Jul 26, 2017 0600 UTC Day 1 Convective Outlook
Updated: Wed Jul 26 05:42:21 UTC 2017 (20170726 1200Z Day 1 shapefile | 20170726 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170726 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 63,521 4,490,274 Des Moines, IA...Rockford, IL...Cedar Rapids, IA...Topeka, KS...Peoria, IL...
MARGINAL 166,157 21,006,784 Chicago, IL...Milwaukee, WI...Kansas City, MO...Omaha, NE...St. Louis, MO...
Probabilistic Tornado Graphic
20170726 1200 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 % 22,889 1,099,814 Des Moines, IA...St. Joseph, MO...West Des Moines, IA...Ankeny, IA...Urbandale, IA...
Probabilistic Damaging Wind Graphic
20170726 1200 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
15 % 64,049 4,673,262 Des Moines, IA...Rockford, IL...Cedar Rapids, IA...Topeka, KS...Peoria, IL...
5 % 165,590 20,942,452 Chicago, IL...Milwaukee, WI...Kansas City, MO...Omaha, NE...St. Louis, MO...
Probabilistic Large Hail Graphic
20170726 1200 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
5 % 86,689 7,073,807 Kansas City, MO...Omaha, NE...Lincoln, NE...Des Moines, IA...Overland Park, KS...
   SPC AC 260542

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1242 AM CDT Wed Jul 26 2017

   Valid 261200Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
   THE UPPER MIDWEST...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
   OF THE CENTRAL PLAINS INTO THE UPPER GREAT LAKES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A PORTION
   OF NEVADA INTO SOUTHERN OREGON...

   ...SUMMARY...
   Scattered thunderstorms, a few capable of producing locally strong
   to severe wind gusts, are expected over portions of the Upper
   Midwest region this afternoon and evening. Storms may also produce a
   few locally strong to damaging wind gusts from a portion of Nevada
   into southern Oregon.

   ...Synopsis...

   Belt of modest westerlies will persist over the northern and central
   Plains through the Great Lakes. Embedded within this regime, an MCV
   currently over South Dakota will continue east through the upper MS
   Valley.  Farther west the cutoff upper low over northern CA will
   deamplify as it begins to shift northeast through northwest NV and
   southeast OR in response to an approaching upstream trough.  At the
   surface a cold front will move southeast through the upper
   Mississippi Valley and Great Lakes region with southwestern
   extension of this boundary continuing through the central Plains.
   Warm front will shift slowly eastward through the middle and upper
   MS Valley region ahead of the cold front.

   ...Upper Midwest through central Plains regions...

   Thunderstorms now over the central Plains will develop east into the
   upper MS Valley supported by a southwesterly low-level jet and MCV,
   but will probably undergo some decrease in coverage later this
   morning. Downstream from this activity an extensive cirrus plume may
   delay or slow diabatic warming of the moist warms sector, but the
   atmosphere should become moderately unstable with 1500-2000 J/kg
   MLCAPE from northern KS through southern half of IA into northern
   IL. Storms will likely redevelop along residual outflow boundaries
   along and ahead of the cold front as atmosphere destabilizes. Some
   mesoscale enhancement in the winds aloft and vertical shear might
   occur in association with the MCV/shortwave trough, with effective
   bulk shear generally from 25-40 kt. However, tendency will be for
   storms to evolve into clusters and line segments with damaging wind
   the primary threat, though some hail will also be possible with the
   stronger storms.  

   ...Western Nevada through southeast Oregon...

   High-based storms will likely once again develop in this region in
   association with upper low circulation as the atmosphere
   destabilizes during the afternoon into the evening. Deeply mixed
   inverted-V boundary layers will support a risk for a few downburst
   winds through early evening.

   ..Dial/Dean.. 07/26/2017

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z