Posts Tagged: supercell
May 10th 2013
On July 19, 2016
- 2013 Storm Chases
Surface analysis 21Z Fri May 10 2013
The setup for storms was driven by a low scooting just north of Lake Erie and Ontario, the supercells in Southcentral and Southeastern Ontario formed along the warm front where a marine / lake breeze boundary interacted with the surface warm front and trigger storms
A weak elevated supercell in a low energy but moderate shear environment approaches Milton
The storm is now passing through Milton, you can see mid level clouds flowing into the storm from the Southeast (image looking west). It also presents a bit of a vaulted type structure with the usual lateral tilt of the updraft. Slight clearing between the "hail" region of the core and the heavier rain is visible just to the right of center.
The biggest problem with this storm if any is the fact that it remained elevated with limited boundary layer interaction and hence produce virtually nothing as far as wind at the surface.
Inflow / outflow and rain as the storm passes overhead and looses some of its structure
Here a screenshot from PYKL3 (Android radar software) showing my location and a weak couplet appearing on the NWS Buffalo Nexrad radar.
Here's the Meso Analysis sounding for a point nearest the storm at the given time. You'll notice the storm is entirely elevated with very little cape and very low topped since the LFC/CCL EL is ~7km.
lon=-79.813855 lat=43.555635
The hodograph data shows little in the way of dynamic shear, all the veering in this ground relative hodoraph is below any of the convective instability.
The storm relative hodograph shows a very different story, veering winds with supportive inflow exist well above the ground into the mid levels allowing the storm to still rotate (although very slowly) despite being elevated.
This explains why this storm took on a supercellular structure.
May 22nd 2016
On July 17, 2016
- 2016 Storm Chases, Tornado Alley
Surface analysis 21Z Sun May 22 2016
July 14th 2016
On July 16, 2016
- 2016 Storm Chases, Uncategorized
Surface analysis 00Z Fri Jul 15 2016
May 16th 2016
On July 10, 2016
- 2016 Storm Chases, Tornado Alley
What a great first chase day! It’s amazing how variable the weather can be. Just the day before it was cold, miserable and downright chilly, but all that changed a great deal in the Texas and Okalhoma panhandle where a system swinging through set the stage for some cold deep convection. Video is at the bottom of the post. Enjoy!
Surface analysis 21Z Mon May 16 2016
June 25th 2015
On June 26, 2015
- 2015 Storm Chases
So this was a weird day! The models had hinted at some week storms the day or two prior. I thought to myself that I would keep today in mind for a local chase. It was looking rather blah as a cold front sinking south pushed up against a very weak warm front.
There were some weak storms that started to fire as early as 12 noon but they looked really poor. Then around 1PM a more dominant cell seemed to fire near Grand Valley and track east-southeast. I headed off to intercept it once I was convinced it was going to hold together for a few scans.
I was really not paying a ton of attention to the velocity data but boy I sure should have been! There was a nice couplet visible!!
The storm near Caledon East came into view once I was just south of Bolton. I was shocked to see a large, ground hugging wall cloud with slow but very visible rotation!
The wall cloud was almost textbook in nature, the only problem was rain from another storm impending on the western most side of it.
This is a better shot of the rain on the western flank from a secondary cell. You can also see the beginning of an outflow driven shelf cloud.
This was the sounding at the time which makes it very clear what the atmosphere was doing. The biggest problem was the nominal convective energy. The storm was working with very little CAPE, barely anything at 400 j/kg!
It was really nice to be able to just stay in one spot and watch the storm slowly creep over. These things are usually cranking in Southern Ontario and moving at 30 - 40 knots. This was a very plains like 10 - 15 knots.
There was plenty of low scud getting drawn in and lofted upwards but I never did see anything really tighten up and threaten to drop a funnel.
I wish the contrast was better! By this point rain from the neighbouring storm was starting to come down steadily and I knew it was a matter of time before this storm ran out of inflow.
This shot looking due west shows the neighbouring storm starting to really darken and now the outflow shelf / gust front is really visible.
The corn gave a really cool twisted effect.
This was my last photo before the wall cloud became buried in rain and the parent storm died. Not bad for only having to drive 10 minutes from home.
After re-positing south I snapped this quick photo of the gust front over Brampton before heading south into Toronto and calling it a day.
Here is a sequence from the King City radar showing the path of the velocity couplet from just south of Orangeville to Bolton.
Here are a couple GIF loops showing the storm and the associated velocity couplet. You’ll also find a time-lapse video at the bottom showing the supercell mesocyclone and associated wall cloud in motion with clear rotation.
April 30th 2015
On June 1, 2015
- 2015 Storm Chases
This was the real start of my chase-cation. There was a very marginal potential for severe storms and tornadoes were a virtual impossibility based on probabilities. It was a usual weird as could be high plains setup where by some miracle of the storm relative wind fields and near non existent moisture, the high plains would somehow produce storms which would grow in strength by evening and eventually everything would be pushed out by a cold front sinking south from Wyoming. Weird things happen above 1500 meters in elevation!
After spending the night in Denver we headed north towards Fort Lupton. Both parts of Wyoming and northeast Colorado looked great for storms. Near for Lupton I had to stop and take a photo of this mountain with a nice grass-hopper jack in the foreground.
After hanging out near Fort Lupton for a while I headed east to follow and watch one storm cell that was just fluff near Dearfield. The thing with these storms that roll off the mountains is that you never know exactly which one will become "the storm". Eitherway, it was still early and the mix of high based and low topped convection was not good!
By this point I decided to head north on I-25. These storms just west of Ft. Collins looked like they were trying to organize but still low topped and high based.
The radar was showing something interesting starting to come together in Wyoming with the storm tracking SSE at around 20 knots while the stuff in Colorado still looked mushy. The thing with chasing on the edge of the front range is that often the storms go up super dry and the radar can be very deceiving. Your eyes are the best tool since you'll often still be able to see more than whatever the radar can see.
On the way to Cheyenne there's a super flat wide open part of I-25 that's always windy where the elevation jumps to 1900 meters! On the way to this particular storm I was being buffeted like crazy, it was hard to stay in my lane!
Once in Cheyenne, the storm began to quickly look more and more organized as it moved into a deeper more moisture rich boundary layer.
The inflow base had that nice chiseled look where each little stub of cloud was condensing right at the lifting condensation level.
I quickly blasted south and east to get around Cheyenne and put myself back ahead of the storm. At this elevation to see a storm registering with reflecitivities so high means that hail is guaranteed. I think the largest stones at this time were around 1 inch.
After popping out from under the storm I was shocked to see it had transformed into a beautiful classic supercell. The storm was super low precipitation, I think dew points were like 40F and cape was only on the order of 1000 j/kg but there was enough directional shear relative to the storm motion to produce this supercell.
Considering conditions were marginal at best I don't think this is all that bad!
I stayed with the storm which was super easy given the 80 MPH speed limits. Unfortunately another storm had developed about 100 miles south in Colorado and outflow from that storm was quickly headed north.
The outflow from the stuff in Colorado killed my nice Wyoming supercell and I headed towards the Colorado storms.
The storm complex which look good on radar became a real mess by the time I got where I needed to be. The high terrain this far west is a blessing and a curse. It helps storms form without needing any of the usual 850mb parameters but at the same time dries out the atmosphere and limits moisture. In this case, as the storm complex moved east the atmosphere became deeper as the elevation dropped but the moisture did not increase with depth and the storm fell apart.
As the storms grew and died in a strange twist they generated their own local moisture fields and began to re-saturate the atmosphere.
Eventually another more organized storm complex formed and started to take root. Strangely enough the inflow was situated on the north side, but given the odd wind fields its no surprise.
This storm which began to exhibit some weak rotation was actually a -counter-clockwise rotating storm but had clockwise reversal of the features. Weird, I know!
Eventually everything became outflow dominated and the storm fell apart.
Near Logan Colorado the fields and road were coated with a covering of hail stones ranging from pea sized to nickle.
Lot's of hail.
The hail drifts at the side of the road were half a foot deep in places after rain had washed the hail aside.
This years chase vehicle! The top antenna is a cellular amp, K40 on the left is for the CB, middle antenna is a Diamond CR-8900 quad band (10, 6. 2 & 70) while the right antenna is a 5/8th 2m whip.
May 3rd 2015
On May 24, 2015
- 2015 Storm Chases
Today was the first real chase day that showed some potential for severe storms. A thermal trof was swinging in from the west and coupling itself with a cold front descending from North Dakota into Eastern Nebraska. The best lapse rates were right on the nose of warm air where there was a southeasterly wind field. The biggest problem at the time was a lack of good 500mb support but otherwise bulk shear numbers were set to rise as the day progressed.
HPC surface analysis 21Z May 3rd 2015
We started by making our way west. After pulling off the interstate near Wood River NE, the road looped around this freshly plowed field and I saw that it was kicking up dust devils. We were just entering the area where the lapse rates were starting to really get steep just along the thermal trof. In fact the winds were actually pretty gusty right in this area and there was some good veering in the low levels.
It was almost like this area where dust devils were being kicked off one after another was sending me a signal.
Needless to say, I love dust devils and had to stop to grab some photos. It's so cool to see them one after another.
I tried to get a shot showing a little more depth and height to the dust devil but it was not easy with the poor contrast between the sky and soil making the vortex visible.
We stopped for gas in Duncan, NE along route 30. I saw that this area had some good cu growth on the visible satellite and it was sitting a long a triple point boundary.
Within about 40 minutes of stopping one of the towers had gone from just that and turned into a CB.
I headed a few miles west out of town and stopped in an area of good clearing to watch the storm develop and grow. It was still very early in the day but it sure looked like a good storm.
I stayed with this particular cell and it grew and morphed with other clouds in the area. It began to exhibit some problems though, namely that the lack of 500mb support was allowing rain to fall through the developing updraft.
There another storm on radar about 50 miles to our south near Lincoln Nebraska that went up quickly and began to exhibit a strong signature on radar.
It look like it was a good storm because it was sitting in a strong area of southerly inflow and secondly it developed along and rode an old outflow boundary from an earlier MCS that rolled through around 10AM CDT.
Jen made the cell to go south to this storm and we did. Jen took this photo as we blasted along the interstate and were just about 30 miles from the storm.
There were some spotters on a local skywarn net giving reports. The storm at this point in time had a pretty nasty core on radar but not much else in the way of structure, lowerings or rotation. The reports that we were hearing indicated golf ball sized hail was falling and getting pretty deep in some places.
On the way to the storm we briefly passed through and stopped in the town of Hickman. The area had suffered some pretty substantial damage from hail shredding the trees and there were golf ball sized stones all over the place.
A little farther down the road east of Hickman we started to run into some of the hail drifts that were being reported on the skywarn net. The temperature also dropped from 90F to a cool 50F thanks to all the ice on the ground.
Here's a bit more of a zoomed in shot showing the amount of hail covering the road.
I snapped this shot of my chase vehicle. You can see way off in the distance the first cell we were chasing.
This was the storms flanking line. Despite looking rather unimpressive the dry air and the steep lapse rates were more than enough to produce all the hail.
It's not too often you see a rainbow that results from hail stones falling but that's exactly what this was. You'll also notice white dots in the field to the right of the frame, those are golf ball sized hail stones.
You can see how the storm had a supercell look on radar despite not having that type of a look from the ground. The purple is where those big hailstones were lurking.
Again, these big golf ball sized hail stones were just laying there.
I decided I was going to take a few close passes along the storms core. The storm was moving slowly, gently drifting towards the southeast and the road network was favourable. If things began to get a little hairy I could also go in the opposite direction and avoid any potential vehicle damage. It was apparent that the hail was really doing some tree shredding.
This was the first close pass I did. You can really see how green it was once you got up under it.
Towards the center left you can see into the storms green core. This area was becoming a vaulted region which meant it was mainly rain free but really big hail was potentially present.
I tried to make a couple passes under the storm and get to the south side but there were hail stones ranging from dollar to golf ball in size getting spit out regularly. In this video grab you can see a few bouncing on the road towards my car.
Eventually I had to sort of go around the storm. I eventually wound up in an area of both inbound and outbound winds. It was really unusual since the wind would randomly blow in different directions. As I started to make my way back towards the storm this little eddy / gustnado spun up and crossed the road.
To my surprise it was loaded with all sort of debris ranging from mud and small stones to twigs and wood chips. It was actually pretty violent and turned the car a wonderful shade of brown!
After our encounter with the gustnado / outflow eddy we stopped to get a better view of whatever the lowering was we had seen before. By the time I got out of the car it was gone but there was clearly a wall cloud trying to form, although a high based one.
You can see our location at time relative to the storm and what might be the edge of the forward flank outflow.
Here's a zoomed in shot of the wall cloud. The storm was now moving into much better bulk shear and you can see how this structure is looking much smoother.
Unfortunately the storm was still pretty high based and older convection to the west was now finally starting to organize!
The new supercell to the west had a bell like look near the setting sun. That's always a good sign since it means a pretty storm is brewing!
I got Jen to show me the iPad with the storm in the background. I figured it was cool to see everything in one shot!
We are the red dot near Sterling.
I eventually gave up on the storm I had been with most of the day since it remained elevated and had no solid lowering. We headed west and this was the second approaching supercell which had some beautiful structure!
This was a reported funnel cloud which prompted a tornado warning. The hill creates the optical illusion that it's on the ground but spotters on the other side confirmed it was just a funnel cloud.
Even without a tornado I love to just see beautiful storm structure!
We were right in the edge of the tornado warning and fortunately the storm was low enough in precipitation that we had a good clean view of all the structure.
This was a tough shot! There was still too much daylight for longer exposure lightning shots so I had to use a 1 second rapid-fire setting to catch this.
I dropped a little south of the storm to avoid getting bonked by the three inch sized hailstones this storm was spitting out!
As dusk turned into night I moved west and setup for lightning shots.
This storm kept going for a very long time but failed to ever produce a confirmed tornado despite the persistent and visible wall cloud to the center-right of the screen.
May 23rd 2011
On April 11, 2014
- 2011 Storm Chases
Where to begin?
We’ll Joplin had been virtually wiped off the map barely 18 hours prior, I was feeling the effects of sleep exhaustion between driving, forecasting, late nights and relatively early mornings.
Today by all accounts was going to be a good chase day with dryline driven storms and a warm front pushing north.
The shear environment was good, not perfect, but very good. The energy values were again off the chart!
With Joplin so fresh on my mind and most chasers retreating west for today’s Oklahoma storms I think another Joplin scenario was hanging over everyone’s heads as a possibility.
There were real concerns that today could be the day Oklahoma City was the target!
The SPC was initially downplaying the risk of severe weather across much of Oklahoma.
That changed with the 1300Z outlook and again was rehashed to be even more ominous with the 1600Z outlook.
We started off by blasting into Southwestern Oklahoma with a whole heap load of other chasers around midday.
A round of early storms fired directly on the dryline and even produced a mid-level funnel.
But it was not meant to be, the storms were rapidly undercut as the dryline began to march east.
I figured since the best energy and moisture were still several hours away that playing this particular portion of the dryline near a developing bulge was the best bet and soon a second super low precipitation storm began to form.
Even in infancy it already exhibited a curved updraft structure.
Interesting to note is that the dryline is not like other boundaries that have a fixed progression. A cold front will keep going until it simply boils away, a warm front will keep pushing north until it eventually get's undercut by a cold front and occlusion occurs.
Drylines are not like any traditional synoptic boundaries. They form from the pooling of dry desert air which is almost entirely a product of westerly winds rising over the higher terrain of the Rockies and then downsloping to the east. This up and down dries out the air while it becomes super heated.
Often the dryline will be several degrees warmer than the moist air to the east of the dryline, so the temperature will often rise with the passage of the dryline.
The dryline is also both progressive and retrogressive, it will linger in the morning, surge east in the afternoon during maximum daytime heating, stall out in the evening and then retreat westward overnight. In fact it's not uncommon to have to the dryline pass a single spot up to four times in less than 24 hours as it surges, bulges and retreats with the cycle of the sun and the natural synoptic flow of the environment.
This was the afternoon surface analysis. A well defined moisture axis developed over eastern Texas stretching north into central Oklahoma.
The dryline was still pushing in from western Oklahoma and a cold front was behind the dryline. Interesting to note is the 102F / 39C temperature in Childress, Texas (KCDS) behind the dryline vs the 88F / 31C in Vernon, Texas (KF05) ahead of the dryline.
We punched the dryline a couple times prior and the temperature on the dash spiked to 40C, it was so hot we rolled up the windows and turned on the AC! It actually felt cooler on the moist humid side of the dryline where it was 34C! We thought rolling down the windows to save gas was a good idea and that the dryline would be refreshing. Apparently, we were wrong!
Now I'm not sure why, but there was a clear warm front pushing north that was not plotted on the surface map, either way this was a critical factor in how storms would develop as the day went on.
The low precipitation storm still bubbling away on the dryline looked to be struggling at this point.
All the other chasers in the area had taken off north after storms started to develop on the warm front.
I figured this was still our best best for an isolated storm since everything to the north was going to be messy and clustered.
Suddenly the wind began to really pickup and inflow to the storm grew quickly.
In a few minutes there were several massive pushes of cloud growth upwards. The storm on radar, still barely breaking 15dBz with no appreciable precipitation started to register tops of over 40,000ft.
It was at this point I knew this particular cell which had been bubbling away all day was going to get its act together.
We all quickly piled into the car and bailed south to get into a better position.
Racing south, I stopped for a moment to jump out and take this photo! We were right under the edge of the storm, it was billowing up to 55,000ft and a massive barber pole updraft had formed.
I was pretty convinced this storm was going to be the storm of the day!
The SPC took the developing severe risk associated with the dryline supercells very seriously and issued the first MCD of the day for Oklahoma.
MESOSCALE DISCUSSION 0910
NWS STORM PREDICTION CENTER NORMAN OK
0651 PM CDT MON MAY 23 2011
AREAS AFFECTED...W-CNTRL AND CNTRL OK INTO NWRN TX.
CONCERNING...TORNADO WATCH 345...
VALID 232351Z - 240115Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 345 CONTINUES.
THE THREAT FOR LARGE HAIL...ISOLATED TORNADOES AND LOCALLY DAMAGING
WIND SHOULD PERSIST THROUGH ABOUT MID EVENING FROM W-CNTRL THROUGH
CNTRL OK INTO NWRN TX.
DISCRETE SUPERCELLS THAT INITIATED EARLIER ALONG DRYLINE CONTINUE
SLOWLY EWD THROUGH W-CNTRL OK INTO NWRN TX. THE ATMOSPHERE REMAINS
STRONGLY UNSTABLE WITH 3000-3500 J/KG MLCAPE. LOW LEVEL
HODOGRAPHS...WHILE NOT EXCEPTIONALLY LARGE WITH 0-1 KM STORM
RELATIVE HELICITY FROM 150-200 M2/S2...WILL FURTHER INCREASE IN SIZE
AS LLJ STRENGTHENS. THIS SUGGESTS A WINDOW REMAINS FOR ISOLATED
TORNADOES BEFORE THE BOUNDARY LAYER COOLS AND INCREASING CONVECTIVE
INHIBITION OVERWHELMS THE UPDRAFTS.
STORMS IN NWRN OK APPEAR TO BE CONSOLIDATING INTO A SMALL
CLUSTER...AND THIS ACTIVITY MIGHT EVENTUALLY EVOLVE INTO A FORWARD
PROPAGATING BOW ECHO AND CONTINUE SEWD ALONG PRE-EXISTING OUTFLOW
BOUNDARY.
The radar couplet as it appeared when I took the barber pole photo. Words cannot describe the intensity of the situation at the time.
This meso here is a solid 60 knot inbound and outbound signature for a gate to gate shear reading of around 120 knots. It was cooking!
I think every meteorology student, every forecaster and TV weather specialist should experience both radar and real world simultaneously at least once in their life.
Experiencing a storm gives physical meaning to the observed radar data, it completes the picture that many struggle to understand and observe.
This really is a classic supercell. Any textbook which has a section on supercells, will often display a picture exactly like this one.
By this point, It was now neither an entirely LP storm nor was it an HP system. It was producing returns on radar of near 70 dBz and observed hail reports of 3+ inches.
Yet, all the updraft structure was perfectly revealed.
When storm chasers talk about how important the dryline is, this storm is a perfect example.
Here we have an isolated storm, in the southeastern quadrant of a mid-latitude low pressure system, where anywhere else on earth there would be no trigger, but here a dryline exists to create a trigger where nature otherwise does not allow storms to form because the shear is always too perfect.
This is natures perfect mistake!
The radar signature was that of a beautiful classic supercell.
Everything about this storm was textbook in nature.
