Severe Storm Outlook Narrative (AC)
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986
ACUS01 KWNS 261645
SWODY1
SPC AC 261644

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1144 AM CDT Mon Jun 26 2017

Valid 261630Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
PACIFIC NORTHWEST AND NORTHERN ROCKIES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL/SOUTHERN PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS NORTHERN
FL AND SOUTHEAST GA...

...SUMMARY...
Thunderstorms with severe hail and strong wind gusts are possible
late this afternoon into evening across the Pacific Northwest and
Northern Rockies in addition to parts of the Great Plains. Other
strong storms may occur along the coastal southeast States.

...Pacific Northwest/northern Rockies...
Gradually strengthening westerlies aloft are expected over the
region today. This will be as an upper low just off the coast of
northern CA continues east-northeastward and a trough amplifies over
British Columbia, while a convectively related disturbance also
shifts eastward from southeast WA/northern ID into MT. It seems
likely that thunderstorms will increase this afternoon especially
east of the Cascades across central/eastern OR into adjacent
ID/southeast WA, in addition to parts of west-central MT.
Strengthening winds aloft/vertical shear will help support some
sustained east/northeastward-moving storms. Isolated instances of
locally damaging winds will be possible with the strongest storms
along with some hail, particularly across parts of OR into ID where
somewhat greater moisture/destabilization is expected.

...Central Plains/southern High Plains...
Under the glancing influence of the Upper Midwest/Great Lakes
upper-level trough, isolated to widely scattered thunderstorms are
likely to develop by mid/late afternoon within a corridor from
southern NE southward into KS. Although mid-level lapse rates are
not particularly steep by late-June standards, gradually returning
moisture, moderate buoyancy, and supercell-favorable wind profiles
(in the presence of strong northwesterly flow aloft) should allow
for isolated severe thunderstorms capable of severe hail/locally
damaging winds as these storms spread southeastward through the late
afternoon and evening hours.

Elsewhere, as a moist upslope flow regime persists, other storms are
likely to develop/intensify across along the southeast CO/northeast
NM Raton Mesa vicinity and higher terrain of interior NM. In the
presence of moderate buoyancy and 30-35 kt of effective shear, some
of the stronger storms will be capable of hail.

Farther south, one or more remnant MCVs may refocus afternoon
redevelopment, including the possibility of a few stronger storms,
across parts of the TX Edwards Plateau and nearby Transpecos
vicinity.

...North FL/coastal GA...
As weak height falls spread toward the region today, a moist
environment and sea breeze circulations in vicinity of a
stalled/slow-moving front may allow for a few stronger storms this
afternoon capable of downbursts.

..Guyer/Gleason.. 06/26/2017

$$



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