May 24, 2018 1730 UTC Day 2 Convective Outlook
Updated: Thu May 24 17:27:44 UTC 2018 (20180524 1730Z Day 2 shapefile | 20180524 1730Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180524 1730 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 61,383 4,148,617 St. Paul, MN...Des Moines, IA...Cedar Rapids, IA...Rochester, MN...Waterloo, IA...
MARGINAL 362,895 24,103,549 Milwaukee, WI...Oklahoma City, OK...Kansas City, MO...Omaha, NE...Tulsa, OK...
Probabilistic Graphic
20180524 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
15 % 61,757 4,258,781 St. Paul, MN...Des Moines, IA...Cedar Rapids, IA...Rochester, MN...Bloomington, MN...
5 % 362,320 23,832,871 Milwaukee, WI...Oklahoma City, OK...Kansas City, MO...Omaha, NE...Tulsa, OK...
   SPC AC 241727

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1227 PM CDT Thu May 24 2018

   Valid 251200Z - 261200Z


   Isolated to scattered severe thunderstorms are possible on Friday in
   parts of the lower Missouri Valley and upper Mississippi Valley. A
   few marginally severe storms are also possible in the southern and
   central Plains, in northern Maine and over the interior Northwest.

   ...Lower Missouri Valley/Upper Mississippi Valley...
   An upper-level trough will move into the lower Missouri Valley and
   upper Mississippi Valley on Friday. At the surface, a cold front
   will advance southeastward into the upper Mississippi Valley
   extending southwestward into the central Plains. Ahead of the front,
   surface dewpoints should generally be in the mid to upper 60s F with
   moderate instability developing by afternoon across much of the
   moist sector. As surface temperatures warm during the day and as
   low-level convergence increases along the front, isolated to
   scattered thunderstorms are expected to initiate. Large-scale ascent
   associated with the upper-level trough will aid convective
   development. Several thunderstorm clusters should develop in the
   afternoon and evening, moving southeastward across the region.

   NAM and GFS forecast soundings suggest the strongest instability
   will be located from central Wisconsin southwestward to southern
   Iowa Friday afternoon. MLCAPE values along this corridor are
   forecast to reach the 2500 to 3500 J/kg range with low to mid-level
   lapse rates approaching 7.5 C/km.  In addition, forecast soundings
   ahead of the front show south-southwest winds at the surface and
   veering winds with height to the northwest at the mid-levels. This
   is forecast to create 0-6 km shear in the 25 to 35 kt range which
   would be sufficient for severe multicells capable of producing wind
   damage and hail. A supercell with isolated large hail and wind
   damage would also be possible in areas that destabilize the most.

   ...Southern and Central Plains...
   An upper-level ridge will move slowly eastward across the Rockies on
   Friday as an upper-level trough moves into the Ozarks. Northwest
   mid-level flow will be in place across the southern and central
   Plains as a cold front advances southeastward into central Kansas
   and the Texas Panhandle. Ahead of the front, a moist airmass will be
   in place with surface dewpoints in the mid to upper 60s F. This
   should result in a corridor of moderate instability by afternoon
   from parts of western Oklahoma into southern and eastern Kansas.
   Although large-scale ascent is forecast to remain weak, low-level
   convergence along the front will aid convective development during
   the mid to late afternoon. Although most of the convection should
   remain isolated, a cluster of storms could organize and persist into
   the evening in areas where mesoscale conditions are favorable.

   NAM and GFS forecast soundings ahead of the front from Clinton, OK
   northeastward to Topeka, KS for 00Z/Sat show MLCAPE values reaching
   the 2500 to 3500 J/kg range with steep low to mid-level lapse rates.
   Winds are forecast to veer with height from the southeast to the
   northwest which could create enough deep-layer shear for a severe
   threat. Hail and strong gusty winds will be possible with cells that
   can develop and persist. However, model forecasts are considerably
   different on how much instability and shear will be available for
   the developing storms on Friday. Also, convective coverage should
   remain isolated due to the limited large-scale ascent. For this
   reason, any severe threat is expected to remain marginal. 

   A shortwave trough and an associated cold front is forecast to
   approach the Northeast during the day on Friday. Ahead of the front,
   surface dewpoints should reach the mid 50s to near 60 F. As surface
   temperatures warm, some instability should develop in central and
   northern Maine by afternoon. In addition, strong deep-layer shear
   will be in place due to a mid-level jet oriented from east to west
   across Quebec. A few thunderstorms may develop in north-central
   Maine on the southern edge of the mid-level jet during the
   afternoon. The strong deep-layer shear may be enough for hail and
   isolated marginally severe wind gusts.

   ...Interior Northwest...
   An upper-level trough will approach the Pacific Northwest Coast on
   Friday. Ahead of the trough, a corridor of instability is forecast
   to develop by afternoon from eastern Oregon northeastward into
   western Montana. Low to mid-level lapse rates will become steep
   along this corridor by late afternoon with isolated to scattered
   thunderstorms developing. The steep lapse rates and relatively cold
   air aloft may be enough for hail and strong gusty winds. Deep-layer
   shear is expected to be too weak for an organized severe threat.

   Tornado:   2%     - Marginal
   Wind:     15%     - Slight
   Hail:     15%     - Slight

   ..Broyles.. 05/24/2018