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SPC Aug 16, 2017 1300 UTC Day 1 Convective Outlook

SPC 1300Z Day 1 Outlook
      
Day 1 Outlook Image
Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0750 AM CDT Wed Aug 16 2017

Valid 161300Z - 171200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS EASTERN KS AND
WESTERN MO...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS MID-MS VALLEY TO
OK...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS UPPER MIDWEST TO
WEST TX...

...SUMMARY...
Scattered to numerous severe storms are likely from Iowa to
Oklahoma, mainly late afternoon and evening. Large hail, damaging
winds, and a couple tornadic storms are expected.

...Upper Midwest to southern Great Plains...
Confidence has increased regarding a probable corridor for severe
storms across eastern KS into northwest MO late afternoon and early
evening. This corridor has been upgraded to Enhanced risk.
Otherwise, both Slight and Marginal risks have been expanded
southwest along the cold front and dryline in OK and west TX. 

An extensive but largely decaying swath of convection is ongoing
across parts of the Mid/Lower MO Valley. Remnants of this activity
may intensify both downstream and in its wake across parts of the
Upper Midwest later today. While diurnal destabilization should be
limited in this region, a veering wind profile with height and
adequate low-level shear may yield transient updraft rotation and a
risk for all hazards. Should greater destabilization become
apparent, parts of this region may be upgraded to Slight risk in
later outlooks.

While the cold front lies across western KS and central NE in the
wake of the decaying MCS, outflow should stall over parts of eastern
KS. The intersection of the remnant outflow and front should be a
genesis region for storm development during the mid/late afternoon.
To its south, large buoyancy should become prevalent with a plume of
MLCAPE reaching 2500-3500 J/kg. While most model soundings depict
weaknesses in the wind profile around 700 mb, deep-layer shear will
be sufficient for rotating updrafts.  While outflow-dominated
supercells may prevail, the potential exists for several storms to
produce large hail, some of which may be significant. A 2-3 hour
time window may also exist for a couple tornadic storms as 850-mb
southwesterlies increase to 30-40 kt. However, orientation of the
front nearly parallel to the mean wind should result in an
increasingly predominant cluster to linear mode in the evening.
Severe wind and some hail should be the primary threats with one or
more MCSs persisting east/south across parts of MO and OK.

..Grams/Dial.. 08/16/2017

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