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Strategy for forecasting storm initiation?

Thanks Everyone.. I have one other question about the mesonet thing. Do you guys know of any mesonet sites like the OKC one? I can't find one for Kansas, CO, TX etc?

I agree this is a great tool in finding the boundaries! Something I have NEVER been good at.

Thanks in advance!

Bp


The only other two that I can think of at the moment would be the West Texas Mesonet and the Iowa Environmental Mesonet, both links are below.

http://www.mesonet.ttu.edu/

http://mesonet.agron.iastate.edu/index.phtml
 
I personally think the RUC does a god awful job with precipitation and I never take what it shows seriously. I will always take the 00Z run of the WRF high resolution over that.
I'm not sure if you are asking how to pick your exact target for storm initiation or how to figure out when storms will fire so I'll give a quick answer to both. Figuring out when exactly storms are going to fire is basically impossible until an hour or two before when you get an 18Z sounding or a good cu field is showing up on satellite. It's a crap shoot trying to figure it out any farther out than that. Look at model soundings. That is one of the best ways. Pay attention to what the convective temperature is and try to figure out what you think the actual temperature is going to be the next day. Maybe the models are off on the surface temps. Figure out where surface temps are going to be higher. .There are tons of things to look at, the cap, moisture, details of initiating boundaries, instability, upper level support, etc. The list goes on and on. You could literally write a book on how to figure out when the cap is going to break and after reading it you would still get it wrong 50% of the time lol. I've been chasing for almost ten years now and the only tried and true methond I have found for being at your target in time for convection to fire is to show up early. I always try to get to my target at least 2-3 hours before I expect storms to fire. It's borderline foolish not to IMO unless you can't get out of town on time or something. Not only do you not want to get your pants pulled down when storms fire way earlier than they are supposed to, which happens several times every year, but being early also gives you time to get to your initial target with time to forecast and adjust your target based on the current conditions and how the day is evolving. I've tried cutting corners by leaving with just enough time to get to my target and you will miss tornadoes because of it.

As far as picking where storms will initiate, that is much easier IMO, but you could still right a book on it. There is no way I can answer that in one post. Some quick tips if you are new to forecasting and chasing though is to look at the models, pay attention to where the western edge of the convection starts in the afternoon. It is starting there for a reason. There is going to be a boundary there so figure out what boundary it is. Once you figure out your initiating boundary look at how it's forecast to move through the day. Maybe it's a dryline and it is going to be basically stationary or it could be a cold front hauling ass. Use common sense when considering that. If it is a quick moving boundary and you'll have less margine for error target farther downstream from where you normally would. When I chase the objective is to get on a tornadic storm, not to be exactly under a storm when it first develops. I love watching storms go up and develop, but I won't risk falling behind the storm before it matures if there are going to be fast storm motions that day. You just need to be smart about it. Another good way to get a rough idea of where storms will fire if you are new to this is look at the western part of the SPC outlook area. Typically that is roughly where storms will fire. Locating boundaries really isn't that tough, so a blend of all of these is very much possible for somebody just getting started in chasing.
I'll try to right a little better answer tomorrow when I'm at work, because it's time for me to hit the sack.
 
Short Fuse Composite Charts:
I made a weather page for Short Fuse Composite Charts for the different
WFO's, all the charts are on one page.

http://supercellweather-shortfuse.blogspot.com/
http://www.chasertv.com/wx/current-weather/short-fuse-composite/
Mike

If you have noticed a problem with some of the offices' implementation of the Short Fuse Composite involving the Theta-E (topping out at 330) it is due to a configuration change that needs to be made in the software of that location. A number of offices came online for the first time last year with the Short Fuse Composite (mostly central plains states... the southern plains states have been lacking for whatever reason).

Mike Umscheid and the DDC ITO were great at helping these new offices get things up and running. (Rapid City was running an early version of the SFC and not sure if they have updated it yet). However, I'm not sure if the other offices ITOs are aware that their theta-e maps are giving incorrect information until this configuration is changed.

Another interesting point I gleaned from talking to Mike is that the principle of "garbage in - garbage out" applies to the SFC. DDC specifically eliminated station datapoints that were unreliable and so you will see that their theta-e contours look much different from, say... Goodland's (where they overlap).

I'd love to see all of the implementation's at the various offices be similarly configured so that they can be the best tools they can be. I do think that if they were properly configured they would be a very good tool for helping with initiation concerns... but you still need to know the "big picture" pattern and you need to be close enough to initiation to get there in time for the show... so there is a good deal of good forecasting, targeting and driving that needs to be done to put yourself in the right area. THEN you can use the SFC (along with your eyes) to see where things are likely to initiate.
 
*SNIPPAGE*
But in most respects this involves a basic convective temperature forecast -- but actually working it out on the sounding rather than going to a website that spits out Tc numbers. This gives me some idea whether convection will occur early, late, or not at all.
*SNIPPAGE*

Tim,
Thanks for this fairly detailed look into your thought process and forecasting process. Very valuable! I do have a question however...

When you say "sounding" are you here speaking of a Real Sounding or a Model Sounding?

If the answer is "Real" can you give a little insight into how you modify it to adjust for latency (making it useful for forecasting later in the day?)

If the answer is "Model" can you tell me which of the models you use for Day One forecasting. Is the RUC always best for Day 1 model skew-Ts or does it vary, depending upon which model has seemed to have the best grasp of that particular situation? Or do you look at multiple model skew-Ts and try to blend them.

I guess I'm interested in not just Tim's answer on this, but anybody who does something similar. Thanks in advance!
 
Brian it's impossible to explain how to pick the best target between the warm front, triple point and drylinle. The only way you'll ever figure that out is if you study meteorology and get a few years experience of watching real life severe weather events unfold. It's not really something that can be explained because there are so many different situations and exceptions to rules. There is no clean cut answer.

On locating the dryline looking at current surface observations is the best way to pin down it's exact location, but you don't have to be exact for chasing purposes. If the dryline is in Kansas or some other place with a poor network of surface stations then look at the dewpoint graident on SPC's Mesoscale Analysis page to figure out where the boundary is. Another great tool on that page is the moisture convergence product. It works great for figuring out where storms will develop along a boundary. I put a lot of weight in what the moisture convergence fields are showing on that page when I'm out chasing. It is usually right and give you the rough location of where a storm will fire before a cu field might give it away.
Another trick that usually works is watching where cumulus clouds first develop along the boundary. A lot of times the first storms will fire where the cu field first started to form. I watch visible satellite like a hawk on chase days. It is definitely one of the best if not the best asset available to storm chasers for day of forecasting.

If you aren't sure where storms are going to develop along the dryline because the dryline isn't well defined, then look at moisture convergence and the 50 degree dewpoint line (during middle and late spring). That will usually put you pretty close. It isn't really important that you get that close though. It is always better to cheat downstream of where you think storms will fire. If you want to get right under the area where storms are going to form so you can watch towers go up then target downstream a ways from where you expect that to happen and wait until the boundary starts to show up on satellite and radar before moving in. If you are within 25 miles or so of the dryline you'll probably be able to see the towers going up along it so you won't even need satellite or radar.

I'm not sure how you missed the dryline by that much, especially by being too far east. I have gotten burned by getting caught behind a surging dryline before, but I don't think I've ever been too far east. Drylines are very easy to locate 90% of the time on chase days. Just watch the dewpoints and if that isn't clear then compromise between the 50 degree td line and the moisture convergence fields. If the wind shift doesn't match up with the moisture gradient then target which ever one is farther east. Watch out for double dryline setups too. They aren't very common, but they do happen and storms can fire on a secondary dryline out farther over the warm sector. I got my pants pulled down in Oklahoma because of that.

I could ramble on for quite some time on this stuff so I better go ahead and stop lol.
 
Thanks Mikey! That was a great explanation! Yeah, I have definitely looked at moisture convergence over the years but I like the 50deg DP line. I will keep that in mind. I am hoping to come out tomorrow night to get set up for a Wednesday/Thursday chase. Hope it comes together.

Thanks again!

Bp.
 
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