Storm Prediction Center Mesoscale Discussion 1445

   Mesoscale Discussion 1445
   NWS Storm Prediction Center Norman OK
   0118 PM CDT Thu Jun 27 2024

   Areas affected...Portions of central and eastern Montana

   Concerning...Severe potential...Watch likely 

   Valid 271818Z - 272045Z

   Probability of Watch Issuance...80 percent

   SUMMARY...The severe-storm threat will gradually increase from west
   to east across portions of central and eastern Montana this
   afternoon. Large hail and severe gusts are the main concerns. A
   watch will likely be needed for parts of the area later this
   afternoon.

   DISCUSSION...Latest water-vapor imagery indicates a band of
   large-scale ascent overspreading west/central MT -- ahead of a
   midlevel trough/low tracking eastward across the Northwest. At the
   leading edge of this ascent, isolated to widely scattered
   thunderstorms are tracking east-northeastward along the higher
   terrain in west/central MT. Over the next several hours, this
   activity will continue spreading eastward across central into
   eastern MT, generally in tandem with the large-scale ascent.
   Additional development is also possible in areas of differential
   heating farther east. Ample diurnal heating/destabilization beneath
   steep midlevel lapse rates (sampled by 12Z regional soundings) will
   erode remaining low-level inhibition and promote a gradual uptick in
   updraft intensity through the afternoon. 

   Around 50 kt of effective shear associated with the
   eastward-advancing trough will support storm organization, and a
   mostly straight hodograph should favor a mix of splitting supercell
   structures and organized clusters. Large hail (some potentially 2+
   inches) and severe outflow winds are possible with the strongest
   storms. The risk of severe gusts (some 75+ mph) should increase with
   eastward extent, especially with any upscale-growing clusters. While
   a brief tornado cannot be entirely ruled out in this area, the
   more-favorable tornado environment should generally develop over
   areas farther east (far eastern MT into the Dakotas), where richer
   boundary-layer moisture and curved hodographs are expected. 

   A watch is likely for portions of the area later this afternoon,
   though timing of issuance is a bit uncertain at this time.

   ..Weinman/Hart.. 06/27/2024

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

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

   LAT...LON   46320967 46920906 47200870 47580813 47800768 48110706
               48290651 48430569 48330512 47910473 46990450 46390455
               45770483 45470550 45220700 45160853 45240924 45430965
               45710987 46030989 46320967