Forecast for May 30

Memorial Day. It's last year on this day that we caught a beauty.

This year looks like an okay setup for supercells, although tornadoes may be a little more elusive than last year.

Here's the rundown.

Moisture: copious. Not a concern, with surface dews around 20C likely to pool and moisture plentiful and deep.


Instability: plentiful. MLCAPEs are likely to be above 2000 J/kg all over the place.



Lift: should be good, with a surface low and fronts galore.

Shear: I have left this one to last, as it's the most telling. The shear is mostly linear, leading to a) linear (i.e. non-discrete) storms, and b) fast-moving storms. This could be a problem.

All that being said, if I could chase, I would begin by targeting Fargo, ND (assuming the NAM is right and actually, the GEM-REG is quite a bit farther north with this system) and going from there.

Day 7: bonus day

We hadn't really counted on chasing today, but it looks really good just to our east. We're currently north of Kansas City, which has a tornado warning out. Doppler looks good.

Anyhow, we're going to target the area of north-central Missouri (I know, not great territory) to western Illinois. Things are lining up there, and it's just a matter of whether or not we'll get lucky.

Day 6 recap

In a word, ugh.

We set out of OKC in the morning and targeted El Reno and points west.

We had lunch in El Reno and watched the dryline bubble up and start deep moist convection. Because of the shear involved, we figured any storm that went up big would be a long-lasting, prolific tornado producer.

Wow, were we wrong.

Just as we lost data coverage (thank you very much, western Oklahoma), the storm fell apart. Problem is, we couldn't see that because of the haze. So we were following along based on tornado warnings relayed by local radio stations.

When we finally got data coverage back, it was obvious we were behind a barely-broken line of potentially tornadic supercells and in no position to catch them.

What hurt, though, was not only that there were damaging (deadly, actually) tornadoes, but also the fact that just about every other chaser, it seems, caught at least one photogenic tornado. Including the storm of the day, which hit El Reno, where we had had lunch.

Ouch.

Day 6 forecast: outbreak?

If there's no other day you can watch, watch tomorrow.

I forecast that Tuesday, May 24, 2011 will be a big day for severe weather and likely tornadoes in Kansas and Oklahoma.

This time I will go with the full run-up.

Moisture - surface dewpoints in the low 70s F (20C+), and 850 dewpoints 15C and higher.


Instability - SBCAPEs and MLCAPEs over 3000 J/kg.


Shear - 0-6 km shear should be 50 knots or higher.



Trigger - Dryline. Weak cap. Need I say more?

We will be targeting Wichita first, then likely refine to points west for initiation, then move east with the storms. As the afternoon and evening wear on, the low-level jet will really get going, making for tremendous low-level shear.

Cons that I can think of include a slight lack of wind at 250 mb, which might not allow for updraft evacuation as efficient as I would like; this would lead to more HP supercells rather than classic.

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I must be missing something, but I can't think of it right now. Here are a couple of forecast soundings for the area.


We will have to be careful tomorrow, as storms will be more dangerous than just about anything I've ever been on. Follow along if you can.

Day 5 recap

We got to western Oklahoma, we were there for initiation, we got onto the right storm.

And still it barely produced. We got a short-lived funnel cloud that may have touched the ground, but if it did it lasted only a few minutes.

I can live with today. We didn't fail at all; the storms didn't produce, is all.

Tomorrow looks wicked...

Day 5: try try again

We're sitting in Perry, Oklahoma, north of OKC. It looks like things are going to fire along a composite warm front/outflow boundary just to our north, but we're also in place if things go on the dryline sitting to our west.

Moisture, instability, shear, trigger: they're all there. Now we play the waiting game. Will we catch our big storm today? Time will tell.

Day 4 recap

So many emotions today. We started off going toward Tulsa, expecting storms to initiate along the dryline and move east.

The dryline did its thing to our north, and once again we were playing catch-up. Mad and frustrated. We expected storms to go all the way down the line, but that wasn't the way it was to go. So we forayed into southeast Kansas, and could never catch up with the storm. Exasperated and vexed. We were close for a long time but it kept accelerating.

We got to the outskirts of Joplin, MO, about 2 miles behind the tornado. We couldn't see it but a) it looked scary on Doppler, and b) we would have to go through a bunch of large hail to catch it. So we bailed south. Terrified at times.




After much south driving, we got to a storm that was gathering strength but we couldn't get to it because of the terrain and lack of roads. Sad and mad.

Then there was another storm we could sort of get to, and we watched it produce a tornado after sunset--we barely saw it. Longing.

We stopped for some lightning pictures along the way. Happiness.

On the way back to the hotel, now, we're hearing reports of major damage and deaths in Joplin. Horrified.

What an exhausting day.

Day 4 forecast

There's a huge area of instability now. MLCAPEs are looking to be in the 3000 to 4000 j/kg range from Oklahoma to Illinois. Flow in the whole area is pretty good, but the best will be in Oklahoma.

That, and the fact that chase terrain is better there, in addition to wanting to be in position for tomorrow, made us decide to try Tulsa. We're currently on the road (no, of course I'm not driving!) and look to be there for just after 1 PM.

We expect a dryline will once again trigger storms and they'll experience lots of shear, moving off toward the northeast. We'll of course have to stay out of the way, though, because the hail is likely to be huge. Baseballs or larger.

Wish us luck!

Day 3 summary

We lunched in Wichita (Chipotle!) then sat for a while in Emporia, where a line of cumuli was persistently sending up pulses. A storm went and it looked kind of lame visually, and so we let it be. Another one went, looked lame again and we let it be. Then, one of the storms we had seen started to look good (according to RADAR) and we were torn: it was going into a relatively dry area, so the tornado potential was reduced. But it was the only game in town.

We got to Topeka after the storm decided to get a monster hook and hit Tulsa hard, with 5 inch hail. The wall cloud was rotating quite nicely, but it was pretty high-based--I would say 6000 feet or thereabouts.

We followed it along until nightfall, but it never really came close again.

While that was going on, my CoD friends sat just southwest of Emporia. Their patience paid off, as initiation along that part of the line finally occurred, starting up the storm of the day. That storm ended up producing a tornado that badly damaged the town of Reading, where one person was unfortunately killed and 5 were injured.

The storm then went on to produce nighttime tornadoes. It looked impressive on RADAR; we could have caught up to it, but doing so at night would be the epitome of hubris, not to mention just pointless and stupid.

Anyhow, patience paid off for my friends, but I don't know that I would have done anything differently. I'll try not to dwell on it too much. There's so much more chasing to do.

Day 3

Today we're taking off north out of Norman. The moisture sees to be in place everywhere east of I-35 and south of South Dakota. So figuring out where to go will be more of a determination of wind shear, as well as logistics.

Therein lies the problem.

The better deep shear will be south, with a 50 knot jet streak emerging out of Texas. Still, though, 40 knots farther north isn't too shabby.

The better low-level shear looks to be in Kansas, with a diffuse surface low right now near Dodge City. This will likely move eastward, backing the winds in its path.

So we have decided to head to Wichita for lunch, then reassess. If I were a betting man, I would put my money on southeast KS, from Emporia to Coffeyville.

The next couple of days are interesting, with a potential cap bust in northeast Oklahoma tomorrow, then two days of triple point play in Kansas and Nebraska. After that, it appears the Gulf will shut down for a couple of days, so we will likely be heading home at that point.

Day 2 recap: ugh

The less said about yesterday, the better.

I'll just say that it was plain that storms would be plentiful and some would rotate. Thing is, an overnight MCS made us go to Texas, where, between construction and stop lights (seems kind of like the perimeter highway around Winnipeg) we could never catch up with storms.

Anyhow, we are in Norman, OK and anxiously await what today brings, somewhere between here and Wichita and points east, I think. Now onto the analysis...

Day 2: reassessment and change of plans

We are now looking to the Oklahoma/Texas border. Better moisture, better upper winds, and less likely to be cloudy all day. We'll see if that pays off.

Heck, at this point we'll see if this decision lasts into the afternoon at all.

Day 2 forecast

Well, after looking at this morning's data (no Norman, OK sounding, thank you very much), it's still as clear as mud.

A surface low is still sitting over the panhandles and southwest Kansas, so a setup similar to yesterday's looks to be in the offing. That means a dryline southward and a triple point somewhere west of our current location of Wichita.

After a leisurely breakfast and discussion amongst us, we decided to sit tight here in Wichita and wait for storms to go to our west. Morning satellite imagery shows clearing starting to occur after the late night/early morning MCS, and west of Wichita should get full sun for at least a couple of hours today.



Wxdog pointed out to me that yesterday's setup wasn't completely ideal, as the storm motion was doomed to take storms away from the instability quickly, and any storm therefore had a low chance of producing a tornado. The reason I mention this is because today's setup is pretty similar. But we'll take what we can get.

The shear vectors in Texas are a little more orthogonal to the dryline (a very little more orthogonal) so those storms may have a bigger chance of being better. Tomorrow's play looks to be around Kansas City, though, and we want to be in place for that one, so rather than go for a long drive for something that was going to happen here anyhow, we'll sit and take that gamble.

As a result of all that, we are unlikely to be on spotternetwork.org until quite a bit later today. If you're looking for us, we're likely to be west of Wichita. The town that was named casually was Pratt, KS.

Day 1 recap: long drive, hazy HP beast, awesome BBQ

We started out the morning ridiculously early, having had a whole 3 hours' sleep. Fargo was the starting point. We drove and drove and drove, and by the time the tornado watch went out for our target area, we were about 2 hours' drive away from it.

We got into Kansas, got as far south as Salina and turned west on I-70 toward Ellsworth. There was the intersection of the dryline and the warm front--the much-ballyhooed triple point. Vigourous convection was just starting to go there, and we were just in time.

If only we could see it.

Coming from the north and east as we were, we were on the cold side of the warm front. That meant haze and a steadily-lowering cloud deck. Visibility wasn't great, but seeing storms in the distance just wasn't happening.

We got to just northwest of Ellsworth when the storm we were targeting got tornado warned. Haha, business at last.

The storm, at least what we could see of it, was showing some not bad rotation (both visually and on RADAR, and let me just say that this area of Kansas has horrible RADAR coverage, such that the lowest beam from the closest unit is about 10,000 feet in the air). But then it started to morph into this beast that had its rotation in the middle of the precipitation--a high-precipitation (HP) supercell. These storms are known for a) copious amounts of rain, b) low contrast and c) very seldom putting out visible tornadoes.

We went along the road with it for about an hour, but it was painfully obvious that the storm was going to stay an HP beast. Furthermore, we were no longer convinced that it was riding the warm front, and therefore ingesting elevated air parcels, so its chances of putting out a tornado were next to zilch. We bailed on that storm and checked out our options.

When we saw we had no realistic storm intercept options, we decided that Salina was nearby, it was dinner time, and one of our favourite BBQ places was there.

We had a wholly satisfying and leisurely dinner (hint: everything there is good!), went back out to the truck, only to open up the RADAR and find that a storm just to our northwest, as in maybe 15 miles, was showing signs of being interesting. Food in our bellies and energy renewed, we set off for that storm.

Well, this not being our day, it decided to become what the previous storm was: an elevated HP bomb. So we finally bailed and are now sitting in Wichita, Kansas, about to hit the hay, but also hoping for some overnight thunder and lightning to round out the night.

Tomorrow (well, now today) looks very tricky: the dryline will once again set up from here down to Texas, and pretty much everything (shear, moisture, CAPE, instability) looks the same right on down the line. The best we can do, then, is wait for any overnight convection and see where the boundaries sit, and play on them.

Ah, chasing: an exhilarating and frustrating endeavour.

Day 1 - wow

So the 12Z information is coming in. I'm having a moment here.

250 mb - a good jet streak is evident at Albuquerque, NM. 90 knots is what it appears to be. That will provide plenty of ventilation for storms that go.


500 mb - 80 knots coming in there. And the approaching temperature is -14, as compared to -10 at Dodge City.


700 mb - 35 knots, but on this one the big story is the crazy cooling coming in--from +8 to -1.


850 mb - soundings all over the place show deep, substantial moisture.


Surface - there's a low in southwest Kansas with a warm front northeast from it and a dryline to the south. Where the two meet is called the triple point, and that's an area of tremendous convergence and shear. That's where we're going.

SPC has a slight risk of severe thunderstorms for the area, with a hatched area (10% chance of EF2-EF5) centred on the triple point. I suspect that, later today, they will upgrade to a moderate risk. In addition to tornadoes, possibly strong, today, the tremendous cooling and thus destabilization coming in tell me that there's a good chance of very large hail. Stay away from it.

Follow us along on Spotter network. We're called Winnipeg chasers.

I'm quietly optimistic about today.

And we are rolling...tor potential is high today.

Well we left Fargo at 6am and are currently near the South Dakota border...

We aim to be at our target somewhere near Russell, Kansas by 5pm local. Latest guidance suggests the triple point will reside in this area with pooling moisture occurring in this zone. Dewpoints are already in the low teens in Srn Kansas as I type so moisture will not be a concern like last week. My favorite part is the orientation of the LLJ from the SSE later on this afternoon. As you climb from H7 to H5...the winds veer nicely. Shear is there...moisture...well you know...instability...ya...and forcing near the triple point should allow for storms to go boom.

We are very excited...a little tired after only 3 1/2 hours of sleep...but hey...that's what it's all about...the only thing we need now is for initiation to hold off until we get there...let the atmosphere cook for a little bit.

T minus a few hours

Hobson lands in a few hours and then we'll be off to Fargo.

Today has been taken up with last-minute preparations. Thank goodness I made a list--otherwise I would most certainly forget something.

I got the rental vehicle at noon and spent about an hour trying to attach the laptop stand to it. I finally got it attached in a sturdy fashion. Clothes, cameras, electronics, check, check, check.

The SPC outlook and model solutions are favourable for us, although the actual target is still somewhat in question. It could be as far southwest as Dodge City, but it'll more likely be farther northeast near Salina. How much cloud sticks around for the bulk of the day will determine whether we get good storms or great ones--more heat leads to more instability, after all.

I'm like a little kid on Christmas Eve. So excited.

Closer and closer...

I'm not going to rehash things I've said over the last couple of days. All I will say is that the forecasts and reasoning have changed very little. Mesoscale details will only be able to be resolved on the day of the chase, so that's where the rest of the fun begins.

Now I have to do some last-minute preparations for the chase.

Here is another to follow us along (aside from this one):

Spotter Network--we'll likely be called Winnipeg Chasers

Narrowing down our target area

So now as the time of our chase draws nearer, more forecast models have our timeframe in its integration period. This provides more solutions but also more confidence in a general target area.

Today we look at the 16/00Z GFS which seems to have settled on a scenario. Whether that scenario is right, well, time will tell.

Day 1 (May 19):

Somewhere near Salina, KS looks like the place to be. Moisture will be returning, there'll be a dryline for initiation, and 500 mb winds look good--great, in fact, if you consider that the area looks to be under the left exit region of the jet (enhancing large-scale lift).






Day 2:
This is a day where we'll have to make a crucial decision: north or south. It looks a lot to me like June 17, 2010, where there were two distinct tornado areas. The delineation was the core of the jet, which I neglected to watch throughout the day, much to my chagrin.

But all that aside, I think I like the southern target because everything else looks equal except for the moisture and therefore the instability. Something south of Oklahoma City.






Day 3:
This looks like a clear Oklahoma chase. (Great. Chaser convergence.) Tulsa or thereabouts.






Day 4:
We're getting way out there in time, now, so the confidence is lower. That being said, it looks like a reload day for the atmosphere, with short-wave ridging over the southern and central plains. Instability looks crazy, though, and if a mesoscale accident can happen, who knows? I'd target southern Kansas, somewhere southeast of Wichita.






Days 5 and 6:
I'll exclude the imagery here, but they look like central plains cyclone plays, either along the warm front or the dryline. Right now the low looks to be west of Omaha on day 5 and in southern Minnesota on day 6. After that, the GFS takes a wiper blade of a cold front across North America, effectively ending our chase.

Again, this is all if the GFS verifies, which is in doubt, seeing as how last week it was showing bad conditions for us now.

Whatever happens, I'm sure we'll catch some awesome storms and meet some great people!

Model differences

The models seem to be settling on a scenario out to 6 days now, one that's favourable for our chase. However, at this time, I must state that the huge wildcard in the mix is moisture--that is, whether or not it'll be there in the abundance we seek.

After 7 days, though, they start to diverge and in a pretty fundamental way, one that would make for vastly different outcomes of the latter part of our chase.

The difference is outlined best by these two 500 mb forecast charts, valid next Saturday evening. The first one is from the GFS and the second is from the ECMWF.




At first glance, they appear pretty similar, both having upper circulations near the coast of California and another near New York City. But in between, the difference is huge.

The GFS has a positively-tilted lead trough over north Texas and the upper midwest, followed by a sharp short-wave ridge over Arizona. On the other hand, the ECMWF has a negatively-tilted trough over the northern plains followed by weak short-wave ridging in advance of the next impulse to be ejected. The difference is that the GFS solution would mean a longer time between storms and likely less low-level moisture availability, whereas the ECMWF solution would mean more low-level moisture and a near-constant barrage of storms, perhaps with a one-day break.

Forecasters far and wide perceive that the ECMWF is the superior model to all others in the mid-range. I have no lazy way of knowing if this is accurate; however, I do know that the wishcaster in me hopes that this is the case.

4 More Days...

Well the 5/15 00Z GFS is coming in and it looks like it's going to be a busy start to our chase trip...

An omega blocking pattern is setting up over N. America and it will hold for a few days or longer with impulses ejecting out of the base of the western trough daily. Wednesday looks to be the first of a busy chase period in SW Kansas, OK panhandle which we will have to miss since I land at 9pm in Winnipeg that night. I'm not worried because moisture will still be returning into that area meaning the tornadic potential for the storms won't be that great(LP Sups with large hail). As moisture continues to advect into the region, this should result in a bigger day on Thursday for north central Kansas vc triple point (classic sups with tornadic potential). We will have to drive a long way as quick as possible to get into position for Thursday if the latest runs verify. I figure we leave Winnipeg as soon as I land and head to Fargo for 1am. Get up at 6:30am, leave by 7:30am in order to be in position by 6:30pm which should be okay. I'd prefer 4pm but hey we are coming from Winnipeg. Friday looks bigger with a dry-line play over central Kansas/Oklahoma as moisture quality continues to improve. Last day I'll talk about is Saturday which again looks like a good dryline play over central Oklahoma.

Let's hope this run verifies...regardless...it looks like an active beginning is shaping up for our Tornado Hunt that runs from May 19-28th, 2011.

Only thing I fear is massive chaser convergence as we play in KS/OK...I'm still hoping for a warm front play over North Dakota near the end of our trip which should keep convergence to a minimum. I'm actually beginning to like Canada for chasing...even though we have fewer storms. It's cool knowing you might be the only one chasing it.

Is it really only a few days now?

It seems like we've been waiting for this time to come around for years. The drab day yesterday here in Winnipeg made storm chasing seem that much further away.

But it's almost here. A few more days, and I couldn't be happier.

So what do the imperfect models have in store? I will turn to the GFS for its "wisdom".

Day 1 (May 19):
This looks like a dryline/warm front intersection chase day. Western Kansas looks to be the place to be, although the moisture quality will be in question, seeing as how they're in the midst of a drought and the dewpoints haven't been as juicy as they normally are this time of year. There is a problem, though: we will most likely be starting off the morning in Fargo, so getting far enough south will be a challenge. Not to say that we won't try, though.





Day 2:
Another warm front and/or dryline chase, but I suspect this one will be more in the way of moisture-dependent.





Day 3:
This looks like the day, if it comes true, that we'll abandon the warm front. Reason being, a) it'll be getting farther and farther away from the good moisture, and b) the upper winds south of it are forecast to be much better. Still, though, this looks like a pretty good chase day, although the territory where the good stuff could happen isn't ideal (the Ozarks and the Ouachitas in eastern Oklahoma.)





Day 4:
Central Oklahoma. That looks better, although with this setup we'll have to deal with about 400 million other chasers. Le sigh.





Day 5:
This is as far as I'm going to go, as the models tend to go into la-la land at this point, and very often much much earlier. But nonetheless, it's a fun exercise. Oklahoma again, maybe a bit farther west.





After this, the GFS goes into a bonanza for us chasers, although at this point I'm going to give it the credit it's due (that is to say, none). But if I were a wishcaster (and some have accused me of it, and rightly so), I would hope for the 14/00Z GFS to be right.