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   TID: SBBSecho 3.28-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0   
   BBSID: CAPCITY2   
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   ACUS01 KWNS 172014   
   SWODY1   
   SPC AC 172013   
      
   Day 1 Convective Outlook CORR 1   
   NWS Storm Prediction Center Norman OK   
   0213 PM CST Tue Feb 17 2026   
      
   Valid 172000Z - 181200Z   
      
   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS COASTAL   
   CALIFORNIA AND PORTIONS OF NEBRASKA AND IOWA...   
      
   CORRECTED FOR NDFD COLOR FILL ISSUE   
      
   ...SUMMARY...   
   Isolated strong thunderstorms will be possible across parts of the   
   West today through tonight. Isolated thunderstorms are also   
   anticipated across the Upper Midwest late this afternoon and   
   tonight.   
      
   ...Eastern Nebraska and southwestern Iowa...   
   Near the base of a negative-tilt shortwave trough and a pronounced   
   100+ kt mid-level jet, strong ascent is expected to develop late   
   this afternoon amid a mixed and modestly moist air mass. Cool   
   mid-level temperatures and surface dewpoints in the 40s and 50s F   
   may allow a few hundred J/kg of buoyancy to develop. This   
   destabilization and strong ascent may support a fast-moving arc of   
   high-based showers/thunderstorms, particularly where surface   
   temperatures reach into the 60s and dewpoints hold above 40 F.   
      
   While buoyancy will be weak, dry low-levels and strong   
   dynamics/background flow could support efficient downward mixing of   
   momentum to the surface. Isolated severe/damaging gusts are possible   
   this afternoon and evening from parts of eastern NE into   
   west-central IA. Convection should weaken rapidly with eastward   
   extent   
      
   Elsewhere, isolated strong storms remain possible across portions of   
   the CA coast ahead of a strong secondary upper trough. This is most   
   likely overnight with a few damaging gusts or a brief tornado the   
   primary risks owing to very strong flow and modest inland moisture   
   advection. No changes were made to the outlook here, see the prior   
   discussion for more info.   
      
   ..Lyons.. 02/17/2026   
      
   .PREV DISCUSSION... /ISSUED 1031 AM CST Tue Feb 17 2026/   
      
   ...Synopsis...   
   Recent satellite imagery shows several disturbances across the   
   western CONUS, including a pair of low-amplitude shortwave troughs   
   within the belt of strong southwesterly flow extending from the   
   central Pacific into the central Plains and a deepening upper low   
   off the Pacific Northwest coast. Intense surface cyclogenesis is   
   anticipated ahead of the lead shortwave as it moves quickly   
   northeastward, with the resulting surface low forecast to move   
   across SD/NE, ending the period over southern MN. Evolution of this   
   surface low and parent shortwave, which will become increasingly   
   negatively tilted throughout the day and overnight, will result in   
   strong forcing for ascent from the Mid MO Valley into the Upper   
   Midwest this evening and overnight.   
      
   Farther west, the previously mentioned upper low is expected to drop   
   slowly southward as a strong jet (i.e. 100 kt at 500 mb) pivots   
   around its western and southern periphery. Very cold mid-level   
   temperatures and strong/persistent forcing for ascent will support   
   isolated thunderstorms along across much of the West coast   
   throughout the day and tonight.   
      
   ...Coastal California...   
   Limited buoyancy is expected to develop along the near coastal areas   
   of CA as very cold mid-level temperatures (i.e. -25 to -30 deg C at   
   500 mb) associated with the upper low continue to advect into the   
   region. This buoyancy coupled with the strong forcing for ascent   
   could result in some deeper, more persistent updrafts across the   
   region today, both within the primary frontal band and any more   
   bowing line segments that may follow it. Given the robust deep layer   
   flow across the region, any deeper, more persistent updrafts could   
   result in some stronger, convectively augmented gusts. Additionally,   
   there appears to be enough low-level curvature to support a brief   
   tornado or two within the immediate coastal regions. Highest   
   potential for either hazards currently appears to be after 00Z in   
   the San Luis Obispo/Santa Barbara county areas.   
      
   ...Upper Midwest...   
   Some low-level moisture return is anticipated across the region   
   ahead of the previously mentioned shortwave trough and associated   
   forcing for ascent. Even so, low-level moisture will still be   
   limited, with dewpoints likely remaining in the upper 40s to perhaps   
   low 50s. This is not expected to be enough moisture for surface   
   destabilization across most of the region, despite strong surface   
   heating/boundary-layer mixing and steepening low-level lapse rates   
   in vicinity of the surface low/front. The only exception is across   
   far southeast SD and far northeast NE where a high-based storm or   
   two cannot be completely ruled out. Any that does develop could   
   produce an strong gust or two, although coverage will likely remain   
   less than 10%.   
      
   Across the Upper Midwest, capping may tend to largely prevail during   
   the day, with elevated thunderstorms becoming more probable   
   east-northeastward of IA into the MN/WI throughout the evening and   
   overnight. Instability does not appear strong enough to support   
   severe hail with this elevated activity.   
      
   $$   
      
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   --- SBBSecho 3.28-Linux   
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