With the tornado outbreak in southern Georgia and northern/central Florida on Sunday that has tragically resulted in significant loss of life, eyes are once again on the weather. I was particularly impressed by the synoptic analysis done by the Capital Weather Gang over at the Washington Post.

I've always found this kind of mesoscale "tale of the tape" analysis to be interesting. Accuweather has made these kinds of analyses/maps, see 3/2/12.

I would like to be able to look at upper-air and surface charts, and be able to explain the weather. How can I do that? What would I have to learn?

Through lots of studying of NWS upper air and surface charts, nullschool.net maps, and reading Cliff Mass's blog, I was able to draw some crude Microsoft Paint renditions of the basic summer weather pattern in the Pacific Northwest:

PNW map 1

PNW map 2

Furthermore, I was also to depict a map of the atmospheric conditions during the 4/27/2011 tornado outbreak, utilizing William Smith's excellent analysis (you'll want to click on the image for a larger resolution):


But I want to learn how to do this on my own. I want to be able to look at charts, and use the charts to make an analysis of a weather event. I'll give you a good example of what I want to do:

During the early morning hours of July 7th, 1999, thunderstorms erupted over southwestern British Columbia and interior sections of WA near the Strait of Juan de Fuca. I know this because I lived through them, I was 7 years old at the time and they kept me up all night. NWS radar archives did not register any precipitation, but Plymouth State University's archives did. Plymouth State's archives also have upper-air analyses; the 00Z 7 Jul 99 analysis shows the shortwave trough draped from the Puget Sound up to southern Vancouver Island. What I want to do is to learn how to forecast the weather at a basic level, then apply this knowledge and look at the upper air, mid-level, and surface analyses, then be able to put them all together to understand this event occurred. I then want to apply this knowledge to be able to predict or analyze other convective thunderstorm events or other major weather events. Other people have recommended reading the content at theweatherprediction.com.

Thank you.

  • $\begingroup$ To be honest, I'm not sure these are often the groundbreaking information they seem. The Accuweather image is basically shows the setup of any decent maturing low pressure system. The upper jet always is collocated with healthy fronts. The CWG article hits more details, but mainly via the SPC MDs, which indeed do go into finer details like mesolows and multi-warm front structures. But the article itself is shaky on details (suggesting Albany is in SE Ga, poor mesolow identification, and perhaps dubious claims about Dixie Alley [or at least this outbreak, which was generally S of usual area]) $\endgroup$ Commented Jan 25, 2017 at 9:46
  • $\begingroup$ So if anyone will come before you and claim "oh, this is what made this setup so special", and just presents one of these maps showing the features, any reasons suggested are probably real oversimplification. Before being educated in meteorology articles like the one linked seemed great... but after better education, honestly they seem to be more meandering prose than sharp information. Even though it is indeed definitely great to look visually at the true ingredients layout, and even can indeed help forecasting/understanding at times. I'll try to explain more in an answer. $\endgroup$ Commented Jan 25, 2017 at 9:57
  • $\begingroup$ As to your 07/07/99 event, always odds to not get radar, but I see it doesn't show up at mesonet.agron.iastate.edu/current/…. Looks like the only radar back then had a limited sight region (atmos.washington.edu/%7Ecliff/actualCoverage.gif) but did cover the area you are looking for. Looks like there may've been radar issues: the Amazon download site shows files missing all of the 6th, then nothing until 8-15Z on the 8th. But that DOES match your window. So looks like radar data may be there if you want to go digging into it more. $\endgroup$ Commented Jan 25, 2017 at 11:40
  • $\begingroup$ You can get the data at s3.amazonaws.com/noaa-nexrad-level2/index.html, but you'll need a program to display it too (perhaps try a trial of GRLevel3 if you don't have it). $\endgroup$ Commented Jan 25, 2017 at 11:45
  • $\begingroup$ Here's proof of concept from downloading one image. i.sstatic.net/3o3So.png Can go back half an hour beforehand. Unfortunately the viewer I usually use works on Level 3, but oddly the NCDC archives don't seem to have that for this time. But given enough effort you could probably do it. Easiest might end up being pyart (eng.climate.com/2015/10/27/…), though I'm not experienced with it myself. But the ncdc.noaa.gov/wct package was how I made this image. $\endgroup$ Commented Jan 25, 2017 at 12:58

1 Answer 1


You're definitely on the right path with wanting to dig into raw data yourself. RAP has always been a pretty solid source of useful basic data.

But in terms of making sense of the data, it indeed will take some practice. You can feel like you're not getting it at all, but suddenly pieces will start to click, much like riding a bike.

Basically, you need to start building from those that know these things. As such, one good insight can be in reading NWS forecast discussions, which you can find among the rich data at kamala.cod.edu or in one big set at this NWS link.

But, at least in terms of storms, I think the place to start has to be the same place that the CWG article relied upon: the Storm Prediction Center. Specifically:

  • Convective outlooks will explain the day's weather picture and large key features
  • Mesoscale discussions offer insight into the finer details that make all the difference, ones which even the most seasoned meteorologists may not always recognize.
  • Then the mesoanalysis tool allows you to dig more into the data yourself and see overlays of a deep variety of parameters. But the tool that may be right down your alley may be the composite map generator tool, which allows you to combine just the noteworthy parts of the key elements onto one image and see how they line up.
  • And then the Severe Weather Events Archive allows you to dig into a great deal of past events, and the Outbreaks Browser lets you see the bigger events in a very sharp, graphical way.

And there's plenty of other great things there too; climatologies, publications, education pages, etc. Now, obviously the majority of this information focuses most directly on severe weather setups (though the SPC does actually also issue winter weather mesoscale discussions [the WPC now does heavy rain MDs, and of course the NHC does the main discussions on tropical systems]), and only regard US events. But these tools can really help even those interested more in other areas and topics get a better understanding of the bigger picture, which sync up well into just about every topic of synoptic and mesoscale meteorology, regardless of location.

Now, in terms of helping you personally narrow down onto the key elements, so that you could make your own composite map... the classic ingredients necessary for thunderstorms (also see here) can be a good starting point:

  1. Instability... the predisposition of rising air to continue rising. Basically warm (and moist) surface air and anomalously cold air aloft.
  2. Moisture... high dewpoints create clouds more readily, form them at lower heights (important for tornadoes), and produce more precipitation/energy for storms. Plus it helps the instability.
  3. Trigger... something to get the air moving to rise so that the ingredients can be realized. There are a WIDE range of possibilities here. Important ones for storms include fronts, the dryline, vorticity advection aloft (incoming vort maxes you see spinning around on water vapor imagery), favorable jet streak quadrants, strong temperature advection (e.g. low-level jets), outflow boundaries, seabreezes/lakebreezes/riverbreezes, gravity waves, diffluence aloft, terrain/orographic lift, horizontal convection rolls/cloud streets, isentropic upglide, and differential heating boundaries. Suffice to say there are a lot of options in play, though some are more common than others. But you'd be surprised how quickly you can get used to finding them with practice. (And it's really a pity there isn't greater information/graphics/videos/explanations on some of those topics... perhaps some of these will eventually work their way here to be questions that can encourage a better, clearer reference to form)

And finally, to really ramp up severe weather, and also primary to tornado threat, you add in ingredient four...

  1. Wind shear... different winds at different height. A combination of how much directional difference there is and how much speed difference. Significantly impacted by upper level jet streaks, low-level jets, and the direction of the surface flow is.

This may sound like a ton. But taking a second look at that Accuweather graphic, it's those same ingredients: enter image description here

So with those basics to start at, the pictures have a pattern to them. And then when you add in the finer details discussed, you can really find the deeper things you won't on the more basic composites. You can see what really DID make all the difference. In the end, it's an investigative science, a continual game of making and refining theories, and it's something you only get better at with practice. Even top meteorologists still don't always have the answers; I don't know whether anyone has come up with a perfect explanation yet for why the supercells on Sunday in Central Florida didn't produce prolific tornadoes. Forecasts do still fail. And so we're always trying to better clear up the details of each past event, so that we'll be better at the next one.

A couple final links... it seems like this journal article might be fairly interesting and approachable for you... and then websites like Stormtrack can be a really great asset, as that's where quite a few chasers/meteorologists often congregate to discuss big weather events. The more time you spend looking at this stuff, engaging in conversation, challenging the reasoning you/others have, and learning, the better you'll be able to form a clearer picture of what's going on. A much better picture than any news article will ever give!

  • $\begingroup$ JeopardyTempest coming in for me again with another clutch maneuver! Is there anything you can't do? $\endgroup$ Commented Jan 26, 2017 at 1:24
  • $\begingroup$ Just as an aside, my other idea was to email Dr. Cliff Mass over at the University of Washington, but he's a busy man and I don't think he'd have the time to answer this question, especially since I'm not a UW student. Perhaps if I phrased it as, "can you suggest some academic papers that go over thunderstorm events in coastal interior areas of Washington and BC?" $\endgroup$ Commented Jan 26, 2017 at 1:28
  • $\begingroup$ It's before my time and the opposite end of the country from me, so no surprise I don't know it. But sometimes the events we remember aren't the ones others do... I'm surprised it's not on a page like climate.washington.edu/stormking/mainindex.html or web.archive.org/web/20000417204756/http://www.seawfo.noaa.gov/… So it may be something Dr. Mass doesn't have much on. But it doesn't hurt to send an email along the lines of "Dr Mass, I'm looking for more information on a storm event from July 7th, 1999, do you have anything on it?" $\endgroup$ Commented Jan 27, 2017 at 5:34
  • $\begingroup$ And if he doesn't have much, there are surprisingly good data archives out there which we can use to pull the basic information on it together, but will take a bit of work. $\endgroup$ Commented Jan 27, 2017 at 5:37
  • $\begingroup$ (you may also find web.archive.org/web/20000304031152/http://www.seawfo.noaa.gov/… interesting, though offtopic to this) $\endgroup$ Commented Jan 27, 2017 at 5:51

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