Jun 17, 2017 1630 UTC Day 1 Convective Outlook
Updated: Sat Jun 17 16:37:25 UTC 2017 (20170617 1630Z Day 1 shapefile | 20170617 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170617 1630 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 69,039 7,949,449 Kansas City, MO...St. Louis, MO...Overland Park, KS...Kansas City, KS...Springfield, IL...
SLIGHT 198,611 30,248,980 Chicago, IL...Indianapolis, IN...Tulsa, OK...Wichita, KS...Toledo, OH...
MARGINAL 306,036 20,646,413 Detroit, MI...Memphis, TN...Milwaukee, WI...Cincinnati, OH...Lexington-Fayette, KY...
Probabilistic Tornado Graphic
20170617 1630 UTC Day 1 Tornado Probabilities Graphic
Probability of a tornado within 25 miles of a point.
Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
2 % 87,618 7,843,829 Kansas City, MO...St. Louis, MO...Overland Park, KS...Kansas City, KS...Topeka, KS...
Probabilistic Damaging Wind Graphic
20170617 1630 UTC Day 1 Damaging Wind Probabilities Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point.
Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 62,029 5,636,107 Kansas City, MO...Overland Park, KS...Kansas City, KS...Topeka, KS...Springfield, IL...
30 % 61,307 7,356,667 Kansas City, MO...St. Louis, MO...Overland Park, KS...Kansas City, KS...Springfield, IL...
15 % 205,465 30,287,273 Chicago, IL...Indianapolis, IN...Tulsa, OK...Wichita, KS...Toledo, OH...
5 % 305,343 21,401,069 Detroit, MI...Memphis, TN...Milwaukee, WI...Cincinnati, OH...Lexington-Fayette, KY...
Probabilistic Large Hail Graphic
20170617 1630 UTC Day 1 Large Hail Probabilities Graphic
Probability of hail 1" or larger within 25 miles of a point.
Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SIG SEVERE 68,711 5,250,861 Kansas City, MO...Wichita, KS...Overland Park, KS...Kansas City, KS...Topeka, KS...
30 % 56,108 5,457,471 Kansas City, MO...Overland Park, KS...Kansas City, KS...Springfield, IL...Olathe, KS...
15 % 186,829 30,111,284 Chicago, IL...Indianapolis, IN...Tulsa, OK...Wichita, KS...St. Louis, MO...
5 % 284,602 15,753,280 Detroit, MI...Milwaukee, WI...Shreveport, LA...Dayton, OH...Rockford, IL...
   SPC AC 171637

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1137 AM CDT Sat Jun 17 2017

   Valid 171630Z - 181200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER EASTERN
   KANSAS ACROSS NORTHERN/CENTRAL MISSOURI INTO CENTRAL ILLINOIS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
   CENTRAL/EASTERN KANSAS AND EASTERN OKLAHOMA ACROSS THE MIDDLE
   MISSISSIPPI VALLEY INTO INDIANA AND SOUTHERN LOWER MICHIGAN...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
   PLAINS TOWARD THE SOUTHERN GREAT LAKES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE EASTERN
   DAKOTAS INTO MINNESOTA...

   ...SUMMARY...
   Severe thunderstorms are expected late this afternoon into tonight,
   mainly from the central Plains across the middle Mississippi Valley
   into southern Lower Michigan, with damaging gusts and hail likely. 
   Isolated severe thunderstorms also are possible this afternoon over
   parts of the Dakotas and Minnesota.

   ...Central Plains across the middle Mississippi Valley into southern
   Lower Michigan...
   Prior convection from yesterday/last night has modified the
   environment across this region with slightly lower surface dew
   points evident this morning.  However, thinning clouds across much
   of this corridor from Kansas into Illinois will promote stronger
   diabatic heating to occur this afternoon, and some recovery of
   low-level moisture with increasing surface dew points from Missouri
   eastward is likely this afternoon.  12Z soundings over the Plains
   maintain steep lapse rates that will spread eastward toward the
   Mississippi Valley this afternoon, contributing to moderate/strong
   instability with MLCAPE ranging from 3500-4000 J/kg over eastern
   Kansas to 1500-2000 J/kg over in the Indiana/Michigan region.  The
   presence of the EML is also likely to delay convective initiation
   from Kansas into Missouri until the late afternoon/evening.

   As a short wave trough over the northern high plains moves
   southeastward in response to stronger west-northwest winds in the
   mid/upper levels, flow over the central plains and mid-Mississippi
   Valley will strengthen enhancing deep layer shear over the region. 
   Model guidance is reasonably consistent indicating that storms are
   likely to develop near an advancing cold front, initially over
   southeast Iowa/northern Missouri, then gradually developing westward
   along/near the front into parts of central/eastern Kansas late this
   afternoon and evening.  The strong instability coupled with 35-45 kt
   deep layer shear will support development of multiple clusters/lines
   of severe storms capable of producing large hail with significant
   hail possible, especially during the early stages of storm
   maturation, and damaging winds as activity moves eastward and
   southeastward through the evening hours.  There are indications that
   some bowing line segment will develop which may promote significant
   wind gusts mainly during the evening hours.

   Farther west over the central High Plains, model consensus indicates
   convective coverage will be more isolated with a few storms
   developing from extreme northeast Colorado area moving southeastward
   into parts of western Kansas.  A deep mixed layer/steep lapse rates
   will be favorable for strong/severe wind gusts and possible hail
   late this afternoon and evening.

   ...Eastern Oklahoma into Eastern Texas and Southwest Louisiana...
   A small complex of strong/severe storms continues to move southward
   into southeast Oklahoma.  The air mass in advance of the activity is
   continuing to warm/destabilize, although a capping inversion on the
   12Z SHV sounding associated within EML provides some uncertainty
   regarding the persistence of the system into the afternoon.  A low
   probability of severe storms has been added into eastern Texas to
   account for this scenario, with potential for additional strong
   storms to develop as far south as southwest Louisiana.

   ...Eastern Dakotas, Minnesota...
   Behind the surface cold front, widely scattered to scattered
   thunderstorms are expected to develop this afternoon with the risk
   for isolated severe hail and gusts.  This potential will be
   supported by the strengthening large-scale ascent and deep shear
   associated with the approaching northern-stream trough in mid/upper
   levels, overlying diabatically minimized afternoon MLCINH and weak
   convergence near a surface trough.  Though conditions will be
   seasonally cool at the surface, with temps in the 60s and dew points
   50s F, this still will support MLCAPE 500-1000 J/kg, with some areas
   of effective-shear magnitudes reaching 30-35 kt.  This threat should
   abate quickly after dark as the boundary layer stabilizes, due to a
   combination of cold advection and diabatic cooling.

   ..Weiss/Cohen.. 06/17/2017

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