SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0224 PM CDT Thu Mar 16 2023
Valid 162000Z - 171200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER MUCH OF
NORTHEAST TEXAS...SOUTHERN OKLAHOMA...AND INTO THE ARKLATEX AREA...
...SUMMARY...
Scattered severe thunderstorms are expected mainly across southern
Oklahoma and into north-central and northeastern Texas, accompanied
by a risk of large hail and isolated tornadoes.
...Southern OK into TX...
Storms continue to increase in coverage and intensity along the cold
front, now extending from near Tulsa OK to just northwest of Wichita
Falls TX with indications of large hail. These storms are tied to
the cold front which is tending to undercut the cells with cool air.
As a result, storms along this boundary may only have brief tornado
potential as it continues across the Red River, and encounters
larger SRH values.
Elsewhere, storms persist in the warm advection zone over northeast
TX and across the Arklatex, but temperatures are currently cool
which is limiting instability and tornado potential. With time, more
unstable air may make it into the area, and a few storms could
become supercells. Other warm-sector storms have formed northwest of
Houston where dewpoints are in the upper 60s F, and these may
eventually have severe potential as they move into a better
low-level shear environment. For more information see mesoscale
discussion 292.
A few cells may also produce large hail late this evening and
overnight near the tail end of the front near and east of the Rio
Grande Valley. Here, capping will be a concern and will likely limit
southward extent.
..Jewell.. 03/16/2023
.PREV DISCUSSION... /ISSUED 1100 AM CDT Thu Mar 16 2023/
...Synopsis...
The northern branch of the prevailing split flow across the northern
mid-latitude Pacific into western North America has become rather
amplified. On the lead edge of this regime, models continue to
indicate that mid-level troughing will gradually consolidate across
the northern Great Plains and upper Mississippi Valley/Great Lakes
vicinity. It appears that this will include at least a couple of
smaller scale perturbations contributing to the evolution of a broad
embedded low, and increased phasing with the lower amplitude
southern branch across and east-northeast of the Mississippi Valley.
A notable southern branch perturbation, emerging from the Southwest,
likely will become increasingly sheared as it accelerates through
increasingly confluent mid-level flow across the southern Great
Plains Red River Valley into the lower Ohio Valley today through
tonight. However, this will be accompanied by intensifying
southwesterly flow along this corridor, including 50-70+ kt around
500 mb.
In lower-levels, a broad belt of 30-50 kt south-southwesterly flow
is currently nosing across the southeastern Great Plains toward the
Ohio Valley. However, this is still largely focused along the tight
height/pressure gradient on the western periphery of a prominent
surface ridge, the center of which is forecast to gradually shift
east of the southern Atlantic Seaboard through tonight. Beneath
this regime, dry/potentially cold boundary-air has been maintained
across the Sabine River/Texas Piney Woods through the lower half of
the Mississippi Valley, and models suggest that this will be slow to
modify.
At the same time, another significant cold intrusion is well
underway to the lee of the Rockies, with strong surface pressure
rises already ongoing across much of the Texas/Oklahoma Panhandle
region. The frontal zone on the leading edge of the cold air is
forecast to rapidly advance southward across much of the Red River
Valley and northwest Texas by late this afternoon, into the lower
Mississippi Valley and northwestern Gulf of Mexico by 12Z Friday.
While significant cyclogenesis is forecast along the troughing
between the surface ridges, across the Upper Midwest and Great Lakes
region, it appears that the rapidly advancing trailing cold front
will undercut and cut off the ongoing moist return flow across the
southern Great Plains. Models continue to generally indicate that
this will preclude substantive destabilization across and northeast
of the Ozark Plateau vicinity.
...Southern Great Plains...
There may be some window of opportunity for appreciable
boundary-layer destabilization along/just ahead of the cold front
from southwestern Oklahoma into southeastern Kansas through early
this afternoon. If mid-level cooling becomes sufficient to weaken
inhibition prior to the arrival of the front, thunderstorms capable
of producing mainly severe hail and wind are possible. However,
this risk may be relatively short-lived, with even the potential for
severe hail diminishing fairly quickly as convection is undercut by
the cold front.
At least a somewhat longer-lived risk for severe weather still
appears like it could initiate in response to a corridor of stronger
low-level warm advection near/east-northeast of the intersection of
the cold front and a sharpening dryline. It seems most probable
that this will occur east of the Fort Sill/Wichita Falls vicinities
around 20-21Z, in an environment characterized by sizable
mixed-layer CAPE of 1000-2000+ J/kg, steep-lapse rates and strong
deep-layer shear. This may initially include a few discrete
supercells with potential to produce large hail and perhaps a couple
of tornadoes, before growing upscale into an eastward propagating
cluster or line. How far east the severe weather potential spreads
remains unclear, and will be limited by the tendency to become
undercut by the advancing cold front and/or ingesting less unstable
air with eastward extent into the lower Mississippi Valley.
Otherwise, higher resolution model output, in particular, suggests
that a separate area of strong/severe thunderstorm potential may
develop late this evening near/south through east-southeast of the
Del Rio area. It appears that this may be supported by forcing for
ascent associated with a southern branch perturbation, near/along
the cold front as it reaches the Rio Grande River vicinity.
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