U.S. Severe Weather Forecast (Convective Outlook)

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000 
acus01 kwns 182001 
swody1 
Storm Prediction Center ac 182000 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0300 PM CDT Tue Jun 18 2019 


Valid 182000z - 191200z 


..there is an enhanced risk of severe thunderstorms from West Texas 
into Kansas... 


..there is a slight risk of severe thunderstorms across portions of 
the plains and middle Atlantic... 


... 
Scattered severe thunderstorms are likely across parts of the 
central and southern Great Plains in multiple rounds this afternoon 
through tonight. Other severe thunderstorms are expected across the 
mid-Atlantic region and parts of the southeast. 


..20z update... 


Remnants of long-lived mesoscale convective system are progressing along the I-70 corridor 
across Kansas. Leading edge of this activity is beginning to intensify 
over northeast Kansas which may propagate a bit farther downstream than 
earlier anticipated. Will expand higher severe probs across portions 
of top County Warning Area to account for these trends. 


Strong boundary-layer heating across the High Plains has contributed 
to near-dry adiabatic low-level lapse rates from southeast Colorado into 
West Texas. Convection will gradually expand in areal coverage along 
this corridor over the next few hours before spreading into the enh 
risk region. 


.Darrow.. 06/18/2019 


Previous discussion... /issued 1152 am CDT Tue Jun 18 2019/ 


... 
An mesoscale convective vortex will continue to drift generally eastward across 
western/central Kansas through the afternoon and evening. A trend of 
thinning/increasingly scattered cloud cover should occur through the 
afternoon, aided by a modest mesoscale convective vortex-peripheral dry slot. Expectations 
are for more of a southeasterly low-level wind component to 
materialize across central Kansas by mid/late afternoon, while 
enhanced mid-level winds otherwise spread eastward across the 
southern half of Kansas. Thunderstorms should initially intensify 
across central/south-central Kansas by mid-afternoon, with moderate 
buoyancy and sufficient deep-layer shear/modest overall forcing 
likely being conducive for semi-discrete supercells, at least for a 
few hours duration. A few tornadoes will be possible aside from 
severe hail/wind as storms spread east-southeastward toward and 
across the I-35/I-135 corridor through late afternoon and 
early/mid-evening. 


..Oklahoma/Texas Panhandle to west/southwest Texas... 
Timing of the peak/most-certain severe risk is a bit questionable 
across parts of this region, but the potential exists for a 
sub-regional corridor to be impacted by multiple rounds of severe 
thunderstorms. At the very least, a conditional severe/supercell 
risk will exist as early as mid/late afternoon across the Texas 
Panhandle/Low Rolling Plains and western Oklahoma within a very 
unstable environment. However, modest convergence and a tendency for 
mid-level warming casts some uncertainty. At the very least, storms 
are likely to move into/across the region later this evening with an 
appreciable damaging wind/hail risk via one or more well-organized 
clusters. 


Farther south, a couple supercells should form over the higher 
terrain of the Texas trans-Pecos with a primary risk of large hail. 
Minor mid-level height rises suggest robust mlcin will hold east of 
the Pecos River, limiting the spatial extent of this threat. A 
separate area of thunderstorms may form near the intersection of the 
dryline and residual outflow boundary trailing from the central 
Texas mesoscale convective system. A deeply mixed boundary layer should support a few 
supercells that might organize into a cluster this evening. Large 
hail and severe wind should be the primary threats. 


..co Front Range/south-Central High plains... 
Scattered thunderstorm development is likely over the Raton Mesa and 
other parts of southeast Colorado by peak heating as a minor 
mid-level impulse in Utah crosses the southern rockies. Amid 30-40 
kt 500-mb westerlies, this activity should spread east and impinge 
on Richer boundary-layer moisture in the Texas Panhandle this 
evening. At least on an isolated basis, supercells capable of large 
hail and possibly some tornado/damaging wind risk can be expected as 
storms spread east/southeastward. 


..mid-Atlantic states/Delmarva... 
An area of organized severe potential is apparent across southeast 
PA, NJ, northern MD, and Delaware ahead of an mesoscale convective vortex/weak surface cyclone 
currently over western PA. Here, some enlargement to low-level 
hodographs in conjunction with moderate boundary-layer heating of 
low 70s dew points should support a risk for a few supercells 
capable of a tornado or two and damaging winds/some hail. Refer to 
mesoscale discussion 1115 for additional short-term details. 


..central Gulf Coast to Carolinas... 
A belt of 20-30 kt west-southwesterly flow will persist amid 
afternoon MLCAPE of 1000-2000 j/kg. This should again Foster a 
threat for mainly locally damaging wind as numerous multicells occur 
through this afternoon. 


..Montana/northern High Plains... 
Isolated strong to severe semi-low-topped thunderstorms will be 
possible this afternoon into evening within a modestly 
moist/unstable environment ahead of an 
amplifying/southeastward-moving mid-level shortwave trough. 
Well-mixed boundary layers could yield severe-caliber wind gusts 
along with some localized/marginal hail potential. 


$$ 

Mesoscale Discussion


000 
acus11 kwns 182149 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 182148 
txz000-182245- 


Mesoscale discussion 1124 
National Weather Service Storm Prediction Center Norman OK 
0448 PM CDT Tue Jun 18 2019 


Areas affected...Texas Panhandle and Texas Caprock vicinity 


Concerning...severe potential...Severe Thunderstorm Watch likely 


Valid 182148z - 182245z 


Probability of watch issuance...80 percent 


Summary...storms are expected to move east into an area of Richer 
low-level moisture over the Texas South Plains and intensify. Large 
hail and severe gusts are the primary risks. 


Discussion...radar mosaic shows isolated, high-based thunderstorms 
over the eastern plains of nm. Surface observations show 
temperatures in the lower 90s degrees f over eastern nm with surface 
dewpoints mixing into the 40s. Farther east, dewpoints range from 
the lower 50s near the nm/Texas border into the lower 60s near the I-27 
corridor. As a result, MLCAPE increases from west to east across 
northwest Texas. 


Westerly flow aloft strengthens from 30kt around 400mb to 75kt at 
200mb. The presence of steep low- to mid-level lapse rates (in 
excess of 8 degrees c/km) underlying high-level shear in the -10 to 
-30 degrees c layer, suggest large to very large hail is possible 
with the strongest updrafts. Upscale growth into storm clusters and 
perhaps a linear band will serve as a transition for severe gusts to 
become the primary risk late this evening. 


.Smith/Edwards.. 06/18/2019 


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


Attention...WFO...oun...lub...Ama... 


Latitude...Lon 35560183 35540054 35220007 34149996 33180028 32980100 
33040213 33490269 34600286 35270254 35560183