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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0744 AM CDT Fri Sep 09 2022

Valid 091300Z - 101200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHEAST AND UPPER GREAT LAKES...

...SUMMARY...
Isolated marginally severe storms may occur across parts of the
Southeast and Upper Great Lakes.

...Synopsis...
An unusual upper-air pattern will persist through the period,
featuring a Y-shaped split ridge extending from central MX northward
to west TX, branching northwestward over the Great Basin and coastal
Northwest, and northeastward across the mid Mississippi Valley.  To
the southwest, Tropical Storm (TS) Kay is expected to turn away from
northwestern Baja and weaken. [See NHC advisories for the latest
track, intensity and tropical watch/warning information on Kay.]

To the southeast, a broad, weak cyclone is evident in moisture-
channel imagery covering much of the central and eastern Gulf Coast
States to parts of GA and FL, with its center over southeastern LA. 
This gyre will weaken slowly through the period with a slow net
northward motion.  A series of small, weak perturbations (some
convectively induced) will move north-northeastward from the eastern
Gulf over parts of AL, GA and the FL Panhandle, with a plume of
relatively maximized 500-250-mb flow and enhanced mid/upper-level
moisture.

North of the ridge, a strong, northern-stream trough is apparent
from a cyclone over the northwestern Hudson Bay region,
southwestward across MT to northern UT.  The synoptic trough is
expected to shift slowly eastward through the period, reaching
eastern ND, western SD, and central/northern CO by 12Z tomorrow. 
Several mesoscale, convectively enhanced/induced vorticity lobes and
shortwaves will eject northeastward away from the height axis,
mainly across the Dakotas, MN, northern WI and western Lake
Superior, and behind the surface cold front.

At 11Z, that front was analyzed from western lake Superior
southwestward through weak lows near MSP, SUX and SPD, westward into
the Sangre de Cristo Mountains of CO.  By 00Z, the front should
extend from eastern Lake Superior across northern WI, central/
southwestern IA, and central/southwestern KS, to near the eastern
CO/NM border.  By 12Z, the front should reach eastern Upper MI,
eastern WI, north-central MO, southwestern OK, the TX South Plains,
and southeastern NM.  In the southeast, a low was drawn near PFN,
with trough east-northeastward over the JAX area.  A diffuse,
quasistationary front was located north of the trough from southern
SC over central GA, southwestern AL, and southeastern LA.  The
trough should shift northward today and effectively blend with the
frontal zone over parts of SC and GA, to coastal areas of AL/MS.

...Southeast...
Widely scattered to scattered thunderstorms should beco*e co*mon
across a broad swath of the eastern Gulf and southeastern CONUS,
with the greatest (but still marginal) unconditional potential for
damaging wind or a brief tornado in the outlook area.  Convection
will develop beneath strongly difluent upper flow and in a corridor
of favorably rich moisture near and south of the front/trough. 
Surface dewpoints in the upper 60s to low 70s F and PW above 2
inches will be co*mon.  Even with insolation-driven heating limited
to patchy/episodic nature by multi-level cloud cover over the
region, MLCINH will be weak, supporting surface-based convective
potential with only subtle lift needed.  High theta-e in the
boundary layer will offset modest lapse rates aloft, enough to
support MLCAPE in the 500-1500 J/kg range.  Though surface winds
will remain weak, low-level shear should be relatively maximized
near the trough (though still marginal for transient supercell
structures).

...Upper Great Lakes...
Isolated to scattered, elevated thunderstorms continue this morning
in bands and clusters, oriented behind and nearly parallel to the
surface front.  Activity will continue to develop episodically into
this evening in a regime of low-level warm advection and elevated
frontal forcing to LFC, and near the eastern rim of favorable
cooling/DCVA aloft.  These factors should overco*e residual EML-
related MUCINH in an environment of marginal buoyancy (MUCAPE
generally under 800 J/kg) and favorable deep shear (effective-shear
magnitudes 40-50 kt).  Hail near severe limits will continue to be
the main concern.

...Inland southern CA to southwestern AZ...
NHC forecasts TS Kay -- now centered just offshore from the
northwestern Baja Peninsula -- to continue weakening as its track
gradually moves further leftward/northwestward over unfavorably cold
Pacific waters.  A prominent outer band of convection has been
apparent in satellite imagery and Yuma, AZ radar for several hours
over the relatively warm northern Gulf of California and northern
Baja, where it is intercepted by mountains.  As the center of Kay
turns away from land, the northward co*ponent of the band's progress
should slow, with uncertainty as to how much (if any) may reach the
international border before low-level hodographs and SRH beco*e too
small to support substantive supercell potential.  At this time,
forecast soundings and cyclone structure still suggest wind fields
and convective organization will be too weak north of the border to
draw an unconditional tornado outlook.

..Edwards/Bunting.. 09/09/2022