U.S. Severe Weather Forecast (Convective Outlook)

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 
the day. 

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 
low-levels stabilize. 

..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. 

.Cook/Wendt.. 06/25/2018 


Mesoscale Discussion

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 

.Dial.. 06/25/2018 

..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