355
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
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