- Day Three
acus02 kwns 160601
Storm Prediction Center ac 160600
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
0100 am CDT sun Jun 16 2019
Valid 171200z - 181200z
..there is a slight risk of severe thunderstorms across portions of
the middle Atlantic...
Isolated severe thunderstorms may occur across parts of the mid
Atlantic into the Ohio/Tennessee valleys and mid Mississippi Valley
on Monday. Other strong to severe storms will also be possible over
portions of the southern/Central High plains.
..mid Atlantic into the Ohio/Tennessee valleys and mid MS valley...
A subtle vorticity maximum should be present over the Ohio Valley
Monday morning, and will likely move eastward across portions of the
mid-Atlantic through the day. A nearly stationary front should
extend west-east across PA and vicinity. To the south of this
boundary, strong diurnal heating is expected, with temperatures
likely climbing into the upper 80s and 90s along/east of the Blue
Ridge mountains. This heating coupled with a moist low-level airmass
will support moderate to strong instability developing by early
afternoon across much of the mid Atlantic. Ascent associated with
the vorticity maximum should encourage initial convective
development across the higher terrain of WV and western MD,
subsequently moving eastward across northern VA, Maryland/DC, southern
PA/NJ, and Delaware through the evening. Forecast soundings from the GFS
and NAM show sufficient effective bulk shear (generally 30-40 kt) to
support multicells and perhaps some marginal supercell structures.
Damaging winds will probably become the main threat as storms
attempt to grow upscale into a small bowing complex, although
isolated large hail may occur initially as well.
Another weak shortwave trough over MO/Arkansas at the beginning of the
period should move northeastward across the Ohio Valley into confluent
flow and slowly weaken. Still, a belt of modestly enhanced mid-level
flow associated with this feature should overlie a moist warm sector
that will be present to the south of a weak surface boundary. Weak
to locally moderate instability coupled with marginal shear may
support occasional updraft organization, with both a damaging wind
and hail threat with any storms that form across from the mid MS
valley into the Ohio/Tennessee valleys Monday afternoon and evening.
..southern/Central High plains...
Some increase in mid-level westerly flow should occur across parts
of the southern High Plains by late Monday afternoon, and isolated
to perhaps widely scattered storms may form along a surface dryline.
Both low and mid-level lapse rates are forecast to steepen through
the day across this region, with moderate to locally strong
instability probable. There should be enough mid-level flow to
provide some potential for storm organization as convection moves
slowly eastward through early evening. Isolated instances of large
hail may be noted with more cellular activity initially, with some
increase in the strong to damaging wind threat with eastward extent.
Generally modest shear magnitudes still suggest the overall threat
remains somewhat marginal.
Farther north, a northern-stream shortwave trough should move across
the Dakotas on Monday, and storms may develop along a weak front
from Minnesota/South Dakota into NE and eastern Colorado. Even though low-level moisture
should remain limited, weak to locally moderate instability should
develop by peak afternoon heating south of the front in combination
with modest shear. There is enough signal in latest guidance for an
isolated hail/wind threat with this activity to extend the marginal
risk northward across parts of the Central High plains.
..maximum risk by hazard...
Tornado: 2% - marginal
wind: 15% - slight
hail: 15% - slight