Mesoscale Discussion

SPC MD 1566

MD 1566 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR CENTRAL MONTANA TO NORTHERN WYOMING

Mesoscale Discussion 1566
NWS Storm Prediction Center Norman OK
1221 PM CDT Sat Jul 05 2025

Areas affected...Central Montana to northern Wyoming

Concerning...Severe potential...Watch likely 

Valid 051721Z - 051945Z

Probability of Watch Issuance...80 percent

SUMMARY...Weak convection developing within the northern Rockies
will intensify over the next few hours as it moves into central
Montana and northern Wyoming. Severe thunderstorm watch issuance is
probable early this afternoon as storms pose an increasing severe
threat.

DISCUSSION...Latest GOES visible imagery shows clusters of agitated
cumulus and a few weak thunderstorms developing across far northwest
WY and within the mountain ranges of central MT. Ascent associated
with an approaching upper low combined with continued daytime
heating will promote further development/maturation of convection
over the next several hours. Latest forecast guidance suggests that
lingering inhibition should be largely removed as temperatures climb
into the upper 70s to low 80s. This is expected to occur between
18-20 UTC and should happen as weak/shallow convection overspreads
somewhat richer low-level moisture in place at lower elevations
across central MT to northern WY. This will result in an overall
intensification of thunderstorms during this time frame. Moderate
flow associated with the mid-level wave will support effective shear
values on the order of 30-40 knots. As such, a few supercells appear
likely with an attendant risk for large hail (possibly as large as 2
inches). This threat appears most probable along the MT/WY border
where low-level moisture is relatively higher ahead of a weak
outflow boundary and dewpoints remain in the mid/upper 50s. With
time, increasing boundary-layer depth through the late afternoon
should promote greater cold pool production and gradual upscale
growth with an increasing severe wind threat. Given these concerns,
watch issuance is anticipated in the coming hours as convection
continues to develop.

..Moore/Hart.. 07/05/2025

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

ATTN...WFO...UNR...BYZ...GGW...RIW...TFX...

LAT...LON   44000610 43620651 43550733 43770801 43980841 44540870
            47160899 47580891 47890861 48100805 48130760 48100700
            47850667 45490585 44920578 44390589 44000610 

MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN