Mesoscale Discussion 1688
   NWS Storm Prediction Center Norman OK
   0348 PM CDT Tue Sep 08 2020

   Areas affected...Central to Southern Colorado

   Concerning...Heavy snow 

   Valid 082048Z - 090045Z

   SUMMARY...The potential for heavy snow will increase heading into
   the late afternoon and evening hours across southern Colorado.
   Snowfall rates between 1-2 inches/hour appear likely, and heavier
   rates are possible at higher elevations.

   DISCUSSION...Afternoon water vapor imagery continues to show the
   gradual southward progression of an upper-level low along the CO/UT
   border. An embedded impulse can be identified propagating around the
   southern periphery of the low into the Four Corners region. Stronger
   mid and upper-level flow associated with this impulse (as noted in
   regional VADs) is increasing convergence along a frontogenetical
   baroclinic zone between 850-700 mb. The slowing of the upper-level
   low has decreased broad lift ahead of the wave somewhat, but strong
   mesoscale lift along the baroclinic zone is compensating for this
   weakness and will continue to favor widespread precipitation.
   Elevated instability has allowed for several lightning strikes and
   areas of heavier precipitation over the past hour, and RAP forecast
   soundings suggest that 50-100 J/kg MUCAPE may remain in place across
   the region through 00 UTC. 

   As thermodynamic profiles continue to cool via evaporative cooling
   and low-level cold advection, this combination of mesoscale ascent
   and instability should be sufficient for heavy snowfall rates
   between 1-2 inches/hour with heavier rates possible at higher
   elevations by the late afternoon/early evening hours.

   ..Moore.. 09/08/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...PUB...BOU...ABQ...GJT...

   LAT...LON   37480390 37100406 36850474 36740514 36800569 37010626
               37290656 37610673 38270689 38690692 39090686 39300664
               39510574 39400471 39150418 38440399 37480390