041
FXUS63 KDMX 210703
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
203 AM CDT FRI AUG 21 2026
KEY MESSAGES
- A FEW ISOLATED STORMS SKIM NORTHERN IOWA OVERNIGHT TONIGHT.
- ADDITIONAL THUNDERSTORMS IN SOUTHWEST IOWA FRIDAY EVENING AND
OVERNIGHT.
- MOSTLY DRY AND SUNNY THROUGH THE WEEKEND!
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 202 AM CDT FRI AUG 21 2026
MOSTLY DRY CONDITIONS WILL PREVAIL ACROSS CENTRAL IOWA ON FRIDAY. A
SLOW MOVING COLD FRONT CURRENTLY POSITIONED ACROSS SOUTHEASTERN
SOUTH DAKOTA WILL CONTINUE PUSHING SOUTHEASTWARD THROUGHOUT THE DAY.
WHILE PRE-FRONTAL CONVECTION REMAINS POSSIBLE ALONG THE BOUNDARY IN
MINNESOTA, ACTIVITY IS EXPECTED TO DISSIPATE AS IT MOVES INTO
CENTRAL IOWA AND ENCOUNTERS A MORE STABLE AIR MASS. A STRAY SHOWER
OR STORM WILL STILL HOWEVER BE POSSIBLE DURING THE EARLY MORNING
HOURS IN NORTHERN IOWA.
BY FRIDAY AFTERNOON, DIURNALLY-DRIVEN DESTABILIZATION AHEAD OF THE
BOUNDARY WILL BUILD MLCAPE TO 2000-3000 J/KG. COMBINED WITH 35-45
KTS OF 0-6KM BULK SHEAR, THE ENVIRONMENT WILL BE CONDITIONALLY
FAVORABLE FOR ORGANIZED SEVERE CONVECTION. HOWEVER, CONVECTIVE
INITIATION CONFIDENCE REMAINS LOW DUE TO TWO PRIMARY LIMITING
FACTORS: HIGH PRESSURE TO THE NORTH ADVECTING MID-LEVEL DRY AIR AND A
WEAK THERMAL GRADIENT ACROSS THE FRONT RESULTING IN BROAD- WEAK LOW-
LEVEL CONVERGENCE. DESPITE THESE INHIBITION FACTORS, THE STORM
PREDICTION CENTER HAS ISSUED A MARGINAL RISK (LEVEL 1 OF 5) ACROSS
SOUTHERN IOWA. IF AN ISOLATED PARCEL MANAGES TO BREAK THE CAP,
ROBUST UPDRAFTS COULD PRODUCE DAMAGING WIND GUSTS AND LARGE HAIL.
THE HIGHEST PRECIPITATION CHANCES (10-20%) WILL ALIGN WITH LATE
AFTERNOON INTO EVENING (GENERALLY AFTER 6PM). POST FRONTAL HIGH
PRESSURE WILL BUILD IN OVERNIGHT, CLEARING SKIES FROM NORTH TO
SOUTH.
ELEVATED HAZE WILL PERSIST TODAY AS NORTHWESTERLY FLOW ALOFT
ADVECTS UPPER LEVEL WILDFIRE SMOKE FROM THE PACIFIC NORTHWEST. THIS
SMOKE LAYER WILL REMAIN ELEVATED ALOFT, WITH NO SURFACE AIR QUALITY
IMPACTS ANTICIPATED.
FRIDAY NIGHT
NORTHWESTERLY FLOW WILL REINFORCE A DRY, SUBSIDENCE AIRMASS ACROSS THE
REGION, SETTING UP QUIET CONDITIONS OVERNIGHT THROUGH SATURDAY
MORNING. THE NEXT WINDOW FOR ORGANIZED PRECIPITATION ARRIVES SUNDAY
EVENING.
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 222 PM CDT THU AUG 20 2026
ANOTHER EMBEDDED SHORTWAVE WILL MOVE ACROSS IOWA LATE SUNDAY
EVENING INTO MONDAY, SLOWING FROM MODEL SOLUTIONS 24 HOURS AGO.
THE UPCOMING WORK WEEK LOOKS TO REMAIN ACTIVE WITH EMBEDDED
SHORTWAVES CONTINUING TO RIDE ALONG THE WESTERN US RIDGE WITH
NORTHWEST FLOW ACROSS IOWA. A MORE ROBUST SYSTEM LOOKS TO MOVE
ACROSS THE AREA ON TUESDAY AND WILL BE THE NEXT OPPORTUNITY FOR
MORE ORGANIZED CONVECTION. AT THIS TIME RANGE DIFFERENCES REMAIN
WITH THE GFS FAVORING A SOUTHERLY TRACK OVER THE EURO NORTHERLY
TRACK.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1052 PM CDT THU AUG 20 2026
VFR CONDITIONS ONGOING AND EXPECTED TO CONTINUE THROUGH THE TAF
PERIOD. FEW SHOWERS AND ISOLATED STORMS ARE STARTING TO SKIM FAR
NORTH AND NORTHEAST SECTIONS MAINLY NORTH OF KMCW AND KALO.
THERE'S STILL A LOW CHANCE FOR A SHOWER TO IMPACT EITHER SITE
WITH SLIGHTLY HIGHER CHANCES AT KMCW THAN KALO. ADDED SHOWER
MENTION INTO KMCW PRIOR TO START OF 06Z TAFS WITH UPSTREAM
ACTIVITY EXPECTED TO WEAKEN SO NO MENTIONS AT EITHER SITE AFTER
06Z. HIGH LEVEL SMOKE MAY KEEP SKIES HAZY ON FRIDAY. SOME
ADDITIONAL SHOWERS/STORMS ARE POSSIBLE INTO FRIDAY MORNING BUT
CHANCES ARE GENERALLY LESS THAN 30% SO DID NOT INCLUDE ANY
MENTIONS WITH LOW CONFIDENCE. SIMILARLY, MAY ALSO SEE SOME
STORMS IN SOUTHWEST OR SOUTHERN IOWA IN THE AFTERNOON TO EARLY
EVENING, BUT SOUTH AND WEST OF TAF SITES. WINDS OUT OF THE SOUTH
TONIGHT BECOME OUT OF THE WEST TO NORTHWEST DURING THE DAY
FRIDAY.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...TDR
LONG TERM...HAGENHOFF
AVIATION...05
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