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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0250 PM CDT Fri Oct 18 2024

Valid 182000Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE FOUR CORNERS AND PORTIONS OF THE SOUTHERN HIGH
PLAINS/ROCKIES....

...SUMMARY...
Isolated severe hail, damaging gusts and a tornado or two will be
possible this afternoon and evening over parts of the southern
Rockies and southern High Plains.  An isolated threat for severe may
locally develop from northern Arizona into southwest Colorado.

...20z Update...
The previous outlook remains valid with only minor modifications to
the Thunder area over the West. Thunder chances should steadily
decrease this afternoon/evening as a deep upper cyclone and a
surface cold front translate southeast with the arrival of a colder
and more stable air mass.

...Four Corners...
Across portions of the Four Corners, a band of low-topped convection
has shown occasional stronger embedded features across parts of
northern AZ and far southwestern CO. A few of these storms could
slowly intensify through the afternoon ahead of the upper low and
cold front. While buoyancy is marginal (generally less than 500 J/kg
of MUCAPE), 50-60 kts of deep-layer shear could support a risk for
transient rotating/organized storms capable of locally strong gusts
or a brief tornado from northern AZ, into parts of northern NM and
far southwest CO. The risk should begin to wane early this evening
as the cold front shifts eastward and the already limited buoyancy
is dissipated.

...Southern High Plains/Rockies...
Initially isolated to widely scattered storms, including a few
supercell structures, still appear likely this afternoon and into
the evening hours across portions of the southern High Plains and
Rockies. The stronger storms will potentially be capable of an
isolated risk for hail/wind and perhaps a brief tornado. The
Marginal Risk area remains unchanged, see the prior discussion for
more info.

..Lyons.. 10/18/2024

.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Oct 18 2024/

...Synopsis...
Water-vapor imagery shows a mid- to upper-level low centered over
the NV/UT/AZ border vicinity and this feature will move
east-southeast into northern AZ before nearly stalling later
tonight.  An associated cold front will push east across the Four
Corners through this afternoon.  Farther east, the southwestern
extension of a Midwest front will push southward through eastern CO
before decelerating near the Raton Mesa.

...Northern AZ into southwest CO through this afternoon...
Strong large-scale ascent immediately ahead of the upper low will
gradually shift east across the Mogollon Rim through the early
afternoon.  The 12 UTC Flagstaff, AZ raob showed weak buoyancy but
an enlarged hodograph.  Visible-satellite and radar imagery show
widely scattered deepening convection near the Rim on the northern
extent of a moist axis from the lower deserts into northern AZ. 
Forecast soundings show surface-based buoyancy (100-400 J/kg SBCAPE)
across northern/eastern AZ.  As a result, a couple of shallow
transient-rotating storms may yield short-duration risk for a brief
tornado and/or locally strong gust.  The risk for strong/severe
gusts may extend as far northeast as southwest CO with a stronger
storm or two before cold front passage later today.

...Southern High Plains and escarpments...
Late morning surface analysis and visible-satellite imagery denote a
low-level moisture plume from west TX into eastern NM, where
dewpoints range in the 50s deg F.  Heating through the mid-late
afternoon will yield generally 500-1000 J/kg MLCAPE across eastern
NM.  Model guidance indicates a weakened capping inversion towards
the late afternoon over the Eastern Plains of NM.  Initially
isolated to widely scattered storm coverage during the 21z-00z
window will transition to greater storm coverage towards sunset and
into the overnight, especially over the northeast quarter of NM. 
Despite the time-lagged nature of the forcing associated with the
upper low, storms will mature into the evening.  The stronger storms
will potentially be capable of an isolated risk for hail/wind. 
Where surface-based buoyancy lingers near the escarpment in the
northeast quarter of NM during the early evening, a threat for a
tornado may develop.