SPC 1200Z Day 1 Outlook

Day 1 Outlook Image

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1223 AM CDT Sat Oct 10 2020

Valid 101200Z - 111200Z


A few tornadoes are possible on Saturday across parts of the Gulf
States.  Severe gusts are also expected across parts of northern New
York into western Maine.

...Tropical Cyclone Delta...

Tropical Cyclone Delta continues its northeast movement across LA
early this morning. As TC Delta lifts into northwest MS later by
18z, significant mid-level drying will surge east and the primary
corridor of deepest convection should become focused from
south-central AL into west-central GA.

Latest model guidance does not allow appreciable buoyancy to develop
immediately ahead of Beta over northern MS, and forecast soundings
strongly suggest updrafts will struggle to attain heights necessary
for lightning. Even so, strong low-level shear warrants at least low
probabilities for locally strong winds or perhaps a brief tornado.
Otherwise, the primary focus for more robust convection should focus
downstream where partial breaks in cloud cover should allow for some
boundary-layer heating and appreciably more instability, especially
from southern AL into west-central GA. While this region will be
along the eastern fringe of stronger low-level shear, forecast
soundings exhibit adequate shear for supercells. Have extended
wind/tornado probabilities downstream into the stronger region of
instability where adequate shear will exist for sustained, robust
updrafts. A few tornadoes and gusty winds are possible with this

...NY to ME...

Early-morning water-vapor imagery depicts at least two distinct
short-wave troughs over ON. The lead feature will quickly shift into
QC as the upstream short wave digs southeast toward the
international border region later this afternoon. Focused mid-level
height falls will spread across QC/northern New England with more
appreciable falls expected after 11/00z over ME. A plume of
higher-PW air will be drawn ahead of the front prior to this wind
shift advancing south of the Canadian border. It appears warm-sector
temperatures will warm quickly ahead of the front which will lead to
convective development as minimal surface convergence will be needed
for parcels to reach their LFC. Latest HREF supports this and
scattered thunderstorms should evolve along the boundary across
southeast ON/northern NY by 18z then spread southeast as the front
surges toward New England. Increasingly westerly flow will favor the
potential for gusty winds with this convection. With the mean flow
expected to be parallel with this frontal convection, this could
lessen more intense bow-type structures. For this reason, will
maintain 15 percent severe wind probabilities.

..Darrow/Moore.. 10/10/2020

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