Severe Storm Outlook Narrative (AC)
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ACUS01 KWNS 260539
SWODY1
SPC AC 260538

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Mon Jun 26 2017

Valid 261200Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL ROCKIES EASTWARD INTO THE SOUTHERN AND
CENTRAL HIGH PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE PACIFIC NORTHWEST...

...SUMMARY...
Thunderstorms with marginally severe hail and strong wind gusts are
possible late this afternoon into early evening across parts of the
Pacific Northwest and from the southern and central Rockies eastward
into the High Plains.

...Southern and Central High Plains/Southern and Central Rockies...
An upper-level ridge will be in place from the Four Corners region
into the northern Rockies with northwest mid-level flow over the
High Plains. At the surface, southeasterly flow will help maintain a
moist airmass across the southern and central High Plains. Models
again forecast moderate instability to develop this afternoon from
the foothills of the southern and central Rockies eastward into the
High Plains. As surface temperatures warm, isolated to scattered
thunderstorms should initiate in the higher terrain of central and
northern New Mexico and in the lower elevations of eastern New
Mexico, southeastern Colorado and western Kansas. In addition to the
instability, forecast soundings show substantial directional shear
and steep lapse rates in the low to mid levels. This will likely be
enough for a few marginally severe storms accompanied with hail and
strong wind gusts. The threat should be concentrated in the late
afternoon and early evening.

...Pacific Northwest...
An upper-level trough will move to the West Coast today as a cold
front advances eastward into the Pacific Northwest. Ahead of the
front, a narrow corridor of maximized low-level moisture is forecast
to set up from southwestern Oregon northeastward into southeastern
Washington and northern Idaho. As surface temperatures warm during
the day, moderate instability is forecast to develop in this zone
with isolated to scattered convection initiating in the late
afternoon. In addition to low-level instability, mid-level lapse
rates are forecast to be steep. This combined with substantial speed
shear in the low to mid levels may be enough for a few marginally
severe storms with hail and strong wind gusts.

..Broyles/Mosier.. 06/26/2017

$$



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