I may be going out on a limb here especially since I can already hear the chainsaws firing up!! But I’ve been trying to figure out what we have not sen more showers across our area this afternoon. There sure appears to be lots of reasons why we ought to be having showers or even thunderstorms. SPC extended the slight risk area into Alabama along what appeared to be an obvious focus for storm development – the outflow from the cluster of storms over Tennessee and Kentucky this morning. But we’ve reached 86 degrees with a dew point of 68, so we ought to be seeing something beginning to pop. But the latest radar at this writing shows zip, nada, nil, nothing!
So I decided to look at the morning sounding from the Shelby County Airport again. I used an interactive sounding page and I got this result.
This was a direct screen capture except I added the green circle to draw your attention to the inversion. I noted that inversion this morning, but I figured it did not seem very strong, at least not strong enough to cap the development of strong updrafts today. The lapse rate above the inversion is certainly notable as SPC mentioned with a pretty steep slope to the temperature profile. While the magnitude of the inversion is not particularly big, the layer encompassing the inversion is pretty deep.
The purple line is the projected profile based on a surface temperature of 87 and a dew point of 68. So it appears that the low level heating is not enough to break the capping inversion since the purple line remains to the left of the ambient temperature profile. And with neutral advection below the inversion and veering wind above meaning warm advection, perhaps we will not see any showers or thunderstorms develop.
Other factors which might play a role in inhibiting convection include the cirrus canopy which has become fairly dense. Arguing against that, though, is the fact that temperatures did warm nicely since we’re sitting around 86 or 87 degrees.
The atmosphere is surely an interesting place about which we don’t always understand.
-Brian-
Parenthetical note: Now that I’m found a “reason” watch the updrafts take off!!!
