Jul 16, 2018 1300 UTC Day 1 Convective Outlook
Updated: Mon Jul 16 12:40:57 UTC 2018 (20180716 1300Z Day 1 shapefile | 20180716 1300Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180716 1300 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 89,440 437,180 Casper, WY...North Platte, NE...Scottsbluff, NE...Sterling, CO...Riverton, WY...
MARGINAL 275,671 20,470,874 Detroit, MI...Cleveland, OH...Toledo, OH...Buffalo, NY...Rochester, NY...
Probabilistic Tornado Graphic
20180716 1300 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 % 60,121 276,877 Casper, WY...Scottsbluff, NE...Torrington, WY...Douglas, WY...
Probabilistic Damaging Wind Graphic
20180716 1300 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 % 70,432 351,771 Casper, WY...North Platte, NE...Scottsbluff, NE...Sterling, CO...Torrington, WY...
5 % 292,790 20,573,457 Detroit, MI...Cleveland, OH...Toledo, OH...Buffalo, NY...Rochester, NY...
Probabilistic Large Hail Graphic
20180716 1300 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 21,866 80,715 No Major Population Center in Risk Area
15 % 74,831 339,387 Casper, WY...Scottsbluff, NE...Riverton, WY...Lander, WY...Torrington, WY...
5 % 135,159 1,758,120 Fort Collins, CO...Greeley, CO...Longmont, CO...Rapid City, SD...Loveland, CO...
   SPC AC 161240

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0740 AM CDT Mon Jul 16 2018

   Valid 161300Z - 171200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL HIGH
   PLAINS AND BLACK HILLS...

   ...SUMMARY...
   Scattered severe storms are expected across parts of the central
   High Plains and Black Hills regions from late afternoon into
   tonight. Large hail and strong to severe wind gusts should be the
   main hazards.

   ...WY/Western NE/Southwest SD...
   A perturbation embedded within a low-amplitude shortwave trough over
   the Pacific Northwest will move east from southern ID towards the
   central High Plains through this evening. Attendant weak large-scale
   ascent should aid in scattered storm development by late afternoon
   across the higher terrain of WY and the Black Hills. Within a
   confluent belt of upper-level westerlies enhanced in between the
   Pacific Northwest trough and a substantially more amplified trough
   over Ontario, elongated hodographs are anticipated to overlap with
   the eastern periphery of the elevated mixed-layer characterized by
   steep mid-level lapse rates near 8 C/km. With a moderately buoyant
   air mass expected across western SD/NE into eastern WY, the setup
   should favor a few discrete mid-level mesocyclones. The
   longer-lasting of which may be those that move south-southeast from
   western SD into the NE Panhandle. Large hail, potentially reaching
   tennis-ball size, along with isolated severe wind gusts should be
   the primary hazards.

   During the evening, this activity will likely grow upscale as
   moderate low-level southerlies strengthen to around 30 kt over the
   central High Plains. This should result in a southward-propagating
   cluster with mainly a strong to isolated severe wind risk in western
   NE before weakening overnight in the northwest KS/northeast CO
   vicinity.

   ...Eastern Great Lakes...
   Scattered storm development is expected across Lower MI this
   afternoon and continuing east of the Lower Great Lakes tonight
   through early Tuesday. Strong mid-level westerlies will lag behind
   the surface cold front, but brief overlap of the warm sector with
   modest effective shear values of 25-30 kt may support transient/weak
   updraft rotation in a few cells. With weak mid-level lapse rates and
   unfavorable nocturnal timing of frontal impingement east of the
   lower lakes, setup will probably only yield localized strong gusts
   capable of tree damage.

   ..Grams/Smith.. 07/16/2018

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z