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SPC Day 1 Outlook

















Sep 13, 2021 0100 UTC Day 1 Convective Outlook
Updated: Mon Sep 13 00:30:16 UTC 2021 (Print Version | 20210913 0100Z Day 1 shapefile | 20210913 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table

 Forecast Discussion
   SPC AC 130030

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0730 PM CDT Sun Sep 12 2021

   Valid 130100Z - 131200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN LOWER
   MICHIGAN ACROSS CENTRAL NEW YORK...

   ...SUMMARY...
   Scattered strong to severe thunderstorms remain possible from Lower
   Michigan into the Northeast States. Isolated severe cells remain
   possible over eastern Colorado into far western Kansas.

   ...Lower MI into the Northeast...
   A fast-moving complex of storms is currently moving into eastern
   Lower MI, and is situated along and north of a synoptic boundary
   which extends eastward into NY. Low-level lapse rates remain poor
   across the entire region, as seen on 00Z soundings. However, the
   moist boundary layer has deepened as well, which is eroding
   inhibition from below. Given strong midlevel winds near 60 kt and
   sufficient elevated instability, a few bows remain possible. In
   addition to the threat with the ongoing activity over Lower MI, weak
   theta-e advection around 850 mb and a strong westerly low-level jet
   may induce additional storms along/north of the boundary this
   evening. Damaging gusts or a few hail reports will be possible.

   ...Eastern CO into western KS...
   Isolated cells persist this evening over eastern CO and are
   gradually drifting east toward the KS border. 00Z soundings from LBF
   and DDC show warm layers aloft which will limit the eastward extent
   of the severe risk. For a few hours, localized severe wind or hail
   will remain possible. For more information see mesoscale discussion
   1734.

   ..Jewell.. 09/13/2021

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