277
ACUS11 KWNS 110913
SWOMCD
SPC MCD 110913
IAZ000-111115-
MESOSCALE DISCUSSION 1919
NWS STORM PREDICTION CENTER NORMAN OK
0413 AM CDT TUE AUG 11 2026
AREAS AFFECTED...MUCH OF NORTHERN AND CENTRAL IOWA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 110913Z - 111115Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...DEVELOPING THUNDERSTORMS MAY CONTINUE TO EVOLVE INTO A
BETTER ORGANIZED CLUSTER THROUGH 6-8 AM CDT. EVENTUALLY, THIS
PROBABLY WILL BECOME ACCOMPANIED BY INCREASING POTENTIAL FOR STRONG
TO SEVERE SURFACE GUSTS, THOUGH HOW SOON REMAINS UNCERTAIN.
DISCUSSION...CONVECTION CONTINUES TO INCREASE AND INTENSIFY WITHIN A
ZONE OF STRONGER WARM ADVECTION, ALONG A TIGHTENING
LOWER/MID-TROPOSPHERIC BAROCLINIC ZONE WHERE SEASONABLY HIGH
MOISTURE CONTENT IS SUPPORTING LARGE CAPE, BENEATH THE NORTHERN
PERIPHERY OF A PLUME OF ELEVATED MIXED-LAYER AIR. STRONGEST STORMS,
NOW FOCUSED SOUTH OF SIOUX FALLS SD INTO THE STORM LAKE IA VICINITY,
HAVE YET TO ORGANIZE OR GENERATE A NOTABLE SURFACE PRESSURE
PERTURBATION. HOWEVER, THIS MAY BEGIN TO CHANGE OVER THE NEXT FEW
HOURS.
WHILE THERE IS CONSIDERABLE SPREAD WITHIN CONVECTION-ALLOWING
GUIDANCE, OF PERHAPS PARTICULAR NOTE, THE LATEST RAPID REFRESH
OUTPUT SUGGESTS THAT CONTINUING INTENSIFYING THUNDERSTORM
DEVELOPMENT MAY BECOME ACCOMPANIED BY THE EVOLUTION OF A
STRENGTHENING LOWER/MID-TROPOSPHERIC CYCLONIC CIRCULATION, BASED ON
ITS DEPICTION OF STRENGTHENING REAR INFLOW TO 50-60+ KT IN THE
700-500 MB LAYER THROUGH 11-13Z. THIS WOULD PROBABLY BE ACCOMPANIED
BY INCREASING POTENTIAL FOR STRONG TO SEVERE SURFACE GUSTS AT SOME
POINT, THOUGH HOW SOON REMAINS UNCLEAR GIVEN THE INITIALLY STABLE
NEAR-SURFACE LAPSE RATES.
..KERR/SMITH.. 08/11/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...DVN...ARX...DMX...FSD...
LAT...LON 43489513 43369280 42739114 41469157 41929321 42189496
42819608 43489513
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN
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