Forecast for 06/05/12

Today's Relative Humidity with wind data (from twisterdata.com)

Phew. The past few days have been tumultuous but I am back with a comprehensive forecast. A cold-soon-to-be-stationary front keeps drifting towards the Gulf Coast. The High Country has only the slightest threat of a shower today, from very weak convergence on both sides of the mountains (from a northerly wind flow). However, the air remains moisture deprived and with a lack of synoptic support and local instability, the shower threat is extremely minimal today. One would have to go south of the NC/SC border to find showers and south of I-20 to find any real storm activity today.

Tonight the easterly flow picks up from a weak high pressure offshore. With the surface relative humidity rising quickly, I can see fog and drizzle developing along the Blue Ridge and Foothills. Tomorrow will actually be cooler than today.

Relative humidity for early tonight with a strengthening easterly flow....

And the saturation by midnight

Highs will not be getting out of the 60's tomorrow.

My tornado index is highlighting Montana as a source of tornadic activity today (not much). This suggests 1)low number of tornadoes (likely), 2)weak tornadoes (likely) 3)short tracking tornadoes (also likely). But what about that small chance over eastern Georgia? Why isn't my index showing this as an area? It is, but the tornado damage potential it is showing for that region is 1)ranked very low compared to other events 2)short lived nature of squall line induced tornadoes or short lived, isolated tornadoes (less than 5) are not represented as well. There are far more conditions which are conducive for an isolated tornado rather than an outbreak. An outbreak is far more likely to be linked to a teleconnection pattern or a favorable synoptic pattern (the case for Montana today).

Storm prediction center tornado probability for today

The case for eastern Georgia is that this is near where a weak southerly branch of the jet stream is merging with a far stronger northern branch. The jet is lower to the ground across eastern Georgia and has a better shear environment. Shear is good as it allows horizontal vorticity to be tilted into the vertical.

Since this is also where the frontal boundary will be today, this is a better environment for strong convective storm formation and for squall lines.

Damaging wind probability for today (storm prediction center)