Now that it's thunderstorm season here in New Hampshire, it would be nice to be able to find out what the vertical wind shear is like at the altitudes that affect thunderstorm formation, to guess whether they'll form. Once cumulus clouds have started to form, it's usually easy to see by just looking up. But when planning one's day in the morning, there often aren't big enough clouds yet.

Can anyone direct me to an easy-to-use source for this?


1 Answer 1


Yes, NOAA's Storm Prediction Center's soundings page is a great source for the information you are looking for, especially the skew-T diagrams and wind hodographs. This site provides current soundings as well as a past archive of 1 week. For the explanation of the soundings diagrams and numbers provided, see the soundings help page.

  • $\begingroup$ Thanks - but I'm pretty clueless as to how to use it. My best guess is, for my purpose, to look for a BRN shear number (center of middle bottom panel) above 20 or so. Am I close? Am I better off eyeballing some graphic? $\endgroup$
    – Ed Staub
    Jul 2, 2014 at 20:44
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    $\begingroup$ @EdStaub It requires quite a level of expertise to predict near future conditions based on current soundings. Though I am a meteorologist, I do not specialize in convection or cloud physics, so I hope somebody else chimes in on this. Higher bulk Richardson number (shear over buoyancy) may imply less chance for forced convection, so you are on the right track. See their soundings help page for explanations on various numbers they give (updated in my answer). $\endgroup$ Jul 3, 2014 at 15:09
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    $\begingroup$ Sorry, I got that backwards - Ri ~ buoyancy/shear. $\endgroup$ Jul 3, 2014 at 16:10
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    $\begingroup$ @EdStaub BRN and shear in general is a better predictor of the type of thunderstorm you'll get rather than whether you will get one at all. Combined with CAPE you have a better predictor (and this is what BRN does and takes into account you'll need more CAPE in a higher shear environment in general) but it still misses the whether a storm will actually initiate. The soundings on the page are are also generally limited to twice a day, this time of year being 8AM and 8PM EDT, so the CAPE (and thus the BRN) shown will evolve as solar heating takes place throughout the day. $\endgroup$
    – casey
    Jul 3, 2014 at 17:55

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