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ACUS11 KWNS 141949
SPC MCD 141948

Mesoscale Discussion 0121
NWS Storm Prediction Center Norman OK
0248 PM CDT Wed Mar 14 2018

Areas affected...Eastern Nevada...western Utah

Concerning...Severe potential...Watch unlikely

Valid 141948Z - 142215Z

Probability of Watch Issuance...5 percent

SUMMARY...Strong thunderstorm activity is expected to develop,
particularly by the 4-6 PM MDT time frame.  Some storms may become
accompanied by a risk for strong gusty winds and perhaps severe

DISCUSSION...Ahead of large-scale upper troughing progressing inland
across the Pacific coast, insolation beneath a cold (and cooling)
mid-level environment is contributing to boundary layer
destabilization across much of the Great Basin.  Although this may
remain generally weak to modest in magnitude, it may become
maximized in corridor across far eastern Nevada into the vicinity of
the Wasatch mountains, within a plume of relatively higher
precipitable water (in excess of .5 inches).  Model output indicates
that this will coincide with strengthening forcing for large-scale
ascent associated with a short wave trough now turning across and
northeast of the southern Sierra Nevada.

Scattered deepening convective development is ongoing, with isolated
thunderstorms already in the process of forming.  It appears that
this may continue another couple of hours, before a more substantive
increase in coverage and intensity commences during the 22-00Z time
frame.  Activity will tend to move northeastward in the presence of
southwesterly deep layer mean flow in excess of 40 kt (perhaps
approaching 50 kt).

Although the boundary layer may not be particularly deeply mixed,
downward mixing of higher momentum in downdrafts may still
contribute to strong surface gusts at least approaching severe
limits.  It does appear that vertical shear could support the
evolution of isolated supercell structures, which would provide the
most appreciable risk for any hail reaching severe limits.  A
tornado may not be completely out of the question, though this
potential still seems rather low.

..Kerr/Hart.. 03/14/2018

...Please see for graphic product...


LAT...LON   39691452 41101365 41071204 38441285 37541422 37901485
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