Tuesday, May 31, 2005

action in the deep south

this evening i watched storms blow up in south texas, near san angelo. a storm popped up and then split, producing both left- and right-movers. the right-mover produced a nice hook, and the left-mover split and the right-mover from that pair also produced a hook. there were sporadic tornado reports from these storms, and lots of reports of baseball-sized hail, including one report from the eastern part of san angelo. i'm capturing these images and should have them posted before too long.

the first day of june 2005 could be an interesting one, severe thunderstorm-wise, across southern manitoba. a warm front appears poised to be parked near the international border, upper forcing should be in place, and moisture is streaming northward. the mitigating factor would appear to be the moisture, but if mixed dewpoints can get into the 15 or 16 degree range, i wouldn't be surprised to see a tube or two.

i'm going to leave on thursday afternoon for a personal chase trip. friday looks to have an excellent setup in southern nebraska, while saturday could be ripe over minnesota or iowa. if i see anything of interest and can find a good internet connection, i'll post about my chases here. and maybe ask my friends to capture some radar images if they can. ;)

Friday, May 27, 2005

gearing up

things are ramping up for the storm chase course.

we got together and decided who was going to be teaching which classes--mainly based on availability, as we're all qualified to teach every one of them.

today the college of dupage left for their second chase trip of the year. they're sticking around illinois, i think, although they'd be better off to use today for positioning--it looks like the central and southern plains might actually get fired up later.

which is good, because after my next set of shifts, i'm going to take off and join them down south, wherever they may be. like i mentioned in my last post, the models are still showing a major pattern shift (but i'll still say i'll believe it when i see it) to something a lot more conducive to severe thunderstorms where they should be this time of year.

i'm also slowly building up a page devoted specifically to the course, a resource for all the learning materials you'll need to excel in it. hopefully i'll have a version of it up and running before i take off to the states.

you know, looking over the first few posts, i realised i have made a glaring omission: why the heck am i doing this blog anyhow? well, here's the answer.

when we're out on the road chasing, i should have a laptop with me, and i'll be logging things--quotes, sights, storms we see or don't see, whatever. and every night, when we find internet connection, i plan to post these things, as well as maybe my own commentary and thoughts on what we've seen. it'll be a way for a) your friends and family to keep up to speed on what we're really up to and b) you to remember this trip--it promises to be a good one.

you'll all certainly meet a lot of interesting people (your classmates, as well as gas station attendants, maybe farmers, onlookers, and, i hope, the students and instructors from the college of dupage's 5th chase trip of the year).

Wednesday, May 25, 2005


this upper air pattern is not being very friendly to us, although there was a funnel cloud and possible tornado near nipawin, sk on victoria day.

i have some spare time at the beginning of june and i currently plan to head south to brush up on my storm chasing skills (in the interest of the course, of course) and maybe see a tube or two. the long-range computer models are hinting at a long wave pattern change at about that time, which would vastly increase the chances of seeing something like that, but because it's so far in the future, i'm not holding my breath.

in driving from edmonton to winnipeg this past weekend, it came clear to me that moisture conditions are pretty good across the majority of the prairies. crops are sprouting almost everywhere, although the greener area right now, contrary to how it usually is, is farther west. edmonton is quite green.

could this be a summer of storms closer to the rockies and a repeat of last year's chill over the eastern prairies?

Wednesday, May 11, 2005

practice makes perfect...

today was another severe thunderstorm day across the united states. this time it was a classic setup in kansas and nebraska.

i got into the office this morning and did my analysis, and right away a couple of things jumped out at me. first, there was a 65 knot jet streak over new mexico. next, there was a strong wind shift at 850 and 925 mb over northern kansas. add in solid dewpoints at 850 and 925. sprinkle in a sharp warm front at the surface and a dryline in western kansas, and the ingredients were set up for an afternoon of severe deep moist convection. (i'll talk another time about why and how all these things are so important, but for now, trust me--they are.)

at about 9 this morning i drew a box of maximum threat for the day--i decided that today was a day to chase virtually. i figured, okay dave, you have to decide where you would drive to for the afternoon initiation. where would it be?

i decided that a good place would be in northwestern kansas, just south of goodland.

in all fairness, chasing a day like this, in terms of where the threat of severe storms is going to be, is easy. it's figuring out which storm to stick to that's the difficult part.

well, in the afternoon, spc issued a pds (particularly dangerous situation) tornado watch--actually 2 of them, and the one farther west was centred pretty much on my "location".

storms ended up firing in the area, and numerous tornado and very large hail reports occurred.

what does all this mean?

well, first, that a good forecast starts from a good analysis. i'll say this over and over and over again. all the models in the world won't help you if you don't start with a good analysis and diagnosis, and only then can you make a judgement call as to whether the model guidance is good or whether it's out to lunch.

second, it's easy to forecast on synoptically evident days. this seems like an almost absurdly obvious statement, but it must be made. i've been forecasting weather of all sorts as my career for a few years now, and i've made quite a few severe weather forecasts--both for the job and for chasing. on days like this, you can almost sit back after your morning analysis, issue the bulletins, and know that pretty much everything is going according to plan. it's on the less obvious days that you have to mine the data for that one crucial piece of information that may lead you in the right (or wrong) direction.

third, it's easy to sit back and say "yeah, i'd go here". but to put in the real miles, to stare at a long road, to gaze upon (and glaze over at the sight of) field upon field of corn, wheat, flax, sunflowers, or canola, is an entirely different matter. trust me on this.

once the storms did fire up today, though, they were moving pretty quickly. this was something i had neglected to take into account this morning. fast-moving storms can really be tricky to chase. you have to be in the right place, you have to have good road options, you have to have good visibility, and you have to have eyes in the back of your head, to make sure another storm isn't bearing down on you. i must always remember to keep storm motion in mind. i much prefer the supercell that sits almost stationary or moves toward the east at about 5 km/h. they're easy to stay away from and nice to view--especially if you want to tripod your videocamera and leave it for a while.

sometime soon, i'll talk about severe thunderstorm forecasting. a primer, if you will, for those interested. especially for those enrolled or hoping to enrol in the course.

Tuesday, May 10, 2005

the things you see when you step back a little

while putting together the page for the animation of the storms crossing the warm front, i noticed something i hadn't seen in these images before: in addition to the warm front being easy to pick out on the radar animation, some of the storms kick out outflow boundaries, which are also easy to pick out, and they all meet west of grand forks at one point.

it makes sense, now that i think about it, because at first, it seemed like the front had surged southward rather suddenly, but then i noticed another boundary right where i would have expected the front in the first place. so the boundary that seems out of place (that sesame street song, "one of these things is not like the other one" comes to mind) is actually the outflow from the storms. it's really neat that you can pick out all these things on the radar--and important to storm chasing.

yes, it all comes back to storm chasing. as we've already seen and will see in the months (and hopefully years) to come, storms tend to form (or be enhanced) on boundaries. cold fronts, warm fronts, drylines, troughs, outflow boundaries, sea breezes, you name it. so if, like in this case, you can easily pick out the boundary, then your work is half done. pick that area as an area of enhanced thunderstorm potential--you'll be surprised how often it works.

Monday, May 09, 2005

'tis the season

for starters, it looks like i (dave) will be the sole poster to this blog, so unless any entry says otherwise, you can assume that it's me.

late this afternoon i managed to capture some good radar images of a splitting supercell in central texas. the shear profile favoured the right mover, and it didn't disappoint. the right mover of the pair continued, and the left mover dissipated. as the storms were at their peak, the spc got a report of 4 and a quarter inch diameter hail--that's just over 10 cm!! when we're out on our chase, i hope we don't run into that--softball-sized hail can ruin vehicles and stop a chase.
the largest hail i've ever seen was about this size, back in july of 2001. i was amazed that the hail didn't smash the windshield, but it didn't. blind luck, i suppose.

as for last night's convection just south of the border, it seems i was right. there wasn't enough low-level moisture to produce tornadoes, although there was one point in the evening where there might have been. it was this time that i also managed to capture on radar, last night. thunderstorms developed rapidly in the warm sector just north of fargo, and moved northward. just to the south of grand forks, the storms intersected a warm front or an outflow boundary--i'll leave it for you to decide what it was--and at that point, one of the storms had that look to it. the kidney bean, hook echo look. but it only had it for one or two scans of the radar.

now, i'm not saying that it had a tornado down at that time, but if it were possible at all during the storm's lifetime, it was possible then. at the very least, it was likely very visually impressive. to boot, there was no rotation evident from the doppler images i had available to me. but then again, if there was a tight circulation, you never know....

so look for those radar images, both of today's texas supercell split, and of yesterday's storm-warm front interaction, in the science area of weather central soon.

Sunday, May 08, 2005

interesting evening already

and just after i (dave) wrote my first post, the spc issued a tornado watch for areas up to the manitoba-north dakota border. too bad it's late on a weekend and mothers' day and i already have plans. otherwise i'd be out for a drive.

that, and the moisture is a bit lacking.

but then again, sometimes tornadoes happen in these setups. currently there's a severe thunderstorm warning for a cell near grand forks likely containing large hail....

bring on summer!

here we go...

this is the beginning of what we hope to be a good blog.

my name is dave, and i'm one of the instructors of the course. i'm 30 years old, and i work as a metoeorologist.

we'll be going out storm chasing sometime in july of 2005, and i'll be one of the drivers for it.
i have a couple of years' worth of storm chasing experience, as does one of the other instructors. but i'll leave it up to him to talk about himself.

this is the first course of its kind (that i know of) in canada, and it will be closely mirroring what our friends at the college of dupage have done. check out their site--it's something to which we aspire some day.