334
ACUS01 KWNS 261947
SWODY1
SPC AC 261946
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0246 PM CDT WED MAR 26 2025
VALID 262000Z - 271200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS WESTERN
PORTIONS OF WASHINGTON AND OREGON...
..SUMMARY
SEVERE THUNDERSTORMS ARE EXPECTED ACROSS PARTS OF THE PACIFIC
NORTHWEST THIS AFTERNOON AND EVENING, WITH SUPERCELLS POSSIBLE WEST
OF THE CASCADES ACROSS OREGON INTO WASHINGTON. THESE STORMS MAY
PRODUCE LARGE HAIL, PERHAPS A TORNADO OR TWO, AND SEVERE WIND GUSTS.
..20Z UPDATE
ONLY MINOR ADJUSTMENTS WERE NEEDED TO REMOVED THUNDER ACROSS
SOUTHERN OK/NORTHERN TX WITH THIS UPDATE. THE SLIGHT RISK ACROSS THE
NORTHWEST AND MARGINAL RISK IN SOUTH TEXAS WERE UNCHANGED.
TEMPERATURES ACROSS THE PORTLAND METRO INTO THE COLUMBIA GORGE HAVE
WARMED INTO THE MID 60S TO 70S UNDER MOSTLY SUNNY SKIES. SURFACE
OBJECTIVE ANALYSIS AND OBSERVED 18Z SOUNDINGS FROM MFR AND OTX
CONTINUE TO INDICATE MLCIN IN PLACE ACROSS MUCH OF THE REGION FROM
THE CASCADES/COLOMBIA GORGE WESTWARD. THE SURFACE FRONT AND MAIN
UPPER-LEVEL FORCING REMAIN OFFSHORE AND ARE EXPECTED TO MOVE
EASTWARD ACROSS THE REGION BY THE LATE AFTERNOON/EARLY EVENING.
FORECAST SOUNDINGS CONTINUE TO INDICATE WEAKENING OF MLCIN ALONG
WITH STEEPENING LOW TO MID-LEVEL LAPSE RATES AS COOLING ALOFT WITH
THE TROUGH MODIFIES PROFILES. THIS SHOULD ALLOW FOR THUNDERSTORM
DEVELOPMENT THROUGH THE AFTERNOON/EVENING, WITH POTENTIAL FOR
SUPERCELLS CAPABLE OF LARGE HAIL, DAMAGING WIND, AND POSSIBLY A
TORNADO OR TWO.
SEE PREVIOUS DISCUSSION BELOW FOR MORE INFORMATION.
..THORNTON/SMITH.. 03/26/2025
PREV DISCUSSION
/ISSUED 1130 AM CDT WED MAR 26 2025/
..PACIFIC NORTHWEST
SATELLITE IMAGERY THIS MORNING SHOWS AN UPPER LOW APPROACHING THE
COAST WITH MOSTLY SUNNY SKIES OVER MUCH OF THE REGION. A 100 KT
500-MB SPEED MAX WILL ROTATE THROUGH THE BASE OF THE TROUGH AND
OVERSPREAD COASTAL OR/WA BY MID EVENING AS THE UPPER LOW SHIFTS
EAST. AN ASSOCIATED COLD FRONT SHOULD ARC FROM OFF THE WASHINGTON
COAST TO SOUTHWARD ALONG THE OREGON COAST BY EVENING.
COLD-AIR ADVECTION IN THE MID LEVELS AND DIURNAL HEATING WILL
CONTRIBUTE TO STEEPENING LAPSE RATES, AND THE DEVELOPMENT OF WEAK TO
LOCALLY MODERATE BUOYANCY (250-1500 J/KG SBCAPE) BY MID-LATE
AFTERNOON. STRENGTHENING LARGE-SCALE FORCING FOR ASCENT AND
NEGLIGIBLE CINH WILL FAVOR ISOLATED THUNDERSTORMS DEVELOPING BY
MID-LATE AFTERNOON AND INCREASING IN COVERAGE THROUGH THE EARLY
EVENING. FORECAST HODOGRAPHS INDICATE SUPERCELLS ARE LIKELY WITH
THE STRONGER, MORE PERSISTENT UPDRAFTS. LARGE HAIL (1-2 INCHES IN
DIAMETER) WILL BE POSSIBLE. THE ELONGATED AND PERHAPS LOCALLY
AUGMENTED HODOGRAPH IN THE VICINITY OF TERRAIN FAVORED AREAS (I.E.,
NEAR THE COLUMBIA RIVER WITH A MODEST EASTERLY COMPONENT) MAY ENABLE
A SHORT-DURATION TORNADO RISK. SEVERE GUSTS ARE ALSO POSSIBLE WITH
THE STRONGER CORES AND OUTFLOW SURGES AS CONVECTION MATURES DURING
THE EVENING AND GRADUALLY DIMINISHING LATE.
..TEXAS LOWER RIO GRANDE RIVER VALLEY
A WEAK DISTURBANCE WILL APPROACH THE RIO GRANDE THROUGH MID
AFTERNOON WITH A CIRRUS SHIELD EXPECTED TO PERSIST THROUGH PEAK
HEATING. A MOIST BOUNDARY LAYER SAMPLED BY MORNING AREA RAOBS AND
SOME FILTERED HEATING WILL PROMOTE WIDELY SCATTERED TO SCATTERED
STORMS DEVELOPING THIS AFTERNOON. RELATIVELY WEAKER FLOW IN THE LOW
TO MID LEVELS WILL LIMIT OVERALL STORM ORGANIZATION, BUT TRANSIENT
SUPERCELL/MULTICELLS ARE POSSIBLE. THE STRONGER STORMS MAY BE
CAPABLE OF A LOCALIZED HAIL/WIND THREAT.
..SOUTHWEST IA
A STRENGTHENING WARM-AIR ADVECTION REGIME OVERNIGHT FROM KS INTO
MO/IA WILL LIKELY LEAD TO THE DEVELOPMENT OF WIDELY SCATTERED
SHOWERS/THUNDERSTORMS IN THE VICINITY OF A WARM FRONT. FORECAST
SOUNDINGS SHOW ELEVATED INSTABILITY (1000 J/KG MUCAPE) DEVELOPING AS
THE PROFILE MOISTENS NEAR 850 MB. A STRONGER STORM CAPABLE OF SMALL
TO MARGINALLY SEVERE HAIL CANNOT BE RULED OUT, BUT THE THREAT
APPEARS TOO LIMITED TO INTRODUCE LOW-SEVERE PROBABILITIES.
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