Apr 18, 2017 2000 UTC Day 1 Convective Outlook
Updated: Tue Apr 18 19:51:31 UTC 2017 (20170418 2000Z Day 1 shapefile | 20170418 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170418 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 114,492 4,285,955 Omaha, NE...Lincoln, NE...Salt Lake City, UT...West Valley City, UT...Provo, UT...
Probabilistic Tornado Graphic
20170418 2000 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20170418 2000 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
5 % 37,611 2,292,689 Salt Lake City, UT...West Valley City, UT...Provo, UT...West Jordan, UT...Orem, UT...
Probabilistic Large Hail Graphic
20170418 2000 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 % 76,869 1,991,617 Omaha, NE...Lincoln, NE...Council Bluffs, IA...Bellevue, NE...Grand Island, NE...
   SPC AC 181951

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0251 PM CDT Tue Apr 18 2017

   Valid 182000Z - 191200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
   NEBRASKA AND VICINITY...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION
   OF EAST-CENTRAL NEVADA INTO NORTHERN AND CENTRAL UTAH...

   ...SUMMARY...
   Isolated strong/damaging gusts will be possible this
   afternoon/evening from eastern Nevada into central/northern Utah. 
   Overnight, isolated large hail will be possible across parts of
   Nebraska and vicinity.

   ...Discussion...
   With prior forecast reasoning/areas still representing the expected
   evolution of convective weather today and tonight, no appreciable
   changes are required to the outlook at this time.

   ..Goss.. 04/18/2017

   .PREV DISCUSSION... /ISSUED 1115 AM CDT Tue Apr 18 2017/

   ...Eastern NV into central/northern UT this afternoon/evening...
   A mid-upper speed max now approaching central CA will move over
   NV/UT by this evening.  An associated surface cold front will cross
   eastern NV and UT this afternoon/evening, providing a focus for
   thunderstorm development.  Though buoyancy will be weak, ascent
   along the front will support a band of convection in an environment
   of strong deep-layer vertical shear and steep low-level lapse rates.
   The stronger storms in the band could produce isolated
   strong/damaging outflow gusts.

   ...NE area tonight...
   In the wake of shortwave trough crossing MN this morning, a
   baroclinic zone will stall near the KS/NE border as lee cyclogenesis
   begins this afternoon across eastern CO.  The boundary layer will
   likely remain capped along the front through the afternoon. 
   Tonight, residual boundary-layer moisture (55-60 F dewpoints) along
   and south of the front will contribute to destabilization above the
   surface in a strengthening warm-advection regime, as a shortwave
   trough approaches the High Plains.  Elevated thunderstorm
   development tonight, in an environment with MUCAPE near 1000 J/kg
   (rooted in the 850-700 mb layer), will pose a risk for isolated
   large hail.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z