- Day Three
acus01 kwns 250551
Storm Prediction Center ac 250549
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
1249 am CDT Mon Jun 25 2018
Valid 251200z - 261200z
..there is a slight risk of severe thunderstorms across Iowa...Far
eastern Nebraska...northern Missouri...and portions of the
A few severe thunderstorms are possible across Iowa, northern
Missouri and far eastern Nebraska on Monday. A few severe
thunderstorms are also expected across the Carolinas during the
afternoon and evening hours.
A substantial mid-level trough over Central High plains will migrate
slowly northeastward toward Iowa throughout the day. A belt of
40-50 kt southwesterly flow aloft will persist on the base of this
trough and migrate into Nebraska and northern Missouri through the
evening. Downstream of this trough, a couple of weaker disturbances
will move eastward from the Kentucky/Tennessee border area toward
the southern Appalachians south of a longer wave trough over the
northeast. Finally, a trough over the Pacific northwest will
migrate across the northern rockies and reach western Montana during
At the surface, and ongoing convective complex will overspread
Oklahoma and southern Kansas along and ahead of a synoptic cold
front. This complex should weaken early in the forecast period, and
the front will weaken later in the period and retreat northward
late. A surface low over far southeastern Nebraska will move slowly
northward into southeastern South Dakota. A very moist airmass will
remain in place across most of the central and eastern Continental U.S..
meanwhile, a progressive surface trough will move eastward across
western and central Montana today.
..Iowa and vicinity...
Scattered showers and a few storms should lift northward across
eastern Nebraska and Iowa during the morning hours. The evolution
of this activity will play an important role in subsequent
destabilization and the resultant severe threat during the afternoon
and evening. General model consensus suggest that sufficient
surface-based instability will develop amidst an area of backed
low-level flow just east of the Nebraska surface low.
Pending sufficient surface-based destabilization, vertically veering
wind fields and cellular convective Mode will Foster damaging wind
gusts, hail, and perhaps a few tornadoes. This threat should
persist through the early evening and weaken thereafter as the
..Oklahoma northeastward to Missouri...
Models suggest that scattered thunderstorms will develop during the
afternoon across the region that will likely be aided by 1) remnant
surface boundaries associated with the early morning mesoscale convective system and
weakening cold front and 2) subtle forcing for ascent associated
with a mid-level vorticity maximum approaching the region from
Kansas. Thermodynamic profiles will become moderately to strongly
unstable and weakly inhibited by afternoon given steep (7-8 c/km)
mid-level lapse rates. Additionally, unidirectional wind profiles
will promote mostly damaging wind and hail with the strongest
..Kentucky/Tennessee eastward through the Carolinas...
A couple of weak mid-level disturbances will traverse the region
during the forecast period - reaching the southern Appalachians by
around 20z. Ahead of these disturbances, strong surface heating and
subtle surface boundaries will aid in development of scattered to
numerous storms during the afternoon. Storms will migrate eastward
and perhaps grow upscale into clusters and linear segments - in part
due to 30-35 kt mid-level flow and weak low-level wind fields. The
presence of numerous storms and well-timed approach of mid-level
disturbance(s) support a concentration of damaging-wind-producing
storms across portions of the southern Appalachians and adjacent
Piedmont. 15% wind probabilities (and a slight risk) have been
introduced for this outlook update as a result.
..western and central Montana...
Steepening lapse rates and 50s f dewpoints will support scattered
thunderstorms develop during the afternoon in advance of an
approaching surface trough and mid-level wave. Deep shear profiles
will support modest organization into forward-propagating linear
segments and clusters. These storms will pose a marginal, and
primarily diurnally driven, risk for hail and damaging wind gusts
during the afternoon and early evening.
acus11 kwns 250453
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 250453
Mesoscale discussion 0872
National Weather Service Storm Prediction Center Norman OK
1153 PM CDT sun Jun 24 2018
Areas affected...northeast nm...Texas Panhandle...northwest OK and
south central Kansas
Concerning...Severe Thunderstorm Watch 215...216...
Valid 250453z - 250600z
The severe weather threat for Severe Thunderstorm Watch 215, 216
Summary...strong to severe storms will persist over the southern
High Plains from northeast nm, the Texas Panhandle, northwest OK into
south central Kansas next couple hours. Ww will locally be expanded east
into north central OK, and severe storms may also begin to affect
the western part of Wichita County warning area. Downstream trends are being
monitored, but it remains uncertain whether spatial/temporal extent
of threat will be sufficient for a new ww.
Discussion...expansive squall line continues southeast from south
central Kansas through northwest OK into northeast nm. Strongest storms
are currently located from northwest OK into south central Kansas along
strongest frontal surge. The downstream atmosphere is less unstable
with only partial recovery from earlier storms. However, degree of
forcing and effective bulk shear within frontal zone should help to
maintain an organized mesoscale convective system next couple hours. Farther west across the
Texas Panhandle, storms are farther behind leading frontal surge and
less organized due to strong capping issues. Nevertheless, some
threat for a few damaging gusts and hail will persist next hour or
..please see www.Spc.NOAA.Gov for graphic product...
Latitude...Lon 35720329 36000158 36350019 37159922 37769856 37969791
37509706 36569730 35749849 35179989 34840137 34660284
34840427 35560412 35720329