Wednesday, April 2, 2014

Thoughts about "SPC Chasers" and Forecasting Severe Weather

Today is one of the first "big" days of the 2014 chase season.  Many chasers are on the road in Oklahoma into Texas.  A system is moving through bringing severe weather to the Southern states and yet ANOTHER winter storm/ heavy snowfall to the Northern states (lucky us in Minnesota!!!).

As the season takes off I keep reading comments about "SPC Chasers" as if they aren't "good enough" as compared to the "experts" that use model data to do their own forecasting.  For those of you newbies, SPC is the "Storm Prediction Center".  This topic keeps popping up in various places, including a photo on Facebook I just saw posted of a dog at the computer and saying "I have no idea what to do"...representing "SPC Chasers" if the SPC website was unavailable.
SPC 1630 Convective Outlook for today
I wanted to make a few comments about this.  First of all, let's NOT look down upon chasers who happen to use SPC products as the main resource for their chase forecasts (outlooks, mesoanalysis, etc).  These tools are actually VERY useful.  SPC happens to be staffed with some of the top forecasters who specialize in forecasting severe weather.  They are behind the desk analyzing data 24/7 to come up with the best, most accurate severe weather forecast possible.  I am VERY grateful for the work they do.  And Yes, I do use their products often!  That's why they are there, to provide us high quality storm forecasts.  So, why not use them?  And if someone chooses only to use SPC for their forecast, who cares?  They may not be able to choose a specific target days or hours before the storms fire, but at least they are using professional guidance on where to be.  And if the SPC website does go down...well they might be out of luck (but can probably find many posts on Facebook from other chasers to figure out a little about where to go).

BUT, I do think it is necessary to be able to interpret radar and UNDERSTAND the storm structure and what is happening in the sky when storms do fire.  This is critical in staying safe and chasing smart.  So, if you are relying on SPC for your forecasts and targeting, please at least learn about the storm and what you are looking at (beyond the tornado!).  Take a Skywarn class, complete some online training, read books, and most importantly...go chasing with experienced, knowledgeable chasers who will be willing to help you learn.  I did.  My first chasing was with experts in the field.  And even though I already took the classes and understood the graphics, the structure, the features, the models, the radar, was a completely different experience being in the field.  I was grateful for being out in the field with true experts and I learned so much. 

Just so you know where I'm coming from...I have a B.S. Degree in Chemistry and Biomedical Science.  I also took several college Meteorology courses, including forecasting...along with a couple extra specialized severe storm forecasting workshops/ classes....from Tim Vasquez and College of DuPage for example.  And it all makes sense to me.  In my forecasting class with Bob Weisman we had to hand plot the weather maps, surface obs, boundaries, etc.  He worked us hard and it was fun!  I loved it all. 

So, yes, I can and do sometimes do my own forecasting using the various models available on the internet (GFS, NAM, RAP, HRRR, etc).  Usually I just look at a few key parameters and determine whether I think the coming day(s) are looking good enough to chase.  But this is usually just a validation of what SPC is already saying.  So, honestly, I usually just rely on what SPC has to say for the coming few days....until the DAY OF....then it's time to do some real-time data analysis.

Real-time surface observations today in the slight risk area.
As far as forecasting goes, I do think it is important for a serious chaser to have some training and knowledge about models AND more importantly about what makes severe weather.  What is happening in the atmosphere at the surface and above?  It's important to understand the "why" and is key in being able to understand the "where"...where to plan your chase for the day....where is YOUR target?

If SPC has a slight risk that covers 11 states (yes, 11!), as they do today (see map at the top...even though some of those 11 states are only little portions of the state), how do you decide where to target if you don't know much about the science and how to read model data?  Ok, yes, SPC does specify what areas have a higher probability of tornadoes in their discussion and even more specifically in an MD.  But, this can still cover hundreds of miles of territory.  To increase your odds of intercepting the best storms of the day it is important to do some of your own data analysis.  Even if you decide to only use the SPC Mesoscale Analysis page, you will need to understand the graphics, what parameters to look at and what to look for.

Personally, on the BIG day, the CHASE day, I use 3 main things: 
1. Real time data (surface obs, soundings, satellite, radar, etc).
2. HRRR model runs (where is the model initiating convection?)
3. SPC outlooks, mesoscale discussions, and watches

I personally don't use SPC Mesoscale Analysis graphics very often, but I do sometimes.  If you do, be careful of "targets" on some of the composite graphics, such as the Supercell Composite.  These are useful in some regards as they are combining many parameters to show where conditions are coming together best for supercells, BUT there are other factors to consider.  The target on the graphic may be quite a bit East of where the actual convective initiation will take place....or it may be highest where the CAP is also strongest so nothing will actually fire there.  Again, it's about understanding the science of what is happening and how to use the model data and graphics you are looking at in order to pick the most accurate target (which can still be wrong...because there's always a factor of luck and timing involved!). 

Hey, if you're an "SPC Chaser" I still love you, you're still awesome, we share a passion for crazy weather!  I love SPC and I use their tools all the time.  Please just be sure you understand the sky, what you're looking at, the dynamics and structure of the storms (particularly supercells!) and how to navigate safely around them.  If you're new and want to learn please reach out to us or other chasers.  We are happy to help! 

See you under the meso!

~Melanie Metz

Image copyright Melanie Metz/

1 comment:

  1. Thank you so very much Melanie for taking the time to explain a lot about the weather and storm chasing! I personally use the SPC a lot so I do appreciate everything you said about them! Thank you again; it was an excellent blog and I personally learned a lot from reading what you wrote! My mind is like a big sponge and I truly enjoyed your teaching and feel like I can turn to you if I ever have any questions about severe storms and chasing them! Big giant hugs of appreciation, Vanessa Coleman