Thom Trimble (left) and
Quinter, KS, Multiple Vortex Tornado, May 23, 2008. First of Three tornadoes to strike Quinter this day.
The mission is to (a) document tornadic thunderstorms; (b) document supercell thunderstorms in general; and (c) get lightning shots. The first two are very rare to relatively rare. Perhaps 1 in every thousand thunderstorms worldwide is a supercell, and of all supercells, less than 15% produce mesocyclone-tornadoes ("Wizard of Oz" type tornadoes).
The first two depend on some aspects of the large scale weather pattern that mostly involve the evolution of the wind patterns at jet stream levels and the presence of low level moisture/instability. The Great Plains is climatologically favored for the juxtaposition of favorable low, mid and upper level patterns favorable for tornadic supercells, on average, the last two weeks of May and the first two weeks of June.
Since I am a synoptic meteorologist interested in weather pattern analysis and forecasting, the chief purpose I have is to understand how the ingredients that produce tornadic supercells and supercells in general come together in the weather patterns that occur during the period of our chase. The challenge for me as a meteorologist is to forecast these patterns in advance and to put myself and my chase partner in a position to view a tornado and/or a supercell. Clearly, if we manage to do that, I have made a successful forecast.
This is important because there are indeed weather patterns that occur in California that produce tornadic supercell thunderstorms. While these patterns are relatively infrequent, they do occur. In order to hone my skills in anticipating these patterns, though, I need to put myself in an environment in which forecasting "tries" at anticipating them occur frequently. Hence, these trips to the Great Plains.
The results of these trips are measurable in the form of publications on tornadic storms in the Great Plains and in California. Also important, is the transfer of the knowledge I acquire into the classes I teach, particularly, Meteorology 302 (The Violent Atmosphere and Ocean, Meteorology 503 (Weather Analysis and Forecasting II), and, most significantly, Meteorology 515/815 (Analysis and Prediction of Severe Storms).
Those students who are reading this and took Metr 302/403/503/698 know about the use of the Ensembles to antcipate pattern evolution beyond about five days. That's made anticipating weather patterns for our chase trip less of a guess than it was even five years ago.
In the case of the first 10 days of the trip, the Ensembles (a blending of the actual forecast with 20 other forecasts made by slightly changing the input variables a very small degree), showed a high amplitude ridge diverting the favorable jet stream winds well into Canada. Known as the "Death Ridge" to veteran storm chasers, a ridge like this persisting for 10 days or more can completely suppress severe storm development. While the actual forecast showed this Death Ridge, many of the ensemble members did not (the orange colors indicate the degree to which the ensemble members disagreed with this pattern).
And, sure enough, the mean ensemble pattern showed the progession of a trough into the Far West, bringing a pattern with potential for a severe weather outbreak in the Great Plains from Tuesday through the following weekend. All but three of the ensemble members showed this trough, though there was considerable variability on its exact location and depth (hence, the orange colors). The ensemble mean's surface pattern suggests southeasterly flow into the Great Plains underneath the favorable upper winds. If this pattern develops, the exact position and strength of these features will determine the nature of the "outbreak" of severe weather that will be sure to occur.
Hence, though the first few days of the trip have been inactive, we expect storms each day from Tuesday through the following weekend. Initially, it appears we will be in eastern Colorado, western half of Kansas, and the western half of Nebraska from Tuesday on.
TARGET: Down Day: Boulder, Colorado. Eventual target central KS (Sunday/Monday)
This is not for May 17, but for May 18 and 19. The NAM is forecasting the formation of a surface low in the Nebraska Panhandle tomorrow (the 18th) and then sags that south into se CO/sw KS on Monday (19th). This is under northwest flow of 40 to 50 knots in the mid troposphere on both days.
Southeasterly or easterly surface flow in southcentral Nebraska on Sunday (17) and central KS on Monday (18th) begins to bring higher dew points and some surface based CAPE into those regions on those days. However, the deep moisture suggested on the GFS (not shown) is not as dramatically shown on the NAM forecasts (which tend to overforecast the moisture field anyway).
So, this is not a travel day, but we will be, keeping an eye on the moisture return for Kansas/Nebraska tomorrow. We'll overnight in Boulder, CO. This will leave us in a good position to get to Nebraska or get further south in Kansas by Monday.
TARGET: Down Day: Boulder, Colorado. Eventual target moved to western KS to eastern Colorado (Monday/Tuesday)
These days (Sunday to Monday) are obviously not "tornado" days.
But, if you look at the NAM forecast hodographs for KONL and KPIR for Sunday afternoon, you can see interesting hodographs with northwest flow. However, the sbCAPE is meager....but is definitely there, as a tongue of 50+F dew points curl up through Nebraska and South Dakota Saturday and Sunday. So....if storms initiate they will rotate...producing nice striated structure shots, albeit with high bases.
If surface dew points do not creep into the 50s, then there will be no storms with an unbreakable cap given those parameters.
If surface dew points creep up into the mid to upper 50s (actually, the NAM, with its moist bias, does do that in north central Nebraska), then perhaps a mesoscale "accident" can occur. As of this time, (Sunday, Noon MDT), it appears that moisture will NOT be returning to KS and Neb today. So we are "down" until we see some evidence of the promised moisture return.
TARGET: Down Day. Estes Park, Colorado. Possible mountain thunderstorm lightning shots
The pattern is now shifting from an unfavorable one for severe convection to one favorable first for thunderstorms (19th), then scattered severe thunderstorms (20th) and then a larger outbreak of storms, possibly supercellular (21st). Today, steep lapse rates evident in the Denver and North Platte soundings suggest an active high based thunderstorm day.
The first storms should form over the Rockies and Raton Mesa and then drift southeastward embedded in northwesterly flow aloft. Low level moisture is still lacking, however. We've repositioned to Estes Park, CO...just outside the eastern border of Rocky Mountain National Park, in the hopes of seeing some night lightning and photographing it. You can see deep cumulus developing already on the satellite image this afternoon just north of Estes Park (the white clump towards the extreme upper middle portion of the image).
Estes Park is right on Highway 34, though, and allows us to quickly get east into the Plains tomorrow, as we expect a more active day in a more traditional pattern on Tuesday.
TARGET: Northeastern Colorado. Denver Cyclone/Possible Supercells/Non-mesocyclone tornados
We're on our way to the region between Akron and Limon CO (northeastern quadrant of the state). A Denver Cyclone has set up in that area, evident in the wind field at the surface. Southeasterly winds are feeding relatively moist air into the region of Colorado at right angles to the Palmer Divide and the Cheyenne Ridge. This is yielding sbCAPE values in the 1000-1500 J/kg range. The 1PM MDT satellite shows cumulus bubbling on the Palmer Divide and the western half of the Cheyenne Ridge.
Deep layer shear will favor some rotation in the updrafts, so we're hoping on seeing a supercell today. Also, there is always the chance of a non-mesocyclone tornado.
After traversing the stretch of Highway 71 between Brush, CO and Limon, we centered on the Cheyenne Ridge area. There the southerly winds coming up through Colorado would be lifted, and diurnal heating should aid the thunderstorm development. A couple of storms did develop, and one developed a mesocyclone. We targeted the eastern most storm 30 miles northeast of Brush. We got to it late in its life cycle, but early enough to note striations in the updraft area above a high base, as well as three middle level "stingers" (altocumulus clumps drawn into the rotating updraft, appearing like prongs sticking out of it).
Satisfied that we'd seen our first rotating storm of the trip, we holed up in Sterling CO.
TARGET: Eastern Wyoming/Nebraska Panhandle/northeast Nebraska
With southerly winds at the surface finally firmly established across the area, surmounted by southwesterly winds in the mid troposphere, we finally have a "traditional" severe weather pattern. This pattern would also favor tornadic supercells, as opposed to just supercells, had low level moisture made it northward into the region. The RUC and NAM suggests that MIGHT occur late in the day, with a strong low level jet, encoming mid tropospheric trough, and a dew point surge into the area from the southeast. Forecast sbCAPE values in the 1000-1500 J/kg range, plus dynamite hodographs suggest that we will see some supercells today, though the tornado risk seems mediocre, if not absent.
Mid level winds never developed as strongly. However, the surface low did. We experienced a "haboob", a dust storm generated by a combination of synoptic scale winds and thunderstorm outflow. Thunderstorms did erupt in the meager boundary layer moisture, as dew points, though much higher than on previous days, never came up to the mid 50s. As we came around the north side of the complex, we were hit with 60 mph winds out of the south, and a blinding combination of dust and tumbleweed, making the experience like an amusement park ride. By sunset, complexes of multicell thunderstorms, with a few embedded supercell structures, covered the Great Plains.
TARGET: North Central KS. Hill City to Hays. Enhanced risk for tornadic supercells.
There is a major risk today for tornadic supercells in much of west central KS. The morning weather map showed a wave cyclone in west central KS, with a warm front, cold front, dry line triple point centered west of Great Bend, KS. Just south of the warm front, a low level jet of southeasterly winds has spread 60F and higher dew points to northern KS.
A strong trough in the middle and upper troposphere is overspreading the region with strong southwesterly winds. This is a pattern favorable for storm ventilation and favorable shear values for supercell thunderstorms.
The morning sounding for Dodge City is the so-called "Loaded Gun", with a potential of nearly 3500 J/kg sbCAPE (with the virtual temperature correction). The soundings north of the warm front, this one for North Platte, are typical for locations along and just north of a warm front (M503 students should be able to recognize that).
Forecast maps show that the area south of Hill City to Hays along Interstate 70, and south through south-central KS will have very favorable conditions for strong tornadoes today, with low level shear values approaching extreme values, and a markedly curved hodograph...all signatures of a thermodynamic/kinematic profile favorable for tornadic supercells. Here is the forecast sounding and hodograph for Great Bend.
The surface pattern is forecast to have a double low structure, with the main wave cyclone centered in northeastern CO and northwest KS, and a weaker low in sw KS. That will bring the moisture northwest into the region from sw Nebraska southeastward into all of north-central KS. A push of dry air with a sort of atypical direction will approach the aforementioned moist tongue from the south, due to the double low structure. Thus, a very marked dry line separating air with dew points in the 20s and air with dew points in the mid 60s, the latter characterized by very high CAPE, will connect with the warm front along the Nebraska border. This triple point will be under strong southwest to south flow in the middle troposphere, creating the potential for strongly helical updrafts.
Given all these forecast parameters, patterns and conditions, if all verifies, then this area will be seeing an outbreak of severe thunderstorms this afternoon, some with very large hail. The hodographs suggest that some discrete supercells will occur, and the low level shear values suggest that some will be producing strong or violent tornadoes.
(Also, see SPC's outlook).
We drove south of Gove, KS, to intercept a supercell that had strong rotation indicated. As we approached it, we could discern massive spirals in the ascending cloud material. There we encountered Chuck and Vickie Doswell. Here's a picture of me and Thom and me and Chuck.
Thus began a frustrating four hours, as we were on every storm that produced a tornado, but each in low light and not much contrast. For example, as we drove up to the Gove Storm, we could see a lowering and, closer inspection, revealed a dust whirl underneath that lowering. That could have been a developing tornado. But the storms were moving at extremely fast speeds...50 mph. Thus, in stopping to take a picture, the storm got north of us, lost in contrast, and then there were many reports of a significant tornado, that we could not see, even though we were within two miles of the storm. All we could see, iniitally, was a rain-free base, and several lowerings.
Then a second storm moved northward in view. This one had another lowering, and we captured what might have been a weak, multiple vortex whirl or tornado developing, soon to be lost in contrast.
A third storm moved northward rapidly. This storm began to develop a hook and had consistent radar presentations of rotation. We followed it northward. As it moved northward, the radar was indicating many rotational signatures, but we had consistent problems staying with it at a far enough northeastern location to maintain contrast. During that time, there were many reports of tornadoes from this storm, though we only saw some suspicious underhangs, and collars. We later found out that that underhang was a tornado and later developed into a cone, and that the collar, from our perspective, was hiding two tornadoes from our view.
Quinter, KS, May 23, 2008: Multiple Vortex Tornado, Looking West. Central tornado wedge, surrounded
by satellite vortices (see four to the south of the road) rotating counterclockwise around tornado cyclone.
TARGET: Northwest Kansas: Enhanced Risk for Tornadic Supercells
This day brimmed with potential for tornadic supercells in Kansas. The potential was so high that enthusiasm of storm researchers and chasers was somewhat dimmed by the prospect of potential damage, injuries and deaths in an area of Kansas that is relatively well populated. The morning weather map showed a rich surge of moisture laden air from the tropics, with dew points in the 60s to lower 70s across south-central KS in strong southeasterly flow. This was surmounted by a very unseasonally strong mid tropospheric flow, greater than 50 knots expected to spread across KS during the day. The combination was expected to create hodographs and buoyancy combinations favorable for strong and violent tornadic supercells.
The surface chart also revealed an outflow boundary in northwest Kansas that was racing southward and interacting with the moisture rich air. Thunderstorm iniitation began at that intersection and just south of it.
This in fact did occur. However, the strong winds aloft created storm motions that were extraordinary for late spring, 50 to 60 mph, compared to the 20-30 mph that is more typical. To put it in plain English, this means that storms would come roaring by at, essentially, unchaseable speeds. Researchers would only have a brief moment to observe the storm or the tornado before it raced out of range. Such storms are notoriously difficult to chase, and, in many cases, impossible to chase unless they are paralleling a freeway.
In this case, the storms were moving at an angle to all the rectilnear roads in KS, and, worse, were in areas through which only dirt roads mostly were found. This turned what should have been a tornado researcher's nirvana for documentation into just an awful tactical mess. This was further complicated by the number of novice chasers, and lookers-on, who littered the road unsafely with vehicles (in some cases, parking in the middle of roads). At one point, this got so ridiculous that the Kansas Highway Patrol closed Interstate 70 when a tornado was expected to cross it, thus stymieing research teams attempting to reach the storm.
This is one reason that I, and my chase partners, never chase in a caravan (more than two vehicles). Large caravans of cars attempting to stay together often cause traffic nightmares, and are obvious targets of the local law enforcement who often assume all such caravans are putting themselves in danger, or are likely to llitter the road preventing emergency vehicles passage.
Also, see SPC's Outlook).
Three Tornadoes Strike Western Portions of Quinter, KS
As the day progressed, the parameters came together to underscore the tornado risk. As a result, when convective initiation began, SPC issued a "Particularly Dangerous Situation" Tornado Watch.
This is adapted from my chase colleague, Chuck Doswell's tornado log, with some pictures taken by me:
"...We struggled with roads, visibility, and various challenges associated with these storms, We were IN Quinter when the first tornado moved in close ... the visibility was terrible from there, and we couldn't see it until it was almost in Quinter. An awesome sight as it emerged from the murk and did a multivortex dance just outside of town. It was rather CLOSE when it dissipated and provided us with an exciting 10 min. We then chased the storm northward for a while, but could never see anything again ... a terrible muddy road and poor visibility conspired against us. We finally broke off from it and raced back southward from HLC - missed the second Quinter tornado by only a few minutes. Then we mistakenly took off southward toward the storm that ultimately hit Ellis, but never saw anything with it. Hence, we missed the THIRD Quinter supercell of the evening (which apparently did produce a third tornado in the vicinity of Quinter) and by the time we had wandered about, it was impossible to catch the Ellis supercell again. Quinter residents should be grateful the town was mostly spared ... it must be some sort of record for that many tornadic supercells in a short time (~ 3 h)
So we had an exciting moment "in the sun"..."
Here is a comment I made to colleagues on this day, after many were dissappointed not to have seen tornadoes, even though there were very many that day. (I might add, many meteorologists did see tornadoes...but the failiure rate was large)
"...I would like to add a dose of common sense to all of the successes and failures of the last three days....
In Kansas on the 22 and 23, if you were fortunate to be on the right road at the right time, you got to see a tornado. If you were on the same storm, just 1 minute removed, you didn't.
In Kansas on the 22 and 23, if you were fortunate to be on the right road at the right time, you had approximately 29 seconds to watch, and then get zooming on dirt roads to keep up with the storm.
Why? Because the visibility was about as bad as I have ever seen out here....for the first Quinter tornado, we literally saw nothing until it suddenly appeared out of the muck for about 20 seconds west of Quinter...and then the storm was gone, never (for us, without a four wheel drive vehicle) to be caught again. We did not have time to get quality pictures, nor did we have time to adjust, since we had to get out of its way (by the way, one of the most exciting 45 seconds of my chase career).
Can you blame yourself if the only way to the second Quinter tornado, apart from muddy dirt roads, was to be on I70, which then was closed, to watch the tornado move across the freeway for a 10 second visual bite?
I actually woke up in the middle of the night last night, feeling extremely inadequate as a meteorologist. Every decision we made, except the first (for the first Quinter tornado) ended up being a half second too late, or a half mile too far. There was only one stupid decision that I could really beat myself up on....but all others were sound. Yet, as I remarked in a post in another thread, almost every one had tales of great pictures, tremendous wedges, driving up to the tornado from 100s of km away etc. Yet where were we? Everyone I know back home saw pictures of tornadoes from, apparently, the vantage point of where we were standing, yet I have to report, I saw only one, and have awful photographic documentation of it.
On the other hand, had there not been so much aerosol seeding, many more of us would have seen more tornadoes, from what normally would be considered close quarters....1 mile away...not 200 yards, as you almost had to be, or in the narrow visual notch northeast of a precip wrapped storm.
It was extremely frustrating and extremely fatiguing....and I do congratulate all of you who saw so much, as we drove from storm to storm, only being too late, or too early, or not close enough, or not at the right angle.
But...there is always tomorrow..."
TARGET: East-central Nebraska
With the nearly stationary trough keeping the actual and forecasted mid and upper tropospheric flow fixed over the central Plains, the focus shifted to eastern Nebraska. The morning weather map showed southerly or southeasterly flow from eastern KS into southeastern South Dakota. The forecast surface chart showed backed flow north of Interstate 80 with 60F + dew points and moderate instability underneath the amplified mid tropospheric flow. Satellite imagery showed that area was cleared out of most clouds, thus allowing ample sunshine to destabilize things and foster initiation of convective storms ahead of the dry line which extended from Oneil, Nebraska southward through the area just west of Grand Island.
Hence our target was the region south of Norfolk and north of I80 in east central Nebraska. This was enough to have Thom change his outbound flight to Omaha (from Denver), since the Omaha Airport was only 50-100 miles or so from our target area, and the possible overnight resting places for us.
Storms did initiate, but seemed to struggle, in the area from the South Dakota border south to I80. One area in particular, west of Albion, Nebraska, had several long lived convective clumps, two of which eventually became supercells.
Here's a picture of the first Albion supercell, looking west. You'll note the lowered base with the wrapping rain current around its west side. This storm had some obvious signs of at least weak rotation, with several mid level bands being entrained into the storm, and a low level "beaver tail" pointing off to the southeast.
This storm moved off to be replaced by a second storm that became, briefly, supercellular. This, too, had wrapping rain currents, an RFD, and eventually, a lowered base that "tried" to become a wall cloud. However, the rotation never really tightened, and the storms eventually petered out. We overnighted in Norfok, Nebraska, about 100 miles from Thom's departure point at Omaha, Nebraska.
TARGET: South-central Kansas: Expecting Tornadic Supercells
Thom departed from Omaha airport. After our overnight in Norfolk, we drove to Omaha, and then I tried to get to west-central KS, which appeared to have the best combination of shear and buoyancy. 450 miles later, I arrived to find a mess of outflow dominated storms, after several showed some promise on weather radar.
As a sidelight, Scott Landolt joins me tonight. He and his group had a bit of turmoil with these storms, as a road they were on turned from packed gravel to dirt. In the driving rain and hail, the dirt was a quagmire and they became stuck. But they were on the other side of the developing squall line from us, and from help further north, so they had to wait out the hail and rain (and tornado potential) until the storms cleared. Three hours later a tow truck arrived, and they were able to get to Hays before all the lodging was booked up. I pulled into Great Bend for the overnight.
Mobile ThreatNet Reflectivity (and Mesocylone Indicators) with
GPS Vehicle Location Shown and Cone Tornado, Pratt, KS May 36, 2008, 7:10PM CDT
TARGET: South-central Kansas to southwest KS to Oklahoma Panhandle
Another eventful chase in Kansas. The morning weather map illustrated the potential. We began the day in Great Bend, KS.
An outflow boundary from the previous night's convection extended from the synoptic scale boundary just south of I70, southeastward into Oklahoma. A surface low pressure area in southwestern KS was associated with a dry line surge into western KS and the panhandles, with a deep, moist air mass from nort-central Oklahoma into southwest central KS.
Forecasts indicated that this portion of KS would have a very unstable air mass by afternoon, surmounted by moderately strong midtropospheric wind. The morning satellite image showed cloudiness east of the area associated with the overnight convection, and the clear area over the moist incoming air.
Forecast soundings and hodographs indicated the potential for long-lived tornadic supercells in the area. Particuarly, we thought that any storm that passed across the boundary extending from northwest to southeast could produce a significant tornado. Hence, the strategy was to stay put. This is difficult to do, given the inclination to "go somewhere." But stay put we did, for two hours until the first storms developed to our west. We took a route southwestward to approach them.
This initial clump of storms amalgamated into two supercels, both of which produced tornado warnings for the area. The northern storm briefly had a good look, with multiple inflow bands coming into a lowered based, partiallly hidden by rain. The doppler indication of strong rotation prompted a tornado warning and the sirens (.mov file) were turned on in a small town. However,by that time the RFD had wrapped around the updraft and sequestered it from the warm inflow, effectively squelching the storm. So we turned to the southern storm.
By the time we drove the 25 miles south to Pratt, the southern storm did not present well on radar. But as we drove through the town, it was evident by the howling inflow from the southeast, and inflow cloud bands (.mov) that the storm was reorganizing. And the radar presentation corroborated this, with the suggestion of a hook echo, and increasing number and magnitude of the shear markers.
We decided to drive north into the wrapping rain curtain associated with the RFD, and then east. This move turned out to be the best one we could have possibly made. As we drove through the featureless black murk, guided only by our knowledge of storm structure, we expected to emerge with the wall cloud east of us, and any possible developing tornado east of us too. This is exactly what happened.
This was another short burst of intense excitement. Within one block, the clouds evolved from a featureless mess, to a lowered base, and there, directly in front of us was a developing tornado, with a large cone hanging down, and occasional multiple vortices snaking around the main funnel. However, just as in the case of the Quinter tornado, we had a brief window of time to observe the thing, no time to set up video, and only take hasty still digital pictures through the car windows or just outside the doors, before the RFD and rain curtains slammed us. The radar corroborates that the tornado occurred at 7:10 PM CDT.
We did try to stay wth the storm, and managed to catch up with it about 10 miles east of town, after we crossed a tornado damage path that it had left (trees down, telephone poles down, irrigation systems tangled up). There a new mesocyclone attempted to form south of the road, with a new lowering, but the storm weakened shortly after that.
We overnighted in Hutchinson, KS.
TARGET: Down Day. Destination is Scotts Bluff as the pattern is setting up for supercells in the central Plains over the next several days
A 550 mile respositioning to Scotts Bluff, Nebraska. Just a long drive through somewhat picturesque portions of the central Plains.
TARGET: Eastern and Southeastern Wyoming
The pattern looked to be setting up an upslope pattern in eastern Wyoming. Surface forecasts showed a strong surface southeasterly flow against the mountains, with dew points in the 50s, underneath moderate southwesterly flow. This was to produce a moderately unstable air mass. While the southeasterly flow did develop, the air mass never did recover.
We awoke to upper 40 deg temperatures and drizzle. The temperatures than struggled to get into the 60s. Surface based CAPE values barely overcame the CIN and convective initiation only occurred in the mountains. The pattern was a bust.
TARGET: Expecting Tornadic Supercells in eastern half of Nebraska. Initial target: Grand Island
This was to have been a big day for us. The end of the story is that there were two targets. One of them, in northeastern Nebraska was just south of a warm front along the South Dakota border, was expected to have very backed surface flow and the best deep layer shear. The other, along Interstate 80, had southerly winds, with moderate deep layer shear. Both areas were expected to have extreme values of buoyancy (>4000 J/kg) and a textbook looped hodograph. However, storms that developed further north would cross the warm frontal boundary and ingest enhanced shear. Strong and/or violent tornadoes would be the payoff if storms evolved as we hoped and expected in that region. Further south, storms would likely be tornadic too, but less likely to be large tornadoes.
Morning satellite imagery showed both areas cleared out. We made a reasoned, but wrong, decision to go north. This was made despite the fact that storms were developing already south of McCook, NE as we turned north. We reasoned that storms would also initiate further north, so we targeted Oneill.
Here's what SPC had to say about the pattern for the day.
Many factors drew us north, despite the encoming storms in the south. First, the area around Oneil was rapidly destabilizing, as evidenced by the rapid tower growth in the area. We arrived in Oneill and camped out at the library, realizing that the southern storms, now 75 miles south of us, were producing tornadoes. SPC diagnostics indicated that the best shear, 0-1 km and 0-6 km, would be in the north. However, we had to get decent storms.
Storms did initiate, but seemed flattened, fuzzy and/or moisture starved. It was clear that the explosion of storms to our south was somehow suppressing our storms. As we tried to recover southward, we saw a spectacular display of mammatus on the southern storms.
However, the sad truth is that we never got to the storms to the south. Many tornadoes occurred along and south of I80 in Kansas. Our overthinking this situation resulted in us missing all of them.
TARGET: Southeastern KS
The cold front sagged southward slowly from Nebraska, and was located roughly on I70 in KS by midday and the mid-tropospheric wind field still showed strong flow over the central Plains. The RUC forecast 500mb wind field suggested that there would be moderate shear, somewhat favorable for supercells, if penetrative convection occurred. Forecast soundings suggested that would be the case in southeast KS. By late afternoon rich moisture field would be southeast of the cold front in southeastern KS, with very high sbCAPE values. And that is what apparently occurred,according to diagnostic charts. What we saw in the area did not verify that, however.
Initiation began occurring in late afternoon. The first towers and all of the eventual "storms" were mushy looking and appeared to be low-topped. My guess, later verified, was that a subsidence inversion was in the mid troposphere and was "robbing" the storms of CAPE. That subsidence inversion, evident in the 0000 UTC Topeka sounding meant that storms would only grow to the mid troposphere. So, that's what did occur, and we were treated to "mushy" cloud towers, with no anvils, and no chance for any real supercell evolution. In fact, not one of these storms produced a severe thunderstorm warning.
We spent the night in Wichita.
Here's what SPC thought.
Here are some pictures of the first storms that developed near Chanute, KS. The first towers west of the town, a few east of the city, some nice crepuscular rays through adjacent towers, a glimpse of the setting sun, and some alpenglow on distant towers.
TARGET: KS/OK Border area from Ponca City to Woodward to Medicine Lodge to Wichita to Ponca City Polygon: Supercells Possible
Scott Landolt and I overnighted in Wichita and will be hooking up with Chuck and Vickie again today (after Chuck left his laptop in Oneill...and had to return there yesterday to retrieve it). During the early morning hours, the boundary south of Kansas began to pull northward, and warm advection swept the area of south-central KS. Layer lifting associated with that destablized soundings regionally and thunderstorms rapidly developed. Cloud-to-ground lightning was frequent and near by for about one hour as these aforementioned thunderstorms came crashing through here around 5AM or so....pretty nice. The boundary is splashing south east of us into northern Oklahoma with a few places with <65F. That then extended northwestward.
So....the forecast NAM soundings for PNC and other places in north-central Oklahoma have amazing buoyancy (PNC had >6000 J/kg sbCAPE forecast) with a reasonable loop in the hodographs, but with marginallly favorable deep layer shear. So it looks like the eventual mode for discrete storms will be HP, but early in their life cycle they will have a chance for tornadoes....particuarly where the low level shear is augmented by low level jet effects.
It does look like the area from ICT to CUH back to Woodward up to AVK and back to ICT is the polygon for our initial target, dictated by the morning analysis, which showed an intersection of boundaries by Enid.
Here's what SPC had to say.
I can't resist pointing out that our risk polygon (mentioned above) was the ONLY area that featured absolutely no storms, in the middle of yet another Tornado Watch. The convective towers struggled all day to break the cap. We spent much of the day looking at the struggling towers. Here's a shot of a pensive Scott Landolt.
In addition, near sunset, in our ride northwest to DDC we watched the west-central Oklahoma tornadic supercell blow up exactly the way we envisioned a storm would on the beautiful boundaries intersecting west-southwest of Enid....but didn't. The storm was strongly rotating and produced at least one tornado, but well after dark. We could see its lightning display all the way up on the Kansas border.
We also noted that the storm carefully circumvented the Tornado Watch.
Oshgosh Supercell, June 1, 2008
TARGET: Northeastern Colorado: Tornadic Supercells Possible
First, grabbing my colleague, Chuck Doswell's, chase post:
"...A quick summary ... we came north from DDC and made it to I-76 at Julesburg, where we watched (on MTN) the multiple cell mess in the western NE panhandle agglomerate into a supercell, and then took off after it. We intercepted it about 30 miles northwest of Oshkosh, NE, where it had its best look. Then a surge of outflow undercut the wall cloud and the storm remained outflow dominant thereafter. We finally wound up about 10 mi south of Julesburg, where we met Brian Curran and Ed Calinese. Staying put there, we saw some gustnadoes to the southeast as the RFD passed us. We also experienced a mild heatburst and then about 3 weak gustnadoes (well after the RFD gust front had passed us), made visible by the tumbleweeds that surrounded us in abundance. One of these actually hit us, with a brief gust of perhaps 35 kts or so - battering us with tumbleweeds. The storm produced some good looks from time to time but never seemed close to producing a tornado after our initial intercept...."
I will add that the storm may have produced a weak tornado early on in its life cycle, as we just approached it. The storm had a blocky wall cloud (with occasional funnel shaped lowerings) that was cycling in transition to an outflow shelf back to being a wall cloud until it finally was just an outflow shelf. This means that the cold outflow from the storm's downdraft was "winning" the battle and undercutting the updraft area. Though still a supercell, it's chances for producing a tornado would be nill unless something changed in the meteorology
Nevertheless, it presented outstanding structure, with curving inflow bands indicating the massive rotation ongoing. In this panorama, the original updraft area (to the left or south, looking west) was undercut, but still showed cyclonic striations, and the storm had split, with the original mesocyclone in the notch off to the right (or north).
Later on, we dropped south of Julesberg to get some structure shots of the pancake layers of the storm, the almost solid looking "panhandle" look of the flanking line. There, we were treated to an outflow created shelf/wall cloud moving nearly directy over us, complete with some shear funnels, gustnadoes, two of which passed directly over us, including an anticyclonic gustnado that probably was on the interface of being a weak tornado.
We overnighted in Ogallala Nebraska.
TARGET: Northeast Colorado
The morning pattern featured strong upslope flow into northeastern Colorado under moderate 500 mb flow. The combined shear and buoyancy forecast for the late afternoon suggested I'd have one last day of seeing supercells.
Here's what SPC had to say.
Pictures (and less Meteorology)
Chuck and Vickie Doswell, Scott Landolt, and I worked a bit hard as we caught up to a supercellular storm on I-70 near Burlington from the west in time to watch it croak, miserably. We left Chuck and Vickie at the Kansas border, and then we drove back to Limon hoping for some initiation along that very strong boundary that still existed (17 dew points to the south, 59 dew points to the north). When nothing appeared to be happening, we just gave up and I got to my hotel near DIA.
We noticed big towers going up near Denver, and we surmised that winds had come around to easterly there. Sure enough, dew points had come up to the mid 50s near Denver. After Scott left for home, the storms in my vicinity actually achieved some structure and were clearly rotating. Eventually, I had two fully-formed LP storms on either side of DIA. Here is the storm south of DIA early on and a bit later, and the storm north of DIA. You can see the backshear on the anvil extending out of the southern storm, and the leaned over appearance of the storm to the north. There may have been some brief funnel clouds in the expected locations on the inside edge of the leaned over tower, but I never did get pictures of those.
Later, I noticed one of the storms from Wyoming came down to Last Chance area and was tornado warned. It also looked like the best supercell of the day, so I am wondering if anyone was on that one.
Of course, we had come through Last Chance only a few hours earlier. All we had to have done is to have waited!! :-) ...for six hours.
I am calling it a "Chase" for 2008. It was great for Thom and Scott and me to chase with Chuck and Vickie, as usual. Good luck to them.
Finally, I can't help but point out that despite some poor tactical decisions and one terrible decision on our parts, we did get tornadoes on film (though poorly) and were chasing during one of the most active ten day periods that I can recall. My posts on the EXT threads leading up to this are still up. The Ensemble Mean did bear out, and we DID have Chaser Nirvana....at least some storm researchers got twenty tornadoes or more during the second to last week of May....and we got two, possibly three tornadoes, and many supercells.