SPC AC 161736

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1236 PM CDT Sat May 16 2020

   Valid 171200Z - 181200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
   MIDWEST/OHIO VALLEY AND NORTHERN INTERMOUNTAIN WEST...

   ...SUMMARY...
   Isolated severe thunderstorms will be possible Sunday afternoon and
   early evening across parts of the Midwest/Ohio Valley and the
   Northern Intermountain West.

   ...Midwest/Ohio Valley...
   A closed upper low is expected to move slowly southeastward over
   Iowa and Illinois on Sunday. A related surface low should be located
   near the Iowa/Wisconsin/Illinois border vicinity around midday
   Sunday, with an eastward-advancing cold front extending southward
   into Missouri, and a low-preceding warm front across
   Illinois/Indiana into Ohio. It still appears that early-day
   convection/clouds will be considerable and likely limiting factors
   for consequential destabilization within the warm sector and a more
   probable severe threat.

   Likely regulated by convection-related boundaries and differential
   heating, current indications are the most probable phasing of modest
   surface-based destabilization and strengthening low/mid tropospheric
   winds will occur from eastern Illinois into northern/central Indiana
   and northwest Ohio Sunday afternoon. Where modest warm-sector
   destabilization (500-1000 J/kg MLCAPE) occurs within a moist air
   mass Sunday afternoon, moderately strong deep-layer southwesterly
   winds and 35-40 kt effective shear will be sufficient for the
   possibility of a few supercells aside from more prevalent line
   segments. Isolated damaging winds and marginally severe hail will be
   possible. Low-level shear/SRH will also be sufficiently strong for a
   low/conditional tornado risk, particularly if/where pockets of
   somewhat stronger destabilization occur near the warm front.

   ...Northern Intermountain West...
   With a prominent upper trough centered off the coast of the Pacific
   Northwest, the exit region of a moderately strong polar jet will
   influence the northern Intermountain West on Sunday. 
   Modest boundary-layer destabilization is expected Sunday afternoon
   in conjunction with diurnal heating and cooling mid-level
   temperatures, with upwards of 500 J/kg MLCAPE possible. Aided by
   forcing for ascent, storms may initiate across northeast Oregon and
   southeast Washington by 21Z and subsequently spread northeastward
   through early evening. Some of these storms may produce severe hail
   and severe-caliber wind gusts.

   ...East Texas/ArkLaTex to Lower Mississippi Valley...
   An upper low should continue to drift east-southeastward across the
   region and otherwise tend to weaken on Sunday. A few strong to
   locally severe thunderstorms cannot be ruled out across the region
   Sunday afternoon/early evening. However, will defer any severe
   probabilities to the Day 1 time frame given the likelihood of a
   weakening low-peripheral wind field and uncertainties regarding
   diurnal destabilization.

   ..Guyer.. 05/16/2020

   CLICK TO GET WUUS02 PTSDY2 PRODUCT

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z