Mesoscale Discussion 1723
   NWS Storm Prediction Center Norman OK
   0316 PM CST Fri Dec 21 2018

   Areas affected...Washington DC area northward into north-central
   Pennsylvania

   Concerning...Severe potential...Watch unlikely 

   Valid 212116Z - 212215Z

   Probability of Watch Issuance...5 percent

   SUMMARY...A threat for brief, mostly sub-severe wind gusts will
   persist with storms migrating across the region over the next couple
   of hours or so.  A WW issuance is not anticipated for this activity.

   DISCUSSION...Recent radar/satellite imagery and lightning data
   indicate increasing convective coverage and intensity recently -
   particularly within a couple of linear bands over central Maryland
   and adjacent areas of Virginia.  A gust to 41 knots was recently
   reported near Gaithersburg, MD within the past half hour.  These
   storms remain in a strongly sheared environment on the cyclonic side
   of 80-90 kt mid-level flow overspreading the area.  Weak instability
   persists, however, owing to mid/upper 50s F surface dewpoints and
   modest mid-level lapse rates.  Still, organized updrafts within this
   region may result in a few wind gusts approaching but remaining
   below severe thresholds and may cause isolated tree/power line
   damage over the next couple of hours.  Brief updraft rotation may
   also not be completely ruled out especially within individual cells
   as backed low-level flow is contributing to 250-300 m2/s2
   storm-relative helicity.  

   Given the brevity/marginality of the severe threat, a WW issuance is
   not anticipated for this activity.

   ..Cook.. 12/21/2018

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

   ATTN...WFO...CTP...LWX...

   LAT...LON   41847743 41837710 41487683 40357690 39427681 38977679
               38727691 38697726 39217778 39397787 39737807 40397807
               40857803 40977802 41847743