817
ACUS01 KWNS 031254
SWODY1
SPC AC 031252

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0752 AM CDT Fri May 03 2024

Valid 031300Z - 041200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NEAR THE
WEST TEXAS CAPROCK ONTO ADJOINING LOW ROLLING PLAINS...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED AREA...AND OVER PORTIONS OF THE CENTRAL PLAINS...

...SUMMARY...
Large hail and damaging gusts are possible over parts of the
central/southern Great Plains from southern Nebraska to west Texas,
along with some tornado potential over parts of west Texas.

...Synopsis...
Today`s transitional mid/upper-level synoptic pattern is a tale of
two cyclones -- one astride the Upper Midwest/Canadian border, and
another digging southeastward out of the Gulf of Alaska.  The broad,
complex leading cyclone will eject northeastward over MB and
northwestern ON through the period.  A trailing shortwave trough --
apparent in moisture-channel imagery over parts of southern ID and
northern NV -- will move east-northeastward to eastern SD and
central NE by 12Z tomorrow.  The strong, well-developed Pacific
cyclone will proceed southeastward to just off the coast of OR by
the end of the period.  Southwest flow aloft will be maintained with
weak synoptic-scale height rises over most of the central/southern
Plains.  Still, sufficient moisture, buoyancy, lift and shear are
apparent for a couple relative maxima in severe potential as
discussed below.

At the surface, 11Z analysis showed a low attached to a cold front
over south-central WY.  The front should proceed southeastward
through the day, extending from southeastern SD to western NE an
central CO by 00Z, with the low over northeastern CO.  By 12Z
tomorrow, the front should extend from a low over IA to south-
central KS, the northern TX Panhandle, and north-central NM.  This
front will overtake a developing dryline over the central High
Plains from north-south, with the dryline position at 00Z over
eastern CO, the western TX Panhandle, and Permian Basin.  A weak/
residual, nearly stationary front extended from a low near FST
northeastward across northwest TX, eastern OK and the Ozarks, and
should continue to lose definition amidst considerable convective
outflow.  The southern rim of that outflow was evident from
southeast TX (between GLS-BPT) across the HOU metro then west-
northwestward to near SJT.  The western part will shift northward
slowly through the day toward the front, which itself should drift
northward up the Caprock.

...West/southwest TX...
Widely scattered to scattered thunderstorms are expected to form
this afternoon near the dryline and the residual outflow boundary
over the South Plains to Low Rolling Plains/Concho Valley regions.
Isolated to widely scattered convection possible farther south off
the dryline past the Rio Grande, and into strongly heated/CINH-
minimized higher terrain of the Serranias del Burro range in
northern Coahuila.  This activity should move eastward across areas
below the Caprock and around the Big Country to Edwards Plateau,
with potential for some of the Mexican convection to cross the Rio
Grande this evening as well.  Supercells -- with large to very large
hail and at least isolated potential for tornadoes -- will be more
probable in and near the 30%/"enhanced" hail area.  Dryline and
orographic activity to the south will be an early hail/wind threat.
Some of this activity may aggregate into clusters offering mainly
strong-severe gusts, with one or two small MCSs possible this
evening into the early overnight hours.

Despite multiple days of MCS and smaller-scale convective activity
to the east and southeast, a reservoir of rich low-level moisture
remains not far upstream across south-central TX and into the
southern Edwards Plateau, where upper 60s to low 70s F surface
dewpoints and PW commonly 1-1.5 inches.  When advected northwestward
amid diurnal heating and beneath steep midlevel lapse rates,
3000-4000 J/kg MLCAPE should become common.  Though low-level flow
should not be particularly strong, it will be backed, contributing
to elongated hodographs ad around 30-40 kt effective-shear
magnitudes.  Splitting storms may be common early, offering the
greatest hail potential (size and coverage).  The damaging-wind
threat will be maximized on the mesoscale where organized cold pools
can develop, and should extend farther east at greater density than
the hail potential this evening into tonight.  In the absence of
substantial large-scale support, tornado potential will be locally
maximized with any supercells that can interact favorably with
outflow boundaries or each other.

...Central Plains...
Large hail and severe gusts are possible from mid/late afternoon
into tonight, from thunderstorms shifting eastward across portions
of the central Plains.  Though nowhere nearly as moist as the TX
outlook area, a diurnally destabilized plume of moist advection
should support a secondary relative max in severe potential
along/ahead of the cold front and dryline from parts of eastern CO
to western/northern KS and southern NE.  Convection should develop
by mid/late afternoon in a regional convergence maximum near and
northeast of the surface low, with MLCINH weakened by favorable
diurnal heating.  Surface dewpoints in the 40s to low 50s F should
be common, with steep surface-500-mb lapse rates, 500-1000 J/kg
MLCAPE and well-mixed subcloud layers.  Effective-shear magnitudes
around 40-50 kt indicate potential for organized convection -- both
in quasi-linear form near the front and initially discrete (but
later merging upscale) off the dryline.  Though activity will
encounter a more-stable boundary layer with time and eastward extent
across KS/NE, at least marginal severe-gust potential may last
overnight as far eastward as parts of the Missouri Valley region.

..Edwards/Broyles.. 05/03/2024

$$