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Most chasers waste precious time on chase day glued to model runs — but that’s the mistake that costs them the storm. Listen to this episode and learn why observed data like soundings, surface obs, and upper air maps become your most powerful forecasting tools when it matters most, and how to use them to make confident, real-time decisions in the field.

00:00 Why Observed Data Is King on Chase Day

00:55 Best Observed Data Sets for Storm Chasers

02:09 What Is the SPC Mesoanalysis?

05:38 The Cheat Code: Vorticity & 3CAPE Overlap

08:23 How to Use Convection Allowing Models

10:18 Why You Can’t Rely on a Single CAM

11:27 Why the 3km NAM Is Worthless

On chase day, the models have done their job — now it’s time to put them aside. In this episode of the Storm Chaser Coaching podcast, host Gabriel Harber sits down with Coach Trey Greenwood to break down why observed data is the single most important forecasting tool on the day of a storm chase, and how to use it to make confident, real-time decisions in the field.

Trey explains that while forecast models like the NAM, GFS, and European Model are essential in the days leading up to an event, they’re simply an estimate of what the atmosphere might do. On chase day, observed data — including upper air maps, surface observations, and morning soundings — tells you exactly what the atmosphere is actually doing. Soundings reveal the instability profile, capping inversions, and wind shear in the vertical. Surface obs help you pinpoint moisture boundaries, surface low positions, and dew point trends in real time.

The episode also dives deep into the SPC Mesoanalysis page, one of the most valuable tools in a storm chaser’s arsenal. Trey walks through the “cheat code” — the surface vorticity and zero-to-three kilometer ML CAPE overlap product — and explains why strong low-level instability co-located with surface spin is a powerful signal for tornado potential, especially in landspout and cold core setups.

When it comes to Convection Allowing Models like the HRRR, FV3, and NAM-3km, Trey urges chasers to use them only as a “check your work” tool rather than a primary forecast driver. Every CAM carries its own biases — the HRRR notoriously overmixes and cratering dew points — so model agreement across multiple CAMs is key before placing confidence in any single solution. And the Three Kilometer NAM? Trey’s verdict: ignore it entirely.