Severe Storm Outlook Narrative (AC)
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829
ACUS01 KWNS 301652
SWODY1
SPC AC 301650

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1150 AM CDT Thu Mar 30 2017

Valid 301630Z - 311200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE
MIDWEST/OHIO VALLEY...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO
VALLEY/MIDWEST AND GULF COAST/SOUTHEAST STATES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE OHIO
VALLEY/MIDWEST AND GULF COAST/SOUTHEAST STATES...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE GREAT
BASIN...

...SUMMARY...
Scattered severe storms are most likely across the Midwest and
Tennessee Valley this afternoon into evening, with other severe
storms along the central Gulf Coast. Damaging winds, a few
tornadoes, and hail will be possible in these areas.

...Midwest and Ohio/Tennessee Valleys...
A closed mid/upper-level low will continue a slow general eastward
progression from the lower MO Valley and Ozarks toward the lower OH
River Valley through tonight. A related surface low will continue to
develop east-northeastward from east-central MO into central IL,
while a warm front advances northward across eastern IL and much of
IN/OH. Overall buoyancy will remain modest today and cloud cover has
remained semi-prevalent into midday across the warm sector. However,
some cloud breaks are noted near/just east of the MS River with
mid/upper 50s and some lower 60s F surface dewpoints otherwise
expected to expand northward in tandem with the warm front.

As gradual air mass destabilization occurs, storms may first
intensify across far eastern MO into southern IL just ahead of the
surface low and in concert with the aforementioned cloud breaks at
late morning. Additional warm sector or near-warm-frontal-related
development should also occur this afternoon into IN/OH this
afternoon, while other storms should form near the cold front across
KY/TN. While buoyancy will not be robust in most areas, long/largely
unidirectional hodographs, albeit with some near-1km AGL hodograph
curvature, will support a mixed mode including supercells and fast
northeastward-moving bows. Severe hail and damaging winds will be
possible, with a least some tornado risk as well, particularly near
the warm front where low-level SRH will be maximized.

...Gulf Coast States/lower MS River Valley...
12Z Upper-air data and contemporary surface observations/visible
satellite imagery show that considerable convective overturning has
occurred across parts of the region via an overnight/early morning
MCS. Ahead of a slow-moving convective cluster across southeast MS
and coastal eastern LA at late morning, the main severe risk should
be confined to far southeast MS into southern AL/FL panhandle and
eventually southwest GA. For additional short-term details, see
Mesoscale Discussion 377.

Farther west, in the wake of the early-morning MCS, some additional
development may occur near the north/south-oriented cold front this
afternoon. However, persistent cloud cover, modest
moisture/buoyancy, and limited near-frontal convergence all imply
that any near-frontal severe risk later this afternoon/evening
should remain limited across the lower MS Valley vicinity.

...Great Basin...
A band of showers and isolated storms is expected to form along a
strong cold front attendant to an amplifying shortwave trough.
Although buoyancy will be scant, well-mixed thermodynamic profiles
ahead of the front should support downward momentum transport of
robust flow aloft and may yield isolated severe wind gusts.

..Guyer.. 03/30/2017

$$



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