690
ACUS03 KWNS 090732
SWODY3
SPC AC 090730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT TUE SEP 09 2025
VALID 111200Z - 121200Z
..NO SEVERE THUNDERSTORM AREAS FORECAST
..SUMMARY
ISOLATED THUNDERSTORMS ARE POSSIBLE ACROSS MONTANA AND THE DAKOTAS,
AS WELL AS THE SOUTHERN HIGH PLAINS AND INTERMOUNTAIN WEST THURSDAY.
UNCERTAINTY ON STORM COVERAGE/INTENSITY REMAINS HIGH.
..SYNOPSIS
A BROAD UPPER LOW OVER THE GREAT BASIN IS FORECAST TO SLOWLY DRIFT
EASTWARD THURSDAY WITH SEVERAL SMALLER SHORTWAVES PASSING THROUGH
IT. AN EMBEDDED PERTURBATION ALONG THE EASTERN FLANK OF THE LOW WILL
ACCOMPANY A MID-LEVEL JET OVER PORTIONS OF THE NORTHERN ROCKIES AND
PLAINS. THIS WILL HELP DEEPEN A LEE CYCLONE AND TRAILING LEE TROUGH
MUCH OF THE HIGH PLAINS.
..MONTANA AND WESTERN DAKOTAS
AS THE UPPER LOW GRADUALLY EDGES CLOSER, AN EMBEDDED SHORTWAVE
TROUGH AND MID-LEVEL JET WILL PASS OVER THE NORTHERN ROCKIES AND
PLAINS THURSDAY AFTERNOON. THE SURFACE LOW OVER CENTRAL MT SHOULD
DEEPEN, INCREASING LOW-LEVEL SOUTHEASTERLY FLOW. A WARM FRONT,
EXTENDING SOUTHEASTWARD FROM THE SURFACE LOW, WILL GRADUALLY LIFT
NORTHWARD WITH 60+ F DEWPOINTS IN ITS WAKE OVER THE NORTHERN HIGH
PLAINS. MODEST LOW-LEVEL CONVERGENCE ALONG THE TRAILING LEE TROUGH
AND NEAR A WEAK COLD FRONT EMANATING FROM THE LOW COULD SUPPORT
ISOLATED STORMS OVER EASTERN MT AND THE WESTERN DAKOTAS. WITH
SUFFICIENT BUOYANCY AND INCREASING FLOW ALOFT FROM THE UPPER JET,
SOME POTENTIAL FOR ORGANIZED MULTICELLS OR TRANSIENT SUPERCELLS IS
APPARENT. HOWEVER, MODEL SOLUTIONS VARY CONSIDERABLE ON THE DEGREE
OF CAPPING AND RESULTING STORM DEVELOPMENT. GIVEN THESE
UNCERTAINTIES, NO SEVERE PROBABILITIES WILL BE ADDED CURRENTLY,
THOUGH SOME RISK FOR SEVERE GUSTS AND HAIL COULD BE NEEDED IN FUTURE
UPDATES.
..CENTRAL AND SOUTHERN HIGH PLAINS
FARTHER SOUTH, THE LEE TROUGH MAY SERVE AS A FOCUS FOR ISOLATED
STORM DEVELOPMENT THURSDAY AFTERNOON AMIDST STRONG HEATING AND
INCREASING LOW-LEVEL MOISTURE OVER THE CENTRAL AND SOUTHERN HIGH
PLAINS. HOWEVER, FORCING FOR ASCENT BENEATH THE SHORTWAVE RIDGE
APPEARS WEAK AS THE MAIN TROUGH AND SHORTWAVE ARE LIKELY TO REMAIN
OVER THE ROCKIES AND FOUR CORNERS WHERE LOW-LEVEL MOISTURE IS
MODEST. WHILE ISOLATED HIGH-BASED STORMS COULD DEVELOP AND POSE A
RISK FOR LOCALLY GUSTY WINDS, CONFIDENCE IN A BROADER SEVERE RISK IS
LOW.
..LYONS.. 09/09/2025
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