U.S. Severe Weather Forecast (Convective Outlook)

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000 
acus01 kwns 260555 
swody1 
Storm Prediction Center ac 260554 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1254 am CDT sun may 26 2019 


Valid 261200z - 271200z 


..there is an enhanced risk of severe thunderstorms late this 
afternoon and evening across the Central High plains... 


..there is a slight risk of severe thunderstorms this afternoon and 
evening across the lower Ohio Valley and middle Atlantic coast 
region... 


... 
Severe thunderstorms, including a few supercells with a risk for 
tornadoes, are expected today across much of the High Plains, into 
the Central Plains. Additional severe thunderstorms are possible 
across the lower Ohio Valley into the mid Atlantic coast region, 
accompanied mainly by a risk for severe wind and hail. 


... 
A large-scale pattern including persistent, prominent subtropical 
ridging centered near the eastern Gulf Coast, and encompassing much 
of the southeast, and large-scale troughing within the mid-latitude 
westerlies across much of the west, will persist through this 
period. Within the western troughing, the most prominent 
perturbation, including a deep mid-level low, is forecast to dig 
inland of the California coast, to the south of San Francisco Bay, 
through the lower Colorado by 12z Monday. As it does, models 
indicate that a downstream impulse will pivot northeast of baja, and 
accelerate across the southern rockies through larger-scale ridging 
across the Central High plains. This likely will be accompanied by 
deepening surface troughing across much of the High Plains, and 
perhaps modest surface cyclogenesis from eastern Colorado into 
Nebraska late this afternoon through tonight, providing a focus for 
considerable strong to severe thunderstorm development. 


Farther east, several convectively generated or enhanced 
perturbations will continue to migrate around the northern periphery 
of the subtropical ridging, and are expected to aid convective 
development along and south of an initial surface front advancing 
southward into/through the mid Atlantic coast region and Ohio 
Valley. 


... 
The short wave emerging from baja is forecast to be substantive 
enough to suppress larger-scale mid-level ridging and contribute to 
a transition to cyclonic flow across and east of the southern 
rockies late this afternoon and evening. It appears that this will 
be accompanied by a strengthening of southwesterly flow to 40-60 kt 
(in the 700-500 mb layer) across the Central High plains, and 
strengthening of initially modest southerly 850 mb flow to 30-50+ kt 
by late this evening, from the Texas South Plains through the 
Central Plains by late this evening. 


Moisture return to the deepening surface trough across the Central 
High plains is already underway beneath north/northeastward 
advecting warm elevated mixed-layer air. Models indicate that this 
will contribute to moderate to large cape across much of the High 
Plains, and into the warm sector of the developing cyclone across 
the Central Plains. 


Various model output does indicate that lower/mid tropospheric warm 
advection could contribute to thunderstorm development by early 
afternoon across parts of western Kansas. This probably will be 
rooted above the boundary layer, before it has a chance to 
substantively destabilize, and it remains at least somewhat unclear 
what impact this will have on subsequent thunderstorm development as 
it spreads northeastward ahead of the approaching short wave 
impulse. 


There appears likely to be at least a narrow corridor of moderate to 
strong boundary layer destabilization across the Texas/Oklahoma 
panhandles into eastern Colorado by mid to late afternoon, which 
should be sufficient to support propagation of thunderstorm activity 
off The Rockies into the High Plains. In the presence of 
strengthening shear, the environment is expected to become conducive 
to supercells with potential for large to very large hail. Although 
low-level hodographs may be initially weak to modest, a few 
tornadoes also appear possible, particularly across the 
Colorado/Kansas border area into the Panhandle region. 


Tornadic potential eastward across the Central Plains this evening, 
as the low-level jet strengthens, remains a bit more unclear. It 
appears that large-scale forcing for ascent may support an upscale 
growing convective system with primarily a risk for strong wind 
gusts along the leading edge of a strengthening surface cold pool, 
across parts of western Kansas into south central Nebraska. 


..lower Ohio Valley into the mid Atlantic coast region... 
Models indicate that seasonably high boundary layer moisture content 
ahead of the southward advancing front will become characterized by 
moderate cape by this afternoon. This will support potential for 
organizing clusters of thunderstorm activity, aided by forcing and 
shear associated with the perturbations progressing around the 
northern periphery of the subtropical ridge. Flow including 30-40+ 
kt in the 700-500 mb layer may be sufficient to support occasional 
isolated supercells, but severe hail and wind appear the primary 
hazards in the presence of generally weak low-level hodographs. 


.Kerr/squitieri.. 05/26/2019 


$$ 

Mesoscale Discussion


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acus11 kwns 260807 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 260806 
ohz000-inz000-260930- 


Mesoscale discussion 0807 
National Weather Service Storm Prediction Center Norman OK 
0306 am CDT sun may 26 2019 


Areas affected...central and eastern Indiana...western Ohio 


Concerning...Severe Thunderstorm Watch 248... 


Valid 260806z - 260930z 


The severe weather threat for Severe Thunderstorm Watch 248 
continues. 


Summary...an isolated wind damage threat is expected to continue 
through daybreak across eastern Indiana into western Ohio. Weather 
watch issuance will likely be needed to the east of ww 248. 


Discussion...the latest radar imagery shows an mesoscale convective system located across 
central and northern Indiana. The mesoscale convective system has a bowing segment across 
the eastern part of ww 248 where wind damage is likely occurring. 
MLCAPE values across central Indiana are estimated to be around 1000 
j/kg. In addition, regional WSR-88D vwps have 0-6 km shear in the 30 
to 40 kt range with unidirectional westerly flow in the low to 
mid-levels. This will likely support a continued wind damage threat 
for several more hours as the line moves eastward toward and into 
western Ohio. 


.Broyles/guyer.. 05/26/2019 


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


Attention...WFO...iln...iwx...ind... 


Latitude...Lon 39558427 39538628 39678671 40118689 40808681 40998634 
40938414 40168404 39868407 39558427