Severe storms impacted the Ohio River Valley region on 5 November, with an SPC Enhanced risk for severe spanning from southwest Illinois into East-central Ohio. Convection developed along a southward moving cold front, south of which strong southerly flow was drawing up very moist air (surface dew points into the upper 60s). The abundant low-level moisture and southerly flow combined with cold temps and strong flow aloft led to favorable instability and deep layer shear across a broad region. All severe hazards (hail, wind, tornadoes) were expected with this event.
Prior to the event, products from GOES-16 revealed valuable information about the pre-storm environment. The GOES-16 Derived Motion Winds, combined with surface METAR observations, allowed for the computation of observation-based deep layer shear (Fig 1). Around 1800 UTC in southern Illinois ahead of the cold front, KSLO measured surface wind speed to be 15 knots from 200 degrees. Directly over the METAR, satellite-derived winds at 459 mb were 56 knots from 253 degrees. This computes to a 0-459 mb (close to 0-6 km) bulk shear of 48 knots, which is more than adequate for supercell storm development. The cold front can be diagnosed in the surface obs at this time in central Illinois.
GOES-16 1-min imagery was available over the region for this event. The VIS/IR sandwich combo, described in previous posts, provides a combination of high resolution with quantitative information. The animation below shows the sandwich combo with a tornado-warned storm in southern Indiana. Overlaid is NLDN CG lightning data and NWS warning polygons.
A little later, severe storms had developed all along the cold front from east-central Missouri through Illinois. Again, the GOES-16 VIS/IR sandwich combo allows one to quickly diagnose important features and phenomena such as overshooting tops, above-anvil cirrus plumes, enhanced-V signatures, and new convective development (Fig 3.).
As the sun set on storms over Ohio, gravity waves were obvious emanating from overshooting tops. These storms produced wind damage and were associated with multiple tornado warnings.
-Bill Line, NWS
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