U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 200048 
Storm Prediction Center ac 200046 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0746 PM CDT sun Aug 19 2018 

Valid 200100z - 201200z 

..there is a slight risk of severe thunderstorms this evening 
across the Ozark Plateau vicinity... 

Thunderstorms may continue to pose a risk for damaging wind gusts 
and perhaps a couple of additional tornadoes this evening across 
parts of southern Missouri and northern Arkansas. 

..01z outlook update... 
Models continue to indicate at least some further deepening of a 
lower/mid tropospheric cyclone across the northeast Kansas/northwest 
Missouri vicinity tonight. This may occur as the stronger of a 
couple of mid-level speed maxima, within broader cyclonic mid-level 
flow, continues to dig from the Central High plains through the 
lower south Central Plains. This is preceded by a bit more modest 
speed maximum and associated impulse, which may weaken while 
pivoting northeastward through the lower Missouri Valley. 

Forcing for ascent and shear associated with the lead impulse are 
providing the support for the most significant convective 
development this evening, which includes isolated supercells and a 
couple of small upscale growing clusters of storms now developing 
northeastward across parts of northwest Arkansas and southwestern 
Missouri. This activity appears generally focused within lower/mid 
tropospheric warm advection along the trailing (southwestern) edge 
of rain-cooled air associated with weak preceding convection. 
Substantive further modification of the rain-cooled air across 
central into southeast Missouri appears unlikely this evening. 
However, a boundary layer air mass characterized by high moisture 
content and moderately large Cape May remain supportive of 
thunderstorms capable of producing strong surface gusts and perhaps 
an additional tornado or two east of Springfield MO/Fort Smith Arkansas 
through The Fort Leonard wood MO/West Plains MO/Batesville Arkansas/Little 
Rock Arkansas areas into the 03-04z time frame. 

Otherwise, isolated strong to severe storm development is ongoing 
beneath northwest mid-level flow across parts of central Kansas and 
to the southeast of the Sangre de Cristo Mountains. However, this 
activity, and vigorous thunderstorms along a small eastward 
advancing cold pool now approaching the Beaufort/Hilton Head Island 
area of South Carolina, all seem likely to pose decreasing severe 
weather potential within the next hour or so. 

.Kerr.. 08/20/2018 


Mesoscale Discussion

acus11 kwns 192248 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 192247 

Mesoscale discussion 1324 
National Weather Service Storm Prediction Center Norman OK 
0547 PM CDT sun Aug 19 2018 

Areas affected...southwest Missouri into northern Arkansas 

Concerning...Tornado Watch 343... 

Valid 192247z - 200045z 

The severe weather threat for Tornado Watch 343 continues. 

Summary...the threat of damaging winds and a few brief tornadoes 
continues across the watch area. 

Discussion...storms continued to develop across southwest MO and 
northwest AR, ahead of a weak surface low and near a diffuse warm 
front. The latest surface analysis indicates 2 hr pressure falls in 
excess of 2 mb, associated primarily with low-level warm air 
advection. Hodograph size on the sgf VAD wind profile has gradually 
been increasing, now with 0-1 srh in excess of 200 m2/s2. This trend 
may persist over the next couple hours, coincident with an increase 
in the 850 mb flow. As such, the north-south oriented line of storms 
that moved out of Kansas into MO is becoming more of a qlcs with swaths 
of damaging wind and/or brief tornadoes possible. 

To the south and closer to the warm front, cells over Arkansas are more 
robust overall in terms of being instability driven with hail cores 
evident on radar. Low-level shear is not as strong as farther north, 
but a brief tornado cannot be ruled out with this activity. 

.Jewell.. 08/19/2018 

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


Latitude...Lon 35269249 35139403 35339419 35719416 36199421 36599432 
37009432 37419435 37839434 38139256 38129247 37799186 
37389149 36779125 36089124 35589154 35389189 35269249