May 31, 2012

Spotter Network Tracker

To our readers: It turns out that the Spotter Network Tracker icon on the right column of the Blog has not been working. It's not just a problem on this Blog, but a general one. Unfortunately, you were not able to track us, and I know that's fun for some. The developer claims to be working on the issue...though, any fix will be late for us for this Chase Season, obviously.

May 30, 2012

Unedited Video of First Stages of Kingman, KS tornado.

This shows the evolution of a non-mesocyclone tornado (sometimes referred to erroneously as a "landspout" by storm chasers) to a mesocyclone tornado (sometimes referred to as a "supercell tornado"). The initial formation was under the flanking line of a supercell thunderstorm, along which shear vortices could be seen at cloud base. The video starts with the formation of a tornadic whirl under such a vortex, visible as a high based funnel cloud and a debris field underneath. Over several minutes this formed a tall dust whirl. But later in the life-cycle, this vortex propagated along the flanking line into the area underneath the main updraft of the storm. At that moment, it developed a Rear Flank Downdraft, and the parent radar echo developed a hook. Thus, the tornado was now a mesocyclone-induced (or "supercell" tornado). Thus, this tornado was a very interesting "hybrid".

May 28, 2012

May 28--Rest Day in Boulder CO

Formation stage of Tornado #9, Kingman, KS, May 19, 2012


Important Updates have been made to May 29, May 25 and May 27 blog entries.  More to come.

I've decided to return home a few days early...so I have a flight out on Tuesday May 29.   It was a productive week.

We had beautiful storms to document on eight of the ten days, and good super cells on five of those.   We also had a flurry of tornadoes....nine total, with two of those mesocyclone-induced, and of the rest, at least four of the non-mesocyclone tornadoes ("landspouts") were beautiful, interesting and somewhat puzzling.

I will go back and look at the events of May 19 and May 25 more closely.  All the decisions were correct on May 19.  

On May 25, we tarried to long on the northern supercell, and figured we could not get back to the really obvious southern storm near Lacrosse by nightfall...so we targeted the middle storm, rather than calling it a day, because of the strong inflow into it.  Although we were rewarded with a  good tornado, we were too far from it at dusk to photograph it well.....but WERE close enough to get a good look at the rope out stage, which was far more interesting than the trunk tornado itself.

But it's also clear we missed the big show on the Lacrosse supercell.

For May 26th, a bit of failure analysis is needed to explain in more depth why the storms we saw were not tornadic.  I think I've got the reason, but I've got to look at the actual observational soundings in more detail before I am sure.

Some curiosities that need to be explained include why storms that crossed the boundaries into better air often died....that is the opposite of conventional wisdom.

Thom and I were both gratified by the fact that we made no significant navigational errors...those have plagued us in the past.  Even missing a turnoff by 5 miles could mean missing a tornado..since tornadoes often don't last more than a few minutes.

We were also gratified that we managed to steer clear of the major chaser convergences...except for a brief time near Russell on May 25.  But even then, we were able to find dirt roads away from the mass of people doing the wrong things...including blocking roads, setting up tripods in traffic lanes, and smashing into one another.

All in all, it was an excellent, exciting and fun trip.  However, 4500 miles in 10 days tells the tail in terms of fatigue.  So though there are chasuble patterns the next few days in the southern Plains, it was time to call it a "chase."


May 27, 2012

May 27: Back to North-central KS

Panorama shot just north of Ellis of departing Hays supercell, shown below, road goes due north. You can see the southern end of the Nebraska line of storms sort of over the road in the distance
What We Saw

We saw multiple storms firing off the dry line/triple point area alluded to below, from around 4PM on, southwest of Hays KS. 

Shot of RFD notch in Hays supercell, illustrating high base.
This shot is looking due west (road goes west)


Shot of same as (2) except showing whole updraft tower.
There was definitely lots of precipitation on the forward flanks. There was also lots of precipitation wrapping around the updraft areas with the weak an broad mesocyclones that had formed.  But the LCLs were so high that the moist adiabatic ascent did not occur in the area of the really wonderful clockwise loops in the hodographs. The key here would be the 0-3 km CAPE, which in May 27ths case was really negligible.
There were some "CAPE-robbers" in the soundings related to the negatively tilted trough that moved northeastward. A negatively trough that is "minoring out" as it moves northeastward is really experiencing height rises relative to a coordinate system fixed with respect to the trough. The height rises hypsometrically are related to temperature rises. 
Fibrous anvil for storm south of Hays near sunset.  
So most of the updrafts we saw had mushy tops. The best look were the storms that we could see in Nebraska. I think that updrafts were weaker for our storms, even if the CAPE area was deep. Not quite "tall skinny" CAPE....but definitely pretty anemic CAPE. 


What was clear was that the atmosphere wanted to produce lots of storms, and there were several surges of initiation northeast of Dodge City.   Storm after storm formed there, but each had those high bases, and each had kind of mushy tops and fibrous anvils.


Departing Hays supercell.  View looking northeast, shot a few miles north of Ellis.
I have posted here some other pictures showing the state of the sky near Hays just before initiation. (panorama).  I've also posted a panorama of the first set of storms after they formed.  And finally there is a picture of a wonderful fibrous anvil with mammatus on it and all sorts of wave like perturbations in the cloud material.









Cumulus field southwest of Hays, just before thunderstorms developed.
First thunderstorms, south of Hays, around 4PM.  View looking southwest.




Meteorological Blather


I am in North Platte, Nebraska this morning with Scott Landolt.


A negatively tilted short wave trough in the middle and upper troposphere will be incoming today. I often don't like them in the Plains....as they often are associated with difficult to diagnose temperature advection patterns in the middle and upper troposphere...meaning weak areas of warm advection producing "CAPE-robbers" in the soundings.

However, models are generating a weak low over southwest KS, which should swing the surface winds around to southeasterly over the area about 50 miles north and south of a line from Hill City to Concordia, KS.  The WRF-NAM has interesting looking soundings and hodographs over north-central KS into south-central Nebraska tomorrow afternoon. Further east, the soundings look too capped.   And even in the area of interest, the recurrent problem of inadequate dew points seems to be indicated, suggesting that storms will be high-based.



However, the general setup is good from north central KS to extreme south central NE.  We'll refine the target later this morning.










May 26, 2012

May 26 Target


Thom leaves today.  After I drop him off at Denver airport, I will try to get northeast into western Nebraska.   There is a really favorable pattern in that area, as shown in the graphic.  Not much time to post today....as I will be alone until I am able to join Scott Landolt, who is  in Nebraska.

This forecast did not pan out.   The area south of the warm front did generate thunderstorms, but they died both of the boundary, not intensified.




May 25, 2012

Preliminary May 25 Target: Quinter KS




What We Saw


Initiation was explosive around 4:30 pm, southwest of Hays KS.   The first storm moved northeast and crossed I70 near Russell KS.  Two other storms developed, one west of Rush Center and the other west of LaCrosse, later in the afternoon and evening.  All three became supercells and all three produced tornadoes.  


The picture at right shows the first storm....shortly after it developed.  We estimate it took only a few minutes between the time it was a small tower and this blossoming cumulonimbus with explosively expanding anvil.


The formation of the base/wall cloud was very interesting.   It formed as a detached scud cloud that drifted under the updraft, attached and developed the classic "bell shape" underhang, as shown in the photo.







This storm became a supercell quickly.  And we followed it as it approached I70, at which time it put down a very brief weak tornado just south of I70.   It had a very impressive radar presentation at the time.  Our position is shown as a white circle on the radar reflectivity plot below.


This is about the time we encountered literally hordes of chasers.   Large tour groups in vans, car caravans, and many groups of people with cameras on tripods, in some cases in the middle of the dirt roads we travelled.   


As we came to one intersection, a person driving an SUV coming from our left, stopped abruptly in the middle of the intersection, and was rear ended by the person driving behind her.  There was large damage to both cars, though neither driver was injured.


We eventually found roads along which few chasers were clustered....and, eventually, when the meteorology got 


somewhat complicated (the obvious storm was weakening and we expected development not the storms further south), it was interesting to see the hordes of chasers stay with the first storm, and we ended up alone with the second tornadic storm we intercepted.  That experience was reminiscent of the experiences Thom and I had years ago, when we had storms "to ourselves."




Even on the first storm, when it showed signs of deviate movement to the right (instead of the radar indicated northeastward motion), we got out on our own.  The picture at the top of this blog entry shows us looking at the mesocyclone area, with the ROTATE armada (an NSF funded project).  You'll note no other chasers in that location.  Also, if you look closely on the right, you'll see the RFD notch corresponding to the center of the mesocyclone to the right of the road.  You'll also see no other chasers in the picture above.....as we had found a dirt road (thank goodness for AWD) that only some chaser colleagues of mine had found...but none of the hordes.




As we dropped south towards the second storm, we noted it had formed a wall cloud, dimly lit by the setting sun.  Just at sunset it produced a beautiful tapered elephant trunk tornado.   Our pictures are blurry because of the low light, but you can see the funnel, and then the "rope out" stage, in which the tornado shrinks in diameter, and is pushed around by the storm's forward flank outflow.  In fact, in the last stage before sunset, the rope was so elongated, 


perhaps for miles, to form a right angle, where the tornado was still in contact with the ground.  I tried a panorama shot with my iPhone....and it too is blurry, but if you look at the center of the picture you'll see the forming tornado.


Forming Russell KS tornado, May 25, 2012.  Sunset...literally. half the disk of the sun was right behind the tornado. This was about 5 minutes after the picture below.   At first I thought the tornado was forming on a separate wall cloud, but now I realize that it was forming where it should...on the northwest part of the bent back horseshoe wall cloud (with the RFD reaming out the middle).  You can see the RFD cut on the image below.



I've also posted a short movie shot with my iPhone video cam showing the anvil lightning associated with the LaCrosse KS tornadic supercell.  That was the storm due south of the one we were on and it turns out that was the storm of the day (producing an EF2 tornado).  We dawdled around too much with Storms 1 and 2 to make it down there by sunset.


I'll post more when I get more time.   But this was another wonderful chase day for us, during a week filled with some frustrations, but lots of 
storms.
video






Meteorological Blather



[Update, 215 PM CDT:  We are currently in Great Bend, KS.  The models are suggesting storm initiation around Dodge City, with storms moving initially northeast towards the boundary.  The hodographs in this area are becoming strongly tornadic...meaning, the wind shear suggests that any storms that move towards the boundary draped just north of us along I70 will become tornadic, with perhaps a strong and violent tornado in there.]


We'll be targeting the region north of a warm front/dryline/cold front join  somewhere near, dare I say it, Quinter, KS (inside joke). This judgment is based before I see the 12 UTC run of the WRF-NAM...so the 06 UTC run and the latest run of the RAP.

There are differences between those, chiefly with the issue of CIN. The RAP forecast soundings in the area of a curious shallow ground-based stable layer or inversion for many places in that area, except just along I70 or so. Don't know why an inversion would be showing up, unless it's outflow related....it's not a frontal inversion, and it is very shallow. The WRF-NAM doesn't have that....

But both models have more than sufficient CAPE, for a change. What is striking is the ENIORMOUS 0-1 and 0-3 SREH projected by both models in the area bounded about 50 miles in diameter from a point somewhere between Wakeeney and Goodland. Geesh. Anyway, that is our target right now. 
















May 24, 2012

Two Potential Targets on May 24: Most likely se KS





Summary


We hung around the area south of Emporia and watched bubbling cumulus.  At around 5PM towers went up along the cold front and one, near Emporia, showed a weak mesocyclone.  It developed a low level inflow tail and briefly had very robust updraft towers and a crisp anvil.   But, it was struggling with the warmer environmental air at 10000 feet or so and never did much.

We stayed with it as it moved along I35, and it became absorbed into the circulation of the storm just north.  The flanking line had areas of strong rotation, probably generated by the shear along the flanking line.  You can see a still of one such area at right....it's the dimple or curved shape in the middle of the picture....caused by the counterclockwise rotation at cloud base.


Meteorological Blather

As the cold frontal wave shifts southeastward and stalls, the RAP has been consistent in seeing a small sub synoptic feature in se/sc Kansas.   You can see it evidenced as follows:  (a) a bent back portion of the dew point and CAPE fields south of Emporia;  (b) a maximum in the 0-3 and 0-1 km SREH fields; and, finally, (c ) the focussing of surface convergence yielding no CIN in that area of 65+ dew points.  For what it's worth, the RAP simulated reflectivity fields generates an isolated storm there, that moves rightward.

We were looking at northeast Oklahoma as a CAPE/CIN-less spot the last two days on the WRF-NAM for the last two days...and that has shifted northward.  

The other potential target would be se CO...with decent hodographs...and surface south to southeast flow, but with very mediocre CAPE.  

Right now, on Thom's last two days, it would be nice to see deep moist convection, rather than the CAPE starved storms we saw yesterday in Colorado.  Also, if the RAP bears out anywhere in that area with that small feature, it might even be a mesoscale accident day.

The map at upper right shows the important features.  The red box encircles our target with the map time positions of boundaries and important features.  The sub synoptic low in central KS is projected to move southeastward during the day....and the box encompasses the region just head of the afternoon position of the cold front.

May 22, 2012

May 23 Target: south-central NE/extreme central KS


What We Saw


The picture above is a panorama of the base of one of two super cells near Kit Carson, CO.  We are looking northeast here.  If you look to the left side of the lowered cloud base, you can see a notch cut out of the cloud base. That is a rear flank downdraft....a downrush of drier, sometimes warmer, air that occurs on the back side of a mesocyclone.


Meteorological Blather

The 0000 UTC WRF-NAM shows an elongated sweet spot from the warm front/dryline/cold front join  over extreme central KS northeastward. The forecast CAPE is 2500 J/kg with (according to the WRF-NAM) no CIN in that area.   The simulated reflectivity product has a storm in south central NE that can be inferred to drop southeastward with a line developing after 0000 UTC.  The forecast hodographs are best in the capped warm sector...but are still good INVO Hastings to Hebron to Concordia to Beatrice north to Lincoln back to Hastings.  

The risk reward here is that the model could be wrong and the area will be capped....the reward is that any storm that can get going will be tornadic.

Now, a developing low pressure area in sw KS is moving the moisture tongue back under very favorable shear in eastern CO and nw KS.   So we have two targets over which to deliberate....and so we will drift west from Belleville KS towards the west, having both targets as possibility for the next hour or so...but we will eventually have to commit to one or the other.


Kingman Tornadoes; #9 May 19, 2012


This was the final Kingman KS tornado...and the most impressive.  We had to move from this location because of large hail (golf ball size).   But as it crossed the road we were on, other chasers filmed one of those wind turbines being bent out of shape.


Forming Kingman, KS Tornado, May 19, 2012

video

Shaky iPhone video camera shot of forming Kingman tornado.   Doesn't do it justice.


May 22 Preliminary Target: e OK/ne TX Panhandles/sw KS


This morning's models and the observations show that the NAM's 0000 UTC dew point field forecast for this afternoon was way overdone in Nebraska...but underdone in western KS into the central OK Panhandle, perhaps a bit further south.  I like the forecast soundings and hodographs for the eastern OK Panhandle and sw KS this afternoon.   With the south winds in combination with WNW flow of 25 knots, 0-6 km AGL shear is about 40 knots over that area, suggesting some super cells in the area, albeit high based, particularly on the western margin of the CAPE field.  The low level shear is not good, however.   

What we can hope for is some mesoscale forcing...for example a surge of the dryline, already suggested by the southwesterly wind push across ne NM and se CO.

With the forecast hodographs, the right movers might be moving hardlly at all relative to the ground, or in "odd" directions, like westward or northwestward.  The inflow area will be on the northwest side of such cells.   But that's if the forecast hodographs verify.

May 20, 2012

Upslope Area of western TX/OK Panhandles/seCO


{Addendum:  we are nearly to the extreme nw TX Panhandle.  Storms are initiating to our west.]

Another potentially interesting pattern....1500 J/kg sbCAPE, 43 knots 0-6 km AGL shear, 300 m2/s2 0-3 km SREH...are the positives.

Where?  Under those deceptive 25 knot WNW winds at 500 mb in the upslope area of the western high Plains.   .   


Actually, the morning analysis indicates favorable upslope flow from Lubbock to Springfield, Colorado...with a substantial southeasterly component to the flow.  Several boundaries are already present in the TX Panhandle.  The latest run of the RAP indicates a focus ...from Springfield, Clayton, down to Amarillo and up again.  The low level helicity values look great there this afternoon, with deep layer shear values nearly 40 knots.   

Here's a graphic showing our initial target area.  And the picture at right shows one of the briefly super cellular storms we saw just north of the New Mexico/border with Colorado.  We were hoping for more, given the outflow boundary's possible interactions with the flow....but such were the cards dealt us this day.

We are drifting to Lamar CO for our overnight stay.

May 20 Target: Southern TX Panhandle/sw OK



Posted Image


Forecast


Thom and I just finished our "morning briefing". Our destination today will be somewhere in the area between Wichita Falls TX and Lubbock.
We plotted soundings from both the WRF-NAM and the RAP and get anywhere from 1700 to 2100 J/kg sbCAPE with virtually no CIN close to the quasi stationary frontal boundary. The hodographs are very interesting for that area. I've provided the one for Wichita Falls at 0000 UTC. And if you want to see both the sounding and the hodograph with all of the indices, that is here:http://tornado.sfsu.edu/SPS.jpg

The weak 500 mb ground level flow belies the more than adequate 0-6 km AGL shear in the area...which with easterly or northeasterly winds at the surface creates really large loops in the hodographs. The "fly in the ointment" is the low level shear....it is virtually nonexistent in the forecasts.



What Happened


The dew points never quite made it up to the levels forecast in the morning model runs.  Also, there were some very interesting interactions between that boundary and the storms.  The richer moisture lay to the north of the boundary, yet when storms crossed the boundary they "croaked".   


Those to the south of the boundary were alive, but were drawing on the anemic moisture, and looked "CAPE starved" and had very high bases.   I created a panorama of one of the storms we observed, just south of Vernon TX.  It clearly was rotating, with mid-level cloud fingers extending into the updraft area.  And you can see an inflow tail to the right.  Yet, it never did much, besides producing 1 1/2" hail.  That's Thom and our vehicle to the right.






 

May 19, 2012

Prolific Tornado-Producing Thunderstorm

Kingman, KS Tornado #9, May 19, 2012
The forecast was a good one.  We'll have to check the digital photos....but our count was 9 tornadoes, including one that was within 2 miles and then 1 mile, on the ground for over 20 minutes, shown at right.

This was initially southeast of Great Bend, KS, but then about 20 miles west of Wichita, all out in open country.

A really outstanding day.




On to southcentral KS


May 19, 2012:  Meteorological Discussion

We're still thinking Pratt, but there is a potential for a target across the border in Oklahoma that will also be reachable.. The best crossover of sfc and 500 mb winds is forecast to be from ICT to Pratt and down into Oklahoma.   Frankly, none of the hodographs I plotted are screaming "come to me".  All of them have adequate deep layer shear, but the low levels are anemic everywhere.  The 0-1 km shear forecast by the WRF-NAM is at best, weak in that area.  

Yet, the WRF-NAM forecasts a small sub synoptic low to form near Hill City, KS at 2200 UTC so maybe that will materialize and both back and accelerate the low level flow.

Anyway, we overnighted in Hays and ran into the College of Dupage storm intercept/research team, led by Paul Sirvatka and Victor Gensini  this morning....all the students diligently doing sub synoptic analyses....it was great to see.

[Addendum:  another target is along the Nebraska-Kansas border north of Concordia.   I just like the storm motions and storm relative flow projected for further south.]

May 18, 2012

First Day....outward and onward

After a very early flight, both of us on short sleep, we are navigating our way through ne Colorado towards the anemic moisture tongue on its way northwestward from Kansas.  We've taken some pictures of our vehicle and will try to load them.  Also, having a difficult time uploading the charts I have annotated.....

Right now, at 3:34 PM PDT, some high based cells that are showing some midlevel rotation are developing southeast of Sterling, CO.  Probably will drift east into sw NE shortly.


A panorama made of seven pictures I shot with mu iPhone camera.
This base was elevated, but rotating.  
We saw three or four high based storms, that had signs of midlevel rotation.  

Our preliminary target for tomorrow is still the Pratt, KS area.  I think there's a good chance of surface based supercells tomorrow.  I also think there may be a couple of tornadoes in KS tomorrow.

Our chase vehicle this year is the same as last year's:  Chevy Equinox
This is the lap top setup.   The square thing at the top is an antenna for the mobile wireless hotspot I have.