wildly between the ECMWF and GFS, with the latter progressing the front much farther SE.

[andyhb]

Nice post, yeah the backing of the 850 mb flow (in addition to its strength) leading to hellish low level shear on the Euro is very interesting and leading to classic Plains kinematic profiles with strong/backing low level flow and strongly veering flow above it. In addition to that, the trough evolution on the Sunday would probably favour a more sustained discrete supercell mode with more subtle forcing for ascent along the dryline.

 

One thing of note, if you do have backing of the low level flow like that, the moisture will have less chance to mix out since it won't be traveling over parched terrain as long as if it were straight from the south.

[Chicago Storm]

18z GFS was slower...and a step towards the ECMWF.

[Superstorm93]

Well the NAM has really been liking Sunday in MO as of late

 

Sounding near SGF: 

 

 

[andyhb]

Seems one constant across the model suite here regardless of evolution for Sunday is some very impressive low level wind fields, even with the positive tilt to the trough.

 

NAM is too far out to take more seriously, but even the GFS has some impressive soundings both near the WF and along the dryline/cold front combination. Still think the Euro has the highest potential though given its extremely robust wind fields with its dryline depiction. The capping isn't completely thermonuclear either owing to manageable 700 mb temperatures, which is something you might not expect with a setup like this.

Latest discussions for Sunday.

 

ICT:

SAT-SUN:

THUNDERSTORMS ARE STILL SCHEDULED TO RETURN THE NEIGHBORHOOD ON SAT AS

THE NEXT UPPER WAVE SWINGS AROUND THE SOUTHERN PERIPHERY OF AN UPPER

CYCLONE THAT WILL GRADUALLY STRENGTHEN OVER THE FAR NW U.S. WITH THE MID

TO UPPER TROF DIGGING/DEEPENING RAPIDLY OVER THE GREAT BASIN SAT NIGHT

& SUNDAY WARM MOIST SOUTHERLY FLOW WOULD ASSERT ITSELF & WITH A WEAK

COLD FRONT SETTLING S/SE ACROSS KS THUNDERSTORMS WOULD DEVELOP FIRST

OVER EASTERN KS WITH THE CONVECTION GRADUALLY SPREADING WEST ALONG THE

APPROACHING FRONT. AS THE DEEP SLIGHTLY POSITIVELY-TILTED UPPER WAVE

APPROACHES DEEP-LAYER SHEAR WOULD INCREASE & SUPPORT SEVERE

THUNDERSTORMS OVER MUCH OF THE CWA.

 

DDC:

Upper level westerly flow over the central High Plains on Friday

will gradually become more southwesterly by Saturday night as the

upper wave digs into the Intermountain West. As the upper wave

approaches on Sunday, a frontal boundary should moves southward into

western Kansas with a surface low pressure system developing along

the front. There are some model differences in the position of this

front during the day Sunday. The faster GFS has it through all of

western Kansas by later in the afternoon while the other models keep

it farther west. This will have significant impacts on daytime high

temperatures as well as where the best chance for thunderstorms will

be. Given the model tendencies, will keep the front farther west

with a fairly significant temperature gradient across southwest and

south central Kansas. The models show 60 degree dewpoints spreading

northward into the central Plains ahead of this front. We could see

an outbreak of severe storms along the front during the later

afternoon and early evening hours as stronger southwesterly flow

aloft moves into western Kansas.

[andyhb]

Still some obscene soundings near the WF/triple point on Sunday from the NAM. If there is anywhere near the level of instability it is showing over any area, storms will go absolutely nuts.

 

Also slowly becoming less aggressive with southward movement of the cold front.

[OUGrad05]

Sunday looks interesting for sure.  Decent CAPE values over much of OK, KS and MO.  Wind profiles look pretty good but velocities on the GFS are kind of hohum at 850 and 700.  Sounding for Tulsa at 7pm Sunday (00z) shows a monster cap though.  Further west, there might be some dryline/frontal forcing to get things going?  

 

I'm curious to just how much slower this system will get given the recent trends.  Definitely not getting much attention her in Tulsa at this point.  Kansas looks pretty interesting IMO.

[jojo762]

Interested to see what the SPC's thinking is about sunday in D3 outlook in a few hours... Lots of model differences for only being a few days out, all of which could make a big difference as far as tornado potential, nonetheless severe weather threat regardless of frontal placement is pretty high IMO. This came up on us really quick too, models didn't show much a few days ago, and now it's looking pretty interesting.

[nwburbschaser]

Interested to see what the SPC's thinking is about sunday in D3 outlook in a few hours... Lots of model differences for only being a few days out, all of which could make a big difference as far as tornado potential, nonetheless severe weather threat regardless of frontal placement is pretty high IMO. This came up on us really quick too, models didn't show much a few days ago, and now it's looking pretty interesting.

The ECMWF has been showing something in this timeframe for at least 5 days if not more.  It really never got away from showing it except for one odd 00Z run a few days ago.

[jojo762]

The ECMWF has been showing something in this timeframe for at least 5 days if not more.  It really never got away from showing it except for one odd 00Z run a few days ago.

oh, I don't have access to the euro... I was talking in terms of the GFS mainly, which has been horrible recently.

[brettjrob]

Also slowly becoming less aggressive with southward movement of the cold front.

 

Yeah, I'm becoming less concerned with the crashing front, given the latest model developments. The NAM trended strongly, and the GFS substantially, toward the ECMWF solution tonight. Also, the CMC has been steadfastly supporting a Euro-like solution for a couple days now. The 00z CMC remains adamant on a frontal position roughly from Garden City to Concordia to the MO/IA border at 00z Mon. In exposing much of KS to the warm sector, possibly featuring high to extreme instability, the potential outcome becomes very impressive, pending moisture and the degree of low-level backing.

[jojo762]

SPC 0600Z outlook out for D2 (Saturday) upgraded to slight risk... Mentioning IF any storms form, they would be supercells capable of producing large hail-- some possibly significant-- and tornadoes... Saturday is a mess for forecasting, because the environment would be pretty favorable for supercells if any storms were to form, even isolated, but the big question is if storms will form given lack of any somewhat recognizable forcing, besides some possible convergence along the boundary.

[andyhb]

   DAY 2 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK

   1231 AM CDT FRI MAY 09 2014

 

   VALID 101200Z - 111200Z

 

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE LOWER MO VALLEY TO

   CNTRL OK...

 

   ...SUMMARY...

   ISOLATED SEVERE THUNDERSTORMS ARE POSSIBLE FROM CENTRAL OKLAHOMA TO

   THE LOWER MISSOURI VALLEY LATE AFTERNOON TO EVENING ON SATURDAY.

   LARGE HAIL SHOULD BE THE PRIMARY HAZARD.

 

   ...SYNOPSIS...

   QUASI-ZONAL UPPER-LEVEL PATTERN WILL BECOME INCREASINGLY AMPLIFIED

   AS A SHORTWAVE TROUGH DIGS OVER THE GREAT BASIN BY 12Z/SUN. A

   SEPARATE NRN STREAM SHORTWAVE IMPULSE SHOULD TRACK FROM THE NRN

   ROCKIES TO NRN PLAINS. AT THE SURFACE...A WEAK CYCLONE SHOULD

   CONSOLIDATE OVER ERN SD SAT AFTERNOON WITH A COLD FRONT ARCING SWD

   INTO ERN KS...WITH TRAILING PORTION BECOMING QUASI-STATIONARY WWD TO

   A CYCLONE IN THE LEE OF THE SRN ROCKIES. A DRYLINE SHOULD EXTEND

   S/SWWD FROM THE FRONT INTO THE EDWARDS PLATEAU OF TX.

 

   ...LOWER MO VALLEY TO CNTRL OK...

   POLEWARD ADVECTION OF LOW-LEVEL MOISTURE WILL OCCUR AHEAD OF THE

   COLD FRONT WITH SURFACE DEW POINTS REACHING THE LOWER/MIDDLE 60S.

   THIS WILL OCCUR BENEATH A PLUME OF STEEP MID-LEVEL LAPSE

   RATES...YIELDING A MODERATE TO STRONGLY UNSTABLE AIR MASS WITH

   MLCAPE AOA 2000 J/KG.

 

   NEUTRAL TO SLIGHT MID-LEVEL HEIGHT RISES ARE ANTICIPATED TO OVERLIE

   THE REGION DURING PEAK HEATING...REFLECTING THE DEARTH OF MID-LEVEL

   FORCING FOR ASCENT. CONVERGENCE ALONG MOST OF THE DRYLINE APPEARS

   WEAK WITH THE DRYLINE RETREATING WWD DURING THE EVENING.

   HOWEVER...CONVERGENCE ALONG THE COLD FRONT AND FRONT/DRYLINE

   INTERSECTION MAY BE SUFFICIENT FOR ISOLATED STORMS LATE

   AFTERNOON/EARLY EVENING. SHOULD THIS OCCUR...40-50 KT EFFECTIVE

   SHEAR WOULD SUPPORT SUPERCELLS CAPABLE OF LARGE HAIL /SOME OF WHICH

   COULD BE SIGNIFICANT/ AND POSSIBLY TORNADOES /MAINLY IN MO/. GIVEN

   THIS POTENTIAL...HAVE UPGRADED TO SLIGHT RISK...BUT OVERALL

   COVERAGE/CONFIDENCE ON WHERE STORMS WILL FORM IS TOO LOW TO YET

   WARRANT HIGHER INTENSITY PROBABILITIES.

 

   ...CNTRL/SRN APPALACHIANS TO MID-SOUTH...

   ANTECEDENT CLOUDS AND PRECIPITATION SHOULD HINDER DIURNAL

   DESTABILIZATION TO SOME EXTENT AMIDST A BROAD AREA OF UPPER 50S TO

   LOWER 60S SURFACE DEW POINTS. POCKETS OF STRONGER HEATING SHOULD

   CONTRIBUTE TO WEAK TO MODERATE BUOYANCY...AIDING IN ISOLATED TO

   WIDELY SCATTERED STORMS DURING THE AFTERNOON. THIS ACTIVITY SHOULD

   REMAIN UNFOCUSED AS LOW-LEVEL CONVERGENCE WILL BE WEAK.

   STILL...WITHIN A BELT OF MODERATE TO STRONG MID-LEVEL

   WLYS...MARGINAL SEVERE HAIL AND DAMAGING WIND EVENTS ARE POSSIBLE.

 

   ..GRAMS.. 05/09/2014

 

   DAY 3 CONVECTIVE OUTLOOK  

   NWS STORM PREDICTION CENTER NORMAN OK

   0230 AM CDT FRI MAY 09 2014

 

   VALID 111200Z - 121200Z

 

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID-MS VALLEY TO THE

   SRN PLAINS...

 

   ...SUMMARY...

   A SIGNIFICANT SEVERE WEATHER EPISODE APPEARS PROBABLE BEGINNING

   SUNDAY AFTERNOON FROM THE MID-MISSISSIPPI VALLEY TO THE SOUTHERN

   GREAT PLAINS.

 

   ...SYNOPSIS...

   A VIGOROUS SHORTWAVE IMPULSE EMBEDDED WITHIN AN AMPLIFIED

   UPPER-LEVEL TROUGH WILL TRACK FROM THE SRN GREAT BASIN TO THE SRN

   ROCKIES. ATTENDANT MID-LEVEL SPEED MAX WILL BECOME CENTERED FROM THE

   SRN HIGH PLAINS TO THE CNTRL PLAINS EARLY MON. AT THE SURFACE...A

   LEE CYCLONE WILL DIURNALLY DEEPEN OVER THE SRN HIGH PLAINS. THE

   DRYLINE SHOULD MIX TOWARDS THE ERN TX PANHANDLE/WRN OK BORDER S/SWWD

   ACROSS THE PERMIAN BASIN. GUIDANCE DIFFERS ON THE ACCELERATION OF A

   S/SEWD-PROGRESSING COLD FRONT OVER THE CNTRL/SRN PLAINS. 

 

   ...MID-MS VALLEY TO SRN PLAINS...

   PERVASIVE AND STRENGTHENING SWLYS AT 700 MB WILL RESULT IN AN

   EXPANDING EML PLUME AND ATTENDANT CAPPING INVERSION EARLY SUN...WITH

   INCREASINGLY RICH BOUNDARY LAYER MOISTURE GIVEN STRONG POLEWARD

   ADVECTION FROM THE WRN GULF. MIDDLE TO UPPER 60S SURFACE DEW POINTS

   SHOULD BECOME ESTABLISHED FROM THE LOWER MO VALLEY SWD...YIELDING A

   BROAD STRONGLY UNSTABLE AIR MASS WITH MLCAPE AOA 2500 J/KG AHEAD OF

   THE DRYLINE/COLD FRONT. THE NRN EXTENT OF STRONG DESTABILIZATION

   SHOULD BE DELIMITED BY EARLY SUN WAA-DRIVEN CONVECTION OVER PARTS OF

   THE LOWER MO VALLEY. SOME OF THIS ACTIVITY MAY CONTINUE E/NEWD

   THROUGH THE DAY WITH AN ISOLATED SEVERE RISK...BUT MORE PROBABLE

   SURFACE-BASED DEVELOPMENT SHOULD OCCUR WITH SWRN EXTENT WHERE

   GREATER INSOLATION OCCURS. STRONG CONVERGENCE ALONG THE FRONT WILL

   LIKELY YIELD INCREASINGLY NUMEROUS STORMS LATE AFTERNOON INTO

   EVENING FROM ERN KS INTO SRN IA. LARGE HAIL /SOME SIGNIFICANT/ AND A

   FEW TORNADOES WILL BE POSSIBLE INITIALLY. THE POTENTIAL FOR

   UNDERCUTTING BY THE FRONT SHOULD YIELD CLUSTER AND EVENTUAL LINEAR

   MODES WITH SEVERE HAIL/WIND HAZARDS PERSISTING INTO SUN NIGHT. A

   LARGE MCS MAY ULTIMATELY EVOLVE GIVEN THE STRENGTHENING LARGE-SCALE

   ASCENT DOWNSTREAM OF THE UPPER TROUGH AND BROADLY UNSTABLE WARM

   SECTOR. 

 

   FARTHER S...CONVERGENCE ALONG THE DRYLINE WILL STRENGTHEN

   /ESPECIALLY INVOF TRIPLE-POINT/ AND INTENSE SURFACE HEATING SHOULD

   REMOVE INHIBITION...WITH ISOLATED TO SCATTERED STORMS DEVELOPING

   LATE AFTERNOON. ALTHOUGH HODOGRAPHS MAY NOT BE OVERLY

   LARGE...CROSS-BOUNDARY DEEP-LAYER FLOW WILL BE FAVORABLE FOR

   DISCRETE SUPERCELLS GIVEN THE DEGREE OF INSTABILITY. RELATIVELY

   LARGE SURFACE DEW POINT DEPRESSIONS SUGGEST VERY LARGE HAIL WOULD BE

   THE PRIMARY INITIAL HAZARD. THE TORNADO RISK SHOULD BE MAXIMIZED IN

   EARLY EVENING AS A SLY LLJ STRENGTHENS AND SPREADS LOWER. EWD EXTENT

   OF OVERNIGHT SEVERE POTENTIAL IS UNCERTAIN OWING TO MODEL

   DIFFERENCES IN COLD FRONT EVOLUTION AND DEGREE OF NOCTURNAL WARM

   SECTOR INHIBITION.

 

   ..GRAMS.. 05/09/2014

 

[andyhb]

Just another thing to consider, if we get some storms hanging around nocturnally and staying rooted in the BL, the LLJ absolutely explodes after 00z as per usual. With LCL heights lowering and the trough still progressing east, that could be quite a nasty threat.

 

I'd say there's a pretty decent shot at a D2 moderate should things keep progressing in the Euro's direction (which appears rather likely). That 700 mb max the Euro has over the dryline in KS/OK at 00z Monday is really impressive in addition to great backing surface flow.

[Thundersnow12]

Sunday reminds me a lot of 4/25/09. 

[jojo762]

Sunday reminds me a lot of 4/25/09.

Agree, very good/close comparison... Though, I feel as though storm coverage/ SVR report coverage will be higher for this Sunday. Also feel the tornado threat is also a bit higher than 4/25/09 given amazing wind fields, and great low-level backing. LCL's/ DP depressions could be an issue on Sunday potentially early on though, which could provide enough time for the storms to become linear before the best tornado threat would be realized.

[Thundersnow12]

Agree, very good/close comparison... Though, I feel as though storm coverage/ SVR report coverage will be higher for this Sunday. Also feel the tornado threat is also a bit higher than 4/25/09 given amazing wind fields, and great low-level backing. LCL's/ DP depressions could be an issue on Sunday potentially early on though, which could provide enough time for the storms to become linear before the best tornado threat would be realized.

 

Maybe. Moisture just east of the dryline till/just after sunset wont be best but storms on Sunday should move into better moisture as moisture advection cotinues well after sunset aided by the strong LLJ. 

[brettjrob]

Sunday reminds me a lot of 4/25/09. 

 

I'd love to find a good reason why this setup is of a much higher caliber, but it's hard to. I clearly recall the two major issues that day: borderline upper-level flow (well-forecast), and moisture mixing out (which we didn't know until that afternoon). Those are the two biggest issues Sunday, too, at least in OK.

 

Minor reasons Sunday looks better: H5 flow is at least 5-10 kt stronger across the dryline, higher-amplitude trough, and it's a few weeks later into the season.

 

Realistically, moisture and LCLs are going to be limiting factors on Sunday; it all comes down to the degree. Assuming the trend towards the northward ECMWF solution continues, I still think Sunday should be somewhat better, but 4/25/09 is a great analog to keep the downside in perspective. What a depressing day that was, and I can't imagine if it didn't have the following day and it was occurring in mid-May after nothing all year...

[Ground Scouring]

Agree, very good/close comparison... Though, I feel as though storm coverage/ SVR report coverage will be higher for this Sunday. Also feel the tornado threat is also a bit higher than 4/25/09 given amazing wind fields, and great low-level backing. LCL's/ DP depressions could be an issue on Sunday potentially early on though, which could provide enough time for the storms to become linear before the best tornado threat would be realized.

I also don't like the veering / weaker low-level wind profiles in KS, which could allow for a line to form given the initially-questionable situation with LCLs and dewpoints (and is also why I think we'll only see a Day 1 MDT Risk, nothing higher, obviously). And of course there are the drought conditions to be considered. A lot (basically, the meat of the event) is riding on the dryline Sunday in wrn OK. It could be a case where one show-stopping storm makes the difference between a fair and a dismal chase day.

[Thundersnow12]

I'd love to find a good reason why this setup is of a much higher caliber, but it's hard to. I clearly recall the two major issues that day: borderline upper-level flow (well-forecast), and moisture mixing out (which we didn't know until that afternoon). Those are the two biggest issues Sunday, too, at least in OK.

 

Minor reasons Sunday looks better: H5 flow is at least 5-10 kt stronger across the dryline, higher-amplitude trough, and it's a few weeks later into the season.

 

Realistically, moisture and LCLs are going to be limiting factors on Sunday; it all comes down to the degree. Assuming the trend towards the northward ECMWF solution continues, I still think Sunday should be somewhat better, but 4/25/09 is a great analog to keep the downside in perspective. What a depressing day that was, and I can't imagine if it didn't have the following day and it was occurring in mid-May after nothing all year...

 

Yep, I remember that day well. Waiting in Shamrock for that first supercell to go and it was crazy hyped to be a big day too. Then moisture mixed out badly and bases were so high. 

[soonertrey]

I definitely don't like the forecast LCLs for W OK on Sunday, especially on the NAM.  I'm concerned that we may have elevated storms until after dark.  Hopefully this is a case where a storm or two can overcome the higher LCLs with the large CAPE and shear that is forecasted.

[nrgjeff]

April 25-26, 2009 is a decent comparison. In both cases the front was lumbering like this set-up. Upper level winds were adequate, but don't forget warm 700 mb temps, also both similar. Both days the lumbering/stationary front paid off more than the DL. I think the DL will go this time but once again hail vs tornado is a forecast issue. I still get a sick feeling about that chase. We were on the cell that produced a beautiful stovepipe and elephant trunk for an international tour group in northwest OK. Thought it was lining out and made a horrible decision to go south (under the cap) about 60 minutes prior to the tornado. Even had a nowcaster tell us to stay the course! Moral of the story: Later into May one can give lumbering fronts more respect.

[brettjrob]

April 25-26, 2009 is a decent comparison. In both cases the front was lumbering like this set-up. Upper level winds were adequate, but don't forget warm 700 mb temps, also both similar. Both days the lumbering/stationary front paid off more than the DL. I think the DL will go this time but once again hail vs tornado is a forecast issue. I still get a sick feeling about that chase. We were on the cell that produced a beautiful stovepipe and elephant trunk for an international tour group in northwest OK. Thought it was lining out and made a horrible decision to go south (under the cap) about 60 minutes prior to the tornado. Even had a nowcaster tell us to stay the course! Moral of the story: Later into May one can give lumbering fronts more respect.

 

Those two days couldn't have been more awful for me, either. That year was pretty rough in KS/OK/TX, so missing the Roll tornadoes on 4/26 (we also thought farther S was the smartest play) came to haunt me for the rest of the year.

 

Thinking about that comparison some more, though, I would say the wave timing on Sunday is a lot better than that event. I'd argue that poor timing was a substantial contributor to the disappointing outcome of 4/25-26 -- i.e., it was too late for D1, too early for D2. Sunday's timing is maybe just a hair slow, but not nearly as bad as 4/25/09.

 

I think the "lesson" you pointed out is a good one, though. For Sunday, areas like S IA, N MO, and perhaps SE NE could be the safest bet to see a tornado, even if the ceiling is theoretically higher farther SW.

[Thundersnow12]

Those two days couldn't have been more awful for me, either. That year was pretty rough in KS/OK/TX, so missing the Roll tornadoes on 4/26 (we also thought farther S was the smartest play) came to haunt me for the rest of the year.

 

Thinking about that comparison some more, though, I would say the wave timing on Sunday is a lot better than that event. I'd argue that poor timing was a substantial contributor to the disappointing outcome of 4/25-26 -- i.e., it was too late for D1, too early for D2. Sunday's timing is maybe just a hair slow, but not nearly as bad as 4/25/09.

 

I think the "lesson" you pointed out is a good one, though. For Sunday, areas like S IA, N MO, and perhaps SE NE could be the safest bet to see a tornado, even if the ceiling is theoretically higher farther SW.

 

 

We also were south that day in southwest OK and south of the Red river. 

 

Yeah the northern target on Sunday looks really nice on the 12z GFS. 

[andyhb]

12z Euro just looks nasty in central KS, looks like it improved instability as well by 00z. It also has a stronger surface low than the 00z run last night.

 

For what it's worth, until LCL heights lower more (i.e. through mid afternoon), I could see Sunday being the kind of day where Arnett 5/4/07 or Rago 5/19/12 type tornadoes are possible further SW. In addition to that, the WF still holds a lot of potential across the suite and I like how you have a good amount of mid level flow overlapping it.

[ZackH]

I'm really swinging to the northern target after finally looking at 12z data. For one, its much closer to me. The only thing that makes me nervous is the possible convective mess early on which could limit the strong instability currently being depicted on all three major models. The other thing I don't like is the turning from 850-500... it looks like it may be just enough to get it done as there appears to be a wide swath of surface backing in the vicinity of IA and northern MO but if it ends up being more unidirectional things could get ugly quick.  Since my big Plains trip starts in the time frame of 5/21-5/24 I think I may just play the northern target if it holds promise and see what I get. The LCL problem makes me nervous in OK... I've played too many of those chances this year already. May play the more sure bet even if the storms are uglier.

[Ground Scouring]

I'm really swinging to the northern target after finally looking at 12z data.  For one, its much closer to me.  The only thing that makes me nervous is the possible convective mess early on which could limit the strong instability currently being depicted on all three major models.  The other thing I don't like is the turning from 850-500... it looks like it may be jut enough to get it done as there appears to be a wide swatch of surface backing in the vicinity of IA and northern MO but if it ends up being more unidirectional things could get ugly quick.  Since my big Plains trip starts in the time from of 5/21-5/24 I think I may just play the northern target if it holds promise and see what I get.  The LCL problem makes me nervous in OK... I've played too many of those chances this year already.  May play the more sure bet even if the storms are uglier.

Regardless of how the situation plays out farther SW, I really don't think the northern target is going to play out very well based on past experience with similar synoptic set-ups…nine times out of 10 convective debris has been a problem. That combined with unidirectional winds will produce just enough overturning to wreck the situation.

[ZackH]

And again, that's my concern for the northern target.  But I do not think the southern target is any more of a sure bet at this stage and I've seen and chased a number of these types of setups that end up working out very nicely.  And if it is about a 1 and 10 chance... then we're due.  But you and I both know outside of this year thus far, northern setups work out more than that.

[thewxmann]

Honestly I think the triple point is the best play. Higher LCL's further south and flow parallel to propagating front further north are valid concerns.

[andyhb]

I also don't like the veering / weaker low-level wind profiles in KS, which could allow for a line to form given the initially-questionable situation with LCLs and dewpoints (and is also why I think we'll only see a Day 1 MDT Risk, nothing higher, obviously). And of course there are the drought conditions to be considered. A lot (basically, the meat of the event) is riding on the dryline Sunday in wrn OK. It could be a case where one show-stopping storm makes the difference between a fair and a dismal chase day.

 

Disagree, if any depiction has the strongest low level wind profiles in a given area, it's probably the Euro in western/central KS. Most of guidance still appears to be trying to catch up to its evolution.