U.S. Severe Weather Forecast (Convective Outlook)

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000 
acus01 kwns 161632 
swody1 
Storm Prediction Center ac 161630 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1130 am CDT sun Jun 16 2019 


Valid 161630z - 171200z 


..there is an enhanced risk of severe thunderstorms across central 
Texas... 


..there is a slight risk of severe thunderstorms from the Ohio 
Valley to the Middle-Atlantic States... 


... 
Severe thunderstorms are most likely across a large part of central 
Texas during the late afternoon and evening, including a few 
tornadoes aside from more prevalent large hail and damaging winds. 
Other severe storms are expected from the Ohio Valley to the 
mid-Atlantic states. 


... 
Although more progressive across east-central Texas, multifaceted 
outflow (and other wavelike features) continues to generally 
decelerate across north-central Texas south of the metroplex 
west-southwestward into the Big Country/Concho Valley, where it 
loosely connects to a surface low in vicinity of the Pecos River 
across southwest Texas. Some northward recovery may occur as these 
features otherwise gradually decay. Regardless, a strongly to 
extremely unstable air mass will otherwise develop through the 
afternoon near/south of these remnant boundaries with ample moisture 
beneath a residual elevated-mixed layer (reference 12z Midland and 
del Rio observed soundings) that extends into 
west-central/south-central Texas. 


Surface-based storms are expected to initially develop and quickly 
intensify this afternoon near aforementioned (albeit modified) 
outflow, and also along the dryline bulge near the Concho Valley. 
Given the degree of instability, a belt of modest mid-level 
westerlies (20-30 kt at 500 mb) will be adequate for supercells and 
multicell clusters amid the large buoyancy Reservoir. 


All severe risks are possible, including damaging winds and 
destructive wind-driven large hail, especially ss storms consolidate 
into a potentially massive south/southeastward-moving mesoscale convective system this 
evening with embedded bows and supercells. A severe threat may 
persist tonight southeast towards the Gulf Coast despite increasing 
boundary-layer inhibition. 


..Ohio River valley to mid-Atlantic states/Delmarva... 
Multiple rounds of prior convection/related outflow across the Ohio 
Valley has effectively established a west/east corridor of preferred 
storm redevelopment/destabilization through the afternoon. A 
decaying band of convection and mesoscale convective vortex across the middle Ohio River 
valley toward the central Appalachians will influence downstream 
development later today into the mid-Atlantic region/Delmarva 
vicinity, although the movement of the mesoscale convective vortex may outrun more 
appreciable influx of low-level moisture and peak destabilization. 


Farther to the west, warm front-resembling modification continues to 
occur with prior outflow across the lower Ohio Valley vicinity 
(southern portions of Illinois/in and western ky) ahead of an mesoscale convective vortex across 
southern Missouri. With near 70f surface dewpoints and ample 
early-day insolation (south of early convection), moderate to 
locally strong destabilization is expected to quickly occur this 
afternoon, supporting an intensification and areal increase in 
surface-based convection. 


Overall, across these regions where storms develop/intensify, 
modest-strength westerlies will support eastward-moving multicell 
clusters/evolving linear segments, with the more intense storms 
capable of wind damage, some hail, and a non-zero tornado risk. 


..north-Central High plains... 
Weak convergence/upslope and differential heating near higher 
terrain will contribute to isolated/widely scattered thunderstorm 
development this afternoon. While the ambient air mass is not overly 
moist (generally 40s to lower 50s f surface dewpoints), adequate 
moisture and steep lapse rates will yield minimal inhibition and 
modest buoyancy (500-750 j/kg mlcape) by peak heating. Buoyancy and 
effective shear should be regionally maximized across the southern 
Nebraska Panhandle/southwest Nebraska and far northeast Colorado, 
although the potential for isolated strong to severe thunderstorms 
capable of hail/wind will exist across a broader part of the region 
mainly late this afternoon through mid-evening. 


.Guyer/Elliott.. 06/16/2019 


$$ 

Mesoscale Discussion


000 
acus11 kwns 161731 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 161731 
txz000-161830- 


Mesoscale discussion 1091 
National Weather Service Storm Prediction Center Norman OK 
1231 PM CDT sun Jun 16 2019 


Areas affected...Texas Big Country into north central Texas 


Concerning...severe potential...watch likely 


Valid 161731z - 161830z 


Probability of watch issuance...80 percent 


Summary...thunderstorms are in the process of initiating, with rapid 
intensification and an increase in coverage probable through 3-4 PM. 
This is expected to be accompanied by the risk for severe hail, 
perhaps a tornado, and a gradual increase in risk for potentially 
damaging wind gusts. 


Discussion...thunderstorm activity appears to be in the process of 
initiating northwest through northeast of Abilene, toward the 
Mineral Wells area. This may be supported by lift associated with 
an area of enhanced lower/mid tropospheric warm advection, on the 
northern periphery of the plume of warm and capping elevated 
mixed-layer air (around 700 mb). This is also just ahead of the 
leading edge of mid-level cooling now advancing south/southeast of 
the Panhandle into the South Plains. 


While activity may be initially rooted above the boundary layer, its 
proximity to an area of enhanced low-level convergence near 
intersecting outflow boundaries may contribute to a transition to 
boundary-layer based storms. Once this occurs, large mixed-layer 
cape (already on the order of 3000-4000 j/kg), will allow for rapid 
intensification. Deep-layer mean ambient westerly flow may only be 
on the order of 15-20 kt, but shear may be marginally sufficient for 
supercell structures initially, with perhaps some early potential 
for a tornado. Otherwise, thermodynamic profiles likely are 
supportive of large to very large hail, with a gradual increase in 
potential for damaging downbursts through 20-21z. 


.Kerr/guyer.. 06/16/2019 


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


Attention...WFO...fwd...oun...sjt...lub...maf... 


Latitude...Lon 33180034 33409947 33519762 32719695 32219816 32180034 
32620069 33180034