Feb 23, 2017 1730 UTC Day 2 Convective Outlook
Updated: Thu Feb 23 17:30:46 UTC 2017 (20170223 1730Z Day 2 shapefile | 20170223 1730Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170223 1730 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 59,124 16,948,809 Detroit, MI...Indianapolis, IN...Columbus, OH...Toledo, OH...Cincinnati, OH...
SLIGHT 88,346 13,483,190 Cleveland, OH...Akron, OH...Sterling Heights, MI...Lansing, MI...Flint, MI...
MARGINAL 115,516 21,952,513 Chicago, IL...Nashville, TN...Pittsburgh, PA...Buffalo, NY...Grand Rapids, MI...
Probabilistic Graphic
20170223 1730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 2 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 59,124 16,976,826 Detroit, MI...Indianapolis, IN...Columbus, OH...Toledo, OH...Cincinnati, OH...
15 % 88,227 13,739,848 Cleveland, OH...Akron, OH...Sterling Heights, MI...Lansing, MI...Flint, MI...
5 % 115,901 21,852,515 Chicago, IL...Nashville, TN...Pittsburgh, PA...Buffalo, NY...Rochester, NY...
   SPC AC 231730

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1130 AM CST Thu Feb 23 2017

   Valid 241200Z - 251200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION
   OF THE OHIO VALLEY AND GREAT LAKES...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE GREAT LAKES...OHIO AND TENNESSEE VALLEYS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE GREAT
   LAKES THROUGH THE OHIO AND TENNESSEE VALLEYS...

   ...SUMMARY...
   Severe thunderstorms are forecast to affect portions of the southern
   Great Lakes, Ohio and Tennessee Valleys on Friday and Friday night. 
   The primary threat appears to be damaging wind, but a couple of
   tornadoes and some hail are also possible.

   ...Synopsis...

   Upper trough will amplify as it approaches the OH Valley Friday
   afternoon and evening. A strong mid-level jet will rotate through
   the base of the trough and into the OH Valley and Great Lakes during
   the evening. Attendant cyclone will move from the middle MS Valley
   at the start of the period into lower MI by evening. Trailing cold
   front will surge southeast and continue through the OH and TN
   Valleys overnight. A warm front extending eastward form the low will
   lift north through the Great lakes.

   ...Great Lakes, Ohio and Tennessee valleys...

   Current observations show low-level moisture remains limited over
   the Gulf Coast states with dewpoints generally in the 50s. Raob data
   from 12Z this morning shows a substantial decrease in moisture above
   the surface in that region. This suggests moist advection associated
   with cyclogenesis and its strengthening southwesterly low-level jet
   will be weak with dewpoints likely to remain in the 50s which is the
   main potential limiting factor. Despite limited moisture, steeper
   mid-level lapse rates associated with cold air aloft and a modest,
   eastward-expanding EML along with some diabatic warming will
   contribute to marginal instability with 400-800 J/kg MLCAPE likely
   to develop in the pre-frontal warm sector. The warm sector will
   remain capped most of the day, but thunderstorm initiation is
   expected along and just ahead of the front by late afternoon or
   early evening as deeper forcing for ascent within the divergent exit
   region of the upper jet overtakes the cold front. Initial discrete
   cells with some supercell structures are possible given 45+ kt
   effective shear. However, storms should have a tendency to evolve
   into linear structures along the cold front. Wind profiles are
   forecast to be largely unidirectional and primary threat should be
   damaging wind, but a couple of tornadoes are also possible with any
   initial discrete development as well as with possible QLCS
   meso-vortices.  

   Elsewhere, storms will be ongoing north of the warm front across the
   Great Lakes, and additional storms may develop in vicinity of this
   boundary during the day. Most of this activity will be elevated, but
   some threat for hail will exist with the stronger storms developing
   near the surface front.

   ..Dial.. 02/23/2017

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0700Z