what is you favorite set up to chase

[Ken Johnson]

What's you favorite set up. The one you have found to produce the most tornadoes....

I like to be just north of the dry line buldge. In an area with a good combination of CAPE and Helicity... If there's a boundry in there, I like that too.

Some people like the warm front, triple point, while others say too many storms form in this area and everything goes HP rather fast.

Some, like myself, like the more isolated storms along the dryline...

What do you think???

 

[Marcus Opitz]

stationary fronts have been my forte. I live too far east to get in on the dryline action.

 

[Ken Johnson]

stationary fronts have been my forte. I live too far east to get in on the dryline action.

Stationary fronts are really good, especially if the low leve jet can get cranking up...

 

[SteveCarter]

My favorite scenario is within 150 - 200 miles SE of a Low pressure center. Jet whipping overhead is a BIG bonus. You HAVE to be between the warm front and the cold front of course. I've found MANY SC's that way, but......many times they converge into a squall line rather quickly.

 

[Jason Persoff]

Warm front chases are very challenging though I've noted that the tornadoes that do form on these fronts can occasionally be stunning. I'm not as fond of them though since I'm usually chasing in haze and unless convection fires later in the day I have more difficulty in spotting key features.

I love a dryline chase any day of the week. The visual sharpness of storms on a dryline is stunning and profound. Notwithstanding, the lightning show after dark is often spectacular with highly visual bolts.

My best chase days involve strong sfc backing against a dry punch with killer daytime heating, great CAPE, strong CAP, and orographic lift. Think: the caprock and the Palmer Divide (where I cut my chasing teeth). I love watching storms form and then entrain in untouched deep moisture. I love dewpoint depressions like this: 100/75 ( ! ).

But most importantly I love the process of chasing more than anything else. In my life I tend to be an "ends person" and chasing is the one outlet where I enjoy the process more.

 

[Shane Adams]

I like to be just ENE of a mesolow. Those seem to always produce, despite fluctuations in other features/parameters. Dryline buldges are cool too, but they are a bit more fickle in my experiences.

 

[Jeff Wear]

Triple points, northeast of a surface low, along a warm front or outflow boundary. If I have the choice between any of those and the dryline, I'll take the former.....I've seen way too many storms struggle to sustain themselves after they move off the dryline.

 

[Brandon Clement]

Give me the dryline in West Tx! The two biggest busts this year were on the triple point set ups on May 11th and on June 2nd. The two best chases I had this year were on May 12th and June 12th in the panhandle. Even if you don't see a tornado on the dryline you will see some great structure and the storm motion is usually very tame. My favorite set-up is the classic dryline with plenty of cape and low level shear.

 

[Adam Atkins]

Favorite

Warm fronts and outflow boundaries never seem to do me any good down here in the southern plains, but it always seems to happen in the northern plains. The convergence is always too weak to overcome the cap down here. I've busted way too many times on outflow boundaries and warm fronts, so in terms of surface parameters, I need that dryline.

I like just south of a dryline bulge where there's a chance of an isolated cell in a region of higher CAPE. In terms of winds, I like backed low-level flow through the first 3 km, ie. SE at 850 hPa, S at 700 hPa. I also like highly diffluent upper level flow associated with a negatively tilted trough.

 

[Jeff Snyder]

I agree with Adam regarding outflow boundaries (OFBs) and warm fronts (WFs) in the southern plains... WFs and OFBs in general seem to provide weak convergence most of the time, so they can be very fickle in terms of initiating convection. I have busted numerous times in WF/OFB situations. Given a favorable orientation, however, OFBs and WFs can provide excellent boundaries on which storms can "anchor" (baroclinically-generated vorticity, etc). Drylines TEND to provide just the right amount of convergence most of the time to initiate discrete convection, since most of the time there is favorable deep-layer shear vector orientation relative to the dryline (45-90 degrees).

Since I grew up in MN, and started chasing in MN, dryline chases weren't really an option. Most of the time, convection initiated off of OFBs or, most of the time, cold fronts (CFs). CF forcing TENDS to be a bit stronger, and the character of many CFs tends to yield shear vectors parallel to the front, thus promoting squall line development.

I guess, from experience, I like the area immediately NE of dryline bulges, in the area of favorably-backed surface winds.

As noted in the publication linked to below, drylines and troughs tend to provide discrete activity in the plains, while fronts largely result in lines.

Dial, G.L., and J.P. Racy, 2004: Forecasting Short Term Convective Mode and Evolution for Severe Storms Initiated along Synoptic Boundaries. Preprints, 22nd Conf. Severe Local Storms, Hyannis MA. [104K PDF]

 

[Mike Johnston]

I kind of favor a setup involving surface convergence that is distinct and identifiable enough to forecast with some confidence at least several hours out, but not so sharp as to force the linear mode. Often, in the potential chase area I keep an eye on (eg. eastern and central KS and NE), this will take the form of a pre-frontal trough. Occassionally, the dry line will punch this far, but that is almost invariably accompanied by some other synoptic process such as a strong surface low.

Since visibility is very important to my enjoyment of a chase, the haze and general cloud cover close to a warm front aren't my ideal. (This isn't always the case, though: as I recall the Audubon, IA chase was along a warm front, but underneath a fairly strong cap, so the sky was nice and blue and the supercell top distinctly visible from a great distance.)

Outflow boundaries are cool, but - at least for my level of experience - kind of a wild card, not a feature I would plan a whole chase day around. Likewise, gravity waves fascinate me, and I hope to learn more about theoretical implications of gravity waves for tornadogenesis. (The Jarrell, TX case is an intriguing example.)

Aside from the surface setup, I found the following paper a very good primer for keeping the severe parameters (CAPE, etc.) in perspective:

A Baseline Climatology of Sounding-Derived Supercell and Tornado Forecast Parameters by Erik Rasmussen and David Blanchard

http://www.wdtb.noaa.gov/courses/dloc/svrp...on%20parameter'

It's a little dated, but the population size in their study I think is large enough to be relevant. In particular, the importance of low LCL's for tornadic storms seems to be greater than I had assumed. Also, the false alarm rate for even the best predictive parameters is very high, which reminds once again how much we don't know.

 

[Steve Miller TX]

Give me a dryline intersecting an outflow boundary in a high CAPE environment and at least 25 knots of storm-relative shear.

 

[Scott Olson]

I also like an outflow boundary intersecting a dryline. I'd take a nice shortwave with a good outflow boundary present and put a nice cap in place. The kind of setup that goes from warm tranquil cloud free day- to a huge monster supercell towering over the sky. Generally I would like to have it about 85/75 T/Td. Throw in a nice vort lobe and 40kts of healthy 500mb flow. And sprinkle 30kts of 0-1km shear and it should be a fun day in the Northern Plains.