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OKpowdah

Moderator Meteorologist
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Posts posted by OKpowdah


  1. That might be helpful. Another helpful difference, in my opinion, is that weak shear is better than "bad" shear. A lot of the forecast soundings for this upcoming period exhibit fairly small hodographs, but sometimes the shape is favorable. These are the situations where big CAPE actually can make a difference. In strongly forced and sheared situations like April 26, where the hodographs are a total mess of VBV and looping back on themselves well below 6 km AGL, there's usually not much to be salvaged thermodynamically. Part of that is just because those profiles often imply a large scale environment favoring many storms initiating and running into one another, though.

     

    For each day in the Monday-Friday period, I think I've seen at least one medium range deterministic run highlighting that particular day as the one where shortwave timing is favorable, and we actually see a robust sfc low and LLJ. But by the same token, there's virtually no consensus on that happening any particular day. Even so, "big CAPE/low LCL magic" is bound to happen at least once or twice somewhere, if only because of interaction with a boundary or something of that nature.

     

    That is a wicked good point.


  2. I usually like to see more upper level confluence to the north/northeast to prevent the strung out SSW-NNE oriented sfc low we see next week. That usually helps in the shear department. One reason I've been cautious about getting excited at all. Though there have been big days with similar configurations. Certainly the ramping up of the STJ makes everything more interesting, on a number of levels. GFS consistently producing dew points in the mid to upper 70s, and astronomical CAPE (cue the "CAPE trumps everything" optimists from 4/26)


  3. I think the crucial factor tomorrow will be the timing of CF advancement southward. The ECMWF still starts sweeping it south between 21z-00z (covering 3 counties in that timespan), which is not good. Any CI signal from CAMs in the warm sector has been right near the triple point, so we need the front to hold steady until at least 00z-01z to have a window before undercutting. Even then, a lot of the CAM runs I've seen appear to show big UH tracks right along or on the immediate N side of the boundary, so I'm not sure how much confidence in true surface based storms I'd glean from that.

     

    Assuming we're fortunate enough for a storm to initiate a county or two S of the triple point, the other thing I'd watch for, similar to last Sunday, is CI timing. Later is better, since hodographs look questionable before 23z-00z.

     

    I'm also wary of the UH streaks up there being associated more with bowing segments. Clearly strong storms, but undercutting + wind profile gets junkier


  4. Sigh.

    NWP will never, and I mean never in our lifetime, replace the human forecaster in severe convective forecasting. The obsession with hi res guidance and CAMs is bad.

    Please review the multitude of professionals who swore on their lives that no way could we achieve dew points in the upper 60s because the Gulf coast dew points the day before were in the upper 50s.

    Respect NWP or get left behind


  5. People get easily stuck on the 5000 CAPE days in Oklahoma. Anything over like 1500 is gravy. CAPE 1500-2000 will not be a limiting factor as far as tornado potential goes.

    Last Tuesday there were several people that only cared about the huge CAPE and claimed it would "solve" all other issues.


  6. Last Tuesday was absolutely a bust. A PDS watch with zero strong tornadoes. Even the 10% hatched tor ... First of all, again, zero strong tornadoes. Second, no one made that 10% tor region thinking "Oh we better cover the QLCS tornado threat". No, that was entirely in anticipation of a supercell mode that never transpired. Hence also the error in location of tors, as pointed out above.

    Finally, the outlook wording was always too strong. Constant mention of high risk, when the tor probs weren't even past the moderate risk threshold, and hail and wind probs were low end moderate. And the only way a high risk was happening without tors would be with an upgrade in wind probs, which was never a threat that was singled out for the day. I want to actually do a study on how many times "high risk" or "upgrade" has been mentioned in past moderate risks. It was absolutely completely unnecessary.

    The SPC, along with almost everyone else, fell on their butts Tuesday.


  7. Yeah Lawton is a good spot or Frederick. Usually when the HRRR clues in on something like this without wavering, it is worth paying attention. Not to mention the overnight convection that everyone was worried about was next to nil.

    Absolutely. Though as a rule, never start in Frederick haha. There are like zero roads out of that place. Snyder is a good waiting point


  8. NSSL WRF (which, in my experience, is the most reliable of the many convection-allowing models run at 00z) is quite discouraging for most of the dryline. Plenty of storms, and many are even discrete with space, but little UH to speak of. A reflection of the abysmal hodographs. It suggests a northern (N KS) and southern (TX) mode to any serious threat, which seems increasingly plausible.

     

    At least it doesn't develop any early-day convection, though.

     

    Unlike WRF ARW and NMMB. Ew.

     

    HRRRX is more encouraging for the dryline in OK


  9. IF something like the 00Z HRRR/RAP occurred and we get some morning convection ( as long as it does not linger, and last well into the afternoon or leave a ton of cloud debris behind, which I doubt that it would due to the incoming EML), it could actually help for later on in the day. By providing a vorticity rich environment as well as OFBs to provide some significant local enhancement of SRH. Counting on that initiation were to reoccur at a favorable time later on in the day, and that convection did not just constantly continue to pop up.

     

    On another note, it looks like the convection that will occur tonight over NE KS/ WC MO will drop an OFB somewhere across EC KS, I believe. 

     

    Similar progression happened during May 24th, just further west


  10. The 12z NAM looses its mind for Monday.  Doesn't appear to convect, but there is great cape, marginal shear, and a cap that appears to break off the dryline based on model soundings.  It's nice to finally see some good lapse rates showing, even on the GFS.  I think this may be a good day to chase.

     

    NAM uses the BMJ convective parameterization scheme, which is pretty strongly dependent on the presence of mid level moisture. As a result, it performs well for tropical-type convection, but can often miss or be delayed with continental convection.

    Especially for a day like Monday, which we know will have sparse convection anyway, take NAM precip with a grain of salt.


  11. With regards to the 1/16-18 shortwaves, also considering that models often erroneously "pick" the leading s/w to be the primary developer in these scenarios. Still worth watching what happens with s/w #2, and think about the benefits of a squashed s/w #1


  12. 66 has been showing up since like the 13th in the extended. I posted those in upstate ny a week ago.

     

    Yup both 66 and 78 have been common analogs for a while now for around the 1/17-18 timeframe. And given the pattern evolution and incoming Pacific energy, these are NOT trivial


  13. I think the key is what happens with the NAO. You can have a strong -AO and the NAO isn't all that negative.

     

     

    All about the maturity of the NAO. There'll surely by positive height anomalies over Greenland, and the DS, but is it actually in true -NAO block form, or just an extension of ridging from the N Atl -- how significant is the cyclonic breaking of said ridge over the DS - and does it happen in time for the 1/17 threat


  14. This is text of a tweet from Sam Lillo.  Cool to see how he lays out what he thinks the progression would be.  I think if the NAO really doe go negative, that might be our saviour for early February.

     

    As Pac jet buckles, +WPO breaks down, Wrn NA ridging retrogrades, CWB over Quebec -> -NAO, + active STJ = Major NE US storm threat 1/16-17

     

    Thanks man! Nothing here has changed. 1/17 continuing to hold interesting potential

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