Jul 16, 2018 0600 UTC Day 1 Convective Outlook
Updated: Mon Jul 16 05:58:21 UTC 2018 (20180716 1200Z Day 1 shapefile | 20180716 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20180716 1200 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 103,617 535,844 Casper, WY...North Platte, NE...Gillette, WY...Sheridan, WY...Scottsbluff, NE...
MARGINAL 222,410 19,901,321 Detroit, MI...Cleveland, OH...Toledo, OH...Buffalo, NY...Rochester, NY...
Probabilistic Tornado Graphic
20180716 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20180716 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 % 103,617 535,844 Casper, WY...North Platte, NE...Gillette, WY...Sheridan, WY...Scottsbluff, NE...
5 % 222,410 19,901,321 Detroit, MI...Cleveland, OH...Toledo, OH...Buffalo, NY...Rochester, NY...
Probabilistic Large Hail Graphic
20180716 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 % 232,201 2,494,504 Fort Collins, CO...Greeley, CO...Rapid City, SD...Loveland, CO...Cheyenne, WY...
   SPC AC 160558

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1258 AM CDT Mon Jul 16 2018

   Valid 161200Z - 171200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   WYOMING INTO THE CENTRAL/NORTHERN HIGH PLAINS AREA...

   ...SUMMARY...
   Locally severe storms are expected this afternoon and tonight from
   portions of the Intermountain West into the central/northern High
   Plains area, where potential for damaging winds and possibly hail
   will exist.  A marginal threat for locally damaging winds is also
   apparent across portions of the Great Lakes area.

   ...Synopsis...
   Modest flow aloft will continue to prevail over the southern half of
   the U.S., where upper ridging will persist.  Meanwhile farther
   north, a short-wave trough crossing the Intermountain West and a
   second/larger trough expanding across eastern Canada and the
   northeast quarter of the U.S. will allow modestly stronger westerly
   flow to evolve across portions of the northern half of the country.

   At the surface, a cold front is forecast to move slowly east across
   the Great Lakes region, while sagging southeastward across the
   Midwest/Ohio valley and southward across the Ozarks and Oklahoma
   through the daylight hours.  By Tuesday morning, the front should
   extend in an arc from central Quebec southwest across the Lower
   Great Lakes and Upper Ohio Valley into the Mid South, westward
   across Arkansas and Oklahoma, and then northwestward across the High
   Plains.

   ...Parts of the Idaho vicinity eastward across Wyoming into western
   Nebraska and surrounding areas...
   As a mid-level short-wave trough moves gradually eastward out of the
   northwestern U.S. into the Idaho/Wyoming vicinity, modest mid-level
   cooling atop a diurnally warming boundary layer will result in
   moderate afternoon destabilization.  Instability will become most
   pronounced across central/eastern Wyoming and into the High Plains,
   where a more moist boundary layer is anticipated in the vicinity of
   the northwest-to-southeast frontal zone.  

   Storm development is expected during the afternoon aided by
   increasing large-scale ascent, with a few stronger cells possibly
   evolving as far west as the southern Idaho/northwest Nevada region,
   but likely more numerous farther east into Wyoming.  With
   enhanced/30-40 kt mid-level westerlies spreading across the area
   atop a low-level easterly component, shear sufficient for
   organized/possibly rotating storms should evolve.  As such,
   potential for locally damaging winds and possibly hail will likely
   accompany stronger cells.

   As a southerly low-level jet evolves over the High Plains during the
   evening, most CAM output suggests varying degrees of
   congealing/upscale growth of convection, possibly resulting in an
   MCS shifting east-southeast out of eastern Wyoming into the
   southwest South Dakota/western Nebraska and possibly northeast
   Colorado area through the evening and into the overnight hours. 
   Presuming this evolution manifests, potential for damaging winds may
   extend into the overnight hours.

   ...The eastern Upper Great Lakes and Lower Great Lakes area...
   Modest destabilization ahead of the slowly advancing cold front will
   support considerable shower/thunderstorm development across parts of
   the eastern Upper Great Lakes/Midwest region during the afternoon. 
   Though stronger mid-level cyclonic flow will remain farther north
   across Ontario and Quebec, 25 to 30 kt mid-level westerlies should
   overspread the warm sector north of the Ohio River Valley,
   supporting potential for locally stronger/organized storms.  With
   both CAPE and shear expected to remain sub-optimal for a more
   widespread severe risk, will maintain only MRGL/5% severe
   probability across areas in the vicinity of the Great Lakes, mainly
   for gusty/locally damaging wind potential.  Storms -- and limited
   wind potential -- will spread eastward with time in conjunction with
   the slow frontal advance, affecting portions of Pennsylvania and New
   York through the evening and possibly into the overnight hours.

   ..Goss/Squitieri.. 07/16/2018

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