U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 280102 
Storm Prediction Center ac 280101 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0801 PM CDT sun may 27 2018 

Valid 280100z - 281200z 

..there is a slight risk of severe thunderstorms over a portion of 
the central and northern plains... 

A few strong to severe storms with damaging wind and hail continue 
this evening, mainly from northeast Wyoming through west and central 
South Dakota and west through central Nebraska. A marginal risk for 
a brief tornado persists over the Florida Panhandle this evening. 

..Central High plains region... 

Storms are in the process of evolving into clusters as they move 
through the High Plains of eastern Wyoming and western NE. Surface 
analysis shows a quasi-stationary front from northern Minnesota through 
central and southwest SD, western NE to along the Colorado/Wyoming border. The 
atmosphere in vicinity of this boundary remains moderately unstable 
with 2000-2500 j/kg MLCAPE maximized across South Dakota where A Reservoir of 
low 60s surface dewpoints reside. Storms moving into southwest NE 
may continue to forward propagate northeast through corridor of 
maximum cape next hour or two. However, warm air at base of the 
elevated mixed layer with 14c at 700 mb sampled by the 00z North 
Platte radiosonde observation suggests these storms may begin to struggle by 02-03z as 
convective inhibition increases substantially. Additional storms 
have recently developed along the stationary front from northwest NE 
into southwest Wyoming. Several cam solutions suggest this activity will 
grow upscale and propagate north through SD, and this seems 
reasonable given the relatively high low-level moisture and 
instability within the northerly surface flow regime on cool side of 
the front. 

..southern High Plains... 

High based storms may continue to pose a risk for downburst winds 
and hail through about 02z before diminishing as the boundary layer 


Have confined the marginal tornado risk area overnight to primarily 
a portion of the Florida Panhandle where low-level jet east of the center 
of Alberto will spread north and augment 0-2 km hodograph size, and 
where convection developing along convergence bands over the Gulf 
may move inland. 

.Dial.. 05/28/2018 


Mesoscale Discussion

acus11 kwns 280132 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 280131 

Mesoscale discussion 0548 
National Weather Service Storm Prediction Center Norman OK 
0831 PM CDT sun may 27 2018 

Areas affected...western and central South Dakota...eastern 
Wyoming...southwestern Nebraska and Nebraska Panhandle 

Concerning...Severe Thunderstorm Watch 123...125...126... 

Valid 280131z - 280330z 

The severe weather threat for Severe Thunderstorm Watch 123, 125, 
126 continues. 

Summary...damaging wind gusts will continue to be the primary threat 
this evening with an isolated large hail risk. A local extension in 
time of ww 123 may be needed in the western Nebraska Panhandle. 

Discussion...storms ongoing from eastern Wyoming into 
western/central Nebraska have generally become more linear over the 
past two hours. 00z soundings from lbf and unr both show steep 
mid-level lapse rates in place ahead of this activity. Klnx VAD 
profile shows around 40 kts of deep-layer shear which is in 
agreement with rap analysis showing 30-40 kts of effective bulk 
shear in northeast Colorado and 45-50 kts in northwest Nebraska into 
western South Dakota. A continued threat for damaging wind gusts 
will exist for at least the next few hours while the boundary layer 
is cooling and surface-based cin is increasing. However, shear 
values are sufficient for continued storm organization and MUCAPE 
values are still ample at 1000-4000 j/kg. A local extension in time 
of ww 123 may be needed for an hour or two in the western Nebraska 
Panhandle for the ongoing severe threat. 

.Wendt/Gleason.. 05/28/2018 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 43860560 44520537 44830478 45030275 45060136 44820047 
44340016 43560000 43289987 42400005 41340022 40420057 
40370122 40550186 41250265 41580378 42070410 43000468 
43360556 43860560