Severe Storm Outlook Narrative (AC)
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ACUS48 KWNS 180848
SPC AC 180846

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0346 AM CDT Fri Aug 18 2017

Valid 211200Z - 261200Z

Subtropical ridging may remain prominent across much of the central
and southern tier of the U.S. through much of next week.  However,
the latest medium range model output suggests that an initially
zonal belt of westerlies, near the Canadian/U.S. border early next
week, may undergo amplification by mid week.  This appears likely to
include a digging large-scale upper trough across the Great Lakes
region, accompanied by a significant cold front, which could
progress through much of the central and eastern U.S. by the end of
the work week.  Forcing for ascent along and ahead of the cold front
may be accompanied by considerable thunderstorm development.  At the
present time, it seems that this may be favorably timed with peak
diurnal boundary layer destabilization across the southern/lower
Great Lakes region into the Ohio Valley, to support severe storm
development Tuesday into Tuesday night.  Severe weather potential
across areas farther south and east becomes more uncertain by
Wednesday, as the front may advance across southern New England and
northern Mid Atlantic coastal areas as early as mid day, and
stronger lower/mid tropospheric wind fields shift
north/northeastward toward the Canadian Maritimes.

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