Severe Storm Outlook Narrative (AC)
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000
ACUS03 KWNS 250730
SWODY3
SPC AC 250730

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Tue Apr 25 2017

Valid 271200Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
SOUTHEAST STATES THROUGH THE OHIO VALLEY AND GREAT LAKES...

...SUMMARY...
At least a marginal risk for a few severe storms will exist from a
portion of the Southeast States into the Ohio Valley and Great Lakes
on Thursday.

...Synopsis...

Lead shortwave trough embedded within a broad synoptic trough will
continue northeast through the Ohio Valley and Great Lakes early
Thursday. Farther upstream, a series of vorticity maxima north of an
evolving upper jet core will advance southeast through the Great
Basin, southern Rockies and southern Plains. At the surface the
cyclone attending the lead shortwave trough will occlude over the
Great Lakes, while trailing cold front continues through the OH and
TN valleys. Trailing portion of this front will stall and return
north as a warm front across TX in response to lee cyclogenesis over
the southern High Plains.

...Southeast States...

Reservoir of richer low-level moisture with dewpoints in the 60s F
will reside over a portion of the Southeast States warm sector
contributing to marginal to moderate instability. It is likely that
a linear MCS will be ongoing over a portion of TN into AL and the FL
Panhandle, and these storms may pose an ongoing risk for mainly
damaging wind as they continue east during the morning into the
early afternoon. Tendency will be for the deeper forcing and
stronger low-mid level winds to develop well north of this region in
association with the shortwave trough moving northeast through the
Ohio Valley and Great Lakes. This may serve as a limiting factor for
a longer duration, organized severe threat. Nevertheless, a slight
risk might be needed for a portion of this region in future updates.

...Ohio Valley and Great Lakes...

The feed of richer low-level moisture will become limited as the
cyclone occludes over the Great Lakes region. However, at least
marginal instability within a strong shear environment will exist in
pre-frontal warm sector, and ongoing storms may pose a risk for a
few instances of mainly isolated damaging wind during the morning
hours.

..Dial.. 04/25/2017

$$



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