Severe Storm Outlook Narrative (AC)
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000
ACUS03 KWNS 250655
SWODY3
SPC AC 250654

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0154 AM CDT Sun Jun 25 2017

Valid 271200Z - 281200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
NEBRASKA INTO SOUTH DAKOTA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
THE NORTHERN PLAINS INTO THE CENTRAL HIGH PLAINS...

...SUMMARY...
Areas of severe thunderstorms capable of large hail and damaging
wind are expected over much of central and western Nebraska as well
as South Dakota during the late afternoon and evening on Tuesday.
Isolated severe storms are also possible from eastern Colorado into
western Kansas.

...Synopsis...
A shortwave trough will move from the northern Rockies toward the
upper MS Valley on Tuesday as a larger-scale upper trough finally
exits the OH Valley and clears the East Coast by 12Z Wednesday. At
the surface, high pressure will move from the middle MS Valley into
the central Appalachians, with low pressure developing over the
northern and central Plains. Southerly surface winds will bring
near-60 F dewpoints northward into the Dakotas by 00Z Wednesday,
with a 50+ kt low-level jet developing overnight ahead of a cold
front. The combination of increasing wind profiles and moisture will
likely result in a few areas of severe storms beginning Tuesday
afternoon across the northern High Plains, and spreading eastward
through Tuesday night.

...Northern Plains into the central High Plains...
Strong heating in combination with cooling aloft will lead to
steepen lapse rates with MUCAPE to around 2000 J/kg likely
developing east of a developing cold front. This front will roughly
extend from the Black Hills into north-central CO by 21Z Tuesday,
and will gradually progress across central SD and NE overnight.
Storms are expected to form along this front with a mixed mode of
storms expected, including a few supercells given sufficiently long
hodographs and a low-level jet increasing late. Large hail will be
the main threat, along with damaging winds as one or more small
MCS`S are anticipated overnight.

Isolated activity may extend southward along the dryline across
eastern CO into western KS, with a supercell or two producing hail
before capping increases during the evening.

..Jewell.. 06/25/2017

$$



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