Another great HSLC case to add

I think we should consider adding the April 4-5 late night QLCS event to our database (it will be in my spreadsheet anyway).  SBCAPE near zero in our area but MUCAPE maybe nudging up toward 500 J/kg along NC/VA border. 0-1km shear through the roof at 50-60 kts.  A rare middle of the night event for our CWA, which included many wind damage reports in our VA foothills and Piedmont, as well as a couple of large hail reports, and it looks like one confirmed EF1 in Surry Co NC. However, we suspect some of the damage near Martinsville may have been tornadic but according to the County EM who surveyed it, it was ruled straight-line (thus an issue we often deal with during many of these kinds of events…weak but fast moving tornadoes embedded in an area of otherwise straight-line winds nearly impossible to differentiate, even to a trained eye).  Not sure if damage surveys have been completed in other CWAs.

This was hinted at by some mesoscale models earlier in the day but as evening came, line out ahead appeared to have stabilized the airmass and mesoscale models actually were less agressive with redevelopment overnight.  Us and SPC a bit behind on this as line quickly redeveloped after midnight, catching us off-guard to some extent, and with minimal staffing sitiational awareness was a challenge to keep up with. The part of the line that produced the confirmed tornado did not show a real strong circulation, but others that we issued TORs for were much more impressive, but as far as we’ve determined did not produce tornadoes (but plenty of wind damage).

We have Level II for GR2Analyst and will be archiving all AWIPS data. I assume RAH has archived the SPC mesoanalysis sector 7 for this. 

Steve K

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5 Responses to Another great HSLC case to add

  1. Matt Parker says:

    I’m a bit swamped right now but wanted to post a comment so that I can check the “notify me” box and follow the discussion. Cheers, Matt.

  2. Michael Cammarata says:

    This was quite an event for the CAE CWA. We had very wide spread straight line wind damage from microbursts of 75-125 mph. We actually hit 75 mph at the ASOS here at CAE. No Tors. There was tons of shear. The SB Cape and 100 mb ML Cape would probably qualify this as low Cape but the MU Cape was in the 750 -1000 range.

    Mike C

  3. Frank says:

    CAPE readings for CHS CWA were too high to qualify for most of the event. An argument can be made that the last couple of reports occurred when the SBCAPE was down around 300 or so, but the MUCAPE was defintiely above 500, actually closer to 1000 at the peak of the event.

  4. We agree that this is a great case. In central NC we had 75 reports of severe weather, just about all from wind damage. Had a fairly well defined broken-S signature that moved across the western Piedmont and then a couple of short lived but fairly well defined circulations just east of the Triad. Two survey crews examined multiple locations today for tornado damage but instead found straight line wind damage, some of it very impressive.

    If you are interested, I archived the SPC mesoanalysis sectors from 12 UTC on 4/5 through 15 UTC on 4/6 along with some regional radar imagery and other data. The zip files are located at the URL below.

    We may put together a more comprehensive posting in a few days.

  5. nws-pat moore says:

    Sorry for the late comment. We need a break from all these significant events.

    Yes, the 4-5 April event was very impressive across the GSP county warning area as well. A rare middle-of-the-night widespread severe event. It was one of those events where a warning could be issued well in advance with very high confidence. We issued 29 warnings and verified all but one of them, most with numerous wind damage reports. The line of convection was very efficient at mixing down a 60 to 70 kt low level jet. We had measured gusts of at least 50 kt at several ASOS and AWOS sites, including KCLT. This event had the highest number of measured severe wind gusts that I know of in our forecast area since 1998. We issued a few tornado warnings but did not have any tornadoes that we know of, although there was one swath of damage in particular that should have been surveyed but was not for lack of manpower.


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