638
ACUS11 KWNS 010014
SWOMCD
SPC MCD 010014
MTZ000-010145-

Mesoscale Discussion 1501
NWS Storm Prediction Center Norman OK
0714 PM CDT Sun Jun 30 2024

Areas affected...southern and eastern MT

Concerning...Severe Thunderstorm Watch 492...

Valid 010014Z - 010145Z

The severe weather threat for Severe Thunderstorm Watch 492
continues.

SUMMARY...Ongoing marginal/isolated severe threat should increase in
intensity and perhaps coverage as cells shift northeastward into
eastern Montana this evening. An additional severe thunderstorms
watch may be needed to the east of WW 492.

DISCUSSION...A single, but longer-lived discrete cell has steadily
progressed northeastward across southwest to south-central MT, now
northwest of Billings. This storm has seemingly struggled within the
weak buoyancy and moderate MLCIN environment, despite ample
southwesterly speed shear above 3-km AGL per Billings VWP data.
Downstream over the western Dakotas into eastern MT, a southeasterly
low-level jet is consistently progged to strengthen substantially
over the next few hours. This will result in increasing forcing for
ascent coupled with low-level moistening that should yield greater
MLCAPE/diminishing MLCIN. It remains plausible that the convection
northwest of Billings should intensify as this occurs. But given
recent observational trends, confidence has lowered on the degree of
convective coverage as depicted by afternoon guidance. Still, an
increase in severe may occur at some point this evening and a
downstream watch is being considered.

..Grams/Smith.. 07/01/2024

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

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

LAT...LON   45041306 45751096 46410966 47090878 48080773 48580676
            48430556 47560500 46890497 46130774 44601283 45041306