Severe Storm Outlook Narrative (AC)
Issued by NWS
ACUS11 KWNS 290319
SPC MCD 290319
Mesoscale Discussion 0583
NWS Storm Prediction Center Norman OK
1019 PM CDT Fri Apr 28 2017
Areas affected...Parts of southern Indiana...northern
Kentucky...southern Ohio...northern West Virginia
Concerning...Tornado Watch 171...
Valid 290319Z - 290515Z
The severe weather threat for Tornado Watch 171 continues.
SUMMARY...Severe weather potential is expected to linger across
severe thunderstorm watch 170 and tornado watch 171 at least into
the 1-2 am EDT time frame. The need for an additional watch farther
east into the central Appalachians is not currently anticipated, but
trends will be monitored.
DISCUSSION...Vigorous thunderstorm activity continues to form within
a relatively narrow zone focused near or just to the cool side of a
quasi-stationary frontal zone across the lower Ohio Valley, near the
river, into the central Appalachians. This is occurring beneath an
axis of 60-90 meter 500 mb height rises, which may be tending to
suppress convection at least somewhat. However, the environment
appears characterized by sizable CAPE on the order of 1000-2000 J/kg
(diminishing in magnitude from west to east), in the presence of
40-50 kt west southwesterly lower/mid tropospheric flow.
This may continue to be conducive to organizing storm structures,
including supercells, accompanied by a risk for potentially damaging
wind gusts and some hail. A somewhat more moist, potentially
unstable boundary layer near the front across parts of southern
Indiana and adjacent portions of north central Kentucky, may still
support potential for an isolated tornado or two. Severe weather
potential with storms spreading east of the Ohio River into less
unstable environment across northern West Virginia may not be
completely negligible, but probably is less than that that exists to
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 38528756 38888705 39428452 39668250 39148034 38408098
38308332 38188531 38028658 37898782 38528756