Topic: Utah supercell and meso footage

[Mike]

These images 27June 2009 used with permission from a US enthusiast 'chaser' (well he admits he knows nothing about chasing per se!) Steve Marwedel.  The storm indicated 3 TVS points during it's movement across his location, the video may have been one of them.  The meso did not produce a tornado in his location and he cannot confirm if it dropped one any time after.







and the video - very cool stuff.  I wish I could get this kind of thing in Darwin, it would be insane.

Cloud Rotation Near Salt Lake City, UT

[Jimmy Deguara]

Mike,

What evidence is there that this is supercellular? It seems like a messy line segment (not being disrespectful more or less a description) quite high based so it is not surprising a tornado did not drop. Nice storms - something you can expect here in Australia during summer.

Regards,

Jimmy Deguara

[Mike]

Am getting some details for you, hopefully they'll have some radar images etc.  Will keep you posted.

[Mike]

  I have the radar image of that storm here..



Here are the SPC reports for this storm - they do mention possible high based supercells and this did produce three TVS's in its lifecycle but no tornado then I would say that confirms it also for this one.  Shear and CAPE are not that good as you'll read hence no real threat of tornado activity for this system.

un 26, 2009 1630 UTC Day 1 Convective Outlook
Updated: Fri Jun 26 15:41:17 UTC 2009

SPC AC 261536

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1036 AM CDT FRI JUN 26 2009

VALID 261630Z - 271200Z

...GREAT BASIN...
A RATHER COOL UPPER TROUGH CONTINUES TO DIG SOUTHWARD ACROSS CA/NV THIS MORNING. STEEP MID LEVEL LAPSE RATES AND POCKETS OF HEATING WILL RESULT IN SUFFICIENT INSTABILITY FOR SCATTERED AFTERNOON THUNDERSTORMS AHEAD OF THE TROUGH ACROSS MUCH OF THE GREAT BASIN. FORECAST SOUNDINGS SHOW MLCAPE VALUES OF 500-1000 J/KG AND EFFECTIVE SHEAR OF 25-35 KNOTS. THIS SHOULD BE SUFFICIENT FOR A FEW ORGANIZED MULTICELL OR ISOLATED HIGH-BASED SUPERCELL STORMS CAPABLE OF HAIL AND GUSTY/DAMAGING WINDS. AREAL COVERAGE OF SEVERE ACTIVITY REMAINS IN QUESTION...SO WILL MAINTAIN ONLY LOW PROBABILITIES OF SEVERE WEATHER AT THIS TIME.
>>>>

[Mike]

Jimmy, just having a think about that video...because it's zoomed in to this particular region and no TVS icons were shown on the radar image at that time, could this be a shear eddy?  I've seen a few photos of late with similar circulation with several so-called mesos but in fact have found out that eddies are quite common with turbulence under a cloud base where shear is prominent.  Given that meso formation viewed is actually a few km or miles wide this perhaps explains the video? What's your view?

[Jimmy Deguara]

Without being there, it's hard to make a proper assessment. It is something we have often seen Australia with outflow dominant severe storms. Very messy system and usually the circulations are embedded in rain areas.

Regards,

Jimmy Deguara

[Brad Hannon]

Mike, just to add some observations of mine - that circulation is rotating anti-cyclonicly in an area of cloud that looks to me like something i've seen plenty of (and been intrigued by many times) on the leading edge of outflow dominant storms (as Jimmy said) with no direct link to any mesocyclone at that stage.  I agree with Jimmy that in the pics it looks like a disorganised line, perhaps either trying to become a nice shelf or falling apart from being a nice shelf! either way, outflow but I wouldnt knock it back down here!

[Mike]

Yes, the more info that I've read about what they saw and the responses also has me agreeing.  Initially they thought a wall cloud was there in the lower left hand corner of the pic, but I disagreed with that - it was simply undercutting from outflow.  The same person had another photo of 3 of these things in one area, one anti-cyclonic and another cyclonic, but given no TVS or anything special from the NWS and given the circulation was only small in diameter it also leaned me towards Eddies also. Thanks for your input guys, much appreciated.