Severe Storm Outlook Narrative (AC)
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995
ACUS11 KWNS 262154
SWOMCD
SPC MCD 262153
MTZ000-270030-

Mesoscale Discussion 1155
NWS Storm Prediction Center Norman OK
0453 PM CDT Mon Jun 26 2017

Areas affected...Portions of central/eastern MT

Concerning...Severe potential...Watch unlikely

Valid 262153Z - 270030Z

Probability of Watch Issuance...5 percent

SUMMARY...A very isolated threat for strong/gusty winds may develop
through this evening. Watch issuance is not expected.

DISCUSSION...Convection has recently intensified across the higher
terrain of the northern Rockies and into the adjacent northern High
Plains, possibly in association with a minor shortwave trough over
western MT/northern ID embedded within large-scale ridging over much
of the western CONUS. The boundary layer has become very well mixed
this afternoon across this region from latest surface observations
and 20Z RAP forecast soundings, and DCAPE estimates now range from
1000 to 1500 J/kg per 21Z RAP Mesoanalysis. VWP from TFX depicts a
modestly veering and strengthening wind profile through mid levels,
with around 30 kt of 0-6 km bulk shear capable of supporting some
modest updraft organization. The thermodynamic environment remains
very marginal, however, with MLCAPE generally 250 J/kg or less.
Regardless, nearly dry adiabatic low-level lapse rates should
support a very isolated strong/gusty convective downdraft wind
threat with developing thunderstorms across central MT though this
evening. Recent runs of the operational HRRR suggest some potential
for one or more small clusters to develop into the northern High
Plains of central/eastern MT over the next few hours. The overall
severe threat will likely remain too isolated to warrant watch
issuance.

..Gleason/Hart.. 06/26/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BYZ...GGW...TFX...MSO...

LAT...LON   45101089 44881210 46471227 47301239 47971258 48481208
            48441003 48320851 47670806 46550789 45530820 45440947
            45101089




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