U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 210059 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0759 PM CDT Fri Oct 20 2017 

Valid 210100z - 211200z 

..no severe thunderstorm areas forecast... 

isolated to widely scattered storms, a couple of which could be 
strong, are expected late this evening into the overnight from the 
Central Plains to Minnesota. 

..Central Plains/upper Midwest... 
Gradual height falls and the increasing influence of cyclonic upper 
flow will overspread the region in conjunction with increasing 
warm/moist advection atop a stable boundary layer. A relatively 
moist/unstable air mass across the south-Central Plains by mid/late 
October standards (sampled by 00z observed soundings such as Dodge 
City Kansas and Norman ok) will advect northeastward tonight. Isolated 
to widely scattered thunderstorms are expected to develop and 
increase late this evening and especially overnight within a 
corridor from NE/northern Kansas into IA/MN. Steep mid-level lapse rates 
and sufficient elevated buoyancy could support a few stronger 
storms, but the overall potential for severe-caliber hail should be 
limited by a modest combination of effective shear/buoyancy. 

.Guyer.. 10/21/2017 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 192020 

Mesoscale discussion 1720 
National Weather Service Storm Prediction Center Norman OK 
0320 PM CDT Thu Oct 19 2017 

Areas affected...southwest New Mexico into a portion of far western 

Concerning...severe potential...watch unlikely 

Valid 192020z - 192245z 

Probability of watch issuance...5 percent 

Summary...stronger storms will remain capable of producing a few 
instances of downburst winds and hail through early evening. Overall 
threat is marginal, and coverage of severe events is not expected to 
become sufficient for a ww. 

Discussion...surface temperatures have climbed to near 80f with 
dewpoints in the mid to upper 40s in the presence of boundary-layer 
mixing, boosting MLCAPE to 400-800 j/kg. Storms over southern nm 
have increased in overall intensity during the last hour, and 
further increase in coverage may occur as forcing for ascent 
attendant to a progressive shortwave trough over Arizona spreads into 
western nm. No substantial increase in winds aloft is expected with 
the approach of the impulse, and vertical shear will remain weak and 
supportive of multicells. Nevertheless, the thermodynamic 
environment with steep lapse rates and inverted-v boundary layers 
will continue to promote a risk for a few instances of downburst 
winds and hail through early evening. 

.Dial.. 10/19/2017 

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


Latitude...Lon 31800602 31970707 32370817 33530845 33830682 33460584 
32500539 31800602