LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Sun Oct 02 2022
Valid 021200Z - 031200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
FOUR CORNERS INTO THE NORTHERN HIGH PLAINS...
...SUMMARY...
Isolated severe hail and wind-producing storms may occur from
eastern Utah northeast into the northern High Plains during the
afternoon into early evening.
...Synopsis...
An upper low will gradually drift from the northern Rockies toward
the northern High Plains while an upper ridge persists across the
Midwest and a mid-level trough meanders along the Eastern Seaboard
today. Surface high pressure is expected to build across the Upper
Mississippi Valley into New England and expand southward through the
day, promoting large-scale subsidence and suppressing organized
thunderstorm potential. However, adequate deep-layer ascent and
buoyancy should accompany the western trough across the Interior
West towards the High Plains, with isolated to scattered strong
thunderstorms expected through the day, and a few severe
thunderstorms cannot be ruled out by afternoon.
...Four Corners Region to the Northern High Plains...
A mid-level dry slot will encourage a corridor of clearing clouds
and associated diurnal heating from portions of eastern UT to the
northern High Plains by afternoon, encouraging surface temperatures
to rise into the 70s F amid upper 40s to low 50s F dewpoints. 7+
C/km low to mid-level lapse rates should develop atop the
aforementioned surface airmass given boundary-layer mixing, with
MLCAPE approaching 1000 J/kg in spots. Though not overly strong,
30-40 kts of effective bulk shear may materialize and overlap the
narrow corridor of instability as a belt of 40 kt 500 mb flow pivots
around the upper low and overspreads the Intermountain West. Point
forecast soundings depict modestly curved low-level hodographs, with
the hodograph above 3 km elongating. As such, a mix of multicells
and short linear segments will be the main modes of convection,
though a few transient supercells are possible, mainly during the
afternoon. The steep lapse rates suggest that a couple of the
stronger cellular storms may briefly produce severe hail while
clustering storms/line segments may support a couple of severe
gusts, particularly wherever cold pool mergers/upscale growth can
occur.
..Squitieri/Kerr.. 10/02/2022
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