May 16, 2012

Long Range Outlook for Tuesday-Friday: Great Potential

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Ensemble Mean Sfc Chart, Wed, 5/23/12

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Ensemble Mean 500 mb Chart, Wed, 5/23/12

Here's what I see in the GEFS for next week. I've posted below the ensemble mean 500 mb and surface patterns for Wednesday, as an intermediate day.

It's a pretty hot looking pattern at 500 mb, but some of the operational runs show that 500 mb trough being "segmented", meaning split into separate disturbances with several distinct vorticity maxima and minima at the same longitude, respectively. That can cause problems with the wind shear (if it is not phased with the CAPE field) and can be associated with suppressing synoptic scale subsidence between those. Leaving that detail aside...impossible to really judge now....

The surface pattern is good from Tuesday through Thursday, at least. I think there is a reasonable chance that buoyancy values in NE and KS even Tuesday, while not as great as they will be later in the week, will be sufficient, with surmountable CIN. 

On both these plots notice the blue colors indicating ensemble spread....over the Great Plains. That blue color indicates very good coherence between the individual ensemble members...enough so that there is pretty good evidence for systematic southwest flow in the middle and upper troposphere, and south-southeasterly flow from the Gulf during that period. One or two of these days MIGHT have "synoptically-evident" patterns...even though it's pretty far out in advance to worry* about that (*worry meaning everyone and their mother's uncle might be making plane reservations in). The saving grace is that this is a mid-week pattern and it seem like well away from the chaser hordes in OKC, DEN and DFW metro areas, and even KC might be a stretch from the area in NE and north-central KS suggested as a threat. MIGHT because the whole threat has to evolve non-linearly....dependent on moisture tongues, shear maxima, low level shear that none of the ensemble members can agree upon yet.