670
ACUS01 KWNS 181942
SWODY1
SPC AC 181940
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0240 PM CDT FRI APR 18 2025
VALID 182000Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN
PLAINS NORTHEASTWARD TO THE UPPER GREAT LAKES AREA...
..SUMMARY
SCATTERED SEVERE THUNDERSTORMS ARE POSSIBLE FROM PARTS OF THE
SOUTHERN PLAINS NORTHEASTWARD THROUGH THE MID MISSISSIPPI VALLEY AND
SOUTHWESTERN GREAT LAKES, MAINLY FROM LATE AFTERNOON INTO EARLY
SATURDAY MORNING. LARGE TO VERY LARGE HAIL AND SEVERE WIND GUSTS
SHOULD BE THE MAIN HAZARDS, ESPECIALLY ACROSS THE SOUTHERN PLAINS
WHERE STORMS WILL BE MORE CONCENTRATED. A FEW TORNADOES ALSO APPEAR
POSSIBLE.
..DISCUSSION
ASIDE FROM SOME MINOR TRIMMING OF THE MRGL RISK AREA ACROSS SOUTHERN
WISCONSIN, AND FROM THE WESTERN OKLAHOMA VICINITY INTO SOUTHERN
KANSAS, NO CHANGES APPEAR NECESSARY AT THIS TIME.
EXTENSIVE CLOUD COVER ALONG THE FRONTAL ZONE -- FROM THE SOUTHERN
PLAINS TO WISCONSIN -- CONTINUES TO MODULATE HEATING/DESTABILIZATION
IN THE NEAR-FRONTAL WARM SECTOR. THESE EFFECTS INCLUDE A
PERSISTENT, STOUT CAP ACROSS THE SOUTHERN PLAINS AREA EARLY THIS
AFTERNOON (PER THE 18Z OUN RAOB).
STILL, STORM DEVELOPMENT IS EXPECTED LATE THIS AFTERNOON, AS
REFLECTED IN PREVIOUS FORECASTS, WITH ALL-HAZARDS SEVERE POTENTIAL
WITH MORE VIGOROUS CONVECTION.
..GOSS.. 04/18/2025
PREV DISCUSSION
/ISSUED 1133 AM CDT FRI APR 18 2025/
..SOUTHERN PLAINS TO THE OZARKS
STRONG SOUTHWESTERLY MID TO HIGH-LEVEL FLOW WILL EXTEND FROM THE
SOUTHERN HIGH PLAINS NORTHEASTWARD INTO THE GREAT LAKES, DOWNSTREAM
OF A MID- TO UPPER-LEVEL LOW OVER THE FOUR CORNERS STATES. A COLD
FRONT WAS ANALYZED FROM THE LOW ROLLING PLAINS NORTHEASTWARD THROUGH
CENTRAL OK LATE THIS MORNING. THIS PORTION OF THE FRONT WILL
CONTINUE SOUTHEASTWARD INTO THE I-44 CORRIDOR BUT DECELERATE TOWARDS
LATE AFTERNOON. A DRYLINE EXTENDS SOUTHWARD FROM THE FRONT OVER THE
TX BIG COUNTRY.
DESPITE WIDESPREAD MID/HIGH-LEVEL CLOUDINESS, FILTERED HEATING OF A
MOIST/DESTABILIZING AIRMASS WILL LIKELY RESULT IN A WEAKENED CAP BY
LATE AFTERNOON. INITIAL SUPERCELL DEVELOPMENT SHOULD POSE A THREAT
FOR LARGE TO VERY LARGE HAIL, POTENTIALLY UP TO 2-3 INCHES IN
DIAMETER. MODEL FORECAST HODOGRAPHS AND AMPLE PW SUGGEST A STRONG
TENDENCY TOWARDS UPSCALE GROWTH INTO AN HP SUPERCELL AND LINEAR
SEGMENT THIS EVENING FROM SOUTH-CENTRAL OK NORTHEASTWARD TOWARDS THE
WESTERN PART OF THE OZARK PLATEAU. COINCIDENT WITH THIS EXPECTED
CONVECTIVE MODE EVOLUTION, AN INCREASE IN THE SEVERE/DAMAGING WIND
THREAT IS ANTICIPATED. THE THREAT FOR A FEW TORNADOES REMAINS
APPARENT, ESPECIALLY ACROSS PARTS OF OK ALONG/SOUTH OF THE FRONT, AS
FAVORABLE LOW-LEVEL SHEAR WILL BE PRESENT THIS EVENING WHERE
SURFACE-BASED SUPERCELLS AND MESOVORTEX POTENTIAL MAY STILL EXIST.
..LOWER MI TO MID MISSISSIPPI VALLEY
IN WAKE OF WEAKENED THUNDERSTORM ACTIVITY ACROSS LOWER MI, A WARM
SECTOR WILL ATTEMPT TO SPREAD NORTHWARD AND DESTABILIZE
ACROSS PARTS OF THE MID MS VALLEY AND SOUTHERN/CENTRAL GREAT LAKES
THIS AFTERNOON. AN UPPER TROUGH WILL ONLY SLOWLY ENCROACH ON THE
UPPER MIDWEST THROUGH LATE TONIGHT. AS A RESULT, SOUTHWESTERLY FLOW
ALOFT WILL BE MAINTAINED AND LIMITED SOUTHEASTWARD PROGRESSION OF A
COLD FRONT IS FORECAST.
MODEL GUIDANCE CONTINUES TO INDICATE SURFACE-BASED THUNDERSTORM
DEVELOPMENT WILL BE INHIBITED UNTIL PEAK HEATING, WHEN FRONTAL
FORCING AND GRADUAL EROSION OF THE CAP LEADS TO ISOLATED STORMS
DEVELOPING FROM MO NORTHEASTWARD TOWARDS THE SOUTHWEST GREAT LAKES.
UNCERTAINTY REMAINS REGARDING TIMING, OVERALL THUNDERSTORM COVERAGE,
AND THE EXACT EVOLUTION OF THIS ACTIVITY. NONETHELESS, STRONG SHEAR
THROUGH A DEEP LAYER AND ADEQUATE BUOYANCY (DUE IN PART TO STEEP
MID-LEVEL LAPSE RATES), WILL SUPPORT ORGANIZED THUNDERSTORMS. THE
STRONGER THUNDERSTORMS WILL PROBABLY POSE A RISK FOR SEVERE HAIL AND
DAMAGING WINDS. THIS SEVERE THREAT MAY PERSIST FOR MUCH OF THE
EVENING, AND PERHAPS CONTINUING INTO THE EARLY OVERNIGHT HOURS.
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