962
ACUS02 KWNS 080558
SWODY2
SPC AC 080556
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT TUE JUL 08 2025
VALID 091200Z - 101200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN PLAINS AS WELL AS PORTIONS OF THE SOUTHEAST INTO SOUTHERN
NEW ENGLAND...
..SUMMARY
AT LEAST ISOLATED SEVERE STORMS ARE POSSIBLE IN THE NORTHERN PLAINS
ON WEDNESDAY, WITH LOCALLY LARGE HAIL AND AREAS OF SEVERE GUSTS.
ISOLATED DAMAGING GUSTS ARE ALSO POSSIBLE ACROSS PARTS OF THE
EASTERN U.S.
.. SYNOPSIS
A MIDLEVEL RIDGE CENTERED OVER THE FOUR CORNERS WILL BEGIN TO BREAK
DOWN ON WEDNESDAY AS A LOW-AMPLITUDE SHORTWAVE TROUGH QUICKLY MOVES
FROM OFF THE NORTHERN CALIFORNIA COAST INTO THE GREAT BASIN.
ADDITIONALLY, A LARGER AMPLITUDE TROUGH WILL MOVE ACROSS SOUTHERN
CANADA. ELSEWHERE, BROAD MID-LEVEL TROUGHING WILL PERSIST ACROSS THE
EASTERN US.
SURFACE LEE TOUGHING WILL EXIST ACROSS THE NORTHERN PLAINS IN
RESPONSE TO WESTERLY DOWNSLOPE FLOW. THIS WESTERLY FLOW WILL HELP
MAINTAIN STEEP MID-LEVEL LAPSE RATES INTO THE NORTHERN PLAINS ATOP A
MOIST BOUNDARY LAYER SUPPORTED BY SOUTHERLY SURFACE WINDS ON THE
EAST SIDE OF THE NORTHERN PLAINS LEE TROUGH.
.. NORTHERN PLAINS
STRONG DIURNAL HEATING SHOULD ALLOW TEMPERATURES TO WARM INTO THE
MID-TO-PERHAPS-UPPER 90FS ACROSS MUCH OF THE DAKOTAS BY MID
AFTERNOON. THIS HEATING, COUPLED WITH SURFACE DEWPOINT TEMPERATURES
IN THE 60FS, WILL SUPPORT SURFACE-BASED CAPE IN EXCESS OF 2500-3000
J/KG WITH LITTLE TO NO CONVECTIVE INHIBITION. ADDITIONALLY, MODEST
NORTHWEST MID-TO-UPPER-LEVEL FLOW ON THE NORTHEAST PERIPHERY OF THE
FOUR CORNERS RIDGE WILL SUPPORT SOMEWHAT ELONGATED HODOGRAPHS AND
EFFECTIVE-LAYER SHEAR AROUND 30 KNOTS.
DESPITE THE REGION BEING DISPLACED FROM THE STRONGER LARGE-SCALE
ASCENT ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE TROUGHS,
ISOLATED THUNDERSTORMS ARE STILL EXPECTED TO DEVELOP BY LATE
AFTERNOON. THE OVERALL THERMODYNAMIC AND KINEMATIC ENVIRONMENT
SHOULD SUPPORT MULTICELL CLUSTERS TO TRANSIENT SUPERCELL STRUCTURES
CAPABLE OF PRODUCING LARGE HAIL -- PERHAPS IN EXCESS OF 2 INCHES IN
DIAMETER. BY EARLY EVENING ANY THUNDERSTORM CLUSTERS PERSISTING WILL
POSE AN INCREASING DAMAGING WIND THREAT.
A CATEGORICAL UPGRADE TO LEVEL 2/SLIGHT RISK WAS CONSIDERED WITH
THIS FORECAST. HOWEVER, GIVEN THE NEBULOUS FORCING MECHANISMS FOR
INITIATING THUNDERSTORMS, UNCERTAINTY REMAINS AS TO THE COVERAGE OF
SEVERE THUNDERSTORMS. AS SUCH A LEVEL 1/MARGINAL RISK WAS
MAINTAINED, EVEN THOUGH A POTENTIAL FOR SIGNIFICANT HAIL EXISTS.
.. SOUTHEAST US TO SOUTHERN NEW ENGLAND
SCATTERED TO WIDESPREAD THUNDERSTORMS WILL DEVELOP DURING THE LATE
MORNING INTO THE AFTERNOON WITHIN A MOIST, UNSTABLE, AND WEAKLY
CAPPED AIRMASS. PRECIPITABLE WATER VALUES AROUND 2" WILL SUPPORT
WATER LOADING OF UPDRAFTS AND A RESULTING POTENTIAL FOR STRONG
THUNDERSTORM WINDS CAPABLE OF SCATTERED WIND DAMAGE.
..MARSH.. 07/08/2025
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