SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0237 PM CDT Sat Apr 12 2025 Valid 122000Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHERN MONTANA INTO NORTHERN WYOMING AND FAR WESTERN SOUTH DAKOTA... ...SUMMARY... Thunderstorms with isolated severe gusts are possible across parts of southern Montana/northern Wyoming to the Black Hills this afternoon and evening. ...20Z Update... The forecast remains on track, and no changes were made with this update. For details, see the previous discussion below. ..Weinman.. 04/12/2025 .PREV DISCUSSION... /ISSUED 1112 AM CDT Sat Apr 12 2025/ ...Southern Montana into Northern Wyoming and Far Western South Dakota... A mid-level shortwave trough over WA/OR will move eastward over ID/MT/WY by tonight, with downstream lee cyclogenesis occurring across the central High Plains. Low-level moisture will remain very limited across the northern Rockies and adjacent High Plains, with surface dewpoints generally in the 30s. But, forcing for ascent and mid-level moisture should be sufficient for high-based thunderstorms to develop this afternoon/evening across parts of northern WY and southern MT. Forecast soundings show inverted-v profiles with weak instability and some increase in mid-level winds, which could support isolated strong to severe wind gusts with this convection as it spreads eastward.