January 29-30, 2013: First Severe Weather Event of the YearJanuary 31st, 2013 at 3:48 pm by Chad Evans under Chad's WLFI Weather Blog
QLCS squall line raced through in the form of one short segment in our northwestern areas & then the main squall line over most of the viewing area January 29-30. Timing of the lines occurred generally between 9 p.m. & 1:30 a.m.
Sporadic severe wind gusts accompanied the line as high as 65 mph. One tornado velocity signature was seen in Carroll County, but rotation signature was largely mid-level & did not drop enough to low-level to warrant tornado warning per NWS.
Trees were reportedly felled in Montgomery County & Tipton counties with an aluminum shed in Carroll County damaged. A trampoline was blown a considerable distance at this site, with limbs & small trees downed northeast of Flora.
Damaging gusts tended to occur where dew points reached 60-61, while much of the intense wind remained a few thousand feet off the ground in areas with dew points below 60 as buoyancy prevented enough updrafts to tap into strong winds close to the ground & bring them to the surface.
Think of an improperly inflated balloon. No matter how much you try to force it upward, it never tends to rise high on its own (lower dew points, bit cooler air). A properly inflated balloon will rise & tap into air currently well above it & float (dew point 60 or 61 & bit warmer air). Same applies to dew points & their associated surface instability.
+80 mph low-level jet & influx of warmth & higher dew points caused the squall line to organize quickly with +115 mph winds at upper levels aiding in lift. Additionally, record warmth preceded the QLCS squall line in the 60s & heavy rainfall accompanied the line & lasted for several hours behind it. This resulted in 1-3″ of rainfall over the 2-day period with areas of minor flooding.
High-resolution model wind projections several hours prior to event:
Precision 18 Doppler radar wind data during event:
Below shows actual measured wind gusts & a few estimated gusts from spotters: