MCS development in CO-NM

An MCS developed tonight in CO-NM in an impressively warm environment aloft.

At first glance, it appears upslope flow penetrated deep into CO and Northern NM, underneath westerly flow. The terrain served to initiate convection. The upslope flow was responsible for transporting some moisture approaching 50 F to the region.

The impressively warm atmosphere apparently did not stop convection along the NM-AZ border either. As with a previous study (Bunkers et al. 2010), this highlights that warm temperatures aloft do not necessarily reflect convective inhibition. The low level moisture, lapse rate aloft, and forcing are important. So why the reliance on these warm temperatures? Forecasters rule of thumb, that when the mid level temps get warm, convection becomes increasingly unlikely. Most likely this "rule" was the recognition of a process of warming by subsidence such that a cap was present and forcing was either weak or non-existent.

So, now that my script is done running here are some stats at 500 hPa:
STATION   T    T90
ABQ       -4C    -6C
DDC       -4C    -6C
LBF        -5C    -7C
MAF       -3C    -5C
AMA      -4C    -6C
top          -7C    -7C
oun         -3C    -6C
fwd         -4C    -5C
epz          -4C    -5C
oax          -6C    -7C
drt           -4C     -4C
crp           -4C    -4 C
bro           -6C    -4C
dnr           -7C    -7C
sgf           -5C    -6C
lzk           -4C    -6C

These are the ones I have checked and all but 1, have exceeded the 90th percentile. It would be interesting to see how often all these stations have simultaneously hit the 90th percentile of warm Temperatures.

post storm analysis

Well my gut telling me that south central OK would be the best play wasn't quite correct.

The second initiation of convection to the south near Lawton just took forever to congeal into a supercell after many many mergers of smaller storms. The hint is that the cap was too strong, or the shear was too strong for the minimal instability being released. This would suggest that the stronger dynamical forcing to the north was a key factor in the rapid transition from small cells into bigger supercells.

The shear though was also questionable at FWD , despite 200 SRH, only the lowest km had significant hodograph curvature. aloft the hodograph was a straight line. At OUN, within some sort of convection, the hodograph was much larger and curvature much more pronounced.

The observed 500 hPa frontal zone was pretty much in contact with the main supercell of the day and had a pretty good connection to the initiation in southern OK. V2 soundings might shed light on this .

Overall I am not sure what to think of an event like this. The soundings to the north in OK appeared to be uncapped and the shear great. Tornado production was similar to the day before ... apparently present but most short lived. Moisture was present, SRH was high, BRNSHR was in the 10-80 range, and the hodographs all had good curvature.

To the south, there was a cap, perhaps weaker forcing until much later, hodographs were curved by trended to be more straightline (window of opportunity was shorter to the south perhaps), but the instability was greater. I did notice that the southern supercells, had outflow attached to them. So perhaps the mid level dryness enhanced cold pool strength. This case has lots of interesting questions.

dynamical devil

The dryline bulge is in western Oklahoma somewhat removed from the 500 hPa frontal zone as seen in water vapor imagery. However the circulation about this front has resulted (or speculated to have resulted in a narrow moist tongue over the proximate location of the dryline in OK.

I expect CI to be imminent, and perusal of vis sat imagery confirms the presence of a cumulus field in western OK. Not sure if the remnant outflow boundary is really a front or if the nocturnal MCS simply cooled and clouded over the northern portion of the front. Thus, not sure if this front is very active....or if it will truly be a focus for CI.

Vis imagery wave clouds would indicate that it is still relatively stable in Central and southern OK.

First echos on the dryline at 18:56 strengthened by 19:14 UTC. Looks like convection is right on time.

The devil is in the dynamics

A nice little potential outbreak today for OK and North TX. Complicated situation as the night time MCS moves away from OKC, with no outflow boundary clearly visible. The low level cloud field is eerily similar to previous days. The complications are that the elevated mixed layer is well into the area, and the 500 hPa frontal zone is already through AMA. Surface convergence will be there to the north but it may be the dynamics that sets this thing off.

The cap is the big player and the models favor this opinion. NCAR ARW run from last night says multiple periods of initiation to the north, remniscent of May 10, again occurring earlier in the 18-19 UTC time frame. Then later on initiation occurs along a dryline boundary (around 22 UTC) before growing upscale. NSSL ARW run is a lot different probably because of the poor precipitation forecast it produced to the west of the MCS. So too much precipitation to the west virtually ensures that a subsequent trigger for new convection occurs earlier.

Both models agree that initial development will be scattered but not isolated. Thus storm interactions and outflow development may hinder chances at discreet, cyclic tornadic supercells. Today may be a tail-end Charlie kind of day.

The models are not very different with the dryline, but it appears the 500 hPa front is much stronger in NCARs run...though i have no proof since the NSSL run does not make available fields aloft...however the CI that occurs in NCARs run appears associated with the 500 hPa frontal circulation. This is inconclusive however because the 850 RH field is near saturated as well. Breaking the cap is easier when the PBL top becomes saturated.

If I were chasing today, I would try to be south of OKC, probably in Norman. Wait to see how the cap holds to the north and if early storms stay isolated and discreet go for them. Then haul ass south later in the day as the next wave of CI occurs along the 500 hPa front. Otherwise south and east of Norman. The show should start by 19-20 UTC either way...3 hours from now.

Not sure of the tornado potential. Yesterday appeared to be ripe for tornados, yet the pictures and reports indicate short lived but strong tornados. Nice supercells on radar, though. wonder if the shear profiles were not ideal enough. The shear profiles from NCARs model at OUN at 21-23 UTC appear good enough, so this may be a right time right place scenario...brief window is implied. To the north it is less certain since storms may be on the warm front. I am still hedging my bets southward of OKC ...