SPC Aug 13, 2017 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0801 PM CDT Sat Aug 12 2017

Valid 130100Z - 131200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PART OF THE
CENTRAL PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
CENTRAL AND NORTHERN PLAINS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS NORTH TX
TO NORTHWEST LA...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN
MD AND ADJACENT EASTERN VA...

...SUMMARY...
Scattered severe storms will continue this evening across portions
of the central and northern Plains, while the overall severe storm
threat will undergo further diminishing in the Northeast and
Mid-Atlantic states.  The exception should be in central and
southern Maryland, where the threat for severe storms could persist
until 02Z (10 PM EDT).

...Central and northern Plains...
A progressive shortwave trough will shift east across the Dakotas
tonight.  Height falls ahead of this trough will result in a
strengthening southerly low-level jet from the central High Plains
through central NE to the eastern Dakotas this forecast period. 
This low-level jet combined with veering winds with height as
westerly mid-level winds attendant to the Dakotas trough increase
some will sustain strong effective bulk shear for additional storm
organization into the early overnight.  Given the presence of
residual moderate instability, and deep-layer forcing for ascent
with the height falls and warm air advection along the strengthening
low-level jet, strong to severe storms are expected to persist this
evening into the early overnight from eastern CO and northwest KS
into central NE.  Farther north across central SD and southern ND,
weakening instability should result in a diminishing severe-weather
threat, though will maintain a marginal severe risk for mainly this
evening.

...North TX to the Arklatex region...
Low-level warm air advection is expected to increase this forecast
period into the Arklatex region within the nose of a strengthening
southerly low-level jet.  This combined with forcing for ascent
attendant to a progressive Red River Valley mid-level impulse should
support continued thunderstorm development through this evening and
tonight.  Residual moderate instability in vicinity of an east to
west oriented surface front and sufficient bulk shear will favor an
isolated severe threat, mainly this evening, with strong/damaging
wind gusts.

...Mid-Atlantic to Northeast states...
Although the overall severe-weather threat will continue to diminish
this forecast period, an isolated threat for strong to severe storms
will persist in the short term across southern MD and a small part
of adjacent eastern VA.  CAPE/shear parameter space favor a
continued severe risk this evening, though this threat will weaken
by late evening.

..Peters.. 08/13/2017

Read more

from SPC Forecast Products http://ift.tt/rxAC6Z