SPC AC 081630

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1030 AM CST Thu Feb 08 2024

   Valid 081630Z - 091200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM FAR EASTERN
   IOWA EASTWARD TO SOUTHWESTERN PARTS OF LAKE MICHIGAN...

   ...SUMMARY...
   A few strong/severe thunderstorms remain possible this afternoon
   through early evening across parts of far eastern Iowa, northern
   Illinois, far southern Wisconsin, and the southern Lake Michigan
   vicinity.

   ...Synopsis...
   A mid-level short-wave trough now crossing the Middle Missouri
   Valley/central Plains will continue progressing northeastward today
   and tonight, while a second feature now in the vicinity of the Lower
   Colorado Valley shifts eastward through the period.  Meanwhile,
   upper ridging over the East will be shunted progressively eastward
   by the aforementioned advance of short-wave troughs farther west.

   At the surface, a rather deep (990 mb) surface cyclone is currently
   analyzed near the ND/SD/MN border intersection, with a cold front
   extending southward across the Middle Missouri Valley into Kansas. 
   This boundary, and the advance of the upper trough, may support
   isolated late afternoon strong/potentially severe convective
   development across eastern Iowa/northwestern Illinois.

   Elsewhere, showers and scattered thunderstorms are expected to
   evolve across the Four Corners states ahead of the aforementioned
   upper trough, and overnight thunder may evolve within an area of
   broad/weak QG ascent over parts of the Lower Mississippi and
   Tennessee Valleys.  Severe weather is not expected in these areas. 

   ...Eastern Iowa/northern Illinois/southern Wisconsin vicinity...
   Low-level moisture remains a primary uncertainty today, with respect
   to potential strong/severe storm development.  Dewpoints remain in
   the upper 30s/low 40s across the Iowa/Illinois area, where model
   forecast soundings -- particularly the RAP -- have consistently
   indicated upper 40s to low 50s dewpoints by late afternoon.  This
   degree of moistening still appears to be a bit aggressive, with
   middle to upper 40s largely anticipated.  

   With that said, very cold air aloft/steep lapse rates will continue
   to overspread this region, and the deep-layer wind field is
   conditionally quite supportive of severe/supercell storms.  At this
   time, we will maintain MRGL risk and all-hazard, low-probability
   outlook.  A couple of storms may develop by late afternoon, in the
   eastern Iowa/northwestern Illinois vicinity, and then shift
   eastward/east-northeastward through early evening, before weakening.

   However, evolution of moisture through the day will be closely
   watched, as the more aggressive RAP model solution -- should it
   appear more likely to occur -- would require consideration for an
   upgrade to the outlook at 20Z.

   ..Goss/Thornton.. 02/08/2024

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