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.
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
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