U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 291631 
Storm Prediction Center ac 291630 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1130 am CDT Monday Aug 29 2016 

Valid 291630z - 301200z 

..there is a marginal risk of severe thunderstorms across the upper Midwest... 

isolated severe storms with wind and hail will be possible this 
afternoon and evening mainly from central/southern Minnesota into 
Upper Michigan. 

..eastern South Dakota to central/southern Minnesota and Upper Michigan... 
Convection has quickly decayed this morning across south-central 
Minnesota/northern WI into western Upper Michigan...but redevelopment is expected 
later today near a southeastward-moving cold front that will 
generally extend northeast/southwestward across northeast/central Minnesota 
into eastern/south-central South Dakota by early evening. 60s f surface 
dewpoints in conjunction with steep middle-level lapse rates will 
result in moderate to strong buoyancy by middle/late afternoon...with 
MLCAPE likely reaching 2000-3500 j/kg. 

With aid of weak late-day height falls via a shortwave trough over 
northern Manitoba...there should be sufficient near-frontal 
convergence in the presence of weakening inhibition for 
isolated/widely scattered thunderstorm development by late 
afternoon/early evening. Weak low/mid-tropospheric winds should be a 
considerable limiting factor with effective shear expected to be 
20-25 knots or less...although relatively strong high/anvil-level 
westerlies may be a favorable factor. In all...multicell clusters 
capable of severe wind/hail are expected late this afternoon into 
evening. Additionally...presuming sufficient near-frontal heating 
and related steepening of low-level lapse rates...a 
landspout-related brief tornado risk cannot be ruled out 
particularly near the slower-moving portion of the front across 
eastern South Dakota into south-central Minnesota late this afternoon/early evening. 

..la/far East Texas... 
Morning observed upper-air data reflects modestly enhanced easterly 
low-level winds across la on the eastern periphery of a weak low 
that is located off of the Texas coast. North of the ongoing 
near-coastal convection...there is some possibility that enough 
heating/destabilization over inland areas will allow for the 
development and intensification of some westward-propagating strong 
storms this afternoon. Should this occur...some stronger wind gusts 
may be possible. 

.Guyer/picca.. 08/29/2016 


Mesoscale Discussion

acus11 kwns 290245 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 290244 

Mesoscale discussion 1607 
National Weather Service Storm Prediction Center Norman OK 
0944 PM CDT sun Aug 28 2016 

Areas affected...portions of northwest Minnesota 

Concerning...severe potential...watch possible 

Valid 290244z - 290415z 

Probability of watch issuance...40 percent 

Summary...an isolated supercell and attendant damaging wind/tornado 
threat may persist another 1-2 hours. 

Discussion...an isolated...discrete and nearly stationary supercell 
over Polk and Norman counties in northwest Minnesota produced a tornado in the 
last 30 minutes or so. This storm developed near a warm front in low 
level convergent flow. Effective shear near 25-30 knots...while on the 
low end for supercells...will be sufficient to sustain this cell in 
a strongly unstable environment. Effective srh values around 200-300 
m2/s2 per 02z mesoanalysis and mvx vwp...coupled with curved low 
level hodographs in the vicinity of the warm front...will continue 
to support low level rotation. That being said...favorable tornado 
threat appears to be over a small area...and will likely diminish 
with time as boundary layer stabilization ensues. 
Furthermore...given slow forward motion of current isolated cell 
leading to development of surging outflow...and only modest low 
level jet development...additional tornado threat should be limited 
in time as well. Convective trends will continue to be monitored. 

.Leitman/Thompson.. 08/29/2016 

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


Latitude...Lon 47869695 48039664 47949597 47609533 47299519 47049523 
46939549 47009601 47159660 47259673 47589691 47869695