SPC AC 271952

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0252 PM CDT Tue Aug 27 2024

   Valid 272000Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
   GREAT LAKES AND UPPER MISSISSIPPI VALLEY...

   ...SUMMARY...
   Severe thunderstorms capable of damaging thunderstorm winds and
   occasional large hail and a tornado or two are possible across the
   Great Lakes region and portions of the Midwest through tonight.

   ...20z Update...
   The prior forecast remains largely on track with minor changes. The
   Slight and Marginal risk area over parts of WI was trimmed behind
   extensive convection ongoing over the Lake and northern MI. Ongoing
   severe storms over parts of the Great Lakes are expected to
   gradually expand in coverage and intensity over southern lower MI,
   northern IL and IN through the remainder of the afternoon and into
   the evening/overnight. The primary risk remains damaging winds
   associated with organized clusters or bowing segments, but hail and
   a tornado or two will also remain possible.

   Farther south into parts of the Mississippi Valley and eastern
   Plains, additional storm development/intensification is probable
   this afternoon within a warm and unstable air mass ahead of a weak
   cold front. Vertical shear is somewhat weaker displaced south of the
   main shortwave trough, but robust boundary-layer heating should
   suffice for periodic intensification of multicell storms. At least
   some damaging wind or hail risk may develop with clusters of strong
   to severe storms across eastern KS and south-central IA from this
   afternoon through the evening.

   ..Lyons.. 08/27/2024

   .PREV DISCUSSION... /ISSUED 1142 AM CDT Tue Aug 27 2024/

   ...Great Lakes/Midwest/Central Plains...
   A rather complex mesoscale scenario exists particularly across the
   Great Lakes region, influenced by multiple MCSs/outflows since last
   evening. Multiple MCVs are apparent across the region including
   western Upper Michigan, potentially including an MCV with evolving
   asymmetric quasi-linear convection across east-central Wisconsin
   late this morning. Within a zone of pre-frontal confluence/augmented
   outflow, MCS persistence and further upscale/southward peripheral
   growth is possible into Lower Michigan/northern Illinois into a very
   unstable air mass, but this is far from certain. For additional
   short-term information, see Mesoscale Discussion 2013.

   Where storm clusters do develop and intensify regionally, ample
   buoyancy, particularly south of the aforementioned late-morning MCS,
   and sufficient deep-layer shear will support damaging wind and
   isolated large hail potential. The severe threat could reach as far
   as the Lake Ontario vicinity late tonight/early Wednesday.

   Farther southwest, nearer to the cold front and potentially
   augmented by residual outflow, CAPE and especially vertical shear
   will be weaker from southeast Iowa/western Illinois into northern
   Missouri and eastern Kansas/southeast Nebraska. A few organized
   multicells are possible atop a strongly heated boundary layer, with
   strong wind gusts and severe hail possible.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z