May 22, 2018 1730 UTC Day 2 Convective Outlook
Updated: Tue May 22 17:30:16 UTC 2018 (20180522 1730Z Day 2 shapefile | 20180522 1730Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180522 1730 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 425,431 9,002,469 Virginia Beach, VA...Raleigh, NC...Norfolk, VA...Chesapeake, VA...Lubbock, TX...
Probabilistic Graphic
20180522 1730 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 2 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
5 % 425,744 9,040,454 Virginia Beach, VA...Raleigh, NC...Norfolk, VA...Chesapeake, VA...Lubbock, TX...
   SPC AC 221730

   Day 2 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   1230 PM CDT Tue May 22 2018

   Valid 231200Z - 241200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE HIGH
   PLAINS AND VA/NC REGION...

   CORRECTED FOR THUNDER LINE ACROSS MAINE

   ...SUMMARY...
   Isolated severe thunderstorms are possible Wednesday afternoon
   across the High Plains and eastern portions of Virginia/North
   Carolina.

   ...Synopsis...
   Upper low currently centered over the western Great Basin will
   gradually shift northeastward toward the central Rockies today while
   becoming even more progressive/open on Wednesday. By 12Z Thursday,
   the resulting shortwave trough will likely extend from central
   Alberta into northeast MT. In response to this upper system,
   cyclogenesis is anticipated across southeast MT with the resulting
   low tracking northward across eastern MT Wednesday night/early
   Thursday morning.

   Farther east, upper ridging initially extending from the Southeast
   into the Canadian Prairie provinces will build throughout the day
   with some minor eastward progression. At the surface, expansive area
   of high pressure will drift from the mid MS/lower OH Valley
   northeastward across the Upper Great Lakes.

   ...High Plains...
   Surface lee troughing coupled with persistent southerly low-level
   flow will continue to encourage moisture return across the Plains
   and High Plains. Additionally, southwesterly mid-level flow will
   advect steep mid-level lapse rates into the region with the
   resulting airmass characterized by moderate instability (i.e. MLCAPE
   around 1500 J/kg). Vertical shear will be fairly weak across
   southern portions of the region while slightly stronger mid-level
   flow will contribute to modestly higher values across the central
   and northern High Plains. 

   Forcing for thunderstorm development is a bit more nebulous with the
   strongest height falls moving through northern portions of the area
   early in the period before diurnal destabilization. Primary forcing
   for convective initiation across the majority of the High Plains
   will likely be surface convergence along the lee trough. There is
   some potential for an outflow boundary across SD, resulting from
   early period, mostly elevated storms, to provide an additional area
   of convergence and lift. 

   Confidence in the intensity and coverage of thunderstorms is still
   too low to increase severe probabilities above 5%. At this point,
   the two most probable locations for a potential increase in
   probabilities appear to be across eastern MT where a developing warm
   front may enhance low-level vertical shear and across far
   southeastern WY and adjacent portions of southwest SD and the NE
   Panhandle where the strong surface convergence is forecast to align
   with relatively higher instability and shear.

   ...Mid-Atlantic...
   Cold front extending southwestward from southern NJ across central
   VA to middle TN is expected to shift southeastward throughout the
   day. Temperatures ahead of the front will likely reach the mid-80s
   amidst dewpoints in the upper 60s, which is supportive of airmass
   destabilization and modest instability. Vertical shear supports a
   predominately linear multicell mode with isolated damaging wind
   gusts possible as a result of water loading within the strongest
   updrafts.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:   2%     - Marginal
   Wind:      5%     - Marginal
   Hail:      5%     - Marginal

   ..Mosier.. 05/22/2018

   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z