7/27 Potential Derecho

[sbnwx85]

Going all in. If it happens I’ll start the first winter storm thread of the season. Potential for a destructive windbag/derecho Monday. SPC outlining a large Enhanced Risk area with SIG1 hatching. Potential upgrade to CIG2.

Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1252 AM CDT Mon Jul 27 2026

   Valid 271200Z - 281200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS
   OF THE UPPER MIDWEST/UPPER GREAT LAKES INTO THE OHIO VALLEY...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   SOUTHWEST SOUTH DAKOTA...WESTERN NEBRASKA...NORTHEAST COLORADO...AND
   FAR NORTHWEST KANSAS...

   ...SUMMARY...
   Severe storms capable of strong to severe wind gusts and large hail
   are possible across the Great Lakes into the Ohio Valley Monday into
   Monday night. More sporadic occurrences of damaging wind appear
   possible in the Mid-Atlantic, Tennessee Valley, central High Plains,
   and southeast Arizona.

   ...Upper Midwest/Great Lakes into the OH/TN Valleys...
   A very moist airmass is in place from the Upper Midwest into the OH
   and TN Valley. This airmass is exists south of a diffuse cold front
   that extends from a surface low over far southeast Manitoba
   southeastward to far eastern Upper MI. One thunderstorm is currently
   ongoing near this boundary over eastern Upper MI. Most of the
   thunderstorms are ongoing just northeast another surface boundary
   demarcating the very moist (i.e. 70+ dewpoints) to it southwest. How
   this warm-air advection activity evolves early this morning will
   have a large impact on the severe potential farther downstream from
   the Mid MS Valley into the OH and TN Valleys through the late
   morning into the afternoon and evening. 

   Much of the guidance is beginning to suggest the warm-air advection
   activity clusters early this morning over the MN Arrowhead vicinity
   before then tracking southeastward within the moisture/buoyancy
   gradient and organizing/intensifying significantly. Synoptically,
   the overall setup matches many characteristics of scenarios with
   strong, forward-propagating MCSs, including a surface boundary
   parallel to the deep-layer shear, at least modest mid-level warm
   advection, and very strong to extreme buoyancy. Given the trend
   within the guidance and favorable synoptics, confidence in the
   development of a strong forward-propagating MCS is high enough to
   adjust the 30% wind probabilities westward while also introducing a
   CIG1 area. There is a chance that both higher wind probabilities and
   a CIG2 may be needed, but predictability regarding convective
   evolution is too low at this time.  

 

[A-L-E-K]

Idk about storms but not sure ive ever experienced this kind of early am heat and humidity, feels like a sauna

[TheNiño]

13 minutes ago, A-L-E-K said:

Idk about storms but not sure ive ever experienced this kind of early am heat and humidity, feels like a sauna

Seriously. I had the same thought. Feels like I’m wearing the air. Pretty dense fog here next to the lake too 

[Baum]

29 minutes ago, A-L-E-K said:

Idk about storms but not sure ive ever experienced this kind of early am heat and humidity, feels like a sauna

Nasty.