SPC AC 011251

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0651 AM CST Wed Mar 01 2017

   Valid 011300Z - 021200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM CENTRAL
   KENTUCKY AND MIDDLE TENNESSEE INTO THE CUMBERLAND GAP...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS
   OF THE TENNESSEE VALLEY INTO THE CENTRAL APPALACHIANS AND
   MID-ATLANTIC STATES...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   MISSISSIPPI EASTWARD INTO THE CAROLINA PIEDMONT AND INTO PARTS OF
   THE NORTHEAST...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   SLIGHT RISK...

   ...SUMMARY...
   Widespread wind damage is forecast across parts of Kentucky and
   Tennessee this morning.  Severe thunderstorms will continue to
   spread across the Ohio and Tennessee Valley regions into the Middle
   Atlantic states, possibly into southern New England by mid
   afternoon.  Damaging winds are the primary severe threat, though a
   few tornadoes and hail will be possible, especially west of the
   Appalachians.

   ...KY-TN eastward into the Mid-Atlantic states...
   Radar imagery early this morning shows an extensive squall line from
   the upper OH Valley southwestward into portions of west-central KY
   and middle TN.  The southern portion of the squall line has had a
   several-hour history of widespread measured severe gusts as it
   tracked from eastern AR into western KY/TN.  A MCV associated with
   this part of the line is forecast to move downstream within a belt
   of 80-90 kt 500-mb flow.  It seems likely the greatest concentration
   of severe gusts and swaths of wind damage will align from near the
   I-65 corridor in TN/KY to the spine of the Appalachians by late this
   morning (16z)---resulting in higher wind probabilities and a
   moderate risk.  It appears increasingly likely destabilization will
   not be inhibited by prior storm activity from the southern half of
   WV east-northeastward into the D.C and DelMarVa areas.  CAM
   guidance, in particular the 01/00z NSSL WRF, appears to have a
   relatively good depiction of the evolving convective lines through
   12z this morning.  Storm-scale guidance moves a squall line into the
   I-95 corridor during the early afternoon (roughly 18-21z) coincident
   with appreciable diurnal destabilization and steepening of low-level
   lapse rates and becoming more favorable for momentum transfer.  In
   addition to the risk for widespread damaging winds, the
   stronger/longer-lived mesovortices embedded within the line may
   yield a weak tornado risk.

   In wake of the early-day squall line over TN, additional storm
   development is possible across the TN Valley south of where
   convective overturning and significant stabilization has occurred. 
   The strong wind profile will strongly favor storm organization. 
   Hail, wind, and possibly some tornado risk could develop before
   upscale growth occurs across AL/GA with isolated damaging winds
   becoming the primary threat towards evening.

   ...northern half of PA into NY and southern New England...
   Destabilization this morning will likely be hindered appreciably as
   widespread cloud cover stunts surface heating.  As the northern
   portions of the squall line over northwestern PA and the upper OH
   Valley pushes eastward this morning, a corresponding risk for strong
   to possibly severe gusts may accompany the line.

   ..Smith.. 03/01/2017

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