SPC AC 171609

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1109 AM CDT Mon Jul 17 2017

   Valid 171630Z - 181200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   MINNESOTA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST
   PENNSYLVANIA INTO VERMONT...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE CENTRAL AND NORTHERN PLAINS AND UPPER MIDWEST...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE NORTHEAST STATES...

   ...SUMMARY...
   Isolated severe thunderstorms are expected this afternoon and
   evening across northern and central Minnesota, and during the day
   from Pennsylvania into New York and Vermont. Additional
   strong/severe storms may occur today and tonight across parts of
   South Dakota, Nebraska, and northwest Kansas.

   ...Minnesota Vicinity...
   Morning water vapor imagery shows a shortwave trough moving across
   ND toward MN.  Models remain consistent in the development of
   scattered afternoon thunderstorms over eastern ND/western MN, with
   storms moving rapidly eastward across the SLGT risk area.  Strong
   heating is occurring in this zone, while dewpoints climb into the
   mid/upper 60s.  This will yield afternoon MLCAPE values over 2500
   J/kg with little cap.  Forecast soundings also indicate favorable
   wind fields, with effective shear values over 35 knots and
   considerable low-level shear.  These parameters should encourage the
   development of rotating/bowing storm structures capable of damaging
   winds and large hail.  12z CAM solutions suggest the potential for a
   fast-moving bowing complex moving into the Arrowhead region this
   evening.

   ...PA/NY/VT...
   Current visible satellite imagery shows mostly clear skies with a
   growing cu field from central PA across southeast NY into central
   New England today.  This corridor should become moderately unstable
   with MLCAPE values over 1500 J/kg.  Thunderstorms are expected to
   form relatively early this afternoon over parts of PA/NY and move
   eastward across the SLGT risk area.  Mid-level lapse rates are
   moderately steep, and winds in the upper-levels are favorable. 
   However, relatively weak winds through much of the lower-half of the
   convective layer lend some uncertainty regarding the overall severe
   risk today.  Nevertheless, the stronger cells and bowing lines this
   afternoon will pose a risk of gusty/damaging winds and hail.

   ..Hart/Picca.. 07/17/2017

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z