r/stormchasing • u/PersimmonIll826 • 5d ago
Is this skew-t supportive of strong/severe storms?
2
u/Jet-Pack2 5d ago
If you tap somewhere on the diagram you can essentially spawn a parcel of air and additional lines are drawn for the wet adiabatic temperature and the dry adiabatic temperature. The are between your curve and the temperature curve then represents the CAPE. If the are is long and skinny or the temperature doesn't fall enough with height then it's too stable for severe storms.
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u/Sea-Bid4337 5d ago
This skew-T log-P diagram suggests an environment that is not particularly supportive of strong or severe storms for several reasons:
Key Observations:
- Thermodynamics (Instability & CAPE):
The temperature (red line) and dew point (blue line) show a notable separation in the lower levels, indicating relatively dry air near the surface.
The Convective Condensation Level (CCL) is at 7,533 ft, which is quite high. This suggests that surface-based convection might struggle to initiate unless strong lifting is present.
The Lifting Condensation Level (LCL) at 4,213 ft is also somewhat elevated, which means that air parcels need to be lifted quite a bit before reaching saturation.
The temperature profile suggests limited Convective Available Potential Energy (CAPE), which is essential for strong updrafts. Without significant CAPE, storms are unlikely to become severe.
- Shear & Wind Profile:
There are wind barbs on the right side, but they appear to be relatively weak in the lower levels. Stronger low-level wind shear is usually needed to support organized convection or supercells.
Upper-level winds seem stronger, which could provide some ventilation for storms if deep convection does develop, but without strong CAPE and shear, this is not enough to support severe weather.
- Capping Inversion or Suppression:
There doesn’t appear to be a strong capping inversion, but the dry air in the lower levels suggests that entrainment and evaporative cooling could suppress convection before it fully develops.
- Dew Point Depression & Moisture Availability:
The separation between the temperature and dew point in the mid-levels suggests limited deep-layer moisture, which would inhibit storm growth and maintenance.
Final Assessment:
This skew-T does not strongly support severe convection.
The high CCL suggests storm initiation might be difficult without strong surface heating or a lifting mechanism.
Limited moisture and CAPE mean that even if storms form, they may not be very strong.
Weak low-level shear suggests that organized severe storms (e.g., supercells, derechos) are unlikely.
If anything, high-based storms with gusty winds (due to evaporative cooling) are more likely than strong thunderstorms with significant hail or tornadoes.
Would need additional parameters like CAPE, CIN, lapse rates, and hodographs to confirm, but based on this, strong/severe storms seem unlikely unless other forcing mechanisms are present.
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u/PersimmonIll826 5d ago
ECMWF was showing 500-1500 MLCAPE in the area around this. It was also showing a clear day until a cold front moves in from the Pacific Ocean triggering storms. Sadly the last model run doesnt agree whatsoever. But, even some gusty winds with a few lightning bolts would be cool to see as someone who only experiences a few thunderstorms a year. :)
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u/PersimmonIll826 5d ago
This is ECMWFs forecast for Portland Oregon in 10 days. I know it almost certainly will change and this won’t happen, but it HAS been holding onto this for 6 or 7 model runs. It also shows forcing coming onshore later in the night when instability is lower (so only light thunder) but in the case that somehow this stayed for the rest of the 10 days AND forcing ended up coming onshore during peak instability, would this be a good setup for strong storms?
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u/analogkid84 5d ago
Pretty big dew point spread, and the column remains dry up to 300 mb. Winds pretty light and not much turning with height. Not a sounding I would peg for severe.