BBS: TELESC.NET.BR Assunto: DAY2SVR: Nws Storm Prediction Center Norman Ok De: COD Weather Processor Data: Wed, 27 May 2026 17:31:57 +0000 ----------------------------------------------------------- ACUS02 KWNS 271731 SWODY2 SPC AC 271730 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Wed May 27 2026 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE COLUMBIA BASIN... ...SUMMARY... Scattered severe storms are possible on Thursday over portions of the Columbia Basin with more isolated storms across the broader Northwest region. Damaging winds will be the primary threat, with some threat for large hail. ...Synopsis... A mid-level shortwave trough currently on the western periphery of the broader mid-level low across California at mid-day Wednesday will move around the low-pressure center and emerge across the Northwest on Thursday. East of this low, a strong mid-level ridge will be maintained across the central CONUS with a mid-level trough in the east. This pattern will result in a mostly nebulous surface pattern other than a more defined area of high pressure across the Great Lakes. ...Northwest... Low-level moisture will increase across the Columbia Basin Wednesday and Thursday, primarily from the northeasterly surface flow. This moisture, combined with cooling air aloft and robust surface heating, will result in abnormally large instability across the region. In fact, the GFS/NAM/RAP forecast soundings show record-high MLCAPE values at OTX tomorrow afternoon. Given the climatological extreme of these values, it seems unlikely to be as high as forecast (1500-2000 J/kg). However, even 750-1000 J/kg MLCAPE would result in an environment favorable for severe storms, particularly across northern Oregon and south-central Washington where even the HRRR shows 1000 to 1200 J/kg MLCAPE. Very steep mid-level lapse rates (near 9 C/km) and moderate shear will also support organized severe storms. The timing of the mid-level shortwave trough emerging across Oregon appears to be well-timed with afternoon peak heating. Therefore, expect storms to initially form across east-central Oregon and move north-northwestward through the evening. Most 12Z CAM guidance shows upscale growth into a linear segment which would likely support a damaging wind threat, particularly given the steep lapse rate environment. For these reasons, have upgraded to a Level 2 Slight Risk across portions of the Columbia Basin. Expanded the wind probabilities across the Cascades slightly as the environment appears to be favorable to the west of the crests. However, it appears the marine layer should move into areas such as Portland prior to the arrival of the storms. Therefore, have kept severe probabilities east of this zone where the marine layer will likely have a stabilizing effect. ..Bentley.. 05/27/2026 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.28-Linux * Origin: Capitol City Online (1:2320/107) ----------------------------------------------------------- [Voltar]