200
ACUS01 KWNS 091239
SWODY1
SPC AC 091237
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0737 AM CDT SUN AUG 09 2026
VALID 091300Z - 101200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE MIDWEST...
..SUMMARY
SCATTERED DAMAGING WINDS MAY OCCUR TODAY INTO THIS EVENING FROM
SOUTHERN MINNESOTA AND EASTERN IOWA EASTWARD ACROSS PARTS OF
NORTHERN ILLINOIS, SOUTHERN WISCONSIN, SOUTHERN LOWER MICHIGAN,
NORTHWEST OHIO, AND NORTHERN INDIANA. DAMAGING WIND AND HAIL ARE
ALSO EXPECTED ACROSS PORTIONS OF THE DAKOTAS.
..MIDWEST
RADAR/SATELLITE COMPOSITE SHOWS A CORRIDOR OF SHOWERS/THUNDERSTORMS
FROM NORTHERN MO INTO SOUTHERN MN AND WESTERN WI ASSOCIATED WITH
ISENTROPIC LIFT ON THE NOSE OF A 40-KT SOUTHWESTERLY LLJ. A
LOCALIZED RISK FOR HAIL/WIND MAY ACCOMPANY THIS ACTIVITY THIS
MORNING AS IT SHIFTS EASTWARD ACROSS THE MS RIVER TOWARDS LAKE MI
THROUGH MIDDAY. CONSIDERABLE UNCERTAINTY REMAINS REGARDING THE
SEVERE FORECAST FOR THE EASTERN IA INTO THE SOUTHERN GREAT LAKES
PORTION OF THE SLIGHT RISK. SHOWERS/THUNDERSTORMS AND RELATED
CONVECTIVE DEBRIS/OUTFLOW WILL BE INFLUENTIAL ON AIRMASS RECOVERY
LATER THIS AFTERNOON. IT SEEMS PLAUSIBLE A WARM FRONT DRAPED OVER
THE CORN BELT THIS MORNING WILL SLOWLY ADVANCE NORTHWARD INTO THE
SOUTHWEST GREAT LAKES WITH AN INCREASINGLY UNSTABLE AIRMASS
DEVELOPING TO THE SOUTH/WEST OF THIS CONVECTIVELY AUGMENTED
BAROCLINIC ZONE.
MODEL FORECAST SOUNDINGS SHOW AMPLE CAPE AIDED BY THE NORTHERN RIM
OF LOWER TO MID 70S F SURFACE DEWPOINTS INTO NORTHERN PORTIONS OF
IL/IN. ADEQUATELY STRONG AND VERTICALLY VEERING WIND PROFILES WILL
SUPPORT 30-40 KT EFFECTIVE SHEAR MAGNITUDES. LOW-LEVEL SRH MAY ALSO
BE LOCALLY BOOSTED IN THE VICINITY OF THE WARM FRONT/EFFECTIVE
BOUNDARY, WHICH COULD THEN PLAY A ROLE IN SEVERE POTENTIAL IF A
SUPERCELL OR LINEAR SEGMENTS WERE TO DEVELOP AND FAVORABLY INTERACT
WITHIN THIS CORRIDOR. RATHER POOR DEPICTION OF THIS MORNING'S
THUNDERSTORM EVOLUTION (I.E., 00Z HREF MEMBERS) CASTS LARGE
UNCERTAINTY WHERE A COUPLE OF MORE INTENSE THUNDERSTORM CLUSTERS
WILL ULTIMATELY DEVELOP. IT SEEMS THE GREATEST POTENTIAL FOR SEVERE
WILL BE CENTERED OVER NORTHERN IL LATER THIS AFTERNOON THROUGH THE
EVENING, BUT CONFIDENCE REMAINS LOW REGARDING DETAILS AND THE NEED
FOR SPATIAL REFINEMENTS OF THE SEVERE RISK AREA AND THE NEED FOR
POTENTIAL HIGHER PROBABILITIES.
..DAKOTAS AND WESTERN NE
A SURFACE FRONT IS EXPECTED TO PUSH SOUTHWARD ACROSS THE CENTRAL
PLAINS, BECOMING ORIENTED ACROSS NORTHERN KS BY TONIGHT. LOW-LEVEL
WARM ADVECTION ATOP THE BOUNDARY, AND SURFACE WINDS BECOMING
SOUTH/SOUTHEASTERLY WITH TIME WILL MAINTAIN 60S DEWPOINTS ACROSS THE
REGION. WITHIN THIS POST-FRONTAL UPSLOPE REGIME, A RESERVOIR OF
MAINLY 60S F DEWPOINTS WILL RESIDE BENEATH MODERATE NORTHWESTERLY
FLOW ALOFT. SUPERCELL WIND PROFILES AND STEEP LOW-LEVEL LAPSE RATES
WILL SUPPORT INITIAL STORMS CAPABLE OF LARGE HAIL AND SEVERE GUSTS,
ESPECIALLY AS THIS ACTIVITY OVER THE WESTERN DAKOTAS MOVES
SOUTHEASTWARD INTO RICHER MOISTURE. A SMALL CLUSTER MAY EVENTUALLY
EVOLVE DURING THE OVERNIGHT WITH AN ATTENDANT RISK FOR SEVERE GUSTS
AND PERHAPS LARGE HAIL.
..SOUTHERN APPALACHIANS
SCATTERED THUNDERSTORM DEVELOPMENT IS EXPECTED OVER HIGHER TERRAIN
WITHIN A SEASONALLY MOIST AND UNSTABLE AIRMASS. STEEPENING
LOW-LEVEL LAPSE RATES AND HIGH PW VALUES MAY SUPPORT LOCALLY STRONG
GUSTS WITH WET MICROBURSTS THROUGH EARLY EVENING.
..AZ
MODEST EASTERLY MID/UPPER FLOW WILL PERSIST ACROSS THE REGION ON THE
SOUTHERN PERIPHERY OF AN UPPER HIGH OVER THE FOUR CORNERS. ANOTHER
DAY OF HOT CONDITIONS WILL PROMOTE STEEP LAPSE RATES AND MODEST
DESTABILIZATION. AS CONVECTION DEVELOPS OVER HIGHER TERRAIN AND
SPREAD WESTWARD, STRONG OUTFLOW GUSTS MAY OCCUR.
..SMITH/KERR.. 08/09/2026
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page